FoundMyFitness - #040 Dr. Eric Verdin on Ketogenic Diet Longevity, Beta-Hydroxybutyrate & HDAC Inhibitors

Episode Date: December 13, 2017

Eric M. Verdin Eric M. Verdin, M.D. is the fifth president and chief executive officer of the Buck Institute for Research on Aging and is a professor of Medicine at UCSF. Dr. Verdin's laboratory focuses on the role of epigenetic regulators in the aging process, the role of metabolism and diet in aging and on the chronic diseases of aging, including Alzheimer's, proteins that play a central role in linking caloric restriction to increased healthspan, and more recently a topic near and dear to many of you, ketogenesis. He's held faculty positions at the University of Brussels, the NIH and the Picower Institute for Medical Research.  In this episode, you'll discover: (00:00) Introduction (07:32) Interventions to prolong lifespan (10:42) The role of insulin pathways in aging (16:25) HDAC inhibition by ketones (27:52) Protein activates mTOR & IGF-1 (30:28) PPAR-alpha activation facilitates benefits of a ketogenic diet (35:28) What biomarkers can predict aging? (39:38) Cellular NAD+ levels decrease with age  (52:47) Ketogenic diet safety  (56:07) Intermittent fasting as an alternative to a keto diet If you're interested in learning more, you can read the full show notes here. Join over 300,000 people and get the latest distilled information on ketogenic diet & longevity straight to your inbox weekly: https://www.foundmyfitness.com/newsletter Become a FoundMyFitness premium member to get access to exclusive episodes, emails, live Q+A's with Rhonda and more: https://www.foundmyfitness.com/crowdsponsor

Hello, everyone. Today's podcast features Dr. Eric Verdin. Eric's laboratory focuses on the role of epigenetic regulators in the aging process, the role of metabolism and diet and aging and on chronic diseases of aging, including Alzheimer's disease, proteins that play a central role in linking caloric restriction to increase health span, and also, more recently, a topic near and dear to many of you, ketogenesis. He's held faculty positions at the University of Brussels, the NIH, the Pekauer Institute for Medical research. He is a professor of medicine at UCSF and is currently the fifth president and chief executive officer of the Buck Institute for Research on Aging. In this podcast, we talk broadly about many interesting

areas of inquiry in aging, especially the areas that Dr. Verden and his colleagues are involved in. But of special interest is his lab's recent publication on a cyclic ketogenic diet, in other words, a version of the ketogenic diet where they rotate a normal diet and a ketogenic diet periodically. Particularly interesting is that it reduced midlife mortality and also memory decline. We also discussed some of the current research, including Dr. Verdins, regarding the role of NAD plus in the aging process, a topic made especially popular due to the research surrounding nicotinamide ribosite, a precursor to NAD plus as a potential anti-aging supplement. A few words about this episode, this podcast I would rate as a six or maybe seven in terms of

technical difficulty. In other words, relative to my other podcasts, there are some that have greater technical depth, but there could be a few stumbling blocks in this one too. So let's talk about those. The three stumbling blocks for this podcast, if there are any, are probably the discussions surrounding EMTOR, P-P-A-R-Alpha, and a family of enzymes known as H-Dacetylases, and the compounds and enzymes that inhibit them, which are known as H-Dac inhibitors. So let's talk about these things right off the top of the list. The first thing I just brought up was EMTOR. M-TOR functions as a master regulator of cell growth and metabolism. Emptor activity is increased when we eat protein, and it's activated by essential amino acid intake, and thus protein intake. When we take in amino acids, we boost the

IGF1 signal, which then triggers protein synthesis and cell growth through the activation of mTOR. Emtore is interesting because on the one hand, most research in the field of aging suggests that we should try to limit the activation of mTOR, which is why we often talk about fasting, caloric restriction, also in some cases protein restriction as strategies for delaying aging. There's also a lot of interest in the aging community in inhibiting mTOR pharmacologically. One candidate, particularly well known for its ability to inhibit mTOR, is known as rapamycin. Maybe some of you have heard of it. On the other hand, sometimes we want a little boost in cell growth and metabolism, and it isn't a bad thing. If you're a bodybuilder, you probably want growth, and to do that, you probably eat more

protein than someone who is sedentary. In this case, you might be deliberately, whether you know it or not, mTOR and its upstream signal IGF1 when you're consuming amino acids in the form of protein. Additionally, we know that frailty is actually a predictor of mortality in the elderly. So what is a person to do? Questions like these are ultimately what make the field of aging and even nutrition very difficult. The answer is almost always it depends on many factors. It could depend on your age, where it's known that elderly actually have a lower all-cause mortality if they consume more protein, perhaps helping mitigate the approximately 10% muscle mass we lose per decade starting in midlife. It could depend on whether or not you're physically active or not, because physical activity

might affect what tissues these growth signals end up concentrated in. Or it could depend on the existing health of your tissues and the amount of DNA damage and inflammation they have been exposed to, which might have the quality of creating an environment of cells just damaged enough that they are just looking for an environment that is rich in growth signals to begin the formation of a cancerous mass. These are all really important things to consider. The truth is, it may be a while before we have all the answers to all of these questions. So that's IGF1 and mTOR in a nutshell.

Caloric restriction, prolonged fasting, intermittent fasting, some anti-aging drugs, and even certain versions of the ketogenic diet that are low in protein, which is the version we're usually talking about, if we're talking about aging research, all have the quality of suppressing mTOR. And this is almost certainly an important part of the cellular me you associated with any type of health span extension that these strategies might confer. Now on to the next potential stumbling block you might find in this podcast, which is PPR Alpha. The first thing you should know about PPAR Alpha is that it is absolutely critical for ketogenesis. It is activated by caloric restriction or fasting and nutrient deprivation, especially

carbohydrate restriction, and plays an important role as a transcription factor in the promotion of the uptake, utilization, and catabolism of fatty acids. It does this by upregulations of genes involved in fatty acid transport, fatty acid binding and activation, and paroxysomal and mitochondrial fatty acid beta oxidation. What we learned from Dr. Verdon in this episode is that activation of PPA-R alpha might play a special role in some of the beneficial effects of the ketogenic diet, at least in mice, because as Dr. Verdon explains, this is one of the biggest differences that his lab has seen between the ketogenic diet fed to mice and a high-fat low-carb diet that was not ketogenic.

What's interesting about the PPR genes is that there are several well-known polymorphisms found in human populations, and some of these have been included in the raw data a person can get from certain genetic providers like 23 and me. Evidence suggests that these polymorphisms can actually have a pretty significant effect on the way in which fat, especially the ratio between saturated fat and polyunsaturated fat, influence blood markers of cardiovascular disease risk. This is a topic all on its own that we don't actually get into in this episode, other than a brief mention, but you can learn more about that by visiting my website at

found my fitness.com forward slash genetics. Once again, that's found my fitness.com forward slash G-E-N-E-T-I-C-S genetics. Finally, we get to the third potential stumbling block of the three I mentioned, histone diacetylases, otherwise known as H-DACs, and histone deacetylase inhibitors, otherwise known as H-DAC inhibitors. H-Dac inhibitors, by virtue of inhibiting enzymes that go around removing acetyl groups from histones, actually increase, the expression of certain genes. Dr. Verdon's work has shown that beta-hydroxybutyrate, a ketone body we produce a lot of during fasting, and when we are under a carbohydrate restriction, can function as a Class 1 H-DAC inhibitor to increase the genetic expression of a gene known

as FOX-O-3. This gene is well known for its role in the protection from oxidative stress and involvement in delaying aging. Not mentioned as a potential stumbling block is also some pretty deep conversation about atophagy, a very important cellular cleanup mechanism that is activated when we fast. But if anything, that part of the conversation should just be a refresher for any of you that heard the discussion with Dr. Guido Kramer. If you're drawing a blank, head back a few episodes and listen to the episode with Dr. Guido Kramer. It's a great one and really gets into the nitty-gritty of the biology surrounding cellular atophagy, an important topic, especially when we're talking about fasting and health span. Okay, that said, you are in

now equipped with a brief primer on mTOR PPAR alpha, HDAC, and HDAQ inhibitors. This concludes the official Found My Fitness intro. Now, away we go to the podcast. Hello, everyone. Welcome back to another episode of the Found My Fitness podcast. I am sitting here with Dr. Eric Verden, who is the president of the Buck Institute for Research on Aging. Now, I recently saw a quote from you that said, you stated that a child born in the year

2007 had a 50% chance of living to be 104 years old. First of all, yes, you did. Can you explain what you mean by that? Because that's pretty exciting. I think it says what it says. It's based on the projection of where the progression and lifespan that has happened during the last 100 years, which has been about two years per decade. I think scientists at Berkeley, actually, I've been able to, this data comes out of a book

that was based on data from Berkeley, suggesting that a child born in 2007 has a 50% chance of living to 104. After reading that quote, I was thinking, well, maybe some of these lifestyle interventions that we know to regulate the aging process that we know that can have a positive effect on health span. Can you maybe tell people a little bit about what are some of the main lifestyle interventions that are known to regulate the aging process, at least? least in animal models?

Yes. And in humans as well. I think there are four broad categories of things that are being considered by the aging field. One is exercise. Is to this day the surest best intervention that we have to increase health span and lifespan. The second one is nutrition. And there's a lot of research going on today trying to understand what is it about

nutrition, is it carbohydrates versus fat versus proteins? What is the relative role of all these nutrients in your lifespan and health span? The third one, which is actually an active field of investigation, is the identification of molecules that mimic either exercise or the sort of exercise memetic or mimic restriction in terms of nutrients, so what we call calorie restriction memetics. And finally, the last part of the whole aging field is the idea of rejuvenation. So the first three approaches are geared towards slowing down the process of aging, rejuvenation takes the approach that once the aging has occurred, how can you repair it and how can you fix it? So I think we have programs here that are studying all four different approaches. I think you're

probably familiar with Jack Lillane, who was one of the gurus that started the American sort of infatuation with exercise, and he said, he lived to 100 years old, and he said that exercise is king, nutrition is queen, put them together and you have a kingdom, which I think is really true. So I think it's, you know, for me and many of my colleagues, I think exercise and nutrition is the cornerstone of what we're trying to do today until we have better drugs. That's a beautiful quote. And in terms of the nutrition, when I think of nutrition, and you mentioned, you know, know, the macronutrient content, trying to understand the ratios of carbohydrates and

protein and fat. I often think of the micronutrients. When I think of nutrition, I train my mentor for my postdoc was Dr. Bruce Ames. And, of course, you know, he's very focused on micronutrients, vitamins, minerals, essential fatty acids and amino acids. But, you know, in the past, you know, a couple of decades, the research has seemed to shown that, you know, limiting these certain macronutrients, you know, protein, fat, carbohydrates, you sort of tweak the amount that you take in. You can alter the way in animal ages, at least

in terms of the way their tissues are aging. You're not necessarily going to, you know, increase their maximum lifespan, but you may increase their average lifespan, which is... Yes. I think we, in the last 20 years, we've learned a lot. And a lot of this, you know, research has been actually causing a reevaluation of some of the public policies that have been enacted in the last 20 and 30 years in terms of what should you eat, when should you eat. So a lot of work is ongoing today and actually generating lots of really interesting data. Along with this, the basic science of aging, I think what people have studied is trying to understand what are the pathways that control aging and see elegans.

in Josophila, the fruit flies, and the little nematod or in mice, one of the major pathways that has emerged is insulin signaling pathway. That was the work of Cynthia Kenyan back in 1990s, showing that the insulin signaling pathways, one of the major pathway that controls aging. Well, if you know this, you can already sort of backtrack and say, well, what is insulin do? It's the major hormone that allows you to utilize carbohydrate.

And so the implication of this is the more carbohydrate you eat, the more you activate the insulin signaling pathway, and the prediction would be that the more, the faster you age. And I think real data really suggests this model. Now, it flies completely in the face of what we've assumed to be correct. You can walk into any store and find low-fat diet and low-fat products. Turns out that we really believe that the culprit is more carbohydrates. And the recent paper just came out, which is really remarkable showing,

analyzing in thousands of humans, a fraction of their total calorie intake that is represented by carbohydrates. And they were able to, so just by interviewing them and asking, what do you eat? And what they showed in this paper is the all-cause mortality was directly correlated to the amount of carbohydrate that one eats. So the people who ate the least amount of carbohydrate showed the lowest all-cause mortality. Wow. Did they differentiate between refined carbohydrates and, for example, vegetables, which are

carbohydrates? They did. They didn't. And I think, you know, this is obviously not our carbohydrates are created equal, but I think possibly a confounder. Irrespective, irrespective, total carbohydrate was a very strong predictor. But obviously, you know, if you, your total carbohydrate intake is, it's very hard to eat a high amount of carbohydrates that are all sort of a low absorption type of carbohydrates.

So typically the people who eat a lot of carbohydrate will eat a lot of the bad ones as well. Right. Yeah, most people that are eating that are probably eating more of a standard sort of American diet, you know, where it's chips and crackers and cookies. And I think people that are following more like of a paleolithic type of diet where they're eating, you know, whole foods and meat and nuts and probably would eat their carbohydrate intake. The bulk would be from vegetables and things like that.

So, but you're mentioning a really important point is that, you know, the, you know, the, the carbohydrate intake and the, you know, the insulin signaling pathway, you know, these things, carbohydrates regulate that, but also you limit your carbohydrate intake when you're fasting. Yes. Correct. I mean... You limit all of your intake.

Essentially, yeah. But you certainly, your insulin signaling goes down, right? And maybe you can talk a little bit about, you know, because fasting is one of the well-known, you know, dietary interventions to that kind of. regulate the way we age. Yes. And the key question about fasting is there's growing evidence that it is beneficial. Intermittent fasting, episodic fasting can actually elicit a response in our bodies and many

animal models that are protective against aging. The question is, how does it happen? So fasting is as growing evidence that it actually increases lifespan and health span. and so-called fasting-mimicking diets are emerging, a group of Walter Longo suggesting that, you know, these diets have really beneficial effect on health span, even in humans. Now, the key question is how do they work? And there are multiple possible mechanisms. And it is possible that the resulting effect is a combination of all of them, of all mechanisms.

So one is decreasing carbohydrate intake. So that would lead to decreasing insulin signaling. The second one is restricting protein intake, which would actually lead to decreased sore signaling and so on. The third one is induction of ketosis, which is a small nutrient, which is generated by your liver during the fasting process. And our work indicates that just ketosis and the ketogenic diet might have beneficial effect all by itself. Yeah, so you recently published a paper, your lab recently. published a paper where you had taken mice, male mice, and given them a cyclic ketogenic diet.

Yes. So that started in midlife? Yeah, actually, it started at one-year-old. One-year-old. So this is about the third of their normal lifespan, so it would be the equivalent of a 30-year-old human. Okay. And you found that it, so exactly what you found, that they increased the health span of these

animals? And also there was some effect on the brain? Yes. Very interesting data suggesting, again, the whole experiment started on the idea, on the observation that there are many similarities between what happens during ketosis on a ketogenic diet and what happens on calorie restriction or fasting. And so we, with a colleague in the lab, John Newman, a number of years ago, we started asking the question, would mice on a ketogenic diet live?

longer. So we spent about a year and a half with John trying to identify the conditions where these mice would be on a fat and protein diet, essentially had zero carbohydrates after one year of age. The problem that we had initially is that they actually loved the stuff. So they would just devour this diet and it got fat. So we were worried that by becoming obese, we would sort of counterbalance the beneficial effect of the kit-to-change diet. So we spent a bit of time trying to solve this eventually, we're able to put them one week on, one week off, and that result in a stable weight in the mice,

and that allowed us to look at their health span and lifespan at the end of their lives. And what we saw was an increased medium lifespan, but about 10%. So early mortality was decreased. but eventually they ended up having no increase in maximum lifespan. We also found a number of other variables associated with health span that were significantly increased, in particular memory. These mice, the most remarkable thing we saw is that these older mice on the ketogenic

diet showed actually better memory than younger mice. And certainly did not see the loss of memory function that one would normally see associated with the aging process. So I think it was a pretty profound observation. I should say also John Ramsey and his colleague at UC Davis conducted the same type of experiment, except that instead of putting the mice on a cycling one week on, one week off diet, they allotted fixed portions to the mice. So they couldn't overeat.

They gave them the same amount of calories that they would have been eating had they been on a normal diet. And so these mice did not get fat and work. continuously on the ketogenic diet. And what they saw is essentially parallel to what we saw, but the effects were even a little better, which suggests that the cycling might have been actually a bit stressful for the mice over the long run. And so I think we're very excited by these two studies because they were conducted independently.

We find out only that we were pursuing the same thing right at the end at the time of publishing, then we decided to coordinate publication of the stories and they came out in the same journal together. So I think they both reinforce each other. There is really clearly intriguing biology there are happening. And this was the first time that this had been reported. Wow, absolutely. It's very exciting. I read your paper. I did not read the parallel paper. I did see the headline for it. But just to kind of go back to the memory thing that your lab identified, So, you know, the ketone body, that's, you know, the major circulating one that's generated is beta-hydroxybuty.

And that's involved in energy metabolism, but also you have found, you know, it has other roles in addition to its role in energy metabolism, which we can talk about in a minute. But what are your thoughts as to why the memory, you know, the memory enhancement was so good or, you know, so robust? Do you think it has to do with energy metabolism, mitochondrial function? or do you know? We do not know, but that's the central question of everything we do right now with respect to the ketogenic diet is really trying to understand.

So beta-hydroxibuterate is generated from our own fat during the fasting process. So when we start fasting, the body needs energy and we'll grab it out of our fat cells. This fat cells release fat in the circulation. It goes into the liver. and the liver transforms the fat into beta-hydroxibuterate. Now, why does it do this? Because our brain cannot use fat as a source of energy. Our brain can only rely on glucose or on beta-hydroxiboutrexiboutes.

And so the way the system is geared up is the fat gets released into the liver, and the liver distributes the beta-hydroxibouterate to the whole brain, who can then use it and spare glucose. Right. So why do you want to spare glucose? glucose, the reason is that once you are fasting, at least for four hours, all of your, the only way you can make glucose is from proteins. And so if you're in a prolonged fast, you start digesting your muscles to make proteins,

to make glucose. And you cannot, you don't want to lose all of your proteins and all of your muscles. So the glucose-sparing effect of beta oxidary is to spare muscle mass if you're fasting. So the system is really carefully engineered. to really generate a whole new way for your body to utilize energy when you're faster. Right. Are you aware of the glucose-sparing effect in the brain where I know it's been shown with, at least in terms of lactate, so the astrocytes in your brain do make lactate because they're glycolytic, and the neurons will take it up, much like beta-hydroxybutyrate,

they go through the same transporter. Yes. But when there's an abundance of lactate, and I don't know if studies have been done on beta-hydroxybutyrate in the brain looking at this specific thing or not. But the glucose sparing that occurs is the glucose gets shunted into the pentose phosphate pathway to make NADPH, which is in a precursor for glutathione synthesis. And so the idea is that under like a traumatic situation, like traumatic brain injury, when there's a lot of oxidative stress happening, you need glutathione to counter some of that.

So it'd be interesting to see in your study if you can look at some of the, of those pathways to see if they're upregulated or making more glutathione, because brain aging kind of is like a traumatic insult, but like slowly chronic, right? I mean, in a way. Well, you know, we published the paper. What got us into this field was an observation that we published in science in 2010 showing that so beta-hydrox butlerate, in addition to being a nutrient, as we just discussed, is also a signaling molecule.

And what we found at that time was that beta-hydrox-bureate, which is quite similar to butyrate. Now, butyrate is a byproduct of bacterial fermentation in our gut, actually, when we eat fibers, these bacteria will digest the fibers into buterate, and this buterate actually circulates in many of us as we live. The buterate was the first known or first identified inhibitor of aged acts, histone diacetylases, which are epigenetic regulators. And so that's suggested that maybe Betahadrox buterate might be an endogenous. regulator of these age dax. Now, the reason why we were interested in age dax is because they've been linked to aging as well. Their Steve Halfand's work has shown that an enzyme called RPD3 in yeast is actually a regulator of the Sertouins, which are themselves regulator of aging. So there's a pathway that's that's in yeast that's been established, actually in Drosophila, as well,

linking RPD3 to SERT2 to aging, the aging process. And these age dachs that I'm talking about are in the same pathway. So that got us to start thinking what could beta-hatroxybureate be also an H-Dak inhibitor, and it was. And then this implicated it might actually be able to regulate gene expression. And some of the key targets that we found were enzymes such as FOX-O-3, which is a major sort of transcription factor in humans linked to aging. And it turns out that Phroxor 3 actually controls the response to oxidative stress. So there's another link there that brings not only via the pentose phosphate and AADPHPH, but beta-Hiburates actually protects against oxidative stress, both as a nutrient but also

as a transcription or regulator. That's super cool. Do you know what levels of beta-hydroxiboutureate are required to sort of flip that switch? So the, this is probably, it's a very good question. It's probably one of the reasons why no one did the experiment before us. Beta butyrate and beta-hydroxiboutureate are poor inhibitors. They have very low efficiency as H-Dak inhibitors. It's in a millimolar concentration.

And as an inhibitor, nobody wants to work on millimolar inhibitors because it's not potent enough. What most people did not realize is that the concentration of, of beta hydroxybutyrate in your plasma or in your brain, during fasting, can go in the milly molar range very quickly. And that's when I was reading a paper discussing these concentrations and was astounded. I thought, well, millimolar concentration, this means that it might really work as an H-Tac inhibitor.

And so we tested this by putting a pump under the skin of mice with beta-hydroxybutyrate and then measuring histone acetylation throughout the mouse. And we found that histone marks, aciditation marks, were going up, suggesting that there was indeed an inhibition of H-DAC. And I think that was the turning point for us. By giving them exogenous beta-hydroxybore. Yes, not even the fasting. Because the fasting or ketogenic diet is much more complicated than just giving better hydrantic

literates. And they were on a normal child diet. Normal child diet. They were not fasted. And we found that their ketone body levels were going very high in the millimeter range. And within a few hours, their histones were becoming hyperacetylid rates. And so that for us, I think, signified that here's a molecule that is produced during fasting under conditions that we know are good for your health.

So ketogenic diet has been indicated, has been shown to have some beneficial effect under a series of circumstances. All of a sudden, we had a potential signaling mechanism, and that's what we've pursued. Yeah, I do remember seeing that paper was published. in science, that, 2010 or something like that. Or 11, yeah. I do remember that paper, a very super cool paper. I actually talk about it quite often when I, you know, when I talk about beta hydroxybutyrate.

So you were giving them, what do you think of exogenous ketone esters? Like, do you think that they're safe? I mean, how, is that something that you've, you know about or thought about? Well, we've thought about it. We are experimenting with them as well. It is one of the central questions. It's most of the beneficial effect that we have seen have been with the ketogenic diet. Again, it's very different from a high beta-hydroxybutyrate level.

And one of the remaining, or at least the next step in this whole field, is really to understand what can we recapitulate with beta-hydroxybutyrate alone. And I think we're working actively on this and so are many other groups. Great. I mean, the ketogenic diet itself is important to realize it's not an easy diet to live on. I mean, I don't mean to be diminishing the merit. Actually, I highlight the merit of people who are in a long-term ketogenic diet. It takes a lot of discipline.

You basically cannot eat a significant amount of carbohydrates. Many people who have been on this diet for a long time actually tout its benefits and the fact that they feel very, healthy and they feel very present. There are a lot of brain effects linked to ketogenic diet. Now, big question is, what can we replicate just by administering BHB, bediatrics, but I heartaches, buterate alone. Yeah, I think that you're absolutely right, you know, and not to mention that with the ketogenic diets, there's also, you know, some people can't really do them. You know, there's certain gene polymorphisms. I know there's one. I know there's

one in the PPR alpha gene, which is important for the whole process of making ketone bodies, and that people have that, they actually can't do that very well. And so it can be sort of dangerous and they can have inflammation. Sort of the opposite profile will happen. So it's certainly something to consider. And then not to mention, like, you found in your paper that you just published this year, was it last month? Yeah. Yeah, last month, that you found, you know, there were multiple changes going on. There was a, I think, there was a decrease in insulin, obviously, and IGF1, and mTOR activity went down.

And then, you know, so that's something you're not going to just get from beta-hydroxybutyrate. Maybe, we don't know. We don't know. I suspect not for the mTOR part, but we also saw, we compared the ketogenic diet to a high-fat diet, which was not ketogenic, That is in which mice ate a large amount of fat but had enough carbohydrates to suppress ketogenicis. And one of the biggest difference, I think actually between these two was the activation

of P-par-alpha. And this is also very exciting because that indicates that maybe a lot of the beneficial effect that we see on the ketogenic diet come from P-par-alpha activation. And there's growing, we've been reading that literature, this seems quite a bit of information there that really hasn't been pursued. as a next direction to try to dissect these effects. Because PPR Alpha is doing something to the mitochondria, what's the main... It's a key enzyme of the fasting response, but it seems to be more highly activated

in response to the ketogenic diet than to a pure high-fat diet. What about fasting if you compare fasting to a ket-a-com. It is activated, we just... We did not compare it to fasting. We compared it high fat to... But I think it just points to a new direction in which we can start dissecting. What is the role of people alpha in these responses? But with your diet, you also limited the protein intake,

and you didn't limit the caloric intake. That was the other study? No, the protein intake was actually 10% isochaloric between all of our diets that we tested and for the other group did the same thing. So we were very careful. not to change the protein intake. And in the other group, actually, they did change a bit the protein content, which could be taken as a confounding variable.

So I think we were very careful in not changing the protein content. Is that standard for, you know, ketogenic diets have grown in popularity. And, you know, so do you think that if the ketogenic diet you used, you hadn't have done a 10% protein if they had done a little bit? bit more. I'm not sure if maybe that technically wouldn't even be a ketogenic diet, but would it have changed the IGF1 mTOR axis as much? You're bringing an important point, which is that a number of people who go on a ketogenic diet tend to compensate by increasing their protein intake, which might actually put them at risk from exactly what you're describing,

increase IGF1 signaling, and increase actually risk of cancer. There's a really close correlation between your IGF1 level and your risk of cancer. So I think this is something that needs to be considered in the future for people who are in a long-term ketogenic diet. And with the calic restriction diets, well, I think I read, there was a study I remember reading that humans that end up doing caloric restriction, like there's the whole society of calic restrictions,

they end up eating, they eat, you know, 30% less calories and they normally would or whatever, something like that. but they end up eating a higher percentage of protein because it's more satiating. So humans sort of naturally gravitate to eating more protein when they're eating less food. Yes. And so what's interesting is a lot of those, I think you even published a study recently looking at biomarkers of aging and lymphocytes or monocytes. Yes, and we saw no difference between people and calorie restriction.

This points again to, and this is something important to consider, when a lot of the work that we do in the lab are done on mice that are isogenic or congenic, so these are mice that are all similar to one another. When we, when takes discoveries and bring, when you bring discoveries to the human population, it is critical to take into consideration the incredible variation between different people and how they might respond to the same interventions. We know from everything that we've studied in medicine that I am not the same as you are and you are different from your neighbor in many biological responses.

And that includes response to calorie restriction. I suspect that in a number of people it will actually do them harm, and in a number of people, it will do them good. We know this when we test different strains of mice by calorie restriction. half of the strains actually responded by a shortening of lifespan, the other half by an increasing lifespan. So we take calorie restriction, for example, as a universal modification that will increase lifespan. It's not what is seen in the literature. And I would say the same is going to be even more true for humans.

So I think this brings, for me, brings up one of the key thing that is lacking in the field of aging is the identification of biomarkers that will allow us to test on an individual basis whether the intervention or the modifications that you're imposing is actually pointing you in the right direction or in the wrong direction. And I would caution anyone who's considering doing something long-term in terms of their health to be very careful and how they feel and how... Because we don't have these biomarkers of aging.

They're emerging, but they're not validated, and certainly not in the human populations. They're emerging in mice models and other models. But that's really where we will be going in the next few years. It's really having true biomarkers that allow us to predict whether a given intervention is beneficial or actually hurtful. Yeah. What do you think are there the top three right now we have for biomarkers for aging? Well, there are, there's, I can tell you, the one that are really exciting me,

there's Alexander Geronkov as a company called in Silico Medicine that is, building biomarkers of aging based on facial recognition and based on metabolites. Just consider how... Metabolites. Yeah, so consider how you and I can look at a human and pretty much guess what their age is for most people. And consider the fact that where this is coming from is the fact that we've lived and we've met thousands of people and we've heard about their ages and we sort of build a database of information. So what Alex and this company have done is they've taken the pictures of thousands of people

and fed them to a deep neural network and artificial intelligence and the computer has been able to learn how to recognize and to link, on average, what is the face of a 70-year-old versus a 60-year-old. So you can do this, and it will tell you what the computer thinks your age is. And for some people, you fall right on, but for the number of people, you find that your age based on your face, it actually looks younger or older. So this would be a reflection of your biological age. He's also been able to do this with blood markers, with 20 or 30 or 40 blood markers.

So usual blood markers by screening a large number of people, he can actually generate standard curves, and then you can put in your blood values and see where you fit. So that's one approach. Bioage is a company in the Bay Area. that is actually pursuing the same idea of looking at artificial intelligence and biomarkers in plasma or in urine or and so on for identifying your age. And finally, one big area is the whole idea of the epigenetic clock. Yeah, Steve Orvat.

Steve Orvat and Trey Eidaker have shown that there are changes in DNA methylation that actually predict pretty closely your chronological age. It's pretty cool. So I think all of those together are emerging. is indicative that there are markers that we can reliably measure. The key is how many of those do we need? How can we reduce this to something that's going to be very strongly predicted, not so much of your chronological age, but of your biological age. Right, yeah. I think there was a study I did read, maybe it was the company that you mentioned, where there was a panel

of blood biomarkers that they looked at like telomer length and immunosin essence, and, you know, the standard panel, and then they looked, they had people, I think it was people that were asked to identify their facial age or something like that, and then they asked their chronological age, and their facial age actually matched their biological age more than they're chronological, or something like that. Exactly. We all know in our acquaintances some people that actually look younger and some people that look older.

And we know this because we have a deep neural network in our head that is. allowed us to build, you know, a reference point so that we can pretty much guess how old people are. And the computer does it even more efficiently because it can be fed tens or hundreds of thousands of pictures. That's cool. I want to try it out. Yeah, it is actually really cool. I just sent off my, I'm going to be getting my telomeres tested, you know, just, I don't know how reliable that's going to be. We'll see. But, you know, I've been getting less sleep than usual because I'm a new mother and that's been a show into effect. But it'll be interesting to See.

Anyways, I sort of, we digressed. I kind of wanted to ask you a little bit about, you know, we're talking about fasting. We talked a lot about, you know, insulin signaling decreasing. IGF1, we've talked about before in the podcast before, with, you know, Walter Longo and others just how the protein restriction seems to really regulate that, and that also regulates aging process, mTOR as well. But something else that really seems to change with fasting is the NAD levels. Yes.

And that's something that, you know, your lab has studied extensively with Icerotun's. Yes. So maybe could you talk a little bit about, because NAD is also extremely exciting to me, and it's pretty popular these days as well. Yes. So NAD has emerged as one of these critical intermediary metabolites. Think of ketone bodies. NAD are all.

I call them currencies. I mean, so think about your organism as a country. You need to circulate energy, and the NAD is one way that our body is utilizing within the cell to convert, to transfer energy. It's almost like the Brinkman truck that carries the money. And NAD can actually, is a so-called hydride acceptor during while we oxidize food. It can actually serve as an acceptor for an electron, and it can transfer them. for example, to the respiratory chain. So it's one way for the energy to be circulated within the cell.

And there's growing evidence that its level decreased during aging. Why that happens is still one of the big mysteries. And so this has yielded a whole approach that trying to understand, first, what are the consequences of decrease in 80 levels? And one of the consequences that enzymes like Sertuit, which rely on an AD to exert all of their beneficial activities actually function less well. That's what happens during aging. But also many other enzymes that are involved in our metabolism are relying on an AD,

and so they function less well. So your intermediary metabolism functions less well. The Sertuins, which are global regulators, function less well. You're basically falling apart. Yeah, essentially, you know, everything becomes a little less efficient. So out of these discoveries came the idea that maybe we should replenish the decreasing level of NAD. And so this has yielded some discoveries such as nicotunamide ribosides, nicotinamide mononucleotides,

which are now being taken by a lot of people and with the hope that it will, you know, correct some of these problems. One word of caution, I think, there is we do not know why these levels decrease. They could decrease because we have decreased production of NAD, but it could also decrease because we have accelerated destruction of NAD, which means if it's accelerated destruction, bringing more into it is sort of like pouring more NAD in a leaky sink. So I think a lot of our work right now is trying to. understand what is the cause of the decrease in an AD during aging.

Because I think it will yield very different solutions. If you find that there's a leaky sink, we'll work at filling, at plugging the sink versus keeping pouring water. I have a theory. Yes. So I know, you know, coming from, I did a lot of work with DNA damage. Yes. And knowing that one of the main enzymes...

Part. Exactly. I mean, if you think about, you know, so one of the main enzymes that repairs damage as we age, DNA damage, PARP, it requires NAD. And it's like if you're accumulating more and more damage as you age, you have to repair more of that damage. And the more and more damage you're having, maybe it's sucking the NAD, you know, sort of like almost a triage where it's like, well, you've got to keep repairing that damage.

So then other things like the mitochondria suffer, you know, so. I completely agree. And actually, so there are two major theories right now that have been proposed in terms of why does NAD go down? One is activated PARP, and indeed as we age, we accumulate DNA damage. It's been shown especially in the brain recently. And so the idea is by activating PARP, you can constantly deplete your NAD levels. The second one is we all have in our body a so-called salvage pathway for NAD, for NAD, because

NAD turns over. There's a so-called salvage pathway that allows it to be recycled back to So we can get an ADE from the food, but also we salvage the one that we utilize. And the salvage pathway has been shown to becoming paralyzed while you age. There's an enzyme called an EMPT. It receives a lot of attention. That enzyme tends to be inhibited by chronic inflammation and a high fat diet. So one way...

So it could be a combination of both of these things, but it could be other mechanisms. Actually, we're working yet on another mechanism, which is that. that there might be accelerated destruction by other enzymes beyond part and getting some exciting results in this direction. Cool. So for people that are not familiar with why, like in terms of what role it plays, you know, in the aging process, you know, it seems as though, at least in some of the studies that I've seen, that mitochondrial function really seems to be important.

And I know that you've shown that the St. 2 and 3 in the mitochondria itself seems to be really important for the mitochondrial function. the mitochondrial function, keeping your mitochondria young. And that mitochondria play a very important role in aging as well. A critical role. Many of the aging pathways that we know, be it the unfolded protein response or mitochondrial biogenesis, all point to efficient mitochondria as one of the key ways to stay young.

And so one reason is because this is a way, so you can generate energy from glycolysis, which is glucose, carbohydrates, which we know is linked to aging, but also via mitochondria via a process co-oxidated phosphorylation. And that process is not necessarily depending on glucose, but it's dependent on an efficient mitochondrial function. So we talked about NAD dependent enzyme. Many of these enzymes reside in the mitochondria. And we found that, for example, the NAD supplementation

that is being tested in a variety of aging model requires 33 quite often. This mitochondrial certuant, yes. Nogynide riboside does? Yes, yes. For example, the paper we've published was focused on the age-associated or noise-induced loss of hearing. So if you actually subject mice or humans to very acute hearing, acute noise, they have a dose-dependence. dependent loss of hearing, you can protect mice completely from this effect by supplementing with NAD.

Wow. With nicotumana fibrozyte, so if you're going to a rock concert, you want to protect yourself, and this is definitely something... Charlie Davidson writers. Yes. In mice, it actually had an enormous effect, and we found that this effect was dependent on 33, so in 33, knockout mice, the effect was lost. Do you know if that was dependent, the 33...

in the mitochondria of stem cells? Or was it just any cell? So in the case of hearing loss, it's dependent on some really uniquely sensitive cells in the inner ear. But generally, there's been sort of an assumption in the field that most of the effect of nicotine ribosides protective effect

are dependent on so T1. I think in... Oh, really? Yes. And in some case, it is. But in this particular case, noise-induced hearing loss, it was really clearly C3. So even the studies that have looked at, for example, I think there was a mouse that had some sort of mitochondrial disorder. Yes.

Even that one was dependent on C-T-1? No, actually, I did not. In that case, I think the assumption was that it might be helping global mitochondrial function. And so there's a growing number of cases, for example, DNA damage associated disease where you see accelerated aging, where people have been testing the effect of supplementation, because those conditions are associated with increased part of activity, just like you mentioned. And in those cases, I think it hasn't always been clearly mapped. What is the real target of NAD that is dependent for the beneficial effect?

Do you know if, so NAD levels do you decrease with age? Do you know, has it been looked at, like, for example, in animals, like in rodents, when they're fasted? Because fasting increases NAD, when they're fasting and they're older, does that help rejuvenate the NAD irrespective of their age? I don't know. I don't know. The answer to that question. I think, you know, one thing that I remember also about fasting, another critical effect of fasting that is really essential in our thinking is, autophagy.

Yes. And so, you know, there's growing evidence also that autophagy by itself responds to nutrient availability. So, NAD levels, acetyl-CoA levels. This is a new area that people are starting to work in, including my labs, trying to understand what is it about acetyl-CoA, which is another thing about the currency exchanger in the cells intermediary metabolite that appears to have. not only role as a nutrient, but also as a signaling molecule.

Acetyl-CoA is in the CREP cycle. It's one of the key intermediary product of the CREP cycle, but it's also the substrate for a whole family of enzymes called the acetyl transferases, which are the opposite of what we were talking about the H-Dax earlier. So I think there's really a lot of cross-talk between all of these pathways, and we're working very actively now. on modulation of signaling the acetyl co-A and these acetyl transfers is yet another approach is to mimic calorie restriction in the fasting state.

Yeah, I had Dr. Guido Kramer on the podcast. Yes, exactly. And he has been studying that as well. You know, it brings up a question, I remember I wanted to ask you, that was sort of, you know, biology is never just black and white because I remember him, with his work, he was talking about how important decreasing protein acetylation was. So for activating atopagy, which happens during fasting. But also during fasting, you have these beta-hydroxybutyrate,

which is now a, was a class two inhibitor? Class one. Class one inhibitor of the histone deacetylase. It's just kind of the opposite, a little. No, because you have to think so. Bellagiccoburate is one step above the sootins. And actually, the class one inhibitors are inhibitors of... Oh, they're inhibitors of...

Exactly. So it fits perfectly if you go back to the... So class one is an inhibitor of histone deacillicilis. Yes. That makes sense now. Okay. So... Thank you.

There was a disconnect in my brain, what I was trying to... You know, because it... So the whole idea of, if you think about acetyl-CoA and we really draw a graph that of acetyl-CoA regulating HATS histone-acetyl transferase, and NAD regulating the Surtuins. And these enzymes quite often say in opposition. Not all of them, but one of the key players in terms of histone-acetyl transferers is P-300. And that's the one we've worked on and Gidochromer as well as worked on. And it makes sense.

You get the same beneficial effects by activating a sartouins, which lowers a satilation, as you do by inhibiting an acetyl transferase, which also lowers acetylation. So the message is that nutrient feeding or low histone acetyl transfers activity or high certain-outin activity all lead to low protein acetylation, which is beneficial. And doing the ketogenic diet? Regulates one step above. Does also, yeah. Yes.

But obviously there's some complexity because there are some histone marks that are depending on one enzyme. So this is an oversimplified model, but so far it holds. What about autophagy with the ketogenic diet? Is that something, I mean, I don't know if it would be... It would be activated because clearly it's a fasting, mimicking diet, but we haven't really studied it directly. Yeah, that would be interesting to look at. Also, the other thing, the other question I would have was, you know, there's a lot of stress on the liver when you're doing that sort of diet, right? You're relying on it for gluconeogenesis to make glucose,

you're oxidizing fat. Do you know if there's any, as anyone looked at, sort of long-term ketogenic diets? We did. The liver seemed perfectly fine. Just imagine the liver is really, think about it as a sort of an energy redistributor. If it's not dealing with fat from joint fasting

and transforming fat into ketone bodies, it is dealing with food coming in from the intestine during feeding. So it's always busy in one way or the other. So I don't think that there's anything to be worried about generating ketosis. I haven't heard of any side effects linked to liver function and so on. The other thing would be at least with mice. In your study, you did cyclic and the parallel study they did, I guess, continuous, but they restricted the calories.

But mice sort of, and this is something that goes back to us, someone that Guido was talking about on the podcast. They have a notoriously fast metabolism. In fact, he said that if you fast amounts for 48 hours, they can lose up to 20% of their body weight, which is, like, phenomenal. I mean, if human could do that, there'd be no obesity, you know. Yes. But so do you think that the fast metabolism, you know, coupled with something like the ketogenic diet

or even just a lot of the fasting studies in general, is something that can, like if we see something like an increase in health span, and we see all these positive benefits and rodents. Is that something that we may have hope in translating to humans, you think? I do think. I mean, it's important to realize that mice are not humans and that there is a tall order in terms of proving something that has happened in mice all the way to humans.

But that's our mission. I mean, that's what we need to do. And you have mechanism. We have mechanism. That's the first step. It's not always predictive and large number of drugs that have been shown to be efficient. in mice, I failed into humans.

But that's the first step that we can take. And I think from our work, I think the next logical step is to go in humans and test. Is the ketogenic diet something that you've considered trying or doing? I have tried. I have tried. And I've been on it for about a year. It's hard to stay on. I call it a somewhat antisocial diet because you can't really drink alcohol.

you can't eat. A lot of the things that we base, you know, our social interactions on, no bread, no pasta, and very little fruits. I think it's... What about vegetables? You can eat some vegetables, but, you know, depending which ones. So I think it, I view this on a global population basis. It's not a realistic goal to expect that everyone is going to be on this ketogenic.

Are you going to continue doing it? No, I'm not on it right now. And I think I find that intermittent fasting is a much easier way to... Is that something you practice? Yes. Not right now, but I have intermittent. So intermittent fasting, like 12 hours, 16 hours or 24 hours? Well, this is still a growing question.

It's a really interesting work coming out at the Salk Institute on the so-called time-restricted eating, time-restricted feeding, showing that it's not just how much you eat or whether you you're eating carbohydrates, but it's also how often you eat and how allowing you every day for a fasting period. I think that's probably some of the most important work that we've seen recently in this whole field. And you know, just think about what dietary authorities today are recommending is three meals and three snacks.

I think based on what we are doing and learning, this is the worst possible way that you can possibly eat. So I think allowing for each day to have these really restriction in terms of calorie intake allows you to activate all these pathways to suppress incident secretion, to suppress store, to activate autophagy. All of these, I think, are really critical. Yeah, I have, in complete agreement with you, I've talked to Dr. Sotchen Panda a couple of times on the podcast, phenomenal researcher.

And I've been doing time-restricted eating ever since I first spoke with him. Of course, when I was pregnant, I sort of couldn't do it. it as well, but I'm back doing it now. And, you know, I do, I do feel much better when I do it. You know, I try to eat all of my food within a 10-hour window. Yes. And I find that that's the best. 14 hours is fasting. Yes. Yeah. And I know that, you know, I think maybe you can answer this question for me, but, you know, it takes anywhere between like 12 to 36 hours to deplete your liver glycogen or something like that. Actually, it can be faster. Yeah. I'm from 4 to 6. hours. You actually deplete most of it, yes.

Does it depend on your physical activity levels and things like that? Yes, obviously. Physical exercise will deplete it much more quickly. In terms of entering ketosis, you actually, so if you border to do 14 hours, it's not enough to really gain significant ketosis. You start seeing this at about 16 hours where your level will slowly rise. Okay. So, yeah, so doing a 14 hour fast every night is something that I at least try to practice.

Yes, no night cap. I think that's the easiest. Yeah, no night gap. I have no glass of milk with a squint of sugar. No wine. But you get used to it. Yes, absolutely. You really do.

And, you know, like I said, I think it's the easiest. I haven't really done a prolonged fast yet. I've spoken with Dr. Walter Longo, and, you know, he was talking about the prolonged fast in humans. Like in mice, I think it's like 48 hours, but in humans, it's a little like four or five days. Yeah. And so he has got this fasting-imicking diet, which sort of mimics some of the effects of I know several people that have done water fest. I haven't braved it yet. Have you tried doing a prolonged fest? Well, I've done, you know, Walter, Valter Longo's diet,

a prolon diet. How was that? It's really, I think it's really interesting science. I think it's, what I like about it is the fact that it really takes this fasting to a scientific level. That is by they're doing the work. One key question is that, so going on this five-day diet is actually an interesting experience because it's not hard. Maybe on day three might be a little hard, but one key question that has not been addressed is if you induce this protective response, how long does it last? And so how often should you do this? Is it something you should do every three months or every once a month or actually once every six months? I think this is the type of information that will allow many of us to really do the intervention when it's needed.

And I think it's going to be a lot of research in this whole area that I'm very excited about. Yeah, it probably depends also on how, you know, do you do time-restricted eating every day? And do you, you know, so what you, what your sort of baseline is, are you, are you, like, obese or overweight or, you know, metabolically healthy? But I agree with you. I think it's an extremely exciting field. And being here at the Buck Institute, you know, for research on aging, you're sort of at the forefront of it all. You know, like you said, there's so many different aspects of the aging biology that's being researched here. If people want to learn more about your work and the buck.

Yes, so we were the first research institute devoted to aging. We were found in 1998, and we have about 220 employees, all focused on aging. and we take great pride in the fact that we started the very simple, most simple model, yeast. We go to sea elegance, nematard, we go to fruit flies, mice, and humans now. And one of the thing that really excites me about the buck is the fact that we have built this incredible body of knowledge over the last 20 years in terms of the basic biology of aging. And I think the field has moved to the point that we're really ready to start translating all of this into humans. And we're seeing, all of us are seeing, you know, the incredible interest from pharma and venture capital in terms of investing in the aging space. And I think we're, you know, we're really well positioned to be writing that next wave, which is going to be bringing all of these incredible discoveries into humans.

And so stay tuned. I'm certainly going to stay tuned. Yes. Thank you so much for taking time. My pleasure. My pleasure. That was great. Want to recap of everything that was talked about in this video, maybe a transcript, a timeline, or more related episodes. You can have all that and more by going to the episodes page on our website and clicking the link to the episode featuring Dr. Eric Verden.

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