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Phytonutrients in Meat and the Nutritional Difference Between Grass-Fed vs Grain-Fed, with Stephan van Vliet

Phytonutrients in Meat and the Nutritional Difference Between Grass-Fed vs Grain-Fed, with Stephan van Vliet

In this episode, we discuss:

  • How different grazing practices affect the nutritional composition of meat
  • The relationship between agricultural sustainability and the nutrient density of meats
  • The results of Dr. van Vliet’s work in the Beef Nutrient Density Project, which studies the relationship between farming methods and the omega-6 to omega-3 ratios of meat
  • The types of nutrients that are diminished in feedlot beef vs. grass-fed beef
  • Whether it is possible to consume phytonutrients, secondary plant compounds, in any significant amount from beef
  • Factors affecting the ability of the body to absorb phytonutrients from animal sources and what that means for people on carnivorous or vegan diets
  • How the principles of food synergy and nutritionism demonstrate the body’s preference for nutrients from whole foods
  • The state of Dr. van Vliet’s research in this field and where it is headed

Show notes:

Hey, everybody, Chris Kresser here. Welcome to another episode of Revolution Health Radio. This week, my guest is Dr. Stephan van Vliet, and we are going to dive into recent research on the nutritional differences between [grass-fed] and grain-fed meat.

Now intuitively, we might suspect that there are significant differences here. We know that for human beings, if a human being changes their diet significantly, then they’re going to see differences in their biochemical markers that reflect health and differences in blood levels of various compounds based on their diet. So, of course, we suspect that that’s also true for animals that are consuming different diets, grass vs. grain feed. And certainly, we have had research in the past that gave us some indications here, particularly for essential vitamins and minerals. But what Dr. van Vliet’s group has done is take that to a greater level of resolution. They’re looking at essential fatty acid profiles like omega-3 and omega-6, but also saturated fat, but in much more detail. They’re looking at carbon chain length and intermediary fatty acids, and then they are also starting to look at the presence of phytonutrients in meat in grass-fed animals versus grain-fed animals. These are some of the same compounds that we get from eating plants, but it turns out that we may get meaningful amounts of them from eating grass-fed animals.

So this was a fascinating conversation. [There’s] a lot of cutting-edge research here, and some really exciting new insights into the importance of regenerative ranching and methods of raising animals and how that impacts animal health and very likely human health. So let’s dive in.

Chris Kresser:  Stephan, it’s a pleasure to have you back on the show.

Stephan van Vliet:  I’m glad to be back, Chris. It’s been a while.

Chris Kresser:  It has been a while, and you’ve been busy. I’ve been really looking forward to talking to you about some of your latest research on grazing practices and how they impact the nutritional composition of meat. Because this is something that I’ve intuitively suspected for a long time, and we didn’t really have, until fairly recently, much data to back up any kind of intuitive suspicions or guesses that we might have had about how grazing impacts the broader nutritional composition. Certainly, we had some data on essential vitamins and minerals and fatty acids and things like that. But that’s just one part of the nutritional composition of meat. An important part for sure. But not the only consideration. So maybe you could just start by broadly introducing what you’ve been up to lately, and what kinds of nutrients and nutritional profiles you’ve been looking at in meat in relation to grazing.

Stephan van Vliet:  Absolutely. So I think since the last time we spoke, I was actually still at Duke University. And I’ve moved to Utah now. So I’m at the Center for Human Nutrition Studies at Utah State University; it’s a great position that opened up here. It’s kind of like a clinical facility where I’m at. It looks like a doctor’s office. So we do a lot of nutrition trials here. But what is nice about the place where I’m at now is that it’s also an [agricultural] school. So there’s this combination of ag culture, human nutrition, and it’s really the sort of field that my research group operates. So that’s been nice. And yeah, we’ve continued a lot of our projects on, as you mentioned, how different grazing practices impact the nutritional composition of meat, and we don’t just study meat. We take a broader look at regenerative agriculture or call it agroecology in science. But it’s basically agricultural practices such as multi-cropping, lay rotations, where you maybe integrate animals and crops, you have maybe multi-species grazing. So things that by the Intergovernmental Panel on Climate Change (IPCC), one of the leading bodies on climate change, suggests or practices that can improve the sustainability of agriculture.

So essentially, what we do in our group is we take a lot of those or look at a lot of those practices and see, well, do they also translate into a human nutrition benefit and potentially a human health benefit when we consume foods from more sustainable or regenerative systems? And it’s really interesting that you noted about, intuitively, how that would make a difference once you feed an animal, right? And I agree; intuitively, it makes sense. But we have to be critical as scientists and look at the data. I come at this from a human nutrition standpoint. And we’d often study people [who] were on Standard American Diets or on Mediterranean diets or other whole foods diets. And if I’d asked you, Chris, after three months on those diets, would you expect a difference in health? You’d probably say yes. If we do that with a cow, [and] then we put them on pasture for the last three months of their life or in a feedlot, one could expect to see differences there too, right? Because [they’re] two completely different diets. And if we do that with lab mice, we expect differences. But for some reason, for a long time with animals, we did not think there would be differences. But a cow is a mammal just like a human. And if you put them on two completely different diets being on a grain-based ration in a feedlot or grazing outside on a large number of plants, you get a very much different nutritional profile, and also an animal metabolic health profile.

Chris Kresser:  Absolutely. I mean, it’s common sense. But as you said, that’s not enough if you want to be rigorous in your scientific approach just to apply common sense. You have to do the research to back it up. And that’s exactly what you’ve been working on. So tell us a little bit about some of the recent work you’ve been up to.

Stephan van Vliet:  So we’ve been working on a project that we started. I don’t know if we’d started already last time we talked. It’s called the Beef Nutrient Density Project. Basically, we are working directly with farmers where we source a lot of beef from the supply chain, and we also buy beef in stores, grass-fed, grain-fed. We work with smaller feedlots that may not feed as much grain or have shorter finishing periods. But basically, the goal of the project is to look at 250 farms, 750 steaks, so three steaks per farm, and to look at the source of nutritional variation and what is causing that variation. And what we are seeing so far, Chris, is that on average, we see that the omega-6 to [omega]-3 ratio is improved in grass-fed beef, as you would expect. It’s about three to one. So for every three omega-6, there’s one omega-3. In the feedlot system, we see that it’s about 10 to one. But it is also important to note that there’s huge variation, about an 11-fold variation in the grass-fed beef systems. What we’re seeing initially in our data is that definitely, the ranchers that use these agroecological practices, such as rotational grazing on biodiverse pastures, moving the animals around regularly, not overgrazing on the pasture, end up with the most favorable omega-6 to [omega]-3 ratios.

We also typically see that the animals are in good metabolic health. We can tell that by the meat, as well, [by] looking at, for instance, oxidative stress markers, and also to find the chemicals, the plant secondary compounds that are thought to largely have anti-inflammatory, antioxidant effects, certainly to the animal. Whether it has [the same benefits] to humans from consuming meat is up in the air at the moment. But [regardless], animal health is improved. We see that those are also the highest when people have used these regenerative or rotational grazing practices among grass-fed beef systems. When animals are grazing more monoculture pastures or they’re overgrazing the pasture, we see a reduction in the nutrient density and then sort of the lowest amounts of these “beneficial compounds,” omega-3s, phytochemicals, long-chain saturated fatty acids, B vitamins, they’re typically a little bit reduced in the feedlot-finished animals.

Chris Kresser:  Yeah, that makes sense to me. Again, it’s one ecosystem where all of these different parts influence the whole. And we’ve had a lot of ranchers on the show over the past couple of years talking about the regenerative practices that you’re referring to, and why they’re so important for animal health, for [the] ecosystem, [the] local environment, health, and then, of course, ultimately, human health, from consuming animals that have better nutritional profiles. With that in mind, like, an 11-fold variation is really significant. Would you say that the grass-fed animals that were on, done in the most conventional way, let’s say, were close to feedlot animals? Or was there still a difference?

Stephan van Vliet:  Yeah, that’s a good question, Chris. And I cannot stick my hand in the fire for it. But my gut feeling tells me that those animals were fed grains, and they weren’t truly grass-fed.

Chris Kresser:  Interesting.

Stephan van Vliet:  That’s what I think because I mean, that’s what the data suggest. And to be fair, these were samples that we just bought in grocery stores. So unfortunately, that also means that we don’t have insight into their practices, per se. Obviously, we know the brand, but we keep [the project] sort of de-identified, obviously. But yeah, looking at [those] data, to me, it suggests that these animals were not like grass-fed. Because sometimes they even had worse omega-6 to [omega]-3 ratios than your average feedlot beef. But I must say, the farmers [who] we worked with directly or [who] sent in samples and filled out their management data, and the ones [who] use these “rotational grazing practices,” agroecological practices, or regenerative practices, as people often say, those rose to the top. A lot of these farmers have omega-6 to [omega]-3 ratios that were closer to one-to-one and two-to-one. So that’s kind of considered the gold standard, really. And they also ended up with high amounts of phytochemicals, plant secondary compounds.

And one thing we also noticed was that niacin, vitamin B3, was also elevated in many of these farmers, and we know that fresh forages provide the precursors to that vitamin. So those were things that we noticed. This was also kind of surprising to me initially, but then looking back on it, this cannot be too surprising because we were so focused in the field on omega-3 fatty acids that we did not really look at saturated fatty acids properly in the past. But what we’re seeing in polyunsaturated fatty acids, we see these very-long-chain ones such as [eicosapentaenoic acid] (EPA) and [docosahexaenoic acid] (DHA) and [alpha-linolenic acid] (ALA) and [docosapentaenoic acid] (DPA), we see those getting enriched, so the very-long-chain polyunsaturated fatty acids. Well, we see the same thing with saturated fatty acids. The very-long-chain ones, such as behenic acid, for instance, or decanoic acid, so it’s C18 and up for the listeners [who] have an idea on the carbon lengths of these fatty acids. But these long-chain ones [are] up as a result of forage-based diets. And what is interesting is that at least in epidemiological studies, circulating amounts of these very-long-chain saturated fatty acids are often neutral, or associated with a decreased risk of cardiovascular disease and diabetes.

So yeah, [it] certainly is interesting. And then another avenue to explore is that saturated fat isn’t saturated fat either. And there’s a concern regarding saturated fats from beef and red meat, and we can go into that, too, and whether that is always justified. But anyway, we do see “more,” at least on paper, favorable saturated fatty acid profile, too. And that was something that was not on my radar.

Chris Kresser:  That’s really interesting. I want to come back to that. But I also want to touch on the phytochemicals briefly because I think this is something that, correct me if I’m wrong, was novel, with your research, or at least, it seems like I might have seen it in one other paper. I could be imagining that. But I’m interested in this. Like you said, we don’t know whether consuming these phytochemicals in meat has any human health effects. We do know that it does seem to benefit the animal. And again, just applying common sense, a healthier animal, all other things being equal, will probably lead to [a] better nutritional profile and composition and [a] healthier human, if they’re eating that animal. But what do we know about—maybe you could give some examples—these phytochemicals, and what we know about how they’re impacting the animal’s health, and any, if there’s anything at all, so far that’s been published, in terms of the human health effects of phytonutrients in meat. Because of course, the common wisdom is you can only get phytonutrients from plants, from eating plant foods. And if it’s true that we can get phytonutrients, as well, from consuming animal foods, that’s a pretty big shift, in the dominant kind of paradigm or idea about nutrition.

Stephan van Vliet:  Yeah, that’s true, Chris. You can get phytonutrients from drinking breast milk, as well.

Chris Kresser:  Right.

Stephan van Vliet:  So whether it’s breast milk, as a baby from a nursing mother, [I’m] certainly not saying you should drink breast milk as an adult. But my point being is if you can find this in breast milk of mothers [who] consume a diet rich in fruits and vegetables, and it’s transferred to the baby like that, it’s not that weird to think that if you feed a phytochemically rich diet to a cow, its milk and meat get enriched in these phytochemicals, [too]. So phytochemicals are secondary metabolites of plants. We call them secondary because, for the longest time, we had no idea what they did. So we thought they weren’t important. They are not essential to the plant’s survival from a metabolism standpoint, but I would argue that without these phytochemicals, which are often plant defense mechanisms against overgrazing [the plant suffers]. So, sometimes a plant likes to maybe be nibbled a little bit, but not eaten fully, or it’s protecting yourself from [ultraviolet] light, or water stress or drought. A lot of times, these [phytochemicals] are plant defense mechanisms. But they’re also volatile compounds, fragrance that attracts animals to eat them. So it has a dual role. But these plant phytochemicals are typically also noted as antioxidants. All phytochemicals or most phytochemicals have a hydroxy group, and that means they are antioxidants.

So they can serve as antioxidants, most of them, at least when animals consume them, and also when we consume them. And it’s really a novel area of research for sure. I often compare it to—I mean, I wasn’t alive, clearly, but I teach a course in advanced micronutrient metabolism where we go over the history of how these vitamins were discovered. And it was about 100 years ago, and there were rapid discoveries about vitamins [and] how they impacted metabolism, and I feel like we’re a little bit in at that stage now with phytochemicals. It is in its infancy; there [are] probably hundreds of thousands of these compounds, but we have identified major ones, and these are things that are often named after the food that they’re rich in. So a major one is cinnamic acid. It is rich in cinnamon, but it’s almost found in every plant. We have caffeic acid [and] benzoic acid. These are all common phytochemicals that are found within plants, but also animals and then humans.

What is interesting about those is that yes, if you consume a more phytochemically rich diet whether you’re a human or an animal, [you will] have higher amounts of these. And what is particularly interesting [in] some of the findings that we’re making regarding animals versus fruits [is that] animals, especially ruminants, consume forages of vegetation that you and I cannot consume. They might be toxic to us, or they might be too fibrous. But they may also contain certain beneficial or medicinal compounds. And that is a way of further providing these to us in our diet. And then, of course, it also further increases the overall phytochemical richness of our diet.

Chris Kresser:  Yeah, yeah, it’s something I’ve always argued is that cattle can transform foods, plant foods that we can’t consume, because of our different physiology into compounds that are beneficial for us. So they do a lot of that hard work for us, and we benefit from it. And this seems to be potentially another area where that’s also true. And I find it particularly interesting in light of the recent popularity of [the] carnivore diet, and a lot of discussion around well, if we look at historical, traditional cultures historically, to my knowledge, we don’t know of a single one that only ate animal foods, like 100 percent exclusively animal foods. Nor do we know of one that ate exclusively plant foods. And it seems that just judging from this ancestral template that some combination of plant and animal foods seems to be best for most people. And that’s a controversial statement these days. But that’s my belief. But it is interesting to me that there’s, that I’ve often wondered, well, if that’s true, we also know that some people are thriving, or at least appear to be thriving from all the ways that we can measure that both subjectively and objectively, on a carnivore diet. And if these phytonutrients are so beneficial to health, which so many studies do suggest that they are, how do you resolve that apparent contradiction? And maybe we don’t know yet. But maybe this is one potential way of resolving that contradiction. That actually, people are getting phytonutrients; they’re just getting them from animal foods instead of plant foods.

Stephan van Vliet:  Yeah, I agree, Chris. And that’s certainly true, although I do want to make it crystal clear that a plant is a better source of phytochemicals than a piece of meat or milk. So I always say that a carrot is a better source of beta-carotene than grass-fed beef is. So I agree that people [who] are on animal-based diets or on carnivore diets are likely to get some of these phytochemicals from animal-sourced foods. But yet, they’re not getting it to the extent that someone on a mixed diet, on an omnivorous diet, would, [which] includes plenty of fruits and vegetables, as well. And I’m with you, Chris; I think for the vast majority of the population, I think they operate best on sort of a spectrum of omnivory having both plant- and animal-sourced foods. But it is true that you always have outliers, that a certain portion of the population seems to be thriving on vegan diets, and a certain portion, and I know we have less data on that, and it’s more self-reported, but seems to be in good health on an animal-based diet.

And I always question whether that means that we should extrapolate that on to how the entire population should eat. I don’t know what your feelings are about it. But I don’t think that every vegan [who] failed a vegan diet [failed] because they didn’t do the diet right. I mean, we know there [are] interindividual differences in nutrient metabolism from many different studies and how you metabolize even things such as iron or carotenoids, and tocopherols, precursors to vitamin[s] A and E. So, to me, it always points to the following: it’s just the incredible resilience as a human being that we can be on a vegan diet or on a carnivore diet and still be alive.

Chris Kresser:  Yeah, yeah, I agree with you. I’ve spoken a lot about this in the past, and have experienced it firsthand when I tried a vegan diet many years ago and also with many, many patients I’ve worked with and many clinicians I’ve trained [who] have worked with patients, as well. So I have a pretty broad perspective on this that’s backed up by a lot of lab testing and data. I think there is such huge interindividual variation in responses to vegan diets for all the reasons that you mentioned, that plants contain a lot of precursor nutrients. And those nutrients often need to be converted into the most active forms for us to get the full benefits. So carotenes are a good example. They get converted into retinol. [Vitamin] K1 gets converted into [vitamin] K2. You have the [ALA], the essential fatty acids. Linoleic acid and [ALA] get converted into the downstream EPA and DHA, or [arachidonic acid] (AA) in the case of omega-6s. You’ve got all of these conversions happening all the time. And those conversions often involve multi-step enzymatic pathways. And each of those enzymes at each of those steps requires the presence of certain nutrients, which often are underrepresented on a vegan diet.

But if you have someone who just genetically is, or because they’re doing a better job at sourcing nutrients, is really efficiently making those conversions, then they could potentially do quite well because they’re still getting all of the downstream active forms of all of the nutrients in adequate amounts.

Whereas if you have somebody who, for either genetic or nutritional reasons, is not making those conversions efficiently, then that person can start to struggle almost immediately, in some cases, and in others, it might take a few months. Or in still others, it could take even longer. And that’s what makes this so tricky because one person might start a vegan diet and have a really great experience, and then someone else starts it, and they feel like they got hit by a bus. And the person who had a great experience naturally thinks, “Well, you must not be doing it right. Because I started it, and I feel great.” But of course, it’s not that simple. And I would just say that yes, it’s possible for some people to do well on a 100 percent plant-based diet. But you introduce a lot of risk that wouldn’t be there if you’re consuming an omnivorous diet where you’re also eating the active preform versions of the nutrients like retinol, or [vitamin] K2 or EPA and DHA instead of just ALA. So that’s my take on it.

Intuitively, it makes sense that cattle raised on more nutritious diets would provide better nutrition for the people who consume them. But what does science show? Dr. Stephan van Vliet, a researcher exploring the omega-6 to omega-3 fatty acid profiles of beef raised according to various agricultural methods, shares his group’s ongoing research into whether farming methods really matter when it comes to nutrition. #chriskresser #phytonutrients #regenerativegrazing #grassfedmeat

Stephan van Vliet:  Yeah, and it made me think of an important point, Chris, when you mentioned that also about the conversion because it’s often something that we hear also on these phytochemicals and we don’t fully understand the pathways yet. Because you have a flavonoid pathway, for instance, within plants where you might actually start all the way with amino acids, right? Because you started with phenylalanine and tyrosine, and it’s converted into a cinnamic acid, coumaric acid, [and] these are common major phytochemicals. Neurogenin and from there on, it goes down to flavanones, isoflavones, anthocyanidins, right? Which are red, they’re purple, they give the berries their nice color. And what we see though, also in the literature, is that people with low baseline intake, when you then increase it, they have a benefit. I mean, there’s a randomized control[led] trial that recently came out in PNAS that looked at, I think it was about 3,500 people and people with low baseline intake of flavonols, improved cognitive function over several years, not ones that are already high intakes, and it’s also common to see.

And also, it’s important to know that [there is] incredible variation among people because even if you, for instance, give a labeled phytochemical to someone, it has a carbon label on it, I won’t get too technical, but it basically [is] like putting a flag on that phytochemical, giving it to someone and then tracing it through the body. Now, this also speaks to the fact that usually, people say, oh, these things have low bioavailability. Well, I do not agree with that 100 percent. Because what you see is that, let’s say if you take fumaric acid as the parent compound and you have that labeled, what would you see as you start enriching 20, 30 other compounds in the blood of people? So there must be some conversion probably by our gut microbiota, perhaps even in our liver, that then actually starts to enrich or produce other compounds or other antioxidants that have a beneficial effect. And some studies would suggest that the bioavailability of the parent compound may only be 1 percent. But if you look at all these other phytochemicals, it may be like 13 percent, 15 percent, and they are measurable in our blood for 48 hours.

Within that, they may go into our cells or brain and escape again, so this is still very much a novel area of interest. But what you also see there is the variation among people, right? With phytochemicals, if you’re very efficient in metabolizing these, that’s why maybe some people might have more benefits than others. And perhaps, some carnivores are very efficient in maintaining these phytochemicals and using them. I mean, we don’t know. But my point being is that, I’d say there [are] now data that [are] exciting about phytochemicals. Also, the Eat Right Foundation for the first time came out with a recommendation on the amounts of flavonoids, and I think it was about 600 milligrams a day. It was based on a meta-analysis of randomized controlled trials. I think they looked at like 120 [trials], or something like that. So I mean, we are certainly learning more and more about these phytochemicals and starting to learn that, hey, they do impact signaling pathways.

For instance, one thing to note is that, if you take a tumor cell and you put phytochemicals on it, you typically see a decrease in tumor growth. Or if you have pancreatic beta cells, you see that it impacts insulin production and things like that. So how [do] they do so in vivo in the human body? We don’t know a lot yet, but it is likely that they are impacting our health. And [it’s] the same thing with animals. What we see is that animals [eat] more phytochemical-rich diets yet they have less oxidative stress. And on paper, that meat looks healthier. But whether that has an appreciable impact on human health, that’s something that we are studying in multiple randomized control[led] trials now.

Chris Kresser:  Yeah, so fascinating. I want to circle back to something you were talking about earlier, which is [the] fatty acid profile in meat and the fact that the ranches that are using the most regenerative practices are probably getting closer to [a] two-to-one, or even one-to-one omega-6 to omega-3 ratio, which is probably closer to the historical ratio of these fats that we consume before industrial seed oils were widely introduced into the diet. Do you think that if someone is eating, like take a hypothetical person who’s exclusively eating meat from a regenerative ranch that’s in that one-to-one, two-to-one ratio. I haven’t done the math on this yet. But if they were just consuming meat and not much seafood, would they be getting enough omega-3s to meet the recommended amounts just from that animal, beef-based diet?

Stephan van Vliet:  Yeah, I mean, there is some modeling work, Chris, in Australian populations and in Irish populations. It’s a combination of modeling work based on intake. But it would suggest that people who eat a decent amount of meat—I mean, carnivores, obviously, probably eat a couple of pounds, a few pounds a day, I think. But what these studies would suggest in more omnivorous populations, that people who eat, let’s say, three [to] four ounces a day or so, that it can have a meaningful contribution to their omega-3 intake and can be up to 30 milligrams or so of combined DHA, EPA, and DPA. And there [are] no official recommendations for the amount of omega-3s that we should eat, right? Most groups recommend anywhere from 100, 200, 300 milligrams, although, in coastal populations, they might go higher than that, especially in Sardinia or some of the Japanese [populations] that are consuming more fish, they might have an intake that is closer to a gram or so even. But my point is, there are some studies to suggest that yes, these omega-3s can contribute meaningfully, especially in populations that eat a lot of grass-fed meat, such as Australians, and the Irish. And there was a nice study that came out I think, a year or so ago from Hannah Ritchie in Newcastle, and she, based on population intake data in the UK, had modeled that about 30 [to] 40 percent or so of daily intake [of omega-3s] recommended by a European agency could be met by eating grass-fed meats. Low, right? And that does not even include eggs. This was only beef. It doesn’t even include eggs or pork or other milk for that matter. So yeah, I definitely think it’s possible. I mean, is there a benefit to eating fish? Yes, absolutely. Fatty fish is a very rich source of DHA and EPA. So if you asked me personally, then yeah, I would often eat fish a few times a week, too. But we eat meat more often, probably than fish, at least most people. So if we eat that from pasture systems, then yes, I think it can contribute meaningfully.

And, again, I don’t have the data. But my hypothesis would be [that] if you have a carnivorous person [who] was eating grain-fed meat versus grass-fed meat, then the blood omega-6 ratio of that person eating grass-fed beef would look a whole lot better.

Chris Kresser:  Absolutely. I just think it’s interesting because again, it’s another paradigm shift, right? Historically, most sources would not list beef as a meaningful contributor to omega-3 fat, the long-chain omega-3 fat intake. And it still isn’t, in many cases, right? We’re talking about meat that’s raised in a particular way. And if the average person is going to the average grocery store and buying the average cut of beef, they’re not going to get this benefit. So this is not applicable to the vast majority of beef that people are encountering in the grocery store at this time. But we both know that there’s a lot happening here in this space, and a lot of people are becoming more and more aware of the benefits of regeneratively raised beef, and people are seeking it out. And they’re ordering it directly from ranches or getting it at farmer’s market[s], or they’re buying it, in some cases, online directly from ranches, even outside of their local area.

So, as this continues to progress, which I hope it does, this will become more relevant. And I’m with you; I’ve been a big advocate for consuming wild-caught, sustainably raised fish and shellfish, particularly the coldwater fatty fish and some of the shellfish like oysters, a really rich source of EPA and DHA. But beyond that, [it’s] also a very rich source of bioavailable protein, selenium, and many other nutrients. So you get more than just the fatty acids. For any number of reasons, many people do not consume enough seafood to really move the needle. It could be because they just don’t like seafood. I’ve had a lot of patients in the past who just don’t care for fish or shellfish. It could be an access issue, either financially, or they live somewhere where they just don’t really have access to fresh fish or shellfish. Some people have environmental concerns. There are lots of reasons that people don’t get enough. So I’m excited by the possibility that properly raised or well-raised beef could actually make a contribution for these folks.

Stephan van Vliet:  Yeah, absolutely. And we know, Chris, from I think there’s, I had probably eight to 10 randomized controlled trials now that find that if you eat pastured meat, and these are studies not just in beef, I think like two or three are in beef. There’s one study even in horse meat. But the point being is that what they see in various randomized control[led] trials is that the blood omega-3 profile goes up when people eat grass-fed meat, and then the control is usually grain-fed meat, and their blood omega-3 profile doesn’t go up. And this was already known, I think, in the ‘90s. Because Sinclair was a researcher out of Australia. He did a lot of that initial work with, where you would compare grass-fed beef and kangaroo and even white fish to look at the impact on the blood omega-3 profiles. And what he shows is that yeah, they do go up, even with grass-fed beef and kangaroo, which is also pastured, of course, pasture finished. I mean, it’s a wild animal. And with grain-fed beef, you do not see this going up.

So you do see this meaningful contribution, and I often get this sort of thrown in my face, too. They say, “Oh, it’s just a few milligrams of omega-3s that are in beef. And if you compare it to salmon, it’s meaningless.” Well, yeah, but studies would suggest that it does go up meaningfully. And I also think [that] this is something we do not fully understand. But I think it comes back to the food matrix, Chris. It’s that when you ingest these compounds as part of a complex food matrix with a bunch of cofactors, typically, the effect is stronger than what you would expect. A very common example of this is vitamin D. If we take a pill of vitamin D, at the exact same amount as something that a food source contains, the food source is about five to 10 times more efficient in raising vitamin D, probably because of the cofactors, or some preformed factors that are there. And I suspect something similar is going on, too, when we eat things such as DHA, EPA, and other omega-3 fatty acids in a complex food source.

Chris Kresser:  Yeah, absolutely. Another Australian researcher whose work I’ve really come to appreciate over the years, I think his name is Gyorgy Scrinis, talks about nutritionism, and he talks about food synergy and how important food synergy is. And this is a great example where we don’t often think about all of the nutrient cofactors, enzymes that are required to metabolize a specific nutrient. And when we isolate it and turn it into a supplement, you aren’t always getting those other nutrients, especially if you’re not combining them in an intelligent way. You used the vitamin D example. That’s a classic one. Another is copper and iron. I’ve had lots of patients over the years who had kind of inexplicable iron deficiency that didn’t respond to iron supplementation. And then, we would test them and find out that they were copper deficient. And copper is required for iron metabolism. You fix the copper deficiency, then all of a sudden, they’re not iron deficient anymore. And vitamin C enhances iron absorption, magnesium enhances the metabolism of vitamin D, and vice versa. So there [are] all these really complex synergies that are happening, some of which we understand, many of which we don’t. And this is yet another reason that eating whole foods or taking supplements that are whole-food based is a lot better than isolated synthetic nutrients, in general.

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Stephan van Vliet:  Yeah, that’s right, Chris. And it also sort of brings me back to the lipid peroxidation, for instance. I mean, if you have more—we know this from vitamin E, right? That’s why a lot of sources with polyunsaturated fats also contain a good amount of vitamin E because it protects the peroxidation of those long-chain fatty acids. And something similar is probably going on, too, when you ingest a good amount of phytochemicals with it. So that could be another reason why grass-fed beef results in further rise of that is because you’re not oxidizing those lipids as much because you have a bunch of phytochemicals that act as antioxidants that come with it in the package, right? And that is something you often don’t have in supplements.

And I agree, we notice from countless research also on things like turmeric and curcumin, right? Curcumin being the main ingredient. And then we take that out and then do a total antioxidant assay, and all of a sudden, it’s much less effective. You see this all the time. That’s why I think a food-first approach is always what I would suggest. And the further I get into this work, also, it makes me realize how little we do know. We’re really scratching the surface.

Chris Kresser:  Yeah, yeah. And that’s both humbling and exciting because there’s a lot that we can still understand. And that knowledge that we’re gaining has already led to some meaningful changes in how we look at things. Along those lines, a lot of the research we’ve had so far that’s evaluating health response to grass-fed versus grain-fed meat has been observational in nature. And I think anyone who’s been listening to this show for any length of time knows what the problems are there. [They] certainly [are] good for generating hypotheses and can be very helpful, especially when those epidemiological trials are well designed and in such a way that they try to at least attempt to control for potentially confounding factors. But it’s almost impossible to control for all of them and even know what all of them are in a particular context.

So, randomized controlled trials can be helpful because they can take another step in eliminating confounders and give us more reliable data. So the last time we talked, you dropped a hint that there might be some randomized controlled trials coming our way looking at this. How does consuming grass-fed meat impact our health versus grain-fed meat? Do you have any updates there?

Stephan van Vliet:  Well, the only update is that we’re pretty deep into the study now. But we haven’t any data yet on it. But yeah, we are doing a study, at least a very acute study right now, [a] post-perennial study. So people come in, they eat an Impossible Burger, they eat feedlot beef or they eat grass-fed beef from a very diverse operation. The grass-fed beef that we feed them has a ratio of [about] one-to-one [omega-6 to omega-3]. We use feedlot beef and an Impossible Burger, too, as a third arm, and I think we’ve completed about 30 people now. And I think [our goal is to measure] about 40 people. So we have 10 to go. But they basically come in on three separate occasions, they eat an Impossible Burger, grass-fed beef, or grain-fed beef. We pull blood from them for five hours, we collect their urine, and we want to see how it impacts their metabolite profiles. Because of some of these phytochemicals, you can measure pretty quickly already in a few hours afterwards, and you can measure oxidative stress markers.

Obviously, we can’t say anything about long-term health, [but] we’re doing that initial study to give us some biomarker data, and then we’re following that up with a longer-term trial where we feed people for several weeks. So that’s the study that is going on. And then we do have a study going on that is somewhat analogous to that, [which] is the study with the Greenacres Foundation. And we’ve sourced all of our foods from regenerative agriculture. So these are all the plant foods and animal-sourced foods, or we source the exact same produce just from the grocery store. So non-organic produce, which is typically produced using more monoculture crops. That’s also a study that we’re about halfway through with. But yeah, [in] randomized controlled trials, you typically need enough people and enough time for something to happen if there is a difference, at least. So those are some of the major studies that we have ongoing in terms of randomized controlled trials.

So unfortunately, [there are] no real big updates yet, but we are going to publish our work that we talked about I think last time; we’re going to publish it this year, hopefully, where we compared a whole-foods diet versus a Standard American Diet. [We’re] also trying to match for food groups as much as possible. So if someone would get some broccoli with butter, we’d go to the grocery store and find the broccoli and butter sauce with 30 more ingredients in it. And those are examples of meals, and we’d get potatoes with some olive oil or fries or things like that, oven fries, to look at, if you eat the same foods and matched for protein, for carbohydrates, for fat, for calories, because a lot of the idea about overprocessed foods right now is that the reason why you get unhealthy is because you overeat. What Kevin Hall’s study would suggest. Well, we try to match for calories in this study, and what we found was that people on the whole-foods diet got healthy quite rapidly. They saw a reduction in triglycerides of about 30, 40 percent in a month. And the people on the Standard American Diet kind of stayed the same because they were consuming a Standard American Diet going into the study. So that’s one study that we will be publishing this year. And it would suggest that the problems with all the processed foods are kind of independent of the caloric piece, or the energy piece. But just eating them in general is problematic.

Chris Kresser:  Yeah, absolutely. Well, I look forward to that research when it becomes available. We’ll have you back on to talk about it. And thanks so much for joining me today. I think this is a really fascinating new line of inquiry where we’re learning so much more, at such a greater level of resolution, I would say, about the nutritional differences between grass-fed and grain-fed meat. And it’s, again, I think intuitively, many of us suspected this, but it’s really important to have the data that back it up. And even within [those] data, we’re all learning something new, maybe some surprises or some things that we might not have suspected, which is why it’s so important to do the research.

Stephan van Vliet:  Absolutely, Chris. I’m always surprised, too, about some of these findings that we make, and then I’m like, “Oh yeah.” But I had not expected that. But that’s what keeps it exciting for us.

Chris Kresser:  Exactly. Well, thanks, Stephan, again. And where can people learn more about your work?

Stephan van Vliet:  So on Twitter, at @VanVlietPhD, so my last name, and then the letters PhD. And if you type in my name on Google or YouTube, there [are] many webinars and invited talks that I’ve given over time where I go through some of the slides on some of the work that we talked about with grass-fed beef and [the] Google Scholar profile. And we also always pay for open access fees so that our papers can be read by anyone really rather than ending up behind a paywall, and a hundred scientists read it instead of our audience.

Chris Kresser:  I really appreciate that about your research. And I know a lot of my citizen scientist listeners do, as well. So thank you for doing that. I wish more researchers did that. I know it’s not always easy to do. So props to you guys for doing that with your papers. Thanks, everyone, for listening. Keep sending your questions to ChrisKresser.com/podcastquestion, and we’ll talk to you next time.

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