Oct 15
If you haven’t already tuned in to the recent sit down between Dave and Ivor Cummins, here’s your reminder to do so! They share their thoughts during the aftermath of Dave’s recent appearance on Peter Attia’s podcast, including their thoughts on mass balance, root causes, and more.
Enjoy!
Oct 08
Peter included a prebuttal at the beginning of his podcast with me that included three central points. I’ll take them one by one.
The first:
Dave was unable to explain the mass balance, meaning how does one account for the greater amount of cholesterol in, and the greater number of, LDL particles. No one, including Dave, is disputing that the phenotype of interest has more LDL-C and more LDL-P. There are only 3 ways this can happen (these are [collectively exhaustive, but not [mutually exclusive]): make more, clear less, transfer from other pools that we can’t see (e.g., cell membranes). I think the data make the first of these by far the most likely driver, but Dave seemed unable to address this and could not explain, to me at least, what could account for this increase in LDL-P/C. So on first principles, my doubt of this model has gone up from the start of this discussion, as the person who developed the model could not actually explain the mass balance. This is one of the most fundamental requirements of any model. And to be clear, even if this fundamental condition were met, it would not be sufficient to make the case that [lean mass hyper-responders or LMHRs] are not at risk. It’s a [necessary but not sufficient] criteria that, in my mind, has failed.
Let me first start with the analogy I used in the podcast of boats/life rafts and walk it all the way through:
So yes, there’s both more creation of the boats and recirculation of the boats. The problem comes when trying to determine how much there is of each from only seeing them in the water alone. One can’t look at the 100 boats (or their life rafts) or the 500 boats (or their life rafts) while in circulation and draw a conclusion on mass balance. Indeed, in this example, once each batch is built, there’s no further change in mass balance, only ongoing recirculation.
I don’t think Peter disputes the liver’s cholesterol pool is fungible and that lipoproteins and their cholesterol cargo are continually reabsorbed, rebuilt and/or reused. There’s still much being learned as to how much, but I doubt anyone would argue it’s very dynamic. But the recirculation is especially important to acknowledge as a relevant component of the overall metric.
Hence, this is why I eventually asked this question of Peter during the podcast when we seemed stuck on this point:
“How much of this cholesterol has already made a lap? Are you thinking of this in terms of it all getting synthesized and then reabsorbed, and then recreated it again?”
If I’m understanding his position correctly — he believes either that lipoprotein cholesterol isn’t making any “laps” (re-sent again in another lipoprotein) or that it is a fixed number of total trips. How else can we not assume this is relevant toward the total balance?
In other words, this suggests the lipid pool within the lipid system is not ultimately fungible from a lipoprotein transport perspective, and that reuse/recirculation is actually limited in a predicable way.
If so, this is certainly a point we’d disagree on.
<Special note: If Peter would like to add clarification or rebuttal to the above response, I’ll include it here>
—
The second:
Dave argues that VLDL production is driving the LDL concentration, but the fact remains that in insulin-sensitive people (which presumably the LMHRs are), the opposite is true: there are fewer, not more, TG being exported from the liver and there is less, not more, apoC-III on the VLDL, thereby reducing, not increasing, their residence time. In other words, LMHR would have less VLDL to LDL conversion than, say, someone with T2D. So again, I can see no evidence whatsoever that his energy model, which can’t be explained on mass balance, and can’t be explained on what is known about the physiology of VLDL and LDL, is plausible.
As per the podcast, I was very up front on this being theoretical. Indeed, I qualify this very early:
Dave Feldman
“With that in mind, here’s what I would speculate. This is purely hypothetical, but I would speculate if you were to grab a whole bunch of people who are … We’ll hopefully get into this model that I’m talking about, that I call lean mass hyper-responders. People who are at the far end of the spectrum, they are athletic, they are thin, and they are very, very low carb, and therefore see very high levels of LDL-C and LDL-P, but they also have very high levels of HDL-C and low levels of triglycerides.
I suspect that they would show a very high rate, proportionally, of VLDL secretion, that they actually are trafficking a lot more, for their energy, triglycerides in VLDL particles, and therefore have succeeding LDL particles as to the explanation as to why their LDL-C and LDL-P would be higher.”
What I’m more interested in is how one can be confident in the opposite. How do we know there are fewer TG “being exported” from the liver in healthy hyper-responders, for example? If we can be, than he’s right, that would put a dent in my theory.
But don’t confuse a blood test for TG as an indicator of TG secretion by the liver. Again, you have to realize the other side of the ledger with uptake by tissues. This is why the three lowest TG blood tests I’ve ever had were following half and full marathons. We wouldn’t confuse glucose entering the bloodstream with glucose found in a blood test for the very same reason — uptake matters.
So without question, I’m extremely interested in any kinetic studies that would involve capturing TG secretion from the liver (aboard lipoproteins, of course) in payload comparisons between healthy hyper-responders vs healthy controls. And I definitely speculate the former would have higher overall TG secretion, yet likely higher TG use as well. But the “export” as Peter puts it, is certainly the key.
<Special note: If Peter would like to add clarification or rebuttal to the above response, I’ll include it here>
—
The third:
Even if you ignore the points above—which you can’t—I am more unconvinced than ever at the notion that we should exclude the roughly 2,000 genetic mutations known to produce a phenotype of high LDL-C, high HDL-C, and low TG. We have 2,000 natural experiments. Surely at least some of these cases (e.g., PCSK9 gain of function) are excellent proxies for the key features of LMHR. Yet to ignore them for imaginary reasons (e.g., having gain of function PCSK9 is somehow toxic to endothelial cells because it impairs their ability to take up cholesterol despite there being no evidence that endothelial cells require PCSK9 to uptake LDL in a receptor-mediated fashion) is to say, in my opinion, one does not want to know the answer to this question.
Before answering this, I’m reaching out to Peter to get clarification on his first sentence. I believe he honestly misspoke on identifying the triad that I’m interested in (high LDL-C, high HDL-C, and low TG) and instead simply meant LDL-C alone. To my knowledge, there’s no study that identifies the phenotype of that triad I’m interested in. (But if you know of one, please contact me!)
…
Oct 08
This final posting in the series is devoted entirely to discussion in the comments on the podcast. Share your opinions in the comments down below on anything and everything about this podcast from your perspective.
I’ll be featuring a number of these comments in this space as well. The likelihood of your comment being featured doesn’t need to align to any particular position, but I do ask that it be respectful and without ad hominem toward anyone in or outside this podcast. (Attack ideas, not people)
Oct 08
|
This is a five part series covering my appearance on The Peter Attia Drive podcast. Please skip to the final post to comment. Part 1 of 5 – Lean Mass Hyper-responders, Oxidized LDL, All-Cause Mortality |
In both this and Part 3, I’m going to “let the tape role” as it were. While I considered trying to summarize many of these parts, I quickly realized it’s too unrealistic here as the ongoing context is important to keep together.
Dave Feldman
I suspect I could get my LDL down to 70 if I was willing to go through with it. There’s another part of this conversation we haven’t had a chance to touch on, but that you might find very interesting since we talked about the liver and again, more theory, so about 80 percent of what I’ve talked about is an explanation that I’m trying to fit onto what I know and this is definitely one of those, but I suspect given the data that I have for the whole second phase of my research that actually part of how I’m reducing my triglycerides in the blood through a certain series of experiments I call carb swap experiments, is that I’m just trying to get a certain threshold of glycogen stores up in my liver, which seemed to be at a certain point, meaning that there will be less VLDL secreted and therefore less LDL. That’s the theory.
Peter Attia
I’m sorry to say again. By moving glycogen, you’re doing what?
Dave Feldman
So again, I’m trying to think about it more like as an engineer, whether right or wrong. I think, okay, if I were trying to engineer this body and I were caring a lot about the long-term tank of storage, which is your adipose sites, but it was also to care about the short-term tank. What is the reason why it would make sense from a mechanistic standpoint as to why the body would want to be so adamant about mobilizing these triglycerides for fuel in a low carb high fat athlete, especially somebody is very lean? The short Occam’s razor from my perspective is it comes down to, well, there’s very little glycogen stores relative to somebody who’s on a high carb diet. This isn’t to say that they have bottomed out glycogen stores, but relatively speaking, there’s less play and because of that, it makes sense as to why the body would activate more lipolysis, have more of the free fatty acids moving through, keep making it more available, etc. Okay, so then how could I tweak that?
Peter Attia
But wouldn’t that also just as easily be explained by the fact that when someone’s walking around with 60 percent of the glycogen in their muscle, there’s by definition, assuming they don’t have, you know, a pathologic condition, there’s not much circulating glucose and therefore it’s probably, they’re also in a low insulin environment which is fostering lipolysis.
Dave Feldman
Right, but it’s gradiated, right? It’s going to have to do with … There’s threshold points which are part of what I’m trying to isolate out and there seems to be a threshold point with me. For example, if I have around 90, it seems to be at the last time I tested it. It’s at around 90 carbs per day, net carbs per day. That seems to be the magic threshold that if I do that for about three days, my LDLC will just drop substantially. Now, let’s see, I did 70 net carbs for three days. I’ve already done that, doesn’t do it. I have to get up to a certain threshold and once I get up to that certain threshold, which seems to be somewhere around 90, all other things being equal, like I have to structure my life around this where like sleep the same amount and so forth. That seems to be the point at which there’s an actual drop and I actually wrap that around one of my presentations is I actually had a fat shake, a ketogenic shake for, I want to say three days for a washout period, and then for just two days I added what I thought would be the calculation to demonstrate what I was looking to do. So I swapped out the fat for carbs, kept it isocaloric for two days. I had one that was a lower amount and one of them was a higher amount.
I can’t remember the numbers right off hand, but then to further emphasize this, I switched back to the high fat diet for the next five days and we saw my LDLC drop almost immediately and continued to remain low for the next five days. And in fact, it got to the lowest point, the end, right?
Peter Attia
So it seems to be at least a sensitive on your carbohydrate intake is your fat intake, right?
Dave Feldman
Correct. And this is very relevant because again, I’m still thinking about this from the energy model-
Peter Attia
But hang on. For this to be … I’m not saying this isn’t interesting, but for this to be relevant, it has to be reproducing something that’s going to last over much longer than five days. How do we know if these effects aren’t transient? And also how do we know they’re relevant if they require an extreme condition such as, one of them, I know you talked about how you just have to force feed yourself a ton of fat.
Dave Feldman
Yeah, that was the very first presentation that I did, where I was having just a very high pro-
Peter Attia
That also dropped your LDLC paradoxically. Correct?
Dave Feldman
Correct.
Peter Attia
Right. But the point is … We have to back up for a moment. Why does any of this stuff matter in the long run? If you’re listening to this podcast or if you’re sitting in front of me as a patient, you have a very important question you have to ask yourself if your LDLP is through the roof as a result of what seems to be your diet. Does it matter and do you want to do anything about it?
Dave Feldman
Right. And this is why this is the most relevant question is if you’re right, and I’m not saying that I know for sure either way. Let’s say that you’re right, you, Peter, you’re right that this, regardless of how we got here, if you have a high LDLP because of being on a ketogenic diet, then there was a lot of people who need to know that if they’re at higher risk and I definitely want to be one of the people that brings that to their attention. I have emphasized this several times before and I’ll say once more, I am on a journey of science, not of advocacy. I’m going to be quite a skeptic, but all of that said, if I come to a point in which I can feel convinced the LDLP is in fact atherogenic, absent remnant lipoproteins, absent having a high HDL, low triglycerides-
Peter Attia
But we already know it’s absent remnant lipoproteins. I mean there’s a thousand studies including this to demonstrate that the atherogenicity between these people and these people, I’m pointing to the Garvey study, has nothing to do with what may or may not be remnants. The LDLP alone here … I think one thing that sort of makes sense-
Dave Feldman
I’ve not seen a study yet, where remnant lipoprotein … I mean I’ll send you the ones I have. If you have somewhere LDL particle is more relevant than remnant lipoprotein, I would be very interested.
Peter Attia
Again, we have to be very careful of what we mean by remnant. So there are clearly going to be a subset of remnants that are potentially the most pathologic on a per particle basis. But I think the body of evidence implicating the causal role of ApoB and LDLP is so overwhelming. Is it perfect? Of course not. But I think what concerns me with this culture, when I say this culture, I mean this sort of low carb culture of LDL doesn’t matter, is if I had a dollar for every time I had to see some low carb enthusiast basically dismissing the idea that LDL is relevant and touting the idea that statins are a big conspiracy theory, that’s a really dangerous problem.
Dave Feldman
It, it’s dangerous if we know … Just generally speaking, I think, dismissiveness in general, of evidence is bad, but we do have to care about the quality of evidence regardless.
Peter Attia
We sure do. So, let me offer a very controversial viewpoint that I can’t believe I’m about to voice publicly. I think one of the challenges in the low carb community is you have a group of people who have become very used to rejecting mainstream information because they did so with nutrition, right? If you are on a low carbohydrate diet, on some level you have decided that the ADA, the AHA, the USDA, the NIH and the CDC are full of shit.
Dave Feldman
I think that’s fair point.
Peter Attia
Okay. So, do you know what I think that when it comes to nutrition, that’s largely true. Okay. Now they think they’re coming around, but I think it’s largely true and I think the body of evidence, the body of literature that pointed towards the Food Pyramid was quite shotty. I don’t think it was nefarious. I don’t think this was as much of a conspiracy as people want to make it out to be. I don’t think Ancel keys with some evil dude who was like scheming away to … I just don’t buy that. I think there were strong personalities and lousy science. Those are very different things.
Dave Feldman
And let me go on the record with saying I basically agree. I feel like-
Peter Attia
This is the easy part to agree with. This is the hard part that’s coming.
Dave Feldman
Okay, good.
Peter Attia
Okay. So what happens is a lot of people get in this mindset of, “Well, look over here, I saw an entire body of evidence that was very easy to dismiss, and by the way, look at the results. You don’t have to be a rocket scientist. If you’re sitting there following the food pyramid, getting fatter and sicker and you abandon it and get better. There’s the proof.” The real problem, and, I again, I apologize for getting on a soapbox. The real problem is when people try to look at the last 50 years of lipid literature through that same lens. Nobel prizes have been won in this field. Now I know that somebody is going to start screaming, “Oh, that’s an appeal to authority. That’s a logical fallacy.” I got it. To you, whoever said that, I acknowledge it, but unless you’re willing to go back and read every one of those papers, something even I have not done though, I’ve probably read more of them than most. We’re talking about apples and oranges with respect to a body of literature here.
The body of literature implicating LDL as having a causal role, a necessary but not sufficient role in the pathogenesis of Atherosclerosis is on a different level from the body of literature that gave us the food pyramid and the real challenge I think in this low carb community, this LDL denying community, is they’re throwing the baby out with the bathwater. Now, part of that is because I think there are too many doctors who are too lazy at the other end of the spectrum. They just assume, “Well, statins or what we give everybody. You know, anybody who’s LDLC is about 100 gets to be on a statin”, and these doctors are equally guilty in my mind of being ignorant and not thoughtful and not understanding the pathophysiology of the disease, but somewhere between these, is a measured space that requires a very careful consideration of the literature.
Dave Feldman
With that in mind, to kind of broad base this pretty well, this whole energy model that we’ve been talking about that I’ve been kind of walking you through, and the audience to some degree, it’s the lens by which I came up with the challenge. I didn’t come up with a challenge because I was just like, “I just, today I just want to tweet out something that I think we’ll get a lot of people annoyed.” I believed that. I looked at those two sides of the dotted line and I said, it looks as if you’re insulin resistant, we tend to see that there are high levels of triglycerides. We tend to see the high levels of VLDL, forget even remnant. We can detect VLDL to a certain extent. We can see that people who are down the range of metabolic derangement, they’ve got that and that tends to be highly associated with cardiovascular disease.
This is all on the energy delivery side. On the other side of the LDL, we tend to see on the support side that there can be further problems in the immunological role and oftentimes that can be induced by likewise, lipolysis. That can actually be something that can … you’ll see on the vitamin E studies, for example, this gets brought up quite a bit. For example, if you if you inject lipopolysaccharides into a body, you’ll actually have a higher fatty acid synthesis that’s going on in the liver along with lipolysis, in order to induce that higher response. So again, we see on that side we see higher levels of triglycerides and I kept coming back to, I kept-
Peter Attia
But you’re also, as we talked about, when you inject LPS in somebody, you’re going to see a higher HDL cholesterol too. I mean, everything at that moment. LPS is a terrible toxin. It’s going to kick the body into a four alarm fire. Of course it’s going to want all of the energy substrate it can muster and all of the hormonal precursors it can muster.
Dave Feldman
Agreed, agreed. So when we’re looking at an association between LDL particles and a bad outcome, we want to absolutely confirm it was the cause and not the association, right? But the same reason that if we were to say, I want to confirm ambulances aren’t the cause of death for people who are dying inside of ambulances.
Peter Attia
Yeah, I mean we have to be a little careful with that analogy. So let’s, let’s be clear. Can you get atherosclerosis without having an oxidized sterol taken up by a macrophage?
Dave Feldman
No. We agree on that. If I could take all of the LDL particles out of your body right now, I could feel totally confident that you will not die of atherosclerosis.
Peter Attia
Okay. So does that not imply that LDL is necessary but not sufficient for atherosclerosis?
Dave Feldman
I don’t disagree with that. Without question, LDL particles are-
Peter Attia
It’s important for some people to understand that because I do think, I mean, put it this way, I’ve certainly heard people in this community argue the following, that the burden of proof should be on the lipidology community to demonstrate that LDL is causal rather than the reverse, and I find that comical, if it weren’t for tragic. Right?
Dave Feldman
Let’s go back to the analogy for a second. Are ambulances causal for ambulance related deaths? Absolutely. They’re a part of the-
Peter Attia
That’s not the same thing, because what you’re basically saying is-
Dave Feldman
I’m emphasizing and association over causation. We both realize that, right? So, okay, it could be in this town, you actually are in worse shape if an ambulance picks you up. There’s very incompetent EMTs, and their life saving measures are poorly done and therefore, if you could ban all ambulances in this town, you’d find that actually-
Peter Attia
A mendelian randomization of ambulances would ferret that out.
Dave Feldman
I would agree if there wasn’t anything associated in the ambulance in the medallion randomization with response by ambulances in the first-
Peter Attia
The only way I think you can discount the Mendelian randomization is if you believe that the mutations that you are measuring … So you’re looking at a series of mutations that are affecting a phenotype. In this case cholesterol level. You’d have to convince yourself that each and every one of those is also effecting something else that’s driving the underlying cardiovascular process. But we’ve already went through this, right? It can’t be the LDL receptor because that’s not even ubiquitous and there aren’t LDL receptors on your epithelial cells.
Dave Feldman
I want this tested on a healthy vascular system. However that’s occurring, I want every cell to have-
Peter Attia
Why does a person with FH not have a healthy vascular system when they’re born?
Dave Feldman
When they were born?
Peter Attia
Yeah. Meaning they inherit a clean slate, right? Someone who’s born with FH has a normal, beautiful vascular system, that over time in most of them becomes destroyed.
Dave Feldman
Just answer this question, is there any cell in somebody who has FH that would function like a normal cell in somebody who doesn’t have FH in order to be able to acquire the lipids or lipoproteins it wants to take?
Peter Attia
Yes. There are plenty of patients with FH who do not have defective, completely defective LDL receptors and therefore are not impeded. Put it this way-
Dave Feldman
Their metabolism is not impeded is what you’re saying.
Peter Attia
Not all of them. Again, we have to be very careful when you talk about FH because there are at least 2000 known versions of that disease. It’s a very cumbersome, so that’s why I think FH gets talked about like it’s one disease, it’s a phenotype that has all of these things that can cause it. So, the broader question is, is everyone with FH struggling to make steroid hormones?
Dave Feldman
I don’t know the answer that question.
Peter Attia
No. In fact, FH maybe slightly protective in the case of an infection and in the case of diabetes and one argument for that … The diabetes one’s a little hard to explain. The infection one, because … I mean, FH has stuck around for a long time, so there may have been a time when having the ability to mount an incredible immune response would have proved to have a survival advantage, and if you have four times the cholesterol of somebody else, that’s one moment in when that could come at a huge advantage.
Dave Feldman
Right, which gets back to the immunological response, but to get back to the larger point, I wouldn’t blame somebody who has a poor digestive system for being malnourished. So, as long as we can count and everybody’s tissues to be properly nourished and-
Peter Attia
I don’t understand what you mean by blaming them, help me understand what you mean by that.
Dave Feldman
What I mean by that is, if there was a problem with absorption of lipids or lipoproteins unrelated to total quantity of LDL particles, that’s what I’m going to care about and I hopefully will have an answer on this soon. I’m actually working with a couple of researchers who I’m trying to get an SNP list together that doesn’t include lipid metabolism issues. So Ronald Krauss, who you had on from earlier, he was talking about this, they are looking right now on, for example, the genetic studies and he was explaining the receptor issues associated with … and this is how you end up with higher levels of LDLC or LDLP, right? Is that you end up having less absorption, particularly on the liver side, but I’m especially interested in non-hepatic tissues-
Peter Attia
But there are, there are people with Niemann Pixie, one like one transporter deficiencies. There are people with ATP binding cassette deficiencies who have a huge increase in cholesterol. It has nothing to do with an LDL receptor. It’s a transporter.
Dave Feldman
I’m not pointing just to the LDL receptor, I’m pointing to just the health of the cell. If the health of the cell is not compromised than I’m interested. If the Lipid metabolism difference-
Peter Attia
But why would someone who’s ATP binding cassette in their enterocyte, that is not appropriately excreting cholesterol, therefore driving up the recirculated cholesterol pool. Why? Why does that mean that they’re endothelium is somehow defective?
Dave Feldman
I would have to follow what the path is that we’re talking about. I don’t know that I could give an answer to that until I can actually see the study that’s associated. If you can take a biopsy of anybody who’s going to have this issue and you can basically effectively see that the cells for which would be targeted, there was not gonna be any problems, I wouldn’t have any problem with using it. I mean basically what we really want, is just the means of just an overproduction on the part of the liver without it touching any other part of the lipid system. And your point, I’ll make your point for you. It’s hard to get an SNP that doesn’t in some way touch other parts of the lipid system, but that’s also the point against it. You see what I’m saying?
Peter Attia
So, so let me ask you this. You’re, you’re saying, “Look, I want more evidence.” And I think science is based on skepticism. I completely respect that, but I think we also have to temper that with some modicum of understanding probability theory and saying, “Look, at some point the probability looks disproportionately one way versus the other. So right now, what would your confidence be in the idea that LDL is playing a causal role in atherosclerosis, just as endothelial dysfunction and inflammation play a causal role in atherosclerosis?
Dave Feldman
Let’s make a distinction, the distinction is, if you’re saying, “Is it part of the development of an atherosclerotic plaque?” It’s nearly 100%. If you’re saying, ” Is the total quantity of LDL particles absent any inflammation or anything else along those lines?”
Peter Attia
Nobody is saying that. Nobody reasonable is saying that. So again, listen to what I said, right? So you’ve got three things that we can sort of use a metaphor and say they’ve formed the three legs of the stool. Three things have to happen for someone to get atherosclerosis. Each of them is necessarily, none of them alone are sufficient. That’s just the nature of complicated biology.
Dave Feldman
Let me help you with the question. I think this would be a better way of asking it. If given the same quantity of oxidative stress, whether it’s low or high, would you rather have 1,000 nanomoles of LDL particles, or would you rather have 2,000 nanomoles of LDL particles? I think-
Peter Attia
Yeah, well, you don’t need to ask me that question.
Dave Feldman
Right.
Peter Attia
I think the question is, what would you rather have?
Dave Feldman
I used to think that I would say the first. That I would rather have 1,000. I would say last year it was probably more like, it could be about the same difference. Learning what I’ve learned, especially with the antioxidative defense system and so forth, and particularly given my own data, especially with the CIMT data that I’ve presented recently. I don’t know if you’ve seen that one as well. I was getting carotid intima-media test every six months. And during those six months in the beginning of this diet, and through the experimentation, I was running at LDLC levels of 200 or higher, LDLP levels of 2,000 or higher. For four tests in a row you can actually see the regression that’s happening on both the left and right side of the carotid arteries. Now-
I’m referring to the Carotid Artery Updates which I’ve been doing every six months and how it was showing a regression. However, that changed following my four-week SAD diet experiment — worth a read!
Peter Attia
Now, again, I don’t wanna get started on CIMT, which is hopefully it’s the same tech doing it the exact same way. I mean, I’m guessing your CIMT initially was pretty good and it may have gotten a little bit better. But, I don’t know. CIMT is even worse than calcium scoring, frankly.
Dave Feldman
Sure enough. But, what-
Peter Attia
But again, Dave, we’re putting a couple of N of how manys, we’re saying, “Look, these three little interesting anecdotes are basically calling us to suggest that the null hypothesis around this topic should be what you’re discussing, rather than what I think is a remarkable body of scientific literature, that is not without its problems, and that is not absolute in its inference.” But-
Dave Feldman
That’s not what I’m saying. What I’m saying-
Peter Attia
That might not be what you’re saying, but it’s certainly what a lot of people are using your words to say.
Dave Feldman
I have an energy model that a lot of people are utilizing probably over-simplistically. But, if my energy model is right, it would suggest as to why, the answer of why-
Peter Attia
But, David, you haven’t even described it correctly to me today. I mean, you’re … I mean, I guess it depends how liberal we wanna be with the term model. But, there is no evidence that the LDL is there to carry cholesterol. You have yet to explain to me where Moffett got his cholesterol.
Dave Feldman
You’re talking about to the quantity that he has it at?
Peter Attia
Yes.
Dave Feldman
I-
Peter Attia
You guys got three times the amount of LDL cholesterol.
Dave Feldman
I think it typically tracks with the total particle count. The people-
Peter Attia
You have to give me the mass balance. You’re an engineer, you know this stuff just as well as I do.
Dave Feldman
If you are a hyper responder coming to cholesterolcode.com right now, and you turn over your lab, I can look at your LDLC before you-
Peter Attia
No, no, no. That’s fine. That’s just pattern recognition. That’s not the interesting thing to me. I’m asking a very important physiologic question, which you have yet to provide an answer to, and it seems to be the central tenant of your belief system. Where did Moffett get his cholesterol? Why does he have three times more than he had before?
Dave Feldman
The short answer to that is, he synthesized it and he’s recycling it. Now, there’s some degree with which he’s synthesizing-
Peter Attia
Okay, so this is a totally different answer than before. He has now increased his synthesis of cholesterol. He doesn’t have the same circulating pool. This is not a shell game with boats. Right?
Dave Feldman
I was talking about circulating before.
Peter Attia
No, but I don’t think, what I certainly didn’t hear you say before was that he has actually increased his own endogenous production of cholesterol.
Dave Feldman
There’s some amount where you’re increasing it in order to meet that existing demand. I don’t know how much that is.
Peter Attia
But, this is different from what I understood you to say earlier, which is the reason he has more cholesterol is it’s just along for the ride with the boats, and he has to have more boats, which defies-
Dave Feldman
No, that is correct.
Peter Attia
But, that defies the principle of mass balance. You can’t create matter out of nothing.
Dave Feldman
I’m not saying he’s creating matter, okay.
Peter Attia
So he had to make more cholesterol. I don’t see a way around that.
Dave Feldman
I’m not disagreeing with him making more cholesterol. I think where we’re disagreeing is, I think you’re saying in total, he’s making three times more every day. Am I wrong on that?
Peter Attia
On average, he is making three times more, or reabsorbing three times more. But, just based on what I’m seeing-
Dave Feldman
Reabsorbing at the liver, or reabsorbing in non-hepatic tissues?
Peter Attia
Probably in the gut. That’s where the majority of the reabsorption is taking place.
Dave Feldman
Okay, in other words, he is sending it back out the other side.
Peter Attia
Well, again, this is what we look at these sterile numbers for. When the desmosterol goes through the roof, plus or minus the phytosterols, that tells you these patients are making more cholesterol.
Dave Feldman
Okay.
Peter Attia
But, here’s the question. If this were purely about energy, he shouldn’t be making any more cholesterol. He should have more particles perhaps, but they should be cholesterol depleted.
Dave Feldman
I’m interested in this, I have no … You answer this question for me. When does somebody make more cholesterol-depleted [lipoproteins]… because everything that I’ve read in Clinical Lipidology and so forth, is it’s like a standard quantity on the non-triglyceride side of the ledger. If you’re making cholesterol on a per particle basis, it can vary on a per particle level, but generally speaking, it tends to hit averages that are fairly consistent.
Peter Attia
But, this is an unusual circumstance you’re describing. Right? This is the whole purpose of this experiment, is you’re describing people who-
Dave Feldman
It’s not unusual-
Peter Attia
… who’s demand you’re saying is so great for triglycerides, but they’re doing-
Dave Feldman
That you make more boats. But, the boats, if they already have a standard composition, why would they change that standard composition per boat?
Peter Attia
Well, think about … So are you telling me you’re saying that the large LDL particle and the small LDL particle in the insulin resistant versus the insulin sensitive patients have the same cholesterol composition?
Dave Feldman
No, that’s my point. My point is getting back to remnant cholesterol. Why is it that I think there would be something that would happen on that dotted line, something before and after. Right? Why would there be … Why would there be a problem with somebody who’s metabolically deranged with their cholesterol relative to one of these people that are theoretically metabolically flexible. Why would there be a difference? And the short answer to that, the short answer is, I don’t know fully all of the aspects to it. I do know though, there seems to be a longer resonance time with VLDLs, and we see that because that’s the [crosstalk 02:57:36].
Peter Attia
Yeah, we know that that’s explained very clearly by APOC-III, the resonance time on the LDL for that matter as well in pathologic states.
Dave Feldman
So if I became more insulin resistant, and therefore, ended up with higher VLDLs I couldn’t, say two years later, have healed that and then have less VLDLs.
Peter Attia
No. I mean, look back to the Garvey study. There’s a reason I printed this up, because I knew we’d be talking about this over and over again. There’s very little difference. To try to impute or infer something about remnant cholesterol from VLDL is as complicated as trying to assess Lp(a) by looking at LDL cholesterol. Think about that for a moment. When you look at LDL cholesterol, if it’s directly measured, do you agree that it’s the sum total of LDL cholesterol plus Lp(a) cholesterol?
Dave Feldman
Yes, I believe that’s how it does work.
Peter Attia
And it excludes VLDL cholesterol and IDL cholesterol because they contain ApoE, whereas the Lp(a) and the LDLP do not. So if you have a direct cholesterol measurement, the LDLC is technically LDLC plus Lp(a)C. But, there is no way on God’s green Earth that you can look at that and infer what the Lp(a) is.
Dave Feldman
Right, without testing directly.
Peter Attia
Yeah, and similarly, we don’t know what’s going on with these VLDLs, meaning in Moffett, because we haven’t measured it. But, we’ve measured this in patients that span the spectrum of insulin sensitive to diabetic, and that doesn’t appear to be the answer. The difference in the atherogenicity, the difference in the resonance time, and the difference in the total ApoB load appears all driven through the LDL particle, not the VLDL particle. So something else explains why they have more LDL.
Dave Feldman
That’s what I wanna find out. Again, I’m very up front about what it is that’s theoretical and what isn’t.
Peter Attia
But, we kind of already know the answer to that question. It’s the triglyceride content.
Dave Feldman
But, until we can actually test it on people who are fat adapted, or [kinetogenic], we can’t say that we do. When we can do a kinetics study … When we can do a kinetics study on VLDL secretion with people who are particularly likely mass hyper-responders, then we’ll have some idea.
Peter Attia
But, Dave, that will only offer you an explanation. It will not change the question.
Dave Feldman
Of risk?
Peter Attia
Yes.
Dave Feldman
Right.
Peter Attia
Let’s say you can do a kinetic study, and hopefully someone wants to fund this, because it is an interesting question. Again, I’ve done the kinetic study on myself, you’ve seen my data.
Dave Feldman
Right.
Peter Attia
I lose triglyceride, not cholesterol.
Dave Feldman
Right.
Peter Attia
Which, I would expect. Right? I am seeing cholesterol basically stay the same in those cells, and it’s during the periods of extensive exercise and fasting, we’re seeing triglyceride movement within the cell. But, the point is, even if this theory turns out to be correct, it’s an explanation not a reason. It’s an explanation for something, but it’s not a reason to ignore it, is it?
Dave Feldman
This is where I think we’re getting circular. It’s an explanation as to why it could be benign or even beneficial, and that’s where we’re disagreeing ultimately, which I figured we would be. Why would you have high LDL for a good reason? And you’re answer would be, “There wouldn’t be one.”
Peter Attia
No, no, that’s not true. There wouldn’t be a good reason with respect to cardiovascular disease, there are plenty of good reasons to have high LDL, we just talked about them. The FH patients obviously get some benefits from their high LDL. But, from a cardiovascular standpoint, I don’t think there is a single good reason to have high LDL, and I am not aware of a single card-carrying lipidologist or member of the community that spends a lot of time in this literature that could come up with one, and I’ve been asking. I mean, it’s something I’ve been very interested in. Give me a teleologic reason to have high LDL from a cardio protection standpoint. I mean, I was asking this question seven or eight years ago, and there is no answer.
So again, doesn’t mean that having high LDL is always bad, but it’s really important to understand this distinction. The other thing to keep in mind is, lots of things in biology are not linear. So look at Gilbert’s syndrome, Gilbert’s syndrome is a very common condition. 10%, maybe not 10%, 2% or 3% of people listening to this have it and probably don’t even know it. But, they have elevated unconjugated bilirubin, but very slightly elevated. So if you’ve had a blood test done, you probably know down at the bottom it says, ALT AST bilirubin. And normal bilirubin would be less than one.
But, these patients with Gilbert typically get to about two. Well, in half a dozen studies, these patients have an enormous risk reduction in cardiovascular disease. Why? Why would having a slight doubling of bilirubin, which by the way, at high levels is toxic. So if you walk around with a bilirubin of 10, you’re not gonna be around very long. And those patients present, they get sick, they have obvious symptoms, they’re jaundiced, and they usually have some pathology that’s leading to it. But, these patients can walk around with a bilirubin of 1.6 to 2, and they seem to be getting a benefit from it. And they also seem to have lower LDL, and even if they don’t have lower LDL, because the literature is mixed on this, they always have lower Ox-LDL. And it may be that the best explanation is that bilirubin has anti-oxidative properties. So they get this protection from cardiovascular disease, but it’s a U shaped curve, or an inverted U shape curve rather. Meaning, as that bilirubin gets higher and higher, they start to lose any of that benefit, meaning, whatever oxidative benefit they get, it’s more than being outweighed by the damage that comes from that elevated bilirubin. So I guess my point here is, even if there’s an explanation for why this is happening, from an energy trafficking standpoint, which again, I really wanna be clear, I do not think there is. I do not think that energy trafficking explains this phenotype. I think that is not the Occam’s Razor answer, I think the Occam’s Razor answer is, they’re making a boatload more cholesterol, because I think we have pretty good data to suggest that.
Dave Feldman
Which I’m dying to test, by the way.
Peter Attia
Yeah, yeah. We should make sure that you can, and that other people can do this. But, of course, the point here is, it still won’t actually answer the question, what should you do about it? Just because there’s a reason for something doesn’t mean that it’s a benign condition, or that it should be ignored.
Dave Feldman
I agree, and not only that, separate subjects. I’ll even go a step further and say, it could be a U shaped curve on this end as well. It could be that you could have an LDLP of say, 1800, and it turns out that’s actually the bottom of the curve, and people at 1800 don’t turn out to be as high a risk as people that are like the one you just showed me, above 3500. I not only grant that, I also further tell lean mass hyper-responders, “I may turn out to be right on my cautious optimism, as far as the risk of cardiovascular disease, but it could turn out that there’s something else we haven’t yet determined.” That’s a problem with this phenotype, which is another reason why we should be sharing all of the symptoms that may be coming along with it as well. But all of that said, all of that said, the larger question is, why then, would I be able to identify a certain set of parameters that, when studied, seem to suggest that high levels of LDLC, I want some with high LDLP, doesn’t prove to be problematic. And that’s why I want to get a hold of something, I want to get a hold of really large-
Peter Attia
But, how will you demonstrate that?
Dave Feldman
By stratifying. Stratifying for high HDL, stratifying for low triglycerides.
Peter Attia
No, no, no. How-
Dave Feldman
Stratifying for high level-
Peter Attia
How will you know if they do or do not have, if they’re not at increased risk for cardiovascular disease? How long will you need to follow them to know that?
Dave Feldman
Well, that depends on the data set I can get a hold of. I’m not in your space so I have to work with other people who are researching-
Peter Attia
Oh, you’re saying you wanna do this with retrospective data.
Dave Feldman
Correct.
Peter Attia
Okay, so meaning this is your challenge to say, “Don’t give me genetic data, don’t give me drug data.”
Dave Feldman
I like just normal non-drug, non-genetic stratified people preferably. And I like to stratify just on those three, just on HDL, LDL-
Peter Attia
Even though your patients probably have some genetic SNPs that are explaining their phenotype?
Dave Feldman
Oh, I would definitely wanna know that as well. That’s why I’m trying to actively get the 23andMe, I would love to send it your way for obvious-
Peter Attia
But, the point is, you’re excluding anybody who has anything that could be called the genetic alteration, even though the patient population you’re trying to understand this is, almost assuredly has a genetic alteration that’s rendering them susceptible.
Dave Feldman
I’m not trying to exclude that.
Peter Attia
But, you just said you don’t wanna consider any of the genetic drivers of FH.
Dave Feldman
Let me emphasize. If you’re making a study that is gene specific, then it’s the gene that drives the detection, the discovery of those people. Right? I don’t wanna do that. I wanna actually see if I can get a broad base study of people who happen to already have high HDL, low triglycerides, and high LDL, and see if they have high rates of not only cardiovascular disease, but all-
Peter Attia
But again, I come back to the FH patients. You can’t find a more broader demographic of people in terms of variable genetic inputs that produce a phenotype similar to what you’re looking at.
Dave Feldman
I think we’re just gonna end up in one of these gotta agree to disagree moments. Until I can-
Peter Attia
Which is fine. I totally respect that. But, I just want you to understand what it sounds like from over here is, you’re looking for six footers, you’re looking for a six footer and you’re not gonna be happy until you see a six footer, and gosh doggone it, you’re not gonna leave the kindergarten classroom until you find one.
Dave Feldman
I would argue the opposite. I would say, “Look, why shouldn’t I be able to grab …” If I could right now just grab a million people in the United States, just absolutely randomly determined. Why would that not be significant data if I found that there was this stratification for which high LDL did not result in high levels of cardiovascular disease or all-cause mortality?
Peter Attia
Well, because if you’re gonna do that honestly, you’re gonna say, “Well, they can’t have a single genetic mutation, they can’t be taking a single drug, and they can’t be on any funky diet.”
Dave Feldman
Let’s say all of that turned out to be true.
Peter Attia
And what if they don’t exist?
Dave Feldman
If I found that out, that would be definitely something I think would be very interesting to my followers. I would turn that back around.
Peter Attia
But, you’ll never know if you found that out or not, Dave.
Dave Feldman
Well, I’ve already found two studies that do stratify for those three. And of the two that do, high LDL does not result in high rates of cardiovascular disease.
Peter Attia
Wait, wait, you’re talking about these glycogen storage disease cases?
Dave Feldman
No, no, no, Framingham Offspring has one study where they stratified by three, and unfortunately my computer is dead or I’d show you the other one. There’s another one that stratified discreetly between below 170 LDLC and above 170 LDLC. And the high HDL, low triglyceride group, when compared to above and below, were nearly identical, both on the high side and on the low side.
The two studies I’m referring to are:
Peter Attia
Yeah but, this study didn’t stratify by ApoB.
Dave Feldman
Right. I would love to have ApoB.
Peter Attia
Okay, but, that’s the Quebec Heart Study for you right there.
Dave Feldman
The Quebec Heart Study has the stratification by all three of those metrics?
Peter Attia
The Quebec Heart Study, here I printed it up here. I mean, basically it’s showing it has nothing to do with the LDLC once you know the ApoB. Look at the risk.
Dave Feldman
Okay. You have to understand, what I’m trying to get is … Sorry. I’m trying to get those three in conjunction. I want to specifically stratify those three. And in software, this is where I get a bit frustrated, because I feel like there’s such a cultural difference between medicine and software. We’re used to having just loads and loads of free data, just we’re awash in free data. Google can’t wait to give me everything that I wanna see. I requested, I’ve actually applied-
Peter Attia
No, I’ve heard you talk about it. Are you being denied that, or did they not have the data?
Dave Feldman
They just don’t return my emails. I mean, there’s even people that I would think would be sympathetic inside the low carb community, and I’m not gonna try to call them out, who I’ve also tried to get this information from. And I just can’t get it, and I want just a nice, clean regression on three axes, that’s all I want. That’s nice and fat.
Peter Attia
So the three axes being triglyceride-
Dave Feldman
Triglycerides, HDL, and preferably LDLP. Now, there is an important distinction we’ve gotta make with ApoB, because ApoB can, in theory, also include remnant lipoproteins.
Peter Attia
Yeah, LDLP is more accurate than ApoB.
Dave Feldman
Right. And LDLP would be extremely fantastic. If you could help me get in touch with that data set I would be very interested, and not with any major adjustments, I mean, whatever Cox proportional might be fine. But, just generally speaking, if I could get a big fat data set and stratify on those three axes, I think that would say a lot as to whether there’s any validity to the energy model overall.
Peter Attia
So when you look at the Mesa data, which stratify on a Kaplan-Meier curve, the difference between LDLC and LDLP. You’re saying that that’s not relevant because why?
Dave Feldman
The thing we’re dancing around here is, obviously when you have high HDLC and you have low triglycerides, it suggests a number of different things. But, more broadly, it’s suggesting a properly functioning lipid energy system, and probably not being in a state of challenge-
Peter Attia
HDLC tells us absolutely nothing. If we’ve seen enough from Mendelian randomizations and in other, how many more CTEP failures do we need to see? HDL cholesterol tells us nothing about HDL function. In fact, any time you increase HDL cholesterol pharmacologically, you seem to make patients worse.
Dave Feldman
I know, but these are modifications to the existing lipid system. If you block cholesterol-
Peter Attia
I get that, Dave. But, boy, if you’re gonna hang your hat on it’s all about HDLC triglyceride, I mean, wow, we are so far beyond that in the lipid world at this point. If you’re gonna go through this brain damage, make it for something worthwhile.
Dave Feldman
But, wouldn’t you predict right now, that if I did hang my hat on those two things, on those two markers, against LDLC or ApoB or LDLP, that it would fail. That if I were to say, “Hey, I wanna get a stratification just of high HDLC and low triglycerides.” That you’d say, “Sure, Dave.” I’ll bet you $10,000, I’ll give you 100 to 1 odds, those people with high LDL, even if you stratify for those two, will still have high rates of cardiovascular disease.
Peter Attia
Again, I’d have to completely see the patient population before I could even hazard a guess.
Dave Feldman
But, right now, you would assume that. Right?
Peter Attia
I am going to assume that LDLP is going to be a stronger maker of prediction than HDLC.
Dave Feldman
And that’s not what I’m making the case on. What I’m making the case on is, whether or not there’s a properly functioning lipid metabolism, which would be indicated by all three of those.
Peter Attia
No, you have absolutely no understanding of the lipid metabolism by looking at HDLC and triglyceride.
Dave Feldman
I think-
Peter Attia
Not even close. No, no, no, we can disagree on things that are nebulous. This is not nebulous, Dave. I mean, you do need … Again, I hate that I’m saying this, because I sound like a jerk and I don’t mean to. You’ve got to spend more time with lipid people, you really do. . . . You’re not dealing with your peers at this. You have to go and figure out … I mean, HDLC is just categorically not a useful metric. It is like a first order term on a … No, it’s not even that. In engineer-speak, it’s the fourth order term on a fifth order polynomial.
Dave Feldman
That hurts, Peter, that hurts.
Peter Attia
No, I mean, come on. It’s just not that.
Dave Feldman
I’m just kidding, I’m just kidding. Look, I-
Peter Attia
It’s super crude. And don’t confuse the ubiquity with its utility. The ubiquity of it is, “Yeah, it’s cheap. It’s easy. Everybody’s got it.” But, let’s not let people listen to this and get lulled into a false sense of, “Hey, if my HDL is high and my trigs are low, who cares what my LDL is.” And unfortunately, that-
Dave Feldman
I wanna prove that right or wrong.
Peter Attia
Well, first of all, you’ll never prove anything in science, so let’s be really clear on our lingo.
Dave Feldman
Okay.
Peter Attia
No, no, no, it’s very important. It’s important for your listeners to understand that.
Dave Feldman
Fair enough, fair enough. But likewise-
Peter Attia
But, nothing is proved, it’s about probability.
Dave Feldman
Sure, but likewise, would you say the lipid hypothesis is proofed?
Peter Attia
Absolutely not. I just said, “There’s nothing outside of mathematics that exists in a proof.” Nothing. And I have the basis of the luxury of having been a mathematician once, so I get it. There’s a luxury of being able to write QED at the bottom. We will never do this here, and if people are sitting there saying, “Well, I’m gonna keep eating my bacon and eggs like it’s mainlining, and ignoring my LDLC because my HDLC is high and my trigs are low, because I’m on a low carb diet, and somehow that makes me special, because no one’s proved that this is wrong.” Wow. That’s not the legacy I want.
Dave Feldman
So what if I continue to find more data sets that actually support that? What do I do?
Peter Attia
I mean, I don’t know. I don’t know what that means. What do you mean by more data sets? Meaning more anecdotes?
Dave Feldman
No, I’m talking like, say I do actually get a hold of Framingham Offspring, let’s say I get a hold of … I forget what some of these larger data sets are, and [inaudible 03:15:01] have to go-
Peter Attia
Mesa.
Dave Feldman
Mesa, sure. Let’s say I can get Mesa and I can stratify for those three and it’s showing the same thing, without doing a lot of adjustments or anything along those lines. What would I tell my followers? I would say, “No, it looks as if, still there’s further evidence that’s showing high LDLC, in this case, is not problematic.” Mesa did actually stratify for LDLP, didn’t it?
Peter Attia
Yes.
Dave Feldman
Yeah. So that’d be a great example. Mesa would be fantastic data to get a hold of. Is that something that you think I would ever actually be able to see or be able to run regressions against?
Peter Attia
I mean, I’ve never thought of it, but I agree with you. That would be great. I don’t know who owns the data.
Dave Feldman
But would that be compelling to you? If it turned out that we could run regressions on it, let’s say that it was in the next room right now and we worked it up on the computer, and sure enough, I went by the stratification I was looking for that are identical to somebody who’d be … And they were typical to somebody who is already a lean mass hyper responder, and it would show that they didn’t have high rates of cardiovascular disease. Would that be compelling data to you?
Peter Attia
I think compelling is the wrong word. The question is, how would it add to the existing body of literature that informs a decision we have to make every day with a patient. And the answer is, “I’d have to see the strength of it and decide, how does this fit into the existing body of literature?” I mean, that’s the only way I can imagine thinking about this. But, everybody listening to this, and you and I, all have to put our heads on a pillow at night with a null hypothesis, against which we have to challenge existing data. I’m not convinced that the null hypothesis here should be anything other than the lipid hypothesis. Now, the lipid hypothesis gets bastardized all the time, it gets misstated all the time, it gets based on LDLC and a whole bunch of other stuff.
But, I’m talking about the real honest to goodness, no bullshit, LDL hypothesis, which again, I’ve written about eloquently, and people have written about it far more eloquently. I should say I’ve written about it in a kluge way, others have written about it eloquently. The lipoprotein, the endothelial damage, the inflammatory changes, all of these things cascading, that’s my null hypothesis. And in the end, if there’s data to counter that, I’m all for it.
But, for example, even when you look at the IL-1, IL-6 agonists, the [inaudible 03:17:19] methotrexate studies that showed you could delay or reduce cardiac events without changing lipoproteins, I don’t think I’m being delusional when I say that doesn’t change the model. It actually feeds into the model. The model is, there are three things that are driving this pathology, if you reduce one of them, things get better. All things equal, if blood pressure goes down, do outcomes get better?
Dave Feldman
I believe they do.
Peter Attia
Absolutely they do. Very potent. Why? Endothelial function. All things equal, if you stop smoking, do outcomes get better? Absolutely. So when you start to look at all these things, and again, with those-
Dave Feldman
But by outcomes get better, you’re specifying-
Peter Attia
Cardiac outcomes.
Dave Feldman
Right, cardiac outcomes.
Peter Attia
The all- cause outcome is a much more complicated question that probably is a podcast in and of itself. So to your question, yeah, Dave, of course. I’d be incredible curious to see this. Who wouldn’t be? But, don’t think that one regression analysis on Mesa is gonna turn over 50 years of data, regardless of what it shows. The question is, how does it alter our understanding and thinking of the problem?
Dave Feldman
Sure. Look, the whole reason I’m even pursuing this particular strata is because of the model in the first place. I had to have something that I could conceive of, that would inform the decision by which I would be looking for what the data is that would disprove it. That’s why I’m in pursuit of disproving it. At the end of the day, Peter, I can’t emphasize this enough. I’m not looking to talk to the echo chamber or looking to just maneuver around inside a number of people that are gonna congratulate me. I specifically-
Peter Attia
But, I think you’re better off going to an NLA meeting than a low-carb meeting.
Dave Feldman
Sure, but they’re freaking expensive. I’ve looked at all of them.
Peter Attia
Get the low-carb community to fund you. If they wanna know the answer, because I don’t think they do, if I’m gonna be brutally honest. I think the worst of that crowd just want their confirmation bias. They have seen these incredible benefits of low carbohydrate diets, and their belief is, nothing can be wrong with this. Like we somehow live in a mono-dimensional, monochromatic world, where it’s that black and white. And if the diet is good for this, it can’t be bad for anything. And they are so wed to that they construct these crazy arguments. But, if they share your passion for truth, then they should happily fund you to go to an NLA meeting and spend a week there, and actually start hanging with these guys who are way smarter than me. I’m a knucklehead, I know a lot about lipids for a knucklehead. But, I’m talking about, the smartest people in the world are the ones you need to be talking to on this topic. And they’re not at low-carb conferences, I promise you that. They’re not on Twitter, and they’re not playing patty cakes on their high-carb, whatever, low-carb blogs. It’s just not about that stuff, man. And again, I think what you’re doing is really interesting. I don’t agree with the model, but I’m glad that you’re pursuing it. I wish you the best in pursuing it with the right people.
Dave Feldman
Absolutely. Perhaps you’ll be able to help me set up with the right people. I would definitely be more interested in finding those voices that can help tear at this model.
Peter Attia
I would be more than happy to help in any way I can.
Dave Feldman
Great. Well, I can’t emphasize enough as I anticipate, I was gonna ask you more questions than you asked me. I’m really appreciative that you took the time to chat with me about this.
Peter Attia
No, my pleasure, Dave. Thank you very much. I apologize if this just took longer than we thought it might’ve, and I know we went off on tangents all over the place. I guess, this will be one where the show notes are probably quite helpful. But, nevertheless, it was great meeting you in person. I didn’t realize it’s only been three years since you’ve been at this. It feels like a lot longer actually.
Dave Feldman
It certainly does for me. And my wife would say its felt twice as long for her. You have to realize something, almost nobody knew about me a year and a half ago, and I knew almost nothing about cholesterol three years before that. So this is absolutely been a fresh journey, and that’s why I have to oftentimes emphasize that I’m not a formally trained biochemist, and I really have a lot of gaps, I’m sure, in my knowledge that I’m looking to fill and find as fast as I can.
Peter Attia
All right. Well, it was great to meet you. Enjoy your time in San Diego. Oh, by the way, for the listener, this is being recorded on July 26th. It will be a long time before this goes up, Dave, so hopefully the listeners will understand that whatever has transpired since then is just … We prerecord these things many months in advance. We may have to bump it up a little bit, depending on maybe we can re-shuffle it and get it out before the end of the year, which is probably right now where it sits in the pipeline. But-
Dave Feldman
You’re gonna subject me to quite a hell, because I guarantee every single follower I have is gonna be knocking on my door until this thing is opened up, so that will be pretty funny.
Peter Attia
Well, we’ll do what we can. Anyway, man. All right. Thanks so much.
Dave Feldman
Absolutely.
Peter Attia
Awesome to finally meet you.
Next part: Guesting on the Peter Attia Drive (5 of 5) – Comments and Featured Thoughts
Oct 08
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This is a five part series covering my appearance on The Peter Attia Drive podcast. Please skip to the final post to comment. Part 1 of 5 – Lean Mass Hyper-responders, Oxidized LDL, All-Cause Mortality |
In both this and Part 4, I’m going to “let the tape role” as it were. While I considered trying to summarize many of these parts, I quickly realized it’s too unrealistic here as the ongoing context is important to keep together.
Dave Feldman
Let’s circle back to remnants real quick.
Peter Attia
Okay.
Dave Feldman
This is why I pause a little bit on the case study that you showed me where you had the triglycerides a bit higher. Now, as you know, what is the poor man’s version of remnants is you basically can just take your triglycerides divided by five. You probably actually …
Peter Attia
No, no, no. We got to be very clear on this stuff. We’re going to confuse the hell out of people.
Dave Feldman
Okay.
Peter Attia
That’s the poor man’s version for VLDL cholesterol.
Dave Feldman
Correct.
Peter Attia
Very important distinction.
Dave Feldman
Fair point. Yes.
Peter Attia
The poor man’s version, which should never be done because it is such an abomination is to take the triglyceride level divided by five, and that number would be an estimate of your VLDL cholesterol.
Dave Feldman
Now, what would you, Peter Attia recommend as the most effective means by which somebody could determine their remnant cholesterol?
Peter Attia
We can’t. It’s impossible. We have no way of knowing remnant cholesterol. Let me be clear. I think I know what you mean by remnant, which is why I’m asking that question. You’re asking pathologic remnant. You’re asking VLDLs that have shed their triglyceride and are now basically pathologic, small. Started out as big, triglyceride rich, and now have shed that through their ApoC-II II LPL pathway, and now have the potential for atherosclerosis, is that what you’re meaning about remnant?
Dave Feldman
No, I now think we may think of it differently. Straight up Wikipedia right now would define remnant cholesterol as basically all cholesterol that’s not in either an LDL particle or in a HDL particle. If you were to just subtract HDL cholesterol [crosstalk].
Peter Attia
If you directly measure total cholesterol, which you can and you can directly measure LDL cholesterol and you can directly measure HDL cholesterol, you subtract those two and you have the amount of cholesterol that is virtually all in a VLDL, and presumably some IDL, if it stick around.
Dave Feldman
Some IDL possibly chylomicrons remnants if you ate recently, but you shouldn’t have any chylomicrons remnants.
Peter Attia
Yeah, that’s very easy to exclude.
Dave Feldman
Right, but effectively, if you’ve had a fasted cholesterol test, pretty much all your remnant cholesterol, pretty much will be in VLDL has longest residence time relative to the IDLs.
Peter Attia
That’s correct, but that’s like telling me outside a very few pathologic states, like [inaudible 01:46:01] and type-III Bs, that’s as interesting to me as your eye color.
Dave Feldman
The remnant cholesterol?
Peter Attia
Yeah.
Dave Feldman
Really?
Peter Attia
Yeah. I mean it’s generally going to be very low. It tracks quite well with triglycerides, though there are lots of examples where it’s been … Actually, I think I brought a copy of one of my other goofy experiments. I don’t know. I probably won’t find it anytime soon, but there is an example of how mine was so far off. It was like a 700% delta between actual versus predicted in one of these studies, but now, the point is yeah, directionally speaking, I would love to see a VLDL cholesterol below 15 milligrams per deciliter as calculated by taking non-HDL cholesterol subtracting the LDL cholesterol, but if you have a direct LDL, cholesterol is your best measurement of that.
Whether it’s 10 milligrams per deciliter, 15 milligrams per deciliter, 20 milligrams per deciliter, that just tells me the sum of cholesterol in all of my VLDL remnants. It tells me nothing about the pathology of them. It tells me nothing about what they’ve done or where they’re going.
Dave Feldman
But, that said, the question then becomes even for as much as what you just qualified, does that become a more powerful predictor relative to something like say LDL cholesterol?
Peter Attia
Maybe, but that’s like saying is rubbing two stones together better than rubbing two logs together to start a fire? It’s like why not just use a Zippo lighter? It’s like we could split hairs on whether non-HDL cholesterol or remnant cholesterol is a better predictor of cardiovascular disease than LDL cholesterol, but again, given that LDL cholesterol is such a crappy predictor of cardiovascular disease, I prefer not to really even think about that.
Dave Feldman
We do have now a situation where this particular phenotype where lean mass hyper-responders will have very low levels of LDL or I’m sorry, of …
Peter Attia
VLDL cholesterol.
Dave Feldman
VLDL cholesterol, have very high levels of LDL cholesterol, will have very low levels of remnant lipoproteins.
Peter Attia
But we don’t know that. There’s no way you’ve measured that. I’ve never measured that. That’s not measurable. In a commercial, I say that’s worth its salt. I think VAP does a vague ass version of that, but it’s bunk, but look at this. Look at Garvey’s studies. We’ll link to this as well. This is actually measuring the number of particles. This is an insulin sensitive person. Their a total LDL-P is about 1,200. Their VLDL-P is about 80. You go to someone whose insulin resistant, but not diabetic. Their LDL-P goes up to 1,435 on average. Their VLDL goes to 84. Their IDL is counted. It’s around area, and then you take the population with type 2 diabetes. Their LDL cholesterol’s up to 1,600 nanomole per liter and their VLDL goes up to 100.
You’re right, the VLDL is going up as you get more insulin resistant, but it does not appear very clinically relevant, because remember this is all the burden of disease, is from these ApoB bearing particles, and so the increase in VLDL particle number is not what’s driving the risk of the disease. You actually had a really nice graph in one of your figures that you titled that is remnant that was going up. You know the figure I’m talking about?
Dave Feldman
Yeah.
He’s referring to this one:
Peter Attia
We’ll link to that as well, but you had a graph that showed I think as people were becoming more insulin sensitive, their pool of remnants was growing. What you perceived as remnants.
Dave Feldman
Well, I actually want to qualify something real quick. If I think it’s the graph that you’re talking about, it was the one downside to that is it was non-fasted remnants, which I’ve been trained to find [crosstalk 01:50:02].
Peter Attia
Oh, got it. Got it. Okay, okay.
Dave Feldman
Which I have a problem [crosstalk].
Peter Attia
It was in one of your talks.
Dave Feldman
It was in one of my talks.
Peter Attia
But anyway, my point is what’s missing from that analysis is ApoB or LDL-P. In other words, the expansion of that … See this study, which is I mean the most elegant study of this ever done shows that if you only saw the top line, this to this to this, everyone would be like wow. The more insulin resistant you get, the more your total burden of ApoB goes up. What this is showing is where is that burden coming from. The VLDL only increased by 20 nanomole per liter, but the LDL-P increased by 400 nanomole per liter.
Dave Feldman
Right, and the point I’m coming to is this is where we’re in uncharted territory because I believe will apply to people who are ketogenic fat adapt. I don’t believe this will apply to people who are very ketogenic fat adapted, and particularly who have these phenotype.
Let me see if I can come at it this way, right now, if I were to be able to get the data set for Framingham Offspring, because that is one of the studies that I was showing out for before, and I could basically just do this basic calculation of remnant cholesterol the way they were talking about, and conceding the point of your time that you said earlier that’s there’s no way to truly know. Would I still come up with a more valuable metric for subtracting HDLC, particularly when associating to all-cause mortality? Relative to say …
Peter Attia
Let me make sure I understand what you’re saying. You’re saying if you could develop an [inaudible 01:56:54] to distinguish between the pathologic remnants of VLDL versus the physiologic remnants …
Dave Feldman
I’m not even developing that. Let’s say I’m not even developing. I’m just taking the existing HDLC and LDLC metrics as they’re recorded right now. I’m just grabbing the data says it is right now.
Peter Attia
Yeah.
Dave Feldman
Will the remnant cholesterol that I get from that subtraction, will that actually be more relevant to all-cause mortality than say LDLC?
Peter Attia
I don’t know, but it would certainly rival it. I mean, again, the data are probably more clearer on non-HDL cholesterol versus LDL cholesterol, that’s typically what the literature talks about, but as you can tell that non-HDL cholesterol and LDL cholesterol are two of the three variables you would need. There’s a strong correlation between non-HDL cholesterol and remnant cholesterol, and yes, I believe non-HDL cholesterol is more predictive than LDL cholesterol.
Dave Feldman
But there’s one problem with non-HDL cholesterol I definitely want to bring up for people who are on a low carb diet. If you’re going to be powered much more by triglycerides directly, literally triglycerides being brought to you in VLDLs, then that is going to be relevant. Now, again conceding Peter, what we talked about before, I can’t know if I can stake my flag on it just yet, but I’d be willing to bet if I’m right on the energy model that if fact you are being powered more by triglycerides found in VLDLs, then you can have a higher resulting LDL particles.
Peter Attia
But, wait. That’s a … sorry, I’ll let you finish, but I think your missing something. Go ahead.
Dave Feldman
No, no. Go ahead.
Peter Attia
No, no. I’ll remember it. I feel bad I interrupted you.
Dave Feldman
Okay. No worries. Effectively, the bigger question is, are particular lean mass hyper-responders show casing directly that they’re being powered much more by triglycerides brought on these VLDL boats, if you will, and therefore having more subsequent LDL particles.
Peter Attia
Okay. My hypothesis is that that is not the case.
Dave Feldman
That it’s the higher degree of synthesis, right?
Peter Attia
Yes.
Dave Feldman
Going on with the cholesterol.
Peter Attia
That’s correct. That it is the higher degree of synthesis, which may or may not also be matched by a higher degree of absorption.
Dave Feldman
How would, if you were wanting to, if you’re going to suggest a way that we could test this, how would you suggest that?
Peter Attia
Before I do that, let me unpack where I think energy is moving from. I think we all agree that someone who is very insulin sensitive on a low carbohydrate high fat diet is utilizing a lot of triglyceride. We agree on that, right?
Dave Feldman
Yes.
Peter Attia
Okay. Let’s take an artificial construct and separate endogenous from exogenous triglyceride. Meaning someone on a low carbohydrate diet is eating themselves, and they’re eating triglycerides from the outside world.
Dave Feldman
Right.
Peter Attia
Assuming they’re in the phase of getting leaner. They’re losing weight or even someone who’s weight’s static, they’re utilizing their own internal stores of triglyceride that they’re replenishing. If they’re staying weight stable, right?
Dave Feldman
100%.
Peter Attia
Okay. The exogenous triglycerides enter the body through chylomicrons that’s a pure lymphatic play through CTAP that’s rapid hydrolysis. I think we all get that. I think it’s this other endogenous pool that’s interesting.
Dave Feldman
And if I could just interject this one thing, because this is one thing we’re dancing around that we both know that probably somebody’s who’s not familiar with my work should be aware of. Chylomicrons, they drop off these triglycerides and they’re just gone. Almost like depending on who reading within minutes or hours [crosstalk 02:00:31]. If you’re taking a fast cholesterol test, Peter, we were talking about it earlier, you shouldn’t see any chylomicrons or chylomicron remnants, they should be gone, and the cholesterol payload on those chylomicrons should be gone.
Peter Attia
That’s correct.
Dave Feldman
With that in mind, go back to the endogenous triglycerides.
Peter Attia
Endogenous means we’re dealing with the pool of triglycerides that are coming out of you as the person. You have adipocytes, adipocytes stored triglycerides, and those triglycerides are hydrolyzed such that you have free fatty acids that will be transported. Where do they go? When they come out of the adipocyte, who picks them up? Albumin. Albumin then does two things. It can take it directly to the muscle, so that the muscle can use in the highly fat adapted athlete, or it can take it back to the liver, and it can be repackaged in VLDL or it could be turned into a keto, if we’re getting into an extreme state of someone who’s ketotic.
Let’s talk about, what’s the guy’s name you said, Moffitt?
Dave Feldman
Craig Moffitt, yes.
Peter Attia
Okay. I remember seeing this in your presentation. He looked like a runner, great athlete, super lean dude, right?
Dave Feldman
Mm-hmm (affirmative).
Peter Attia
Do you have Moffitt’s number handy? Can you give it to me?
Dave Feldman
You, know what? I probably can. Glad you mentioned that.
Peter Attia
Even just directionally. I mean, I remember seeing this a few weeks ago.
Dave Feldman
Got it. Okay, just one second. This is perfect.
Peter Attia
Okay. I’m going to read this off to everybody, so Craig Moffitt who looks like a super fit dude, who’s running around, has a total cholesterol of 457 milligrams per deciliter. His LDL cholesterol is 335. His HDL cholesterol 109, and his trig is 67. I’m assuming you did the math correctly. I’m not going to check it, but if that’s presumably the LDLs direct, his remnant cholesterol is 13 milligrams per deciliter, and by the way, that’s not terribly far off from what you would get by the trig by five formula. He’s not that far off. Okay, fine.
Where is he getting his energy. Let’s say he’s out for a run. He’s not eating anything and he’s fat adapted, and he’ll say he’s fasted, let’s make it even easier. He’s fasted going out for a run. His adipocytes are releasing free fatty acids to albumin. The albumin is taking some fraction of that to the muscle directly, and they’re undergoing beta oxidation there. The albumin’s also going back to the liver, and some amount of that is being converted into beta-Hydroxybutyric, which goes down its own metabolic pathway, and some amount of that is being packaged in either a VLDL or an IDL because remember there’s still de novo ILDL production in the liver, just as there’s the novo LDL production.
Those VLDLs and IDLs are leaving the liver and dropping off their payload of lipid to the tissue. The tissue’s basically getting ketones from the liver, triglyceride from albumin directly to the muscle and triglyceride through the VLDL and IDL directly to the muscle. Do we agree on that?
Dave Feldman
We do. I’m just going to expand a little bit on what you just said. So, yes, it’s full body lipolysis, and that he’s releasing the free fatty acids. In the literature they’re usually calling it, NEFA, non-esterified fatty acids, but we’ll just keep it to free fatty acids. It’s getting released from all [crossatlk 02:04:32].
Peter Attia
We usually measure them by the way as one.
Dave Feldman
Yeah. It’s a little frustrating because a lot of these terminology gets interchanged, but the free fatty acids are ultimately making it back to its liver getting packaged into the VLDLs. What we’re talking about the target sites of the muscles for which are making use of triglycerides. I should emphasis that I believe that the primary purpose of the creation of those is to replete everything. It’s not just to fuel the muscles, it’s also to put it back into the adipocytes that just now released it as well.
In other words, Craig Moffitt like many people who are lean mass hyper-responders, if we could install a little turnstile into their adipocytes. We would see that turnstile just spinning like crazy. They barely park the triglycerides there before it’s heading right back out, and that’s because there’s less total adipose mass overall in Craig Moffitt compared to somebody who’s a lot heavier, and therefore there needs to be more global supply of VLDLs relative to somebody else who has a lot more fat mass.
Peter Attia
But this depends on his energy requirement?
Dave Feldman
Absolutely.
Peter Attia
I mean, of course while he’s running, and again, I wrote a blog post on this a lot time I ago, which I guess we ought to link to. It’s something about fat flux. I don’t remember the name of it exactly, but the gist of it was over simplifying a fat cell as having two input doors and one output door. The two input doors as being the de novo lipogenesis door, which is still an esterified entry door, but I separated as a different storage. Meaning it’s coming from a carbohydrate, not from a fat, and then you have the re-esterification door, which has the turnstile that allows fat to go right back in, and then you have the lipolysis door, which allows the fat to exist. A person who is in fat balance has a situation where L, lipolysis equals the sum of the esterified de novo lipogenesis plus the re-esterified fatty acids. Agreed? That’s just straight up math balance.
Dave Feldman
Yes, yeah.
Peter Attia
When Craig’s running, he’s in negative fat flux. Make no mistake about it. His de novo lipogenesis is zero at that moment. His esterification is something, and his lipolysis has to be something bigger.
Dave Feldman
Right.
Peter Attia
If he’s not depleting glycogen, which if he’s highly fat adapted, he’s not.
Dave Feldman
And maybe it’s worth putting on a distinction. I’m not talking about whether they were successfully at the moment that he’s running. Successfully re-esterifying these fatty acids back into the adipocytes.
Peter Attia
And they might be though. That’s my point, because we don’t know. What we know is that in, which goes back to the question …
Dave Feldman
But do we know that it’s the job of the liver to keep maintaining that buffet? To keep putting that energy back out there, and generally speaking, we do know that. It’s just to what degree?
Peter Attia
No, I mean my hypothesis is yes. My hypothesis is, which is not by the way, I don’t think is a commonly held view. I think a lot of people would disagree with me, but my view is that the liver is the an ergo stat of the body. I borrowed that term from Mark Friedman, who wrote an amazing chapter on this in 2008. That has been one of the most influential things in my thinking on appetite, but he described the liver as the an ergo stat. It was, an engineer will appreciate the nomenclature. It looks kludgy to someone who’s not an engineer to say why would he call it an ergo stat, but in engineering speak, that makes perfect sense, but that the liver is probably most susceptible to detecting some currency of circulating energy and circulating metabolites.
ATP would be the most logical thing for it to be sensing. Probably ratio the ATP to ADP, or ATP to AMP, or ADP to AMP, something like that, but yeah. I think the liver … I mean, I think most people appreciate how impressive the liver is in general. I was just talking to a patient this morning, and I said, “Look man, here’s the deal. Anything that goes wrong with you can be supported extracorporeally. You get into a coma, no problem. You need to go on a left ventricular assist device, okay it sucks, but it’s there. You need dialysis, you need a ventilator, all that stuff, we do not have extracorporeal support for the liver. It is too complicated.
Dave Feldman
Anybody who follows me knows just how much I’m loving this because you’re the preacher’s preaching to the choir by far. I’ve often referred to the liver as the straight laced partner, who always puts up with your crap. Whatever you’re giving it, it’s having to pour us out and figure out, and balance the ledgers, and get everything in.
Peter Attia
No, no. That’s a great point, and that was part of the other point I made to this patient, who was not in any way opposing that view. He was just asking if the elevation we’d seen in his liver function tests, which was mild could explain a synthetic issue to which the answer is not a chance in hell under normal circumstances because the liver has an enormous capacity to do its job under even the most ridiculous stress.
Yeah, but going back to Craig, at the moment that he is running, which is the same as saying if someone’s losing weight while they’re on a low car diet, they are in negative energy balance. They are in negative fat flux, and again, when I say losing weight, let’s ignore the water weight and stuff. I’m talking about legitimate weight loss or shedding of …
Dave Feldman
Metabolism exceeds.
Peter Attia
Yeah. Yeah, but that’s what it means, right? On a practical level, it means lipolysis, the amount of fat that is leaving the fat cell has to exceed that which is reentering it, and again, I don’t know that this is entirely relevant, but you’ve eluded to it, so worth reiterating. Not all of that is oxidized. Some of that free fatty acid leaves doesn’t get oxidized, and guess what? It’s mopped back up provided the hormonal mill you still permits it.
Dave Feldman
Yes.
Peter Attia
We agree on the completely. I look at his remnant cholesterol of 13 milligrams per deciliter, and say okay, it doesn’t tell me anything. I apologize. Your question was looking at that, what could we infer?
Dave Feldman
Yes, actually, and this probably gets to just a larger problem that I feel like remnant cholesterol is helping us to address is why is it that anybody would have high triglycerides at all? Why aren’t all triglycerides making their way to either the tissue that’s using it immediately, the skeletal muscle or the cardiac tissue, or to the adipocytes if the body means to not have it sitting inside of lipoproteins part in your bloodstream.
Peter Attia
That’s a totally separate question. I want to come back to this remnant cholesterol question, though.
Dave Feldman
But this is why the original graph that we talked to, this is why I draw that dotted line. I draw a lot of people’s attention to it is …
The dotted line I’m referring to as shown in this graphic, which was up on the screen we were using.
Peter Attia
Can you go back to that?
Dave Feldman
I’m sorry. I’m trying to find another one. Okay, yeah. This is the core emphasis.
Peter Attia
This is the energy delivery support diagram for the person who’s going to be looking at this later?
Dave Feldman
Right.
Peter Attia
Okay.
Dave Feldman
I mean, if I’m going to way oversimplify it, but not by too much – chylomicrons’ job deliver fat-based energy.
Peter Attia
Yeah, and is so far gone that it’s not really entering the discussion we’re talking about outside a very, very rare diseases.
Dave Feldman
HDL, not to deliver energy will just say, things not related to delivering energy, but I just call it support, generally speaking. Operations not related to delivering energy.
Peter Attia
I agree with that.
Dave Feldman
Okay. Last line. Liver, this being the ApoB containing lipoprotein is the one lipoprotein that clearly is pulling double duty.
Peter Attia
No, no, but hang on. Remember this is where your diagram at which you acknowledge is over simplified. The over simplification is hurting you. The liver has three purple arrows coming out of it, the VDL, IDL, LDL.
Dave Feldman
Agreed, which is why earlier I was emphasizing that I believe there’s a higher secretion of VLDLs overall for those people with lean mass hyper-responders, which is very relevant to our discussion.
Peter Attia
How do we know that?
Dave Feldman
It’s a theory. I’m not saying that. What I’m saying is as if this area was fatter, if the VLDL secretion is at a greater degree, it would make sense why there would be more remodeled final LDL particles remaining, and why would we see the inversion pattern in the first place? Because it originated in order to deliver more of those triglycerides, which was brought about.
Peter Attia
Why the excess cholesterol? If that were the case, Dave, wouldn’t you hypothesize that the LDL particle would be very high because you have more VLDL particles, but they’re shedding all of their triglyceride in an effort to deliver their energy payload, but you shouldn’t have an increase LDL cholesterol. You should actually have a reverse discordance from what we see in the insulin resistant patient where we typically see the LDL particle number, being this proportionately higher than the LDL cholesterol by percentiles, of course, and absolutely members, that’s always the case. In other words, if I was buying your hypothesis I would say the LDL cholesterol should be very low. You should have very cholesterol depleted skeleton particles that were mostly used to shed triglyceride as VLDL.
Dave Feldman
But instead, we see the concordance. We see the LDLC and the LDL-p very concordant in people who don’t appear to have other types of diseases.
Peter Attia
Well, at that point they’re so high. It’s hard to know, but clearly not discordant in the direction that would make sense given your hypothesis. In other words, what I’m getting at is, why is there so much cholesterol in those LDLs.
Dave Feldman
Correct me if I’m wrong, but as far as the actual drop off rate, the LDLC is still going be relatively standard on a per particle basis in a healthy subject. How much variability is there typically in LDLC per LDL particle because again, correct me if I’m wrong, I thought that the secretion level tends to be fairly standard, like a spare tire is standard for a car.
Peter Attia
Yeah, it’s …
Dave Feldman
The triglyceride levels can be very variable.
Peter Attia
Yeah, but the cholesterol levels. I mean they have capacity to carry a lot, but think about it. If you have large and small particles that even for the same amount of triglyceride have different amounts of cholesterol, but the bigger point is, where is the cholesterol coming from? If we go back and look at my guy, or look Moffitt. Moffitt’s LDL cholesterol was 335 milligrams per deciliter.
Dave Feldman
Right, but that’s what’s in circulation in the blood at that time.
Peter Attia
Hang on. Just to be clear, Dave, is there any point during his 24 hour day when that number is 30 milligrams per deciliter of LDL cholesterol in his bloodstream.
Dave Feldman
I don’t believe so.
Peter Attia
In other words, if you take the area under the curve, if we could get real time LDL cholesterol number on Moffit, and integrate him over 24 hours, we could argue for argument’s sake, he’s going to be always over 300 milligrams per deciliter. Hus AUC would be very high.
Dave Feldman
For the existing traffic of the LDL particle, I mean basically what we’re talking about is what’s, I almost want to say it in terms of birds in the air. You have so many ships that have left the dock, that are continuing in circulation, but I guess here’s a different question that I’ll pose back to you.
Peter Attia
But, wait. I’m actually asking this because I’m trying to understand it.
Dave Feldman
How much of this cholesterol has already made a lap? Are you thinking of this in terms of it all getting synthesized and then reabsorbed, and then recreated it again?
Peter Attia
Let’s go back and make sure we’re agreeing on the same conditions here. Notwithstanding the experiment where they eat a ton of fat and they go from having incredibly high LDL to very high LDL, but let’s just take Mofitt, over the course of a week. Assume you could do real-time LDL cholesterol sampling on him.
Dave Feldman
And specifically, LDL cholesterol?
Peter Attia
Yes.
Dave Feldman
Okay.
Peter Attia
Or everything. Everything that’s on your page. You could sample his total cholesterol, his HDL cholesterol, his LDL cholesterol, his VLDL cholesterol, and his LDL particle number. You could sample all of these things in every second for a week. I think we’re agreeing that he will always have a very high LDLP and a very high LDLC and a low VLDLC. Correct.
Dave Feldman
Unless he eats a lot of fat.
Peter Attia
Okay. Yeah. Let’s, we’ll come back to that after, but yes.
Dave Feldman
Sure.
Peter Attia
Okay. So, given that the half-life of his LDL is a day, where is that extra LDL cholesterol coming from?
Dave Feldman
I believe it’s being recycled.
Peter Attia
Well, it’s always being recycled. How is his being recycled? So, so where is his, where is he deficient in cholesterol that a person who has an LDL cholesterol of 100 is not?
Dave Feldman
I guess I don’t understand the question. Where is he deficient?
Peter Attia
Yeah, if he’s got 335 milligrams per deciliter of cholesterol in his LDL particles, are you telling me that he has less cholesterol in his cell membranes or less of it somewhere else?
Dave Feldman
No.
Peter Attia
So he has more cholesterol in his body.
Dave Feldman
Correct.
Peter Attia
Why?
Dave Feldman
For the same reason that we would have say, life rafts on a boat and once we have more boats, we have more life rafts. So, if we had a harbor just outside this window, right? And you had 100 boats and on those hundred boats, their main job is to deliver something unrelated to life rafts. They’re delivering cargo to the other island. Right? And they deliver, and 100 of them go out, 100 of them come back. And then demand on that island has changed. Now they need to deliver five times as many things as they were delivering before.
Peter Attia
But the problem with that analogy is it assumes a completely fixed number of life rafts per boat.
Dave Feldman
It definitely does.
Peter Attia
But that’s not how the lipids work.
Dave Feldman
How does it work?
Peter Attia
There’s much more flex in the system. And furthermore, you could ask the question in reverse, why isn’t it higher?
Dave Feldman
Why wouldn’t LDLC be higher per boat?
Peter Attia
No, why wouldn’t LDLC be higher in that patient? In other words, what’s regulating it? What’s regulating how much LDL cholesterol he has?
Dave Feldman
The demand for the boats themselves for LDL particles.
Peter Attia
But what’s driving that demand? This is, I think where we differ, right?
Dave Feldman
The demand of the delivery for the triglycerides. The demand is for the cargo, the originating cargo that is clearly getting used.
Peter Attia
Right, but we agree that the VLDL vanishes very quickly.
Dave Feldman
The VLDL remodels to LDL very quickly.
Peter Attia
Yes, but if you go through the kinetics of this, I can’t follow why he should still have that much LDL cholesterol unless he is making more cholesterol. In other words, I’ve tried to think of this 10 ways to Sunday, the only way on a mass balance that I can explain this hypothesis is if he’s making more cholesterol.
Dave Feldman
And not if he’s recycling the same cholesterol? Certainly he’s making more relative to someone who doesn’t.
Peter Attia
Only if he were depleting it in some other store. So in other words, I’m making this up, but if you could say, well, all of us … I mean you probably know this. Everyone loves to quote this fact, right? But red blood cells have more cholesterol in them than LDL particles, right?
Dave Feldman
Right, right.
Peter Attia
So the, the LDL denier loves to say, “Well, we don’t think red blood cells are causing atherosclerosis and yet they have more LDL.” Whatever. But my point is, unless you’ve depleted a pool of cholesterol elsewhere in his body, just on mass balance, you had to make more of it.
Dave Feldman
As far as I understand, the liver can recycle cholesterol as many times as it wants to.
Peter Attia
Again, that’s true, and the liver and the gut have a very clear pathway, which he described.
Dave Feldman
Correct me if I’m wrong, the liver is the only organ that can actually degrade cholesterol, right? Non hepatic tissues can’t degrade cholesterol.
Peter Attia
Well, again, it depends what you mean by degrade. Remember, cholesterol has no caloric value. It’s not a metabolite. It’s not something that we metabolize, right? We turn it into-
Dave Feldman
If you were synthesizing more, you’re saying it’s going to go somewhere if it needs to be synthesized more.
Peter Attia
Right. If you’re synthesizing more, presumably you have a higher growth of the organism. You have more cells, you need more cells because obviously probably the highest demand for cholesterol is for cell membranes. So that’s what I’m trying to figure out. It’s like, where is all this extra cholesterol coming from? If it’s not being synthesized de Novo?
Dave Feldman
And that’s my larger point. The inversion pattern is part of what should bring this to light. Is, why then, when I have an enormous amount of fat over three days, I would see my LDLC dropped by 73. Why would I see my LDLP drop by 1,115 in three days from eating huge amounts of dietary fat? Why would that happen?
Peter Attia
I mean, it’s an interesting question. I’m just not sure. All it’s basically saying is you have a way to perturb those levels. I mean, I’ll give you another anecdote here. So, you know, I did a one week fast, I went Keto for a week and then ate nothing for a week and now I’m actually back on Keto for a week and I’m checking my blood every seven days. So that was my LDLP before I … That was just me. That’s my normal LDLP. So I’m walking around at 920 nanomoles per liter. This is after months and months of time restricted feeding with virtually no carbohydrate restriction other than just I don’t eat crappy carbohydrates.
Dave Feldman
Right.
Peter Attia
So then I went Keto for a week and look, my LDLP actually went up. Now I don’t think I would meet criteria for being a “hyper responder” because it went up to 1380, which is not that high, but you know, that’s still a significant jump for me. Right? Okay. What should it have done when I fasted for a week? Shouldn’t it have gone up according to this model?
Dave Feldman
Well, here’s the catch. The catch is, I only know the three day window. I don’t have a lot of data from people who fasted for a week, as in just water fasting.
Peter Attia
I do.
Dave Feldman
Okay. You do? Good.
Peter Attia
Yeah. I’ve done this on multiple patients who have done three, five and seven day fasts.
Dave Feldman
Okay. Who are fully ketogenic and you’re saying it typically goes-
Peter Attia
Not always ketogenic. No. Sometimes they’re just, you know, fat adapted. Sometimes they’re not. Sometimes they’re actually insulin resistant and we use the fast to kick them into a state of Ketosis to make it easier. But, and again, I want to be very careful. This is simply just anecdote because I’ve only done this on maybe 30 people, but this is not uncommon. I mean, look, my LDL cholesterol went from 64 to 37 after the fast. I mean it went way down.
Dave Feldman
Wow. Fantastic.
Peter Attia
And that’s consistent with what I see. Now, that’s not the reason I’m fasting. To be clear. I’m not using a fast to manipulate lipid proteins. I’m doing it for a completely unrelated reason, but my point is I always see, and again I can say always because it’s a relatively small end. Obviously, at a large enough and you’re going to see counterexamples to anything and everything, but the general principle seems to be under caloric deprivation, LDL goes down and under fat deprivation LDL goes down.
Dave Feldman
I’ve got to put in the one footnote and it’s an annoying footnote that I keep putting in. I really need to. And this is why I’m dying to get these parts of the exercise. I need to look at a population that also is not getting any, particularly weight training or resistance training and so forth, because that seems to impact it. Whether it’s my theory or not, that seems to impact overall lowering LDLC numbers. I’d be very interested about this in fasting.
Peter Attia
I’ve got that in my patients. Not every one of my patients lift weights despite my best efforts. So, again, I think the more common thing that we see is that when you put people on a high fat diet, the ones that go on to have this hyper response, as you note, their trigs usually go down, their cholesterol goes through the roof and it’s driven by a doubling, tripling, or even greater output of synthetic biomarkers like desmosterol. Now, for reasons I don’t understand, you also tend to see at least two of their three phytosterols go up. Now, one thing we didn’t talk about though, I wrote about it, so I’m sure you know about this, is this seems reversible. If you eliminate the saturated fat.
Dave Feldman
It does seem to matter in this case, and you’ll like this, at least in our own data with ApoE4s, seems more likely if you’re an ApoE4, you will see a drop somewhat in saturated fats.
Peter Attia
So I don’t think I have a large enough sample size because I’ve only put seven patients through that protocol. Which is, and I wrote about the very, very first one. So that’s probably the only one that you’ve seen that I’ve talked about, but this was a young guy who went on a Ketogenic Diet, was crushing it, meaning like everything was going well. I mean he’d gone through the adoption period. His performance was exceptional, mentally never felt better. He was not an overweight, or metabolically ill guy to begin with. He was just kind of a normal software guy who just decided he wanted to take it to the next level. But then he showed up with labs, not unlike these. He was the first guy I ever saw where there was a greater than sign on the LDLP.
Dave Feldman
Right. It maxes out at 35.
Peter Attia
I was like, “Oh, I didn’t actually realize the assay stopped at 3,500. This guy is my guy.” He looked better on some of the other metrics. He didn’t actually have a lot of the inflammatory stuff. This was before the Ox LDL assay was commercially available. So I didn’t have that. But you know, his CRP and is LPPLA2 we’re okay. But we had the discussion, right, which is the discussion that at the end of the day I’m accountable for having, which is what are we going to do about it? And he was young. I mean the guy was 30, so it wasn’t like we had to do something tomorrow. This is not a guy who’s going to have a heart attack in a week.
Dave Feldman
Because I think when you originally writing about it, he actually pushed back a little bit. Like he wanted to come up with a-
Peter Attia
Well, what he pushed back on was, because I basically said, “Look man, I don’t think the Ketogenic diet’s right for you. These numbers are crazy.” And he was like, “Yeah, I don’t ever want to go back to what I was doing before.” I mean he basically said in not so many words, like I’d rather die of a heart attack and feel this good. And he’s not saying like, “I’m going to die of a heart attack tomorrow”, but he’s like, “Look, I’d rather live to 60 and feel this way, than live to 70 and not.” Which I say totally fair by the way. That’s a very reasonable trade off to make, but let’s also think about this a little more logically. So that was actually probably the first case I ever discussed with Tom and this was I think back in 2011 and it was actually this discussion I think that lead Tom to go on to write the lipidaholics case, even though it wasn’t the patient that he used in that case because he then went out and found others like them.
What we just decided was on biochemistry first principles, our hypothesis was it’s the saturated fat, more than the ketones. Because that was the other thing, this guy didn’t want to leave ketosis. My thought was, let’s just dial this back, get you out of Ketosis. So our hypothesis was both ketones and saturated fat can be readily converted into cholesterol, but if he’s adamant on staying in Ketosis, let’s at least get his SFA down to 25 grams per day. Which was hard. This is a guy that was eating about 100 grams of SFA a day, maybe 80 grams. I mean, it was a lot. We basically just made most of it MUFA. So I said to the patient, I said, “Look, the way we could do this just for no other reason as the purpose of a thought experiment is, you’re going to basically have to become a nonstop olive oil, Macadamia nut eater. Even even the avocado you can’t go hog wild on because eventually you’ll get too much carbohydrate out of it for this purpose.”
And sure enough, I think he came back at like 1300, after eight weeks or something like that. So six more patients have been so adamant about staying in Ketosis and not taking any medication but wanting to go through this experiment and all of them have had the same response. Which is, if you can get them to main line MUFA, you fix the whole problem. Without reducing or increasing to any measurable effect, how much fat they’re consuming.
Dave Feldman
Have you been keeping track of their PUFA levels too? Because it’s hard to add a lot of MUFAs-
Peter Attia
Their PUFA was going up.
Dave Feldman
And you know, the issue with that, with adding more PUFA, is the downside is there’s the potential that you’re actually adding more peroxidation on the particle basis.
Peter Attia
Yeah. Yeah. I mean, I think it depends. This is one of those areas where I’m trying to get a lot smarter and I want to make sure I’m not sitting in the echo chamber. I’ve historically, you know, measured RBC levels of arachidonic acid and all of those things and tried to keep track of the ratio of that to the EPA and the DHA, but ultimately I don’t really think I know the answer to this yet. And I also don’t think … My guess is PUFAs are not as bad as I have historically thought them to be, but they’re probably not as good as MUFA. So not withstanding that, I just want to talk about this from the level of the thought experiment, so to speak. My sample size of those people is too small to know if there’s a relationship to their ApoE gene. To your point, what I’m hearing you say is maybe that’s more … That’s something that you’re more likely to do in someone who’s an ApoE4 carrier.
Dave Feldman
It’s been a proportional kind of thing that we’ve sort of noticed.
Peter Attia
I don’t know, but what I do know is it seems to point back to this idea that the hyper responders … That the Occam’s razor here is that they’re making more cholesterol. Because that makes sense from a mass balance standpoint. Again, I’m still-
Dave Feldman
And I would have agreed with you were it not for this energy inversion that I see. If it were not … The very thing that I said from earlier that I could move my LDLC to where I want to move it. That would be based on me basically arranging for a few days to eat to a certain level and I’d be pushing down my LDLC by eating up to a certain-
Peter Attia
Notice you’re pushing up and down on LDLC within super physiologic levels. Meaning, if I recall seeing your data, do you mind showing me that again?
Dave Feldman
Unfortunately, the computer died. That’s why I’ve had it closed, but yes, what you’d see as an inversion graph and-
Peter Attia
I’m very familiar with it and we’ll obviously link to it, but it was, as I described it, you’re showing that you can move your LDL between the ranges of very high and stupidly high.
Dave Feldman
No, like I’ve, I’ve moved my-
Peter Attia
What’s the lowest you’ve ever got your LDL?
Dave Feldman
98, and I suspect-
Peter Attia
Okay.
Next part: Guesting on the Peter Attia Drive (4 of 5) – Energy Status, Risk, Testing the Hypothesis
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