64: The Metabolic Health Benefits of Fermented Foods with Dr. Ben Bikman

Hello. Welcome to the Metabolic Classroom. I'm Professor Ben Bickman, biomedical scientist and professor of cell biology. Thanks for joining me for the lecture today. In today's lecture, we are discussing fermentation and fermented foods. That might seem like a strange topic for a metabolism scientist to talk about. Actually, it's going to be more relevant than you think, and I hope I make that clear. One point though, as I start this conversation is just to help you appreciate perspective on the topic, which of course is coming from. It's the perspective of a metabolic scientist, not only one who focuses on nutrients and the hormone response to these nutrients when we eat them, but also a scientist who has conducted and published papers on bacteria and the unique metabolism of these bacteria. And they are different. Bacteria do not metabolize the same way our normal, our cells do, or animal cells do. So the topic is fermentation. In the overview, we're going to discuss the metabolic value of fermentation and define it. Of course, we'll start with that point and then I want to highlight some of the examples, some of the common examples of fermented foods, because while you may understand the principle already, or after I explain it, you might not appreciate just how common this is. But then I also want to talk about some of the products of fermentation and the, and some other molecules like anti nutrients. It might seem a little bizarre to bring that in, but it's going to be much more relevant than it seems. Okay, so firstly, first part of the lecture, let's just understand fermentation. Very, very briefly. Fermentation is the metabolic process where micro, a microorganism like a bacteria, will convert carbohydrates into other organic molecules. Now, it is an emphasis on carbohydrates because starches and sugars are the, the primary fuel source for these bacteria. They don't want to eat fats, they don't want to eat amino acids or proteins. They want to eat a carbohydrate source that is their fuel. In fact, they're not going to eat the other fuels, they're not going to eat fat, they're not going to eat ketones, they're going to eat carbohydrates. Now, I mentioned that they have a product of these organic molecules and I'll, I'll revisit that in a moment because it's, it's actually a really powerful effect not only on what you eat and the taste of it, but also what the fermented product is now doing in your body. Okay, so let's now that I've defined it, where again, fermentation, again, at its simplest is just bacteria coming and eating the starches and sugars from a particular food. So what are some examples of this? Well, it could be anything with a lot of starches and sugars. So one example, and one of my favorites personally, is from fermented dairy. So dairy is a unique food because as far as I know, it is the only food that is naturally high in all three macronutrients that is very uncommon. You have carbohydrates like plants, fruits and vegetables, which are almost purely carbohydrate. Sometimes a little fat, sometimes a little protein, but overwhelmingly it's just pure carbohydrate. Then you have in nature animal sourced foods, which is overwhelmingly fats and proteins, unless it's dairy, because, yes, dairy is rich in healthy dairy fats. It is rich in dairy protein, which are among the best and most bioavailable. And then lastly you have the dairy sugar or lactose, which gets converted into glucose. So if you ferment the dairy, it doesn't touch the fats, it doesn't touch the proteins. It, however, does not leave the lactose untouched. So it wants to go in and does indeed go in and eat all of the lactose, leaving behind yogurt. Or my personal favorite, kefir. Yes, I say that the Russian pronunciation because of my being fluent in Russian, but. Or kefir, or kefir as we would call it in the West. But kefir is this fermented milk, which again is one of my absolute favorite drinks. Now, when you drink that, think for just a moment what is the difference between drinking, say, kefir or drinking pure milk? You know, sure, it's a little thicker, but also it tastes quite different. And we're going to talk about that in a moment. Moment. Also, speaking of taste, think about something like cabbage. And now it's been fermented. And now we have sauerkraut or we have kimchi. Those are fermented products. Tofu is a fermented product. Beverages are often fermented. Of course, all alcohols are fermented. In fact, that's one of the other products of fermentation. Depending on what you're fermenting and the bacteria you're using, they can produce alcohol as a byproduct, in addition to some other molecules that we'll talk about in a moment that I continue to tease you with. But certain beverages, basically beers, you know, kombucha. Kombucha is also a fermented product. So all of these are products that we consume that are, that utilize fermentation. Now let's start, let's transition using some of these just as an example and talk about why I am an advocate of fermentation when it comes to foods, particularly when it comes to carbohydrates. You know, my first rule of nutrition is control carbohydrates. That is includes a focus on fiber if you're eating carbohydrates, but also a focus on fermentation. Fermented foods will generally lower the glycemic index of, of whatever the original source, whatever the original food was. And that of course makes sense. The glycemic index or more, more better the better one would be the glycemic load is going to predict what this food is going to do to the individual's blood sugar levels. You eat something that has a lot of starches and sugars, no surprise, it has a high glycemic load and your blood sugar levels go up a lot. Of course, with that and very relevant to me and you, I hope blood insulin levels will follow that. And the more frequently you're spiking your blood insulin, the more likely you are becoming insulin resistance independent of just the consequences of the hyperglycemia, which itself is relevant. So we have foods. Anytime you take a natural food and now you've fermented it, the glycemic index or glycemic load is going to be reduced. So that's an immediate benefit for, from my perspective. So for example, if you have a fermented milk like kefir, and it has, it has been shown to improve glycemic control and lipid profiles in people with type 2 diabetes. There was a good study, Osta Drahimi, Ostradehimi et al in 2015, finds that these, that this fermented milk will elicit superior metabolic improvements in like HbA1C and fasting glucose over drinking normal milk. And I'm still an advocate of normal milk too, particularly in children. Now, what about something like sourdough? One of the unfortunate things with sourdough nowadays is that it's actually hard to buy actual sourdough. What you think you're buying is sourdough is in fact nothing more than normal bread that has been, that has had a little bit of vinegar added to it. Interestingly, vinegar itself is, is a product of fermentation, but they have just added that directly in. So you're not getting, you're not having the bacteria remove the starches from the from the grain, from the flour, like you would with a, with a true sourdough. But if it's a true sourdough, and when you're buying it, just look and see if it mentions something about a starter, a sourdough starter, and it doesn't show that it's just had vinegar added to it. Sourdough bread, a product of natural fermentation, does have a lower glycemic response to compare compared to conventional bread. And of course, the fermentation will reduce some of the starch load, which helps lower postprandial glucose levels. So the glucose levels after you eat the sourdough is going to be substantially less than if you eat just conventional bread. And again, the same thing goes for any of the products of fermentation that I mentioned earlier. Pick any of them and the glycemic burden that comes with it will be reduced. Again, that's because the bacteria have already done some of that work for you. They have already removed the carbohydrate, some of it or all of it, and then left behind these products of fermentation. Alcohol in some instances, or transitioning to the next part of this lecture, one of my favorite topics, short chain fatty acids. So short chain fatty acids are produced. They are a metabolic byproduct of the fermentation. This includes things like acetate, like acetic acid. That's what you get in vinegar, or propionic acid, or butyric acid, which is a product that you don't get much of, but that's found a little bit in butter. And that's where the name butter comes from, because of that short chain fat. But these are the short chain fats, acetate, propionate and butyrate. They are uncommon in our modern diet, largely because we do not eat fermented foods. Now that is a difference. I'm not a historian, but we can intuitively understand this. Before the age of preservation of packaging up foods and refrigeration, it was very common for foods that our ancestors ate, plant based foods and even dairy, to have undergone some degree of fermentation. So these molecules, these short chain fats, and they are literally just like a fat, not a long chain fat, not a medium chain fat, but the shortest of them. These three in particular, acetate, propionate and butyrate, they used to be such a common part of our diet, but they're not again, because we typically shun these fermented foods deliberately or just accidentally. That is unfortunate. Now it is in fact these short chain fats that give the fermented food, the tart flavor. Earlier I had mentioned the difference between drinking kefir versus milk. Why, of course, other than a little bit of change in viscosity, why is the kefir so much more tart or sour? That's because of the short chain fats. Short chain fats have that taste in the mouth. So anytime in nature you're tasting something sour or tart, it would have been because of some fermentation. And that's what they're faking when they just add a little bit of vinegar into the fake sourdough. Now, why am I, why am I a metabolic scientist, such an enthusiast of short chain fats? Multiple reasons, and let's just take a moment to elaborate some of them. One of them is gut health. Short chain fats help maintain the integrity of the gut barrier. So those, this is something I've discussed in previous metabolic classrooms, but this phenomenon of leaky gut, and I'm going to revisit it in the future metabolic classroom soon. But normally with the gut barrier or the epithelium, that's the lining, the cellular lining of the, of the gut, it has very, very tight junctions and nothing is slipping through the junctions. Anything that's coming in is moving through the cells and the cells get to choose what comes in and what doesn't. These short chain fats help keep those barriers, those, those gap junctions, very, very tight. Short chain fatty acids also promote an anti inflammatory milieu within the body, helping control inflammation, particularly originating from the gut, but also it feeds the gut cells. So the gut cells themselves will actually metabolize these short chain fats, these epithelial cells and use it for energy. Very, very helpful. Also there is an internal, an internal metabolism. As much as I just was focusing on the gut and what's happening in the gut, including feeding the gut cells, these short chain fats will be absorbed into the bloodstream. They should be, that's a natural response. And these short chain fats can influence metabolic processes that help, that are very helpful. For example, they can stimulate directly the biogenesis of new mitochondria in cells throughout the body. So when short chain fats hit the bloodstream and then begin going to various cells, like let's say, muscle cells, it will stimulate the muscle cells to produce more mitochondria. It also improves insulin sensitivity at tissues throughout the body, which of course has a remarkable benefit as insulin resistance is not only the most common chronic disorder worldwide, but also the most likely to contribute to the chronic diseases that we're also Afraid of, like diabetes, Alzheimer's disease, heart disease, et cetera. One other point, and a final one about short chain fats, is that they're very ketogenic. Let me just riff on that for just a moment because it's an interesting point. What makes a short chain fat so much more ketogenic than a long chain fat? Ketogenesis is a product of how rapidly liver cells are burning fat. Long chain fats, yes, they're certainly burned. They are very burnable, but they also are very storeable. So the liver could very readily store those fats if the, if insulin is telling it to, as one, one example of, of a regulation point. But the shorter the fat gets, the harder it is for the body to store it as fat. Indeed, when you get to the level of short chain fats, it is impossible. You cannot store short chain fats. A cell has literally nothing to do with them but burn them. In fact, another sort of tangent within a tangent. I just received an email from an individual who has a genetic deficiency in the ability to burn fat because they have a deficiency in this enzyme, cpt. A little, a little too nitty gritty here, but CPT is an enzyme that controls the movement of long chain fats into the mitochondria. So they can't burn long chain fats very well. But guess what a workaround is in these kinds of individuals, of course, eating shorter chain fats, like medium or short chain fats, because they don't need that CPT regulator, they just go right into the mitochondria to get burned. So if a fat gets burned and burned very quickly, like short chain fats, they're much more ketogenic. So it's no surprise that the more short chain fats an individual has in the blood, like from consuming fermentation, fermented foods, the more they're going to elicit ketogenesis. And they'll have an easier time being in ketosis if that's something that's important to them, like it might be in certain disorders. Okay, now that's some of the direct metabolic benefit of the product. The products of the fermentation, but also the bacteria themselves can provide a benefit to the body. Because after all, if we're eating fermented, fermented foods, the bacteria are there, you know, when you're drinking an, an unpasteurized kefir, for example, or unpasteurized kimchi or sauerkraut. So pasteurization would kill all these bacteria. But if it's unpasteurized or raw, then you are consuming the bacteria as well. So now you have the magic of the probiotics. So fermented foods contain live bacteria if they're raw, that can help balance the gut microbiota, improving digestion and even other things like immune function. So numerous benefits and of course probiotic supplementation, particularly if you know you're actually getting live bacteria, have been shown to be very therapeutic for myriad gastrointestinal disorders and, and autoimmune disorders and even metabolic function as well. So just as a personal preference, when I'm focusing on fermented foods, and I'm not giving anyone any advice, of course, in this regard, but I like to when I can focus on raw and unpasteurized sources. Now, some of all of this I have discussed in various venues before. So some of you who have been connected with me for some time might not deem any of this to be particularly novel. And now you're clamoring for something new. Let me give you something new that you might not have heard me discuss before, which is antinutrients. I've certainly never discussed antinutrients in the metabolic classroom previously. At least I don't think I have. But antinutrients are worthy of discussion and they're also of course, first and foremost worthy of defining. So these are natural occurring compounds found in various plant based foods and they inter, they interrupt the absorbed and utilization of various nutrients that we consume. This includes things like minerals or proteins or other nutrients that we would want to be absorbing. But these anti nutrients literally bind them and block them from coming in. Well, needless to say, that's not optimal because there are some of these things like iron and zinc, you know, for example magnesium. There are minerals that we need and proteins. These are things we have to get in. That's why we're eating that particular food. It's to get things like this macro and micronutrients, the antinutrients get in the way. Now what are some examples for this? Because it sounds like it's made up, but just think about this for a second. If, if we were dropped in the middle of an unfamiliar forest and you would say, well, look at all these plants we can eat. In fact, the reality is, at best we would get no benefit from virtually all of them. At worst, they kill us, they poison us. You know, plants can't run away like an animal can. The animal's defense is its ability to get away from us or attack us back. A plant can't run away, but it can attack us back. Even if after the fact, by consuming it, it wants to make us regret it and ensure that we don't come back and do it again. Now, in our intelligence, we have selectively bred certain plants to have much more modest levels of these antinutrients, but they are molec that are inherent to all plants. Now, I don't mean to imply that a human can't eat any plants and be healthy, but I hope that there's an implication that plants do contain molecules that would want to discourage us from eating them. And some people may be particularly sensitive to those molecules. Now, what are some of them? I could just find and think of really four easy examples and obvious ones. One of them is phytic acid. Phytic acid is found in seeds in particular, and nuts and grains and legumes. But what it can do is bind minerals like some I mentioned, calcium, iron, zinc, and prevent their absorption. So it keeps them in the gut to just be excreted in waste from the intestines. So foods that are particularly or diets that are very reliant on these kinds of foods, you know, nuts, seeds, legumes, they may be getting unhealthy levels of phytic acid and then may be developing slowly a deficiency in these minerals. Calcium, iron, zinc. Another form of an antinutrient is lectins. Lectins are proteins found in legumes and grains that can interfere with the absorption of nutrients and still cause some distress. Another one you've possibly heard of is oxalates. Oxalates are particularly enriched in leafy greens, also nuts and seeds. But they bind to calcium and prevent calcium absorption. But at the same time, if the oxalates get into the blood, they can form these crystals, which can lead to stone formation. It's almost like their own version. This is like an oxalate version of gout. So a lot of people who suffer from frequent kidney stones will often be told to avoid diets foods that are rich in oxalates, like leafy greens, nuts and seeds. Now, the last one is tannins. Tannins can be enriched in teas and coffees, but they are iron blockers. They don't want the body to absorb iron. And if there's a lot of tannin consumption, this can be a concern for people who have low iron already, or it can exas it can cause the low iron. Now, why am I bringing up anti nutrients? What's the point? Well, there is wisdom in the way our ancestors used to eat these kinds of plants, including things like coffee. Why do we ferment the coffee beans for a period of time. Because fermentation will remove antinutrients, thereby improving the bioavailability of the essential nutrients that we want. So with each of these ideas in mind, during fermentation, the activity of the phytase enzyme increases. So fermentation increases this, the the ability to degrade phytic acid and it breaks it down into its component parts. In particular in this case inositol and phosphates, which are both perfectly benign molecules. In fact, in the case of inositol, it's even beneficial. So when we are consuming the grains and legumes and other sources of phytic acids, if we have allowed the food stuff to go undergo fermentation, now we have a greater absorption of those minerals that the phytic acids were attempting to block, namely iron, zinc and calcium. Fermentation can also degrade lectins, which are these proteins like I mentioned earlier, that can bind not only to the intestinal lining, damaging the lining and increasing the tendency for leaking molecules in or bacteria in, but it also will affect nutrient absorption. And the microbial activity during fermentation will break down these lectins, reducing that anti nutrient effect. And the same thing goes with tannins. Tannins are also reduced which can help improve iron absorption, a very important micronutrient or mineral, and even oxalates. Fermentation has been shown to lower oxalate levels in foods from like leafy greens and grains. These microbes will just take the oxalate and break it down, preventing the oxalates from in turn preventing this antagonism towards nutrient absorption. Now there was some, there were a handful of studies that I found that actually documented some of the reductions and, and just some of them are worth noting. Like for example, cassava. Cassava is a, is a starchy plant that is eaten in various parts of the world. The fermentation of cassava using bacter bacteria can actually reduce some of these anti nutrients to significant levels. Like for example cyanide. Yes, cyanide that can poison and kill you. Cyanide is present in cassava. Well under fermentation, you reduce this. Cyanide levels are reduced by 86%. Tannins are reduced by 73%. Oxalate is reduced by 61%. Phytic acids reduced by 72%. That is some substantial reduction in some pretty harmful molecules. Also with legumes and cereals that if you allow these grains and legumes to undergo fermentation, phytic acids will be reduced by over 50%. Lectins from fermented Beans were found to be down by 95%. So you're cutting it in half and you see this reflected throughout myriad other examples of fermented foods. So all of this I hope, is just impressing upon you the relevance and even, dare I say, importance of fermentation when it comes particularly to these starchy sugary foods. Now let's sum it up as we wrap up the lecture. Over the course of what we discussed today, we talked about just what fermentation is, particularly how bacteria can come in and eat up the glucose sources, the sugars and the starches, reducing the amount of glucose our body has to deal with and the subsequent insulin spike that would come with it at the same time, while it is removing the stuff we don't want, because remember, there are such things as essential fats, there are such things as essential proteins or amino acids. There's no such thing as essential carbs. Now again, I'm not saying we can't eat them, but how awesome is it that these bacteria have come in and removed the one thing we don't need and replaced it with other beneficial things like short chain fats. And I listed some of the benefits of short chain fatty acids. Also, if we're consuming the raw fermented food, we're getting probiotics as well. So we have the additional benefit of putting some new healthy bacteria in our intestines, which helps the overall health of the microbiome, which in turn helps metabolic and immune function. Also, the last point we, we discussed was the removal of antinutrients. These almost myth little monsters that come that are inherent in all plants, but ideally in profoundly lower levels. Like usually fruits have lower levels. You'll notice not one time did I mention fruits here. So some, not all plants are the same when it comes to these anti nutrients. But our ancestors were wiser than we give them credit for. And often they would bury these things in a little pit and sprinkle some other stuff on them or even use their own spit to get bacteria in these, in these little stewing little pods of fermentation and then get it all up and dry it and eat it. So what can you do about this? My advice would be to find a way, if you're so inclined, to incorporate some fermented foods. I've already mentioned my favorite. I love kefir. I also love sauerkraut. It's one of my favorite things more and more. Just as a point of interest, my diet tends to be pretty meat heavy, you know, a lot of protein and fat and a lot of focus on fermented foods, partly taste. The older I get, the more I find I just like things that have a stronger taste than I used to. But also, there's pretty good justification for focusing on fermentation. So in my mind, focusing on fermentation fits very well into my first cardinal rule of eating smartly and increasing your insulin iq, namely focusing on fermentation by and being a part of controlling carbs. Thank you for joining me. Until next time, more knowledge, better health.