#75 Intestinal Permeability: the Bacterial link to Aging, Brain Barrier Dysfunction & Metabolic Disorder

A big objective for Metabolic Health Summit is really to bridge the gap from science to implementation. And as we were organizers planning for this event, we had a short list of people who really have the proficiency, the knowledge, the skills to transmit or translate science to the public. And high on that list was Dr. Rhonda Patrick. And around this time, Dr. Patrick, Rhonda, graciously invited me to be on her podcast, FoundMyFitness Podcast. So she had actually came to our lab maybe about 4 or 5 years ago. And so I told my co-hosts, Angela and Victoria, I was like, well, I think I can ask Rhonda Patrick. I didn't wanna do it in an email. I don't think I did. So I asked her in person.

She had— I'll have to say she was very task-loaded during this time, so I am extremely grateful that she took time out of her busy schedule with a lot of things going on in her life right now to join us at Metabolic Health Summit. And I'm gonna give a short introduction. She has quite a long bio, but Dr. Patrick is a scientist and a health educator based in San Diego. She runs a popular website and podcast on YouTube channel called FoundMyFitness. Yes. Her areas of focus include micronutrient deficiencies, the role of aging, and the role of genetics and epigenetics in health status, the benefits of exposing the body to hormetic stress such as sauna— and heat stress is why I do the hot tub— and various forms of cold exposure, exercise, and fasting, and also plant phytochemicals and the importance of mindfulness stress reduction and sleep.

So really taking a holistic approach to metabolic health, but health in general. Her work has been published in journals like Experimental Neurology, FASEB, Nature Cell Biology, and Trends in Cell Biology. Dr. Patrick's talk is titled Intestinal Permeability and the Bacterial Link to Aging, Brain Barrier Dysfunction, and Metabolic Disorder. And with that, let's— without further ado, let's invite our speaker to the stage. Thank you, Rhonda. Good evening, everyone. I'm so excited to be here. Thank you, Dom. Thank you to the organizers, Victoria Field and Angela Poff, as well. I'm so excited that this finally worked out. You guys have, you know, invited me a few times, so I'm just so happy to be here tonight.

I am discussing something I haven't— I'm excited actually because this really pressed me to— there's some topics that I've been really interested in lately and diving into, doing a lot of research literature reviews on. And so I was like, I need to push myself to learn more about this, and what better way to do that than to present on it, right? So I'm going to be presenting on something a little bit new in terms of things that I've talked about, generally speaking. I'm going to talk about the role of intestinal permeability. And today we're going to cover— we're going to cover how— what intestinal permeability is and how it can lead to the release of a bacterial product called lipopolysaccharide, or LPS, which is a type of endotoxin.

It's present in the outer cell membrane of gram-negative bacteria, the bacteria that are inside of our intestines. We're going to talk about how LPS, as it's called for short, bind to lipoproteins in circulation and how this can play a role in atherosclerosis. We're going to talk about how LPS can compromise the blood-brain barrier and also how that plays a role in the development of neurodegenerative disease. We're going to talk about the role of, of LPS in the way we feel, in our mood. And then finally, we're going to get into what everyone's probably most interested in, is what do we know about certain lifestyle factors that can regulate intestinal permeability? So let's start off by talking about what intestinal permeability is.

So if you look sort of at a schematic of our intestinal lining, we have enterocytes. These are gut epithelial cells. They are connected to each other by tight junctions. These are groups of proteins that are basically connecting our gut epithelial cells together so that they're forming a tight barrier. Basically, it's one component of the gut barrier. Another component would be the mucin secreted by our goblet cells in the gut. So intestinal permeability refers to— most, most of what's understood with intestinal permeability has to do with some disintegration or disassembly of tight junctions, which allows Bacterial products like lipopolysaccharide. It allows bacteria, it allows food antigens to leak into circulation.

So we're gonna talk about what happens when this, you know, when LPS specifically is able to leak into circulation. So what effect does LPS in circulation have on cardiovascular health? So lipoproteins, everyone here is familiar with what lipoproteins are. They originate in the liver. Their main role is to transport triglycerides and other goodies, other lipids and cholesterol as well, to other tissues. Mostly they're transporting triglycerides. Our tissues, our cells cannot make triglycerides. Most of our cells can make their own cholesterol. So it's really important to have triglycerides being transported around because they're a really important source of energy. So, of energy.

There are various shapes and sizes of lipoproteins, from VLDL, or very low-density lipoprotein, to low-density lipoprotein LDL, to small dense LDL, or small dense low-density lipoprotein. And as these lipoproteins start to transport around our circulation and donate triglycerides, for example, to other tissues, they beget They get smaller in size, and also they become more dense. Well, LPS binds to lipoproteins. It actually binds to all of them through a lipid-lipid interaction. And it's actually thought that this is one of the protective mechanisms that our body has to prevent lipopolysaccharide from causing, for example, sepsis. And we know that lipoproteins play a role in actually lowering LPS levels in our circulation.

And this happens because the LPS is bound to, for example, the LDL molecule. So lipoproteins are recycled. They're cycled through the liver. There is a protein present on lipoproteins called ApoB. ApoB interacts with the LDL receptor in the liver and is absorbed, taken up, and that's how it's recycled. Well, because LPS is attached to lipoproteins, the LPS also gets lowered or decreased in circulation. And this has been shown in a variety of mechanistic studies, for example, using statins, which lower LDL through a variety of different mechanisms. One of many includes increasing the number of LDL receptors and therefore increasing the recycling of these lipoproteins. And subsequently, LPS has been shown to be lowered in circulation after statin use, for example.

So again, this really seems to be a protective mechanism. Lipoproteins bind this lipopolysaccharide to help prevent our bodies from having massive inflammation and undergoing sepsis. And so one of the ways it does that is by increasing lipoprotein production when— basically when LPS levels become elevated. And then the lipoproteins then recycle the LPS through— for the liver. But not all lipoproteins are getting recycled, as most people here know. There are a variety of sizes of lipoproteins. We've now had increasing evidence that the smaller and denser LDL particles don't get taken up into the liver as well.

And mechanisms have been worked out on this, including because as the LDL particle gets smaller in size, the ApoB protein that is interacting with the LDL receptor becomes somewhat obscured. And so when this ApoB is supposed to bind to the LDL receptor, it's, it's not binding as well, and therefore it's not getting taken up and it's not being recycled as well. And subsequently, that means that the LPS particle bound to the LDL is staying in circulation. So what consequence— what's the consequence of this? If we have a small, dense LDL particle that's not getting recycled, it's actually in circulation longer. And there's been evidence that these small, dense LDL particles will insert themselves into the arterial lining, the arterial wall.

And of course, the LPS is a signal to our immune cells. Resonant macrophages sense the LPS signal, and it's like, oh, I've got to get rid of that bacteria because it's a threat. So it comes and tries to engulf through phagocytosis what it thinks is a bacteria, but which actually is a small dense LDL particle with an LPS bound to it through a lipid-lipid interaction inserted into the arterial wall. And so it phagocytoses that entire lipoprotein, and you get the formation of what's called a foam cell, sort of a soft plaque. And this is stuck in our arterial wall, the lining of our arteries. And as it's sitting there for more and more time, it undergoes more inflammatory and oxidative transformations, which then causes the foam cell to become stiffer and more plaque-like.

So this is the beginning of atherosclerosis. There's been a variety of animal studies nicely documenting this as well with the small dense LDL particle and LPS, and in fact even showing if you, for example, increase the production of butyrate-producing bacteria in the gut, which can help prevent LPS leakage, that can sort of reverse some of these effects. Quite interesting. So that's sort of one aspect of what LPS can do when it's in circulation to cardiovascular health. The next question is, what about the brain? What effect can LPS in circulation have on brain health? So the blood-brain barrier, much like the gut barrier, is made up of a series of endothelial cells that are bound to each other and held together through tight junctions.

Again, these proteins that are— a group of proteins that are holding the endothelial cells together. On the basement membrane side of the blood-brain barrier, we have a variety of different cell types sort of all interacting together— pericytes and microglial cells, which are the brain's resident immune cell, as well as astrocytes. And together, they're making up the blood-brain barrier. So LPS, again originating from intestinal permeability, can actually break down some of the tight junctions itself. And it binds directly to receptors present on microglial cells. These are called toll-like receptors, toll-like 4 receptors, and we're going to talk a little bit about that in more detail in a moment.

But when that happens, it actually shifts the microglial cells in the brain from a protective mode to an attack mode. And so they kind of change their phenotype, and this sort of results in the astrocytes moving away from the parasites in the basement membrane. And so you end up getting then an even further breakdown of the blood-brain barrier. It becomes more permeable. And this is sort of the beginning of this vicious cycle where then, you know, you sort of have a slow, sort of insidious, more permeability effect because more LPS and other inflammatory molecules and other things are getting into the brain. And then it's, you know, changing the phenotype of our microglial cells, for example. and this sort of this vicious cycle of neuroinflammation.

So why should we care about, you know, blood-brain barrier breakdown? Well, the blood-brain barrier is key for brain aging. In fact, nearly 50% of all dementias, including Alzheimer's disease, begin with the breakdown of the smallest vessels in the brain. In fact, biomarkers of blood-brain barrier breakdown precede classical biomarkers of Alzheimer's disease, like tau tangles and amyloid beta-42 aggregates. LPS in circulation also affects the way we feel. So healthy individuals that are injected with LPS experience symptoms of depression, depressive mood, feelings of social disconnection. They also have elevations in inflammatory cytokines like TNF-alpha, IL-6, compared to people that are injected with a saline control.

There have been a variety of studies that have now sort of established causation with respect to the role of inflammation in depression and basically in the way we feel, in our mood. And there's been a variety of mechanisms that have been sort of delineated. One of those has to do with the metabolism of tryptophan. So tryptophan is an essential amino acid we get from our diet. It is transported into the brain. Once it's in the brain, it gets converted into serotonin, which is an important neurotransmitter that regulates mood. It regulates cognition. It regulates impulse control, long-term planning. It's important for a variety of cognitive functions.

Well, if there is acute inflammation or even sort of low-grade chronic inflammation, this can shift the metabolism of tryptophan such that tryptophan is not transported into the brain. Rather, it's converted into a metabolite called kynurenine. And kynurenine has been shown to accumulate in the brains of people with depression, also neurodegenerative disorders. Kynurenine gets converted into a neurotoxin called quinolinic acid, which also has been associated with a variety of neuropsychiatric disorders, bipolar disorder, schizophrenia, as well as neurodegenerative disorders. I have exercise on here because exercise, as most people here are familiar with, is very— it's been shown to be important for brain health, for cognition, for the way we feel.

And part of that is because it increases the transport of tryptophan into the brain before any conversion into kynurenine. So it actually increases the transport of tryptophan in the brain and also the conversion of tryptophan into serotonin. So sort of a summary of this part of my talk is that intestinal permeability can lead to the leakage of bacterial products, like lipopolysaccharide, LPS, into circulation. And we talked about cardiovascular health and atherosclerosis, but it also affects the brain. And it can generate inflammation, inflammatory responses, That can change tryptophan metabolism, change the way serotonin production is made, but also it affects the blood-brain barrier, and that can also affect the way our brain is aging.

So LPS in circulation is not a good thing, and maintaining a healthy gut barrier is important for both cardiovascular health and for brain health. But there's other mechanisms by which LPS can sort of wreak havoc on on our health. And this has to do with the binding of something that's a receptor on almost every single cell in our body. It's called toll-like receptors. We have these everywhere. We have them on our immune cells. So toll-like receptor 4, TLR4, LPS binds to these receptors. And when it does this in immune cells, of course, there's lots of inflammatory responses that are generated. But it also leads to what's called inflammaging, the aging of our immune system, where our immune system becomes less robust at protecting us against pathogens as we age.

It also becomes better at making inflammatory cytokines and doing it in a sort of shotgun approach, where it's kind of like there's a lot of collateral damage. The Toll-like receptors, when they interact with LPS on muscle tissue, it's been shown to impair glucose uptake into muscle tissue. which, of course, would affect metabolism, cause metabolic dysfunction. On liver cells, it's been shown to play a role in nonalcoholic fatty liver disease. And in the brain, we talked about a few problems with the breakdown of blood-brain barrier. It's been shown to also lead to depression, as well as neurodegenerative disease. So let's talk about what happens when these toll-like receptors on immune cells are activated and inflammation and inflammatory biomarkers are elevated.

So for example, people that are— this is a different study than one I mentioned previously. This is an even lower dose of LPS. When people are given a low dose of LPS such that there's really no clinical symptoms, no clinical endpoints that were noticeable, the individuals had an up to 200-fold increase in their inflammatory biomarkers. So they had a 25-fold increase in TNF-alpha, a very powerful pro-inflammatory cytokine, and a 100-fold increase in IL-6, which is also a pro-inflammatory cytokine. They also had an increase in markers of insulin resistance. HOMA-IR increased by 32%, and markers of insulin sensitivity decreased by 21%. So this is, this is kind of evidence that even a low dose of LPS— remember, LPS originates from the gut— can massively increase biomarkers of inflammation.

And, you know, the, the levels of LPS we're talking about are chronically elevated in people that are overweight and obese. So we're going to talk about that in a minute. But inflammation itself has been shown to play a role in aging. It's been shown to accelerate epigenetic aging clocks. So these are epigenetic signatures that have been identified by Dr. Steve Horvath, Dr. Morgan Levine, and others. Basically be able to biomark biological age. There was a study that was done by Dr. Levine and colleagues where people who had head and neck cancer that were undergoing radiation and chemotherapy treatment combined, their epigenetic— they had this treatment done, and immediately after their treatment, their epigenetic clocks accelerated by 5 years. So that's like they had aged 5 years.

6 months to a year later, most people's epigenetic aging clocks returned back to baseline, returned back to normal, except for people who still had elevated inflammatory cytokines. Those individuals with elevated inflammatory cytokines at the 6-month mark or 1-year mark after their treatment still had massively aged epigenetic aging clocks. So chronic inflammation can accelerate epigenetic aging. It's also been associated with accelerating aging itself. In fact, suppression of inflammation has been shown to be important for aging and the quality of life, as well as cognition.

So this was a cohort— large cohort study out of Japan where a variety of biomarkers were measured in individuals that were elderly, individuals that were centenarians, so they were 100 years old, individuals that were semi-supercentenarians— these are individuals that are 105 years old— or supercentenarians who are 110 years old. And a variety of biomarkers were measured, everything from long-term fasting blood glucose levels, so HbA1c, to liver function, to lipids, to kidney function, to telomere length and immunosenescence, to biomarkers of inflammation. And the only thing that was predictive of an individual basically living to the next stage was suppression of inflammation, so low markers of inflammation.

And that was also the only thing that was predictive of cognition, like being cognitively capable in older life as well. So I think probably what most people are interested in now are, okay, well, it seems as though it's really bad to have LPS, in our circulation, and it originates from our gut. When our gut barrier is in some way, shape, or form compromised, intestinal permeability occurs. So let's talk about some lifestyle factors that are known to affect gut permeability or intestinal permeability. Since we've been talking about the brain and we've been talking about the role of LPS from the— originating from the gut, On the brain, it's a two-way road. So the brain also affects the gut.

And I think that anyone in this room who's gone to graduate school or med school or any kind of higher education and has experienced the massive stress probably has felt some kind of gut symptoms. I know I did. I mean, there was definitely like— there's an association between being chronically stressed and having a GI problem. And it took me a while to figure that out when I was in graduate school. I didn't know what was wrong. I thought maybe I had, you know, IBS or something, and turned out it was actually stress. So there's been some nice studies done. In fact, people giving a presentation release LPS into their circulation. So in fact, you probably measure my LPS right now, I'm sure it'd be off the charts compared to yesterday when I was having fun with my family Disneyland.

But a lot of the mechanisms have been worked out on this. And in fact, one of the stress hormones that is released when we are stressed is corticotropin-releasing hormone. And this binds to a type of immune cells that are present at the level of the gut called a mast cell. There are receptors for corticotropin-releasing hormone on mast cells. And when— so when that stress hormone binds to the mast cell, the mast cell releases proteins proteases, which then degrade a bunch of proteins that make up the tight junctions that hold our intestinal gut membranes, our enterocytes together. And so this causes— again, this is intestinal permeability. This is what happens. And that allows food antigens to leak into circulation, allows LPS to leak into circulation.

It allows other things as well, bacteria. So this is how psychological stress in the form of a talk you're giving, or financial stress, or, you know, social relationships. Lots— there's lots of different— taking care of a sick family member. There's lots of ways that a person can be stressed. Graduate school. But it's kind of— I think it's important to realize that managing our stress is really important for our, you know, our gut, basically, and for helping to prevent Intestinal permeability. Probably not surprising, what's called an obesogenic diet, something that can lead to obesity. This is a combination of high fat, high sugar, low fiber. So you can feed people a high fat, high sugar, low fiber diet, and after about 4 weeks, you know, their LPS levels are increased by 71%.

I would argue that you could just do this and then 1 hour later measure that, because— Yeah. There's something called postprandial endotoxemia, which is the release of— as I mentioned, LPS is a type of endotoxin. So it's often— you'll see in the literature the words interchange, lipopolysaccharide, LPS, or endotoxin. So food itself, I mean, when we eat meals, there's postprandial inflammation. Part of that postprandial inflammation can be connected to LPS that is released. Not all of it, but part of it. So an obesogenic diet, something that can make people get fat, can also increase LPS levels. Obesity itself has been associated with higher circulating levels of biomarkers of intestinal permeability, such as zonulin. And we'll talk a little bit more about zonulin in a minute.

And so there's been this sort of, is it the chicken or the egg? Is it the obesity that causes LPS to be released from intestines and is basically causing intestinal permeability? Or is it the diet that's causing the obesity that's doing it? And it turns out it's probably both. There seems to be evidence of both of these things occurring. And so then what you have, again, is one of those vicious cycles, because you have the diet that's causing the obesity to— that's basically wreaking havoc on your gut health. and LPS, basically. And then the obesity itself is also doing it. And in fact, weight loss can decrease markers of intestinal permeability. So people that were obese that decreased their BMI by about 7 were also able to decrease markers of intestinal permeability.

And there's a million reasons why we should, you know, lose weight if we're overweight or obese. Obesity in extreme cases, very extreme cases, can, can have a massive effect on lifespan. So extreme obesity— this is a meta-analysis of about 20 prospective studies— found that extreme obesity, a BMI between 40 and 45, is associated with a 7-year decrease in life expectancy. Morbid obesity— this is a BMI between 55 and 60— is associated with a 14-year decrease in life expectancy. So there's, you know, there's every reason to want to lose weight and particularly, you know, lose fat and visceral fat, and there's a lot of ways that that can happen.

I know a lot of great speakers at this event will discuss that, but probably one of the easiest ways that Dr. Rowe just mentioned a moment ago is caloric restriction. And it's— there's a lot of ways that you can get to caloric restriction. You can count your calories and diet. You can skip meals. Yeah. You can exercise and skip meals. There's lots of ways to do it. But I think at the end of the day, the reality is that when you limit your food intake, you can lose weight. It's effective. Binge drinking is something that also has been identified to cause massive LPS release from the intestines. Probably a lot of people that already have underlying gut issues are more familiar with this because they've probably noticed when they drink alcohol, they might start to have gut issues.

And so binge drinking— this is for women about 3 to 4 drinks, and for men, like, 4 to 5. So it's a lot. I mean, this is more relevant for a college audience, to be honest. But it's important to keep in mind, right? I mean, binge drinking does increase LPS. I think most of us are probably more interested, what about moderate alcohol consumption? What effect does that have? And there's been associations with moderate alcohol consumption and small intestinal bacterial overgrowth. So the bacteria in our gut mostly are localized to the distal end of our large intestine, or our colon as it's called. Bacteria are not really supposed to be in the small intestine. I mean, this is where fats are absorbed. It's where simple sugars are absorbed, proteins.

So the complex carbohydrates are mostly broken down in the colon. But when bacteria make their way into the intestines, it can cause problems. It can cause zonulin release, and we'll talk about why that's important for intestinal permeability in a minute. But so there is some connection between moderate alcohol consumption and small intestinal bacterial overgrowth. I will say this. I mean, there's not a ton of literature on this, and it's quite likely, like we all know, observational studies There's a million factors. I mean, maybe it's a combination of people that already have some underlying gut issue, or maybe it's a combination of people that are eating an obesogenic diet and drinking alcohol, or they're stressed and they're drinking alcohol. You know, maybe it's a two-hit hypothesis.

Like, we don't really know, but it's something to keep in mind. Alcohol can be hard on the gut, especially in combinations with other things that are hard on the gut, like stress, for example. So let's talk a little bit more in detail about the zonulin that I've mentioned a couple of times. Again, looking at the intestinal gut barrier, we have our enterocytes that are connected together through tight junctions. So gliadin is one of 2 proteins that is present in gluten. So gluten is found in a variety of different types of whole grain sources. Gliadin binds to a receptor on the, on the surface of our intestinal epithelial cells called the CXCR3 receptor. And when that gliadin binds to that receptor, it causes the release of a protein from our enterocytes, our gut cells, called zonulin.

And zonulin then binds to a series of other receptors present on the epithelial cell surface. When that happens, this then causes tight junctions to disassemble. And when that— when the disassembly of our tight junctions happens, again, that's intestinal permeability. We can have things going from our gut into our circulation like LPS. A lot of this work was pioneered by Dr. Alessio Fasano at the University of Massachusetts Hospital. It is thought that, you know, so people with celiac disease, it's thought that gliadin is the major problem for them because of this mechanism, the release of zonulin and therefore disassembly of the tight junctions, which actually still disassembled for quite a long time and allow LPS to then go into circulation and do all the things that we just talked about.

With people that don't have celiac, it's thought that it might be a more transient opening and closing. So just to kind of play devil's advocate here, well, you'd think, OK, well, if gluten has gliadin and gliadin is going to release zonulin and that's going to disassemble my tight junctions even for 30 seconds. Like, I don't want that, right? So I mean, that's kind of what I'm thinking. But again, to play devil's advocate, when you, when you look at some of the observational data and people that are eating whole grains, we see that people that are eating whole grains seem to have a lower all-cause mortality, for example, compared to people that are not eating it.

Now again, as Dr. Rowe pointed out, nutritional observational studies are just— I mean, it's like a disaster for establishing causation. And I think— I mean, I could just point out like 10 things, but, you know, with studies like this, for one, whole grains include a variety of gluten and non-gluten containing proteins. The non-gluten ones wouldn't have gliadin. So these are things like quinoa, buckwheat, oats, millet, you know, barley. And the other would be, okay, well then maybe people are eating whole grains or just eating less refined grains. And in fact, that is the case. People that are eating whole grains are eating less refined refined grains.

And so there's a million things that you can look at here, but at the end of the day, it still kind of makes you go, hmm, well, maybe I shouldn't freak out too much if I have a little bit of gluten. And the same goes when you look at biomarkers of inflammation. People that eat whole grains have lower biomarkers of PAI-1 and also of C-reactive protein compared to people that are not eating it. But again, people that are eating these whole grains In fact, if you look at the methods of this section, it's all whole grains. It's not just gluten-containing ones. So we know that whole grains are a good source of fermentable fiber for bacteria in the colon. And fermentable fiber is then, by many bacteria, converted into butyrate. So butyrate is a short-chain fatty acid.

It is the major energy source for colonocytes. These are your— these are the enterocytes, the— Colonocytes. The gut epithelial cells that I was talking about, they're producing about 70% of all the energy for those cells. And so there's also been a variety of studies that have shown, for example, if you give butyrate to an animal, it can prevent LPS leakage, and it can prevent the formation of atherosclerosis in animal models that are predisposed to this, for example. So butyrate produced by bacteria in our gut is actually a good thing. There are a lot of different dietary sources of butyrate that don't include gluten. So pectins, for example, are a type of fermentable fiber. This is found in berries. It's found in root vegetables. It's found in citrus.

Beta-glucans are a really good source of fermentable fiber. They're found in mushrooms, oats, and barley. Inulin is another source of fermentable fiber. It's found in garlic, onions, and artichokes. And resistant starch is another source, and it's found in green bananas and cooked and then cooled potatoes. So these are other dietary sources of fermentable fiber that are known to increase butyrate, or— and also increase butyrate-producing bacteria in the gut. But there's other lifestyle factors that can affect butyrate as well. So omega-3 fatty acid consumption is able to increase the concentration of butyrate-producing bacteria in the gut. Aerobic exercise training can increase the production of butyrate-producing bacteria in the gut independent of diet.

And time-restricted eating is also able to increase the production of different types of butyrate-producing bacteria in the gut, because bacteria in our intestines are also on a circadian rhythm, much like every cell in our body are on a circadian rhythm. We'll hear a lot about that from Dr. Satchin Panda in a couple of days. But time-restricted eating, basically having the absence of food seeing our gut, is important for basically decreasing non-butyrate-producing bacteria and increasing butyrate-producing types of bacteria in the gut. What about dietary fat?

So if you were to take— this study's been done— if you take 300 calories in the form of a glucose beverage or orange juice or cream, heavy cream, and you look at first inflammatory biomarkers after consumption of those 300 calories from either of those beverages or water, but there's no calories in water, inflammatory biomarkers will be elevated in the glucose-containing beverage, and they'll be elevated in the heavy cream, but not the orange juice. Only the heavy cream increases LPS. The glucose does not, which is very interesting. There are meta-analyses that have been done looking at fat and LPS, and it seems as though fat can be hard on the gut, particularly saturated fat without fiber. Now, does that mean fat is bad?

No, I think that we've established that quite nicely over the last couple of decades. I think that If you look at the quality of evidence here, you'll see a couple of things. One, that most of the fat sources used are processed oil. They're coconut oil or palm oil. And when you look at the high-fat studies, they're mostly given also with a biscuit or something that's a refined carbohydrate. And there's enough evidence out there to show that saturated fat in combination with refined carbohydrates seem to really be key for increasing LPS from the gut. But I just kind of wanted to point this out, because I think as we are kind of shifting— there's a metabolic paradigm here where we're learning maybe fat and saturated fat isn't as bad as we thought— that we shouldn't just throw everything out.

There are still things to consider, and there's a lot of interacting and nuanced factors here. And I think that looking at the effect of dietary fat on LPS leakage from the gut is one that we should probably explore more and explore it better. So saturated fat and then, and then polyunsaturated fat in the form of omega-3 has been shown to lower LPS leakage from the gut. In the form of omega-6, like vegetable oil, in humans, if the vegetable oil is, is heated, it increases LPS leakage from the gut. But if it's not heated, it doesn't seem to have any effect. In humans, in animal studies, omega-6 will increase LPS leakage from the gut. But animal chow, when the pellets are made, it's possible that the omega-6 is heated. I mean, there's just no telling.

I think the bottom line is also when you look at some of these studies, when you have saturated fat with a fiber matrix, the LPS response is blunted. So it kind of made me like I like cream in my coffee, and I was kind of looking through all this literature. And the one thing that I really seemed to see consistent was, like, when you just have fat, like, just fat, like putting butter in your coffee or cream in your coffee, like, it does seem to be harsh on the gut. And a variety of mechanisms have been worked out on that. Bile acids, which are increased for the absorption and digestion of dietary fats, are— is one thing that's been shown to basically affect gut permeability. And the fiber actually slows the absorption of the fat, much like it does with glucose as well. Yeah.

So I do think that I may reconsider putting so much cream in my coffee, because that might be affecting my LPS. But the other thing is emulsified fats seem to be really bad for LPS leakage. So does this mean that a ketogenic diet is bad for our gut, or is leaking LPS into circulation? No, there's no evidence of that. And in fact, there's such profound changes in metabolism when you're in ketosis that it's quite, I think, a good hypothesis that, you know, any— if there even was LPS leakage, that maybe there would be a blunting of the inflammatory responses. Or in fact, like I mentioned in a question to Dr. Rowe, I'm very interested in the production of beta-hydroxybutyrate during ketosis and how this may travel perhaps even to the intestines and affect colonocytes and energy metabolism.

In our gut cells that are helping maintain the gut barrier. And I would love for anyone to do some experiments on this, because I think it's a really interesting and wide-open field that no one's looked into. And I honestly, if there's any graduate students looking for their dissertation hypothesis, I think it would be really interesting to look at that. So you can biomark intestinal permeability, a variety of biomarkers in the literature. I mentioned zonulin, a big one. The lactose-mannitol ratio directly measures 2 non-metabolized sugar molecules that are able to permeate your intestinal mucosa. This is something that a primary care physician can order for anyone. I'm actually going to try to get this done now that I've really been diving into this literature.

I'm going to try to do it after a couple of different types of meals that I eat. And it seems as though 1 hour after a meal is when you really get the peak. Peak of an LPS response from food. So I'm personally going to try this out. This is all just me experimenting here, so I'm not saying that it's going to really tell me much. But this is used in the literature. Lactose-to-mannitol ratio is used as a biomarker for intestinal permeability. I wanted to get into omega-3 because it was quite clear that omega-3 in human studies and in animal studies seems to blunt the LPS the postprandial endotoxemia, as it's called, or the LPS response after a meal. And there's been a variety of mechanisms that have been worked out to understand how this is.

And it seems as though there's a few things happening. I mentioned already omega-3 increases butyrate-producing bacteria. Butyrate-producing bacteria help prevent intestinal permeability. That's been shown. The other thing— the other way is that omega-3 increases the production of something called intestinal alkaline phosphatase, or IAP, as it's shown on the screen. So if we're looking again at our gut barrier, quote unquote, we have our enterocytes connected by tight junctions. The intestinal alkaline phosphatase does a variety of things. One, it can— it basically degrades and destroys LPS itself. It also changes the LPS-producing bacteria in the gut, so it seems to to decrease the LPS-producing bacteria and then increase the butyrate-producing bacteria.

So this is another way that omega-3 may affect inflammation, like through a totally different mechanism than all the other mechanisms that we already know about. And omega-3, I just want to spend, spend a moment talking about because it's so important. And low omega-3 intake from seafood has been identified as one of the top 6 preventable causes of death. This was, this was a big study that was published a few years back out of Harvard. And omega-3, there's a variety— there's 3 different sources of it. So there's a plant source of it that you can find in walnuts or flaxseeds or chia seeds. This is alpha-linolenic acid, or ALA. And then there's omega-3 that is found in seafood.

So there's the microalgae, but also the fish and all the, you know, the sea animals and sea creatures that are eating the macroalgae, it accumulates in their, in their adipose tissue. So there's eicosapentaenoic acid, EPA, and there's docosahexaenoic acid, or DHA. And so it was the omega-3 from seafood that was identified as being responsible. So basically, not getting enough omega-3 from seafood was identified as leading to 84,000 deaths a year. So 84,000 deaths a year were attributed to low omega-3 intake from seafood, that was comparable to trans fats, which was responsible for 82,000 deaths per year. Literally like the same. And if you walk into any grocery store and you look on the shelves, like everything's marketed, no trans fat, this is zero trans fat.

Everyone knows that trans fats are bad. Everyone knows that trans fats are bad for our health. And so people— it's in the public mind, do not eat trans fats. Yeah. And yet omega— low omega-3 intake from seafood was identified to cause the same amount of deaths as trans fat. But nobody's thinking about omega-3. You don't walk into a grocery store and see all the foods— we don't have omega-3, or we do, we have it from seafood. We are seafood. This is fish. We have omega-3. It's really important. And I think it's— I really like this because it— the way I like to think about food is what we should be eating. What do we need to— what is the point of eating, right? We're supposed to be getting nutrients, micronutrients. These are essential vitamins, minerals, fatty acids, amino acids.

We're supposed to be getting these from our food, but we're not. And instead of focusing, focusing so much on what we shouldn't eat, we should focus on what we should be eating. And honestly, when you do that, like, you don't eat the other stuff. It's like, well, that doesn't contain what I need, so I'm not gonna eat it. And I think it's just a simplified way of looking at diet, and it really helps. You can always focus on what not to eat and still be deficient. in important vitamins, and minerals, and micronutrients. So I really think it's an important way to eat. Back to the omega-3. It's just— it's really— I think, to me, there's overwhelming evidence now that omega-3 is really important for health.

So the omega-3 index— this was identified by Dr. Bill Harris and his colleagues, Clemens von Schacke, back in 2004. This is the omega-3 fatty acid level in a red blood cell membrane. And it's, it's a long-term marker of your omega-3 status compared to something like, what, 95% of people measure, which is omega-3 in plasma phospholipids. So red blood cells take about 120 days to turn over, so they have quite long of a half-life. And so if you really want to know someone's omega-3 status, you have to measure the right thing. Otherwise, you could be biomarking what they had for dinner a couple of weeks ago, and And it's like, oh, I had fish a couple of weeks ago, and then all of a sudden they're, they're marked as someone that's got high omega-3.

So I think this is also a potential for a lot of confounding literature. But on top of that, again, you just— we have to measure the right thing to like get good information, right? So a high omega-3 index has been associated with a 90% reduction in sudden cardiac death. In the United States, the omega-3 index is about 4% or lower. When I say a high omega-3 index, I mean, uh, 8% or more. So high omega-3 index has also been associated with a 5-year increase in life expectancy. So people with an omega-3 index of 8% or more have a 5-year increase in life expectancy compared to people with an omega-3 index of 4% or lower. Interestingly, in Japan, people have a 5-year increase life expectancy compared to United States, and they also have an omega-3 index greater than 8%.

And I want to sort of end my talk with something that sort of blows my mind, and I think you guys will find interesting as well. And that is that low omega-3 index, a low omega-3 index of 4% or less, was comparable to actually smoking. So everyone knows that smoking is bad for health. If you look at the red line, the red curve here, low omega-3 index and and a smoker had the lowest life expectancy. The green, the top, the highest life expectancy was a high omega-3 index, 8% or more, and a nonsmoker. But if you look at the orange here, that was a smoker with a high omega-3, had the same life expectancy as a nonsmoker with low omega-3. So again, omega-3 seems to be extremely important for health. So I'm going to end my talk with that.

We talked a lot about intestinal permeability, the role of intestinal permeability in cardiovascular health. in our brain health. We talked about the way we feel. We talked about lifestyle factors that can regulate it and devil's advocate stuff to think about as well. And with that, I'll say thank you so much for listening, and I hope you guys learned something interesting and enjoyable tonight. Thank you. Thank you so much, Rhonda. We're going to open up the floor for questions, and we have some questions coming in from the virtual platform. So, and many of them you answered during— as they were coming in, you answered them. And but one I think you may have answered, but I didn't catch it. Is there a lab test for circulating lipopolysaccharide or LPS?

Is there a commercially available lab test available that people can utilize to measure this? Is my mic— do I need to stand by this or I'm good? Okay. So there is a lab test for circulating endotoxin, and it's notoriously terrible because it's like false positives are so easy. So I mentioned the lactulose to mannitol ratio. That is a much, I think, more accurate biomarker of intestinal permeability, which would— I mean, directly measuring LPS would be great, but until we have a better sensitivity assay, I think that it's prone to false positivity. So I have a question, just to butt in, sorry. For intestinal permeability, we've connected with a group that are using PEG-400 as one of the tests, and I would like to get your opinion on that.

I, you know, I don't know much about that one, so I'll say beyond the scope of my knowledge. You. Yes, I have a question. If there's a role with nonsteroidals in affecting intestinal permeability. Great question. I don't know the answer. I think that's a really interesting— in fact, there may be literature on it I just am not aware of. Next, please. I had a couple of comments and a question. The first, to your earlier question, myself and some colleagues published a paper recently where we talked about, in part, alternative metabolic pathways in enterocytes. And you see, based on the preclinical data that we have so far, that MCT-1 is expressed on the basolateral membrane of enterocytes, so they can take up ketones from from circulation.

And actually, the common pathway with butyrate is acetoacetyl-CoA before it goes into the mitochondria. So they actually have converging metabolic pathways. So we think that ketones can be used to fuel enterocytes. The second thing, when you're talking about LPS, I think what you're really talking about is E. coli LPS because that's what's used experimentally, and it's really good at developing inflammatory I do it in my lab. I was doing it on Monday. However, there's, you know, LPS on any type of gram-negative bacterium, and there's an increasing body of literature that says that actually LPS from various bacteria are directly communicating with the immune system. They're immunomodulatory. This is our gut talking to us.

And so just talking about LPS going, you know, increasing in the blood and that being bad, I don't think is— Yeah. really right. And pretty much everything that we do increases circulating LPS. So you go for a 30-minute jog and you'll increase intestinal permeability, you'll increase LPS. And so where the rubber really meets the road is in metabolic disease, because it's only when you're insulin resistant that having elevated LPS is an issue, because being insulin resistant in the first place increases circulating LPS. But then you also have a scenario where things like transient increases in LPS like postprandial endotoxemia, you don't have the beneficial anti-inflammatory effects of an insulin spike to counteract that.

And then you're also going to have things like a discordant lipoprotein profile where you can have more small dense LDL where LPS is going to bind to and not be cleared. So I wonder if we should be focusing less on LPS because we're always going to have some and it's always going to go up intermittently. And if we just actually do the things that we know work to improve insulin resistance, then that's really going to solve the issue. I think that you brought up some really interesting points. I think for me, the way— like, looking at the effect of the toll-like receptors and understanding toll-like receptor activation from LPS. And I think, you know, there— with anything, there's a hormetic stress kind of effect, right?

Like, you can go exercise and have a little bit of intestinal permeability, and it's a type of exercise where you have a whole host of beneficial adaptive responses that are going to counter that. So your net effect is going to be lower inflammation, even if toll-like receptors are being activated on immune cells, and liver cells, and muscle tissue, and brain, and the microglia, for example. So I think context is important. And so it's not the same as if you have someone who has a chronic low level of constant LPS leakage.

But I do think the toll-like receptor and looking at the effect of toll-like receptor activation and the chronic insidious type of activation of it is kind of more what I'm— you know, I think that's kind of connecting them in the sense of the more sort of chronic low-grade activation. So, so yeah, I think that, I think that you brought up really, really interesting points, and thank you for telling me about, about the beta-hydroxybutyrate. We have time for 2 more questions. Okay, maybe mine will be quick. Is there a reason why someone with intestinal permeability who we treat with a lot of the things that you said and feels better, they're so quick often to come back into it versus some people seem to be like they just don't experience intestinal permeability no matter what they eat or do?

Yeah, I mean, I think that even getting to the young gentleman's point, you know, you have a variety of factors that are affecting it, and that's kind of why I mentioned with saturated fat. I mean, you look in the literature and it's like, yep, saturated fat and intestinal permeability. But when you start to dive a little deeper, it's like, oh, but the saturated fat was a certain type of this processed oil, and maybe it's the palmitic acid plus the refined carbohydrate, or maybe it's the alcohol plus the stress, or maybe it's multiple things in combination with genetics, getting to the personalized response. I mean, some people respond terribly to ketogenic diets, and some people respond great. So I mean, there's always individual variation. There's a lot of, you know, there's a lot of contributing factors to health. And so it is— it's hard to just say like there's one villain and there's one like, you know, what do you call it, good guy or hero, right? Yeah.