cvictorg
New Member
http://chriskresser.com/rhr-what-science-really-says-about-the-paleo-diet-with-mat-lalonde?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+thehealthyskeptic+%28Chris+Kresser%29
Invalid Inference 1: Our Paleolithic ancestors ate Pale this way and they were free of disease
Mat Lalonde: Absolutely, so I can quickly cover some of the three main criticisms that I had that I talked about in other venues including the Ancestral Health Symposium, and then we can go beyond that because I think there are other really interesting things to discuss. Before I do that, I’m just gonna tell people straight up I truly believe in evolution as a scientist, and if you go to YouTube and you type in or you search for Why Evolution Is True by Jerry Coyne, you can watch that, and I agree 100% with everything that’s on there, and I went to see Jerry when he gave a talk here at Harvard, and he was fantastic. I’ll also say that the goal of my talk at the Ancestral Health Symposium was to help people better justify why they’re using this dietary approach or lifestyle. You know, I do realize that I ruffled some feathers because there are some folks who are coming out of field, and I’m coming out of field, but not that far, you know, chemistry and medicine aren’t that far off. But there are some folks who are coming from different fields, and really all they’re grasping on is this evolutionary thing, and they don’t realize that all it is really at the end of the day is a great way to formulate hypotheses, and I was seeing a lot of mistakes made in the blogosphere, and I was afraid that it was going to prevent a lot of professionals from taking our movement seriously. So that was the goal ultimately, and you know, it’s just so simple to ridicule the whole caveman argument that I wanted to go beyond that, I wanted to give people a little bit more to think about, so if you are on a paleo diet, or what I prefer to say actually, because there’s really no such thing as a paleo diet. The foods aren’t available anymore. You can try to mimic it. That’s the best you can do. But a diet that’s meat, vegetables, tubers, and fruits. That’s what I call it. Typical arguments for this will go like this: Our ancestors and modern hunter-gatherers consumed a diet that was mostly devoid of grains, legumes, and dairy, and they were virtually free of diseases of civilization. People then make the invalid inference that consuming a diet mostly devoid of grains, legumes, and dairy will thus allow us to be free of diseases of civilization. Why is this invalid? Well, Chris, maybe you can reiterate your shark attack analogy for us.
Chris Kresser: Sure, yeah, so it’s been observed for quite some time that when people consume more ice cream, there’s an increase in shark attacks. So, obviously that means that eating ice cream increases your risk of getting attacked by a shark. Right, Mat?
Mat Lalonde: Of course! Probably you eat too much ice cream, and then you drown in the sea, and they you move around a lot, and the sharks are attracted to you, and your blood tastes sweet.
Chris Kresser: Right. So maybe there’s another explanation?
Mat Lalonde: Maybe it’s because the temperature is rising.
Chris Kresser: Uh-huh…
Steve Wright: No way! No way!
Chris Kresser: So the temperature goes up, and more people go in the water, and then more people get attacked by sharks.
Mat Lalonde: That’s correct. And when the temperature goes up, there’s also more people that eat ice cream because it’s cold and it’s yummy.
Chris Kresser: Ahhh. So, yes, this is a perfect example of why we have to be careful, assuming that correlation equals causation, which we’ve talked about, of course, many times on this show.
Mat Lalonde: That is correct. So, temperature here is what we call the variable that wasn’t observed, a confounding factor, in that it’s involved in everything, and there’s a lot of that that goes on in these observational epidemiologies. You can’t observe everything, so there’s almost always going to be, especially when it comes to human beings that are very complex and multivariate that live in a very complex and multivariate environment. You are never going to see everything. So observational epidemiology is great for formulating hypotheses and asking questions, but it doesn’t answer any questions. The same is true about this statement. You know, it’s just an observation. It’s just a correlation. You can’t say for sure that, yes, it is the case that if we eat like that we’re going to avoid the diseases of civilization, so you have to be very, very careful with that.
Chris Kresser: Right, but as you pointed out earlier in the show, it’s reasonable to use that as a starting place, to say: OK, that’s an interesting observation, and maybe we can do some further investigation and see whether that’s actually true.
Invalid Inference 2: We haven’t evolved enough to thrive on modern agriculture
Mat Lalonde: Absolutely. So let’s move on to the second one. This is one that I see often. It goes something like this: We evolved over millions of years without consuming the foods that became readily available only after the advent of agriculture. Hence, we’re not adapted to these foods. But this assumes that a species isn’t adapted to a food because it’s never consumed it. And if you look at the evolutionary record, that’s incorrect. There are plenty of examples throughout evolution where species discover novel sources of food and thrive on them.
Chris Kresser: You mean like humans and meat?
Mat Lalonde: Exactly! I was just about to say that. You know, humans started out by eating fruits, plants, insects. Then they scavenged bone marrow from bones and also brains from skulls, and eventually became some of the meanest, baddest hunters on the planet.
Chris Kresser: Right, and that changed our physiology along the way, right?
Mat Lalonde: Absolutely.
Chris Kresser: We went from having a much larger gut that was good for fermenting rough cellulose and carbohydrate to a much smaller gut and a bigger brain.
Mat Lalonde: Yeah, so you look at the expensive tissue hypothesis, and then you know, I’m at Harvard, so I have to mention Richard Wrangham. Cooking also had a huge, huge part to play in that.
Chris Kresser: Right.
Mat Lalonde: You know, when you cooked plant matter or meat, it became more easily digestible so your gut could get a little bit smaller and you got better nutrition as a result. If you look throughout history, you’ll see that food itself is a huge driver of evolution. You know, the availability of food has driven some major adaptations. And that’s another part where I didn’t ruffle some feathers, but I think I was misinterpreted during my seminar talk at AHS, where some people seemed to think that I was implying that adaptation was very quick. And I didn’t say that. I said that adaptation depended on time and pressure. And if the pressure is very high, then it can be very quick. So European herders becoming adapted to lactose, for example, would be a great example.
Chris Kresser: Yeah, so let’s talk about genetics a little bit longer than we’ve talked about the last two, because I’m personally fascinated by genetics and epigenetics, and I think it’s a good example of where an argument that seems like it makes a lot of sense on the surface can go wrong once you start to understand more of the science behind it.
Invalid Inference 3: We should live like our ancestors because we’re still genetically the same
Mat Lalonde: Absolutely, so that’s my third criticism, actually, if you want me to get that out of the way.
Chris Kresser: Yeah, do that.
Mat Lalonde: We’ll lump this into genetics and epigenetics because the third thing I hear a lot is our genes are virtually identical to those of our Paleolithic ancestors so we should live like they did. And this has to be the most ridiculous statement of them all because here is a group of people that claims to take an evolutionary approach to life, yet shows it does not understand evolution. Human beings and chimps have virtually identical genomes to the tune of 99.5%. The difference between a human being and a chimp is in gene expression in the epigenome. Just because two species have similar genes does not mean that they will both thrive in similar environments or with similar food sources. You know, one of the mechanisms through which adaptations arise is a change in gene expression. It would be absurd to suggest the epigenome of modern humans is identical to that of our Paleolithic ancestors, given the substantial changes in environment and food that have occurred since that era.
Chris Kresser: Right, and this is what’s so interesting to me is that when we talk about the pace of change, epigenetic changes can happen very quickly. You know, we’re talking about pressure for genetic changes, and that can actually happen more quickly than most people think. You mentioned lactase persistence or ability to digest lactose into adulthood. Well, that’s happened, as you know, Mat, within the last 8000 years, which is actually pretty quick in terms of evolutionary history.
Mat Lalonde: That’s the blink of an eye.
Chris Kresser: A blink of an eye. So I know a study in 2007 where researchers looked at DNA from skeletons of people who died in northern or central Europe about 7000 to 8000 years ago, and there were zero, none of them had lactase persistence at that time. And then another study from the Bronze Age, about 3000 years ago, with a similar population found that about 25% had the allele for lactase persistence, and then today in some Scandinavian countries, I think, like Sweden and Denmark, lactase persistence has reached about 95% penetrance in the population. And the cow herding tribe, the Tutsi tribe in East Africa, I think, has about 90% lactase persistence. So that’s a huge genetic change in a short period of time, but even that period of time is incredibly long compared to how quickly some of these epigenetic changes can happen, right?
Mat Lalonde: Absolutely.
Chris Kresser: A good example, and you might even know this study. In 2003, the fat yellow mice –
Mat Lalonde: Yes.
Chris Kresser: — that always give birth to other fat yellow mice. And researchers gave these, they separated them into two groups, and one group was the control, and the other group they gave supplements that improved methylation, which we’ll talk about a little bit more in a second. And the group that got these methylation supplements, guess what? They didn’t give birth to fat yellow mice like you would expect them to. They gave birth to skinny brown mice instead. And the amazing thing is the genes were exactly the same in these babies. They were right where they were supposed to be, but the supplements had turned off or silenced the gene that makes these mice fat.
Mat Lalonde: I have a picture of the mice side by side it you want to put it up with the podcast.
Chris Kresser: Yeah, that would be great.
Mat Lalonde: Yeah, I think they’re Agouti mice.
Chris Kresser: Agouti mice, that’s exactly right. And so this process of genetic suppression, which is epigenetics, is called DNA methylation. And we’ve talked a little bit about methylation before, and I think I talked a lot about it on a show with Robb, but methylation occurs when a methyl group binds to a gene and changes the way it expresses itself. So this can happen… I mean, these changes are triggered by environmental factors. Some of the recent research suggests that even the first few days after conception some of these profound epigenetic changes are happening due to methylation, you know, turning genes on and off just in a matter of days after conception in the womb. So we can say that it does take often genetic changes a very long time to happen, but on the other end of the spectrum we’ve got these epigenetic changes that can happen in utero and during our lifetime.
Mat Lalonde: And you know, since you mentioned that, there are a lot of people that now believe that genetics has nothing to do with obesity, and I highly disagree. If you imagine this happening in human beings, the plumper yellow mouse would be at a huge disadvantage from the start, relative to the lean darker mouse.
Chris Kresser: Right, and then there’s the developmental origins hypothesis, which I’ve talked about before, where David Barker, a researcher in the UK, found that 20 years ago babies that are born at a very low birth weight are more likely to become obese and experience metabolic problems later in life because if this happened, for example, during in a hunter-gatherer population or during the Paleolithic and a baby was born into a time of scarcity and famine, they might experience epigenetic changes that made their metabolism more efficient at extracting calories and hoarding energy because that would help them survive in that environment. But today if you have a mother who is poorly nourished during gestation and that baby is born with that same thrifty metabolism into an environment where you can walk down to any corner and get unbelievably calorically dense food at any time you want, then that thrifty phenotype that helped that baby survive in a time of food scarcity would cause things like obesity and diabetes and heart disease today.
Invalid Inference 1: Our Paleolithic ancestors ate Pale this way and they were free of disease
Mat Lalonde: Absolutely, so I can quickly cover some of the three main criticisms that I had that I talked about in other venues including the Ancestral Health Symposium, and then we can go beyond that because I think there are other really interesting things to discuss. Before I do that, I’m just gonna tell people straight up I truly believe in evolution as a scientist, and if you go to YouTube and you type in or you search for Why Evolution Is True by Jerry Coyne, you can watch that, and I agree 100% with everything that’s on there, and I went to see Jerry when he gave a talk here at Harvard, and he was fantastic. I’ll also say that the goal of my talk at the Ancestral Health Symposium was to help people better justify why they’re using this dietary approach or lifestyle. You know, I do realize that I ruffled some feathers because there are some folks who are coming out of field, and I’m coming out of field, but not that far, you know, chemistry and medicine aren’t that far off. But there are some folks who are coming from different fields, and really all they’re grasping on is this evolutionary thing, and they don’t realize that all it is really at the end of the day is a great way to formulate hypotheses, and I was seeing a lot of mistakes made in the blogosphere, and I was afraid that it was going to prevent a lot of professionals from taking our movement seriously. So that was the goal ultimately, and you know, it’s just so simple to ridicule the whole caveman argument that I wanted to go beyond that, I wanted to give people a little bit more to think about, so if you are on a paleo diet, or what I prefer to say actually, because there’s really no such thing as a paleo diet. The foods aren’t available anymore. You can try to mimic it. That’s the best you can do. But a diet that’s meat, vegetables, tubers, and fruits. That’s what I call it. Typical arguments for this will go like this: Our ancestors and modern hunter-gatherers consumed a diet that was mostly devoid of grains, legumes, and dairy, and they were virtually free of diseases of civilization. People then make the invalid inference that consuming a diet mostly devoid of grains, legumes, and dairy will thus allow us to be free of diseases of civilization. Why is this invalid? Well, Chris, maybe you can reiterate your shark attack analogy for us.
Chris Kresser: Sure, yeah, so it’s been observed for quite some time that when people consume more ice cream, there’s an increase in shark attacks. So, obviously that means that eating ice cream increases your risk of getting attacked by a shark. Right, Mat?
Mat Lalonde: Of course! Probably you eat too much ice cream, and then you drown in the sea, and they you move around a lot, and the sharks are attracted to you, and your blood tastes sweet.
Chris Kresser: Right. So maybe there’s another explanation?
Mat Lalonde: Maybe it’s because the temperature is rising.
Chris Kresser: Uh-huh…
Steve Wright: No way! No way!
Chris Kresser: So the temperature goes up, and more people go in the water, and then more people get attacked by sharks.
Mat Lalonde: That’s correct. And when the temperature goes up, there’s also more people that eat ice cream because it’s cold and it’s yummy.
Chris Kresser: Ahhh. So, yes, this is a perfect example of why we have to be careful, assuming that correlation equals causation, which we’ve talked about, of course, many times on this show.
Mat Lalonde: That is correct. So, temperature here is what we call the variable that wasn’t observed, a confounding factor, in that it’s involved in everything, and there’s a lot of that that goes on in these observational epidemiologies. You can’t observe everything, so there’s almost always going to be, especially when it comes to human beings that are very complex and multivariate that live in a very complex and multivariate environment. You are never going to see everything. So observational epidemiology is great for formulating hypotheses and asking questions, but it doesn’t answer any questions. The same is true about this statement. You know, it’s just an observation. It’s just a correlation. You can’t say for sure that, yes, it is the case that if we eat like that we’re going to avoid the diseases of civilization, so you have to be very, very careful with that.
Chris Kresser: Right, but as you pointed out earlier in the show, it’s reasonable to use that as a starting place, to say: OK, that’s an interesting observation, and maybe we can do some further investigation and see whether that’s actually true.
Invalid Inference 2: We haven’t evolved enough to thrive on modern agriculture
Mat Lalonde: Absolutely. So let’s move on to the second one. This is one that I see often. It goes something like this: We evolved over millions of years without consuming the foods that became readily available only after the advent of agriculture. Hence, we’re not adapted to these foods. But this assumes that a species isn’t adapted to a food because it’s never consumed it. And if you look at the evolutionary record, that’s incorrect. There are plenty of examples throughout evolution where species discover novel sources of food and thrive on them.
Chris Kresser: You mean like humans and meat?
Mat Lalonde: Exactly! I was just about to say that. You know, humans started out by eating fruits, plants, insects. Then they scavenged bone marrow from bones and also brains from skulls, and eventually became some of the meanest, baddest hunters on the planet.
Chris Kresser: Right, and that changed our physiology along the way, right?
Mat Lalonde: Absolutely.
Chris Kresser: We went from having a much larger gut that was good for fermenting rough cellulose and carbohydrate to a much smaller gut and a bigger brain.
Mat Lalonde: Yeah, so you look at the expensive tissue hypothesis, and then you know, I’m at Harvard, so I have to mention Richard Wrangham. Cooking also had a huge, huge part to play in that.
Chris Kresser: Right.
Mat Lalonde: You know, when you cooked plant matter or meat, it became more easily digestible so your gut could get a little bit smaller and you got better nutrition as a result. If you look throughout history, you’ll see that food itself is a huge driver of evolution. You know, the availability of food has driven some major adaptations. And that’s another part where I didn’t ruffle some feathers, but I think I was misinterpreted during my seminar talk at AHS, where some people seemed to think that I was implying that adaptation was very quick. And I didn’t say that. I said that adaptation depended on time and pressure. And if the pressure is very high, then it can be very quick. So European herders becoming adapted to lactose, for example, would be a great example.
Chris Kresser: Yeah, so let’s talk about genetics a little bit longer than we’ve talked about the last two, because I’m personally fascinated by genetics and epigenetics, and I think it’s a good example of where an argument that seems like it makes a lot of sense on the surface can go wrong once you start to understand more of the science behind it.
Invalid Inference 3: We should live like our ancestors because we’re still genetically the same
Mat Lalonde: Absolutely, so that’s my third criticism, actually, if you want me to get that out of the way.
Chris Kresser: Yeah, do that.
Mat Lalonde: We’ll lump this into genetics and epigenetics because the third thing I hear a lot is our genes are virtually identical to those of our Paleolithic ancestors so we should live like they did. And this has to be the most ridiculous statement of them all because here is a group of people that claims to take an evolutionary approach to life, yet shows it does not understand evolution. Human beings and chimps have virtually identical genomes to the tune of 99.5%. The difference between a human being and a chimp is in gene expression in the epigenome. Just because two species have similar genes does not mean that they will both thrive in similar environments or with similar food sources. You know, one of the mechanisms through which adaptations arise is a change in gene expression. It would be absurd to suggest the epigenome of modern humans is identical to that of our Paleolithic ancestors, given the substantial changes in environment and food that have occurred since that era.
Chris Kresser: Right, and this is what’s so interesting to me is that when we talk about the pace of change, epigenetic changes can happen very quickly. You know, we’re talking about pressure for genetic changes, and that can actually happen more quickly than most people think. You mentioned lactase persistence or ability to digest lactose into adulthood. Well, that’s happened, as you know, Mat, within the last 8000 years, which is actually pretty quick in terms of evolutionary history.
Mat Lalonde: That’s the blink of an eye.
Chris Kresser: A blink of an eye. So I know a study in 2007 where researchers looked at DNA from skeletons of people who died in northern or central Europe about 7000 to 8000 years ago, and there were zero, none of them had lactase persistence at that time. And then another study from the Bronze Age, about 3000 years ago, with a similar population found that about 25% had the allele for lactase persistence, and then today in some Scandinavian countries, I think, like Sweden and Denmark, lactase persistence has reached about 95% penetrance in the population. And the cow herding tribe, the Tutsi tribe in East Africa, I think, has about 90% lactase persistence. So that’s a huge genetic change in a short period of time, but even that period of time is incredibly long compared to how quickly some of these epigenetic changes can happen, right?
Mat Lalonde: Absolutely.
Chris Kresser: A good example, and you might even know this study. In 2003, the fat yellow mice –
Mat Lalonde: Yes.
Chris Kresser: — that always give birth to other fat yellow mice. And researchers gave these, they separated them into two groups, and one group was the control, and the other group they gave supplements that improved methylation, which we’ll talk about a little bit more in a second. And the group that got these methylation supplements, guess what? They didn’t give birth to fat yellow mice like you would expect them to. They gave birth to skinny brown mice instead. And the amazing thing is the genes were exactly the same in these babies. They were right where they were supposed to be, but the supplements had turned off or silenced the gene that makes these mice fat.
Mat Lalonde: I have a picture of the mice side by side it you want to put it up with the podcast.
Chris Kresser: Yeah, that would be great.
Mat Lalonde: Yeah, I think they’re Agouti mice.
Chris Kresser: Agouti mice, that’s exactly right. And so this process of genetic suppression, which is epigenetics, is called DNA methylation. And we’ve talked a little bit about methylation before, and I think I talked a lot about it on a show with Robb, but methylation occurs when a methyl group binds to a gene and changes the way it expresses itself. So this can happen… I mean, these changes are triggered by environmental factors. Some of the recent research suggests that even the first few days after conception some of these profound epigenetic changes are happening due to methylation, you know, turning genes on and off just in a matter of days after conception in the womb. So we can say that it does take often genetic changes a very long time to happen, but on the other end of the spectrum we’ve got these epigenetic changes that can happen in utero and during our lifetime.
Mat Lalonde: And you know, since you mentioned that, there are a lot of people that now believe that genetics has nothing to do with obesity, and I highly disagree. If you imagine this happening in human beings, the plumper yellow mouse would be at a huge disadvantage from the start, relative to the lean darker mouse.
Chris Kresser: Right, and then there’s the developmental origins hypothesis, which I’ve talked about before, where David Barker, a researcher in the UK, found that 20 years ago babies that are born at a very low birth weight are more likely to become obese and experience metabolic problems later in life because if this happened, for example, during in a hunter-gatherer population or during the Paleolithic and a baby was born into a time of scarcity and famine, they might experience epigenetic changes that made their metabolism more efficient at extracting calories and hoarding energy because that would help them survive in that environment. But today if you have a mother who is poorly nourished during gestation and that baby is born with that same thrifty metabolism into an environment where you can walk down to any corner and get unbelievably calorically dense food at any time you want, then that thrifty phenotype that helped that baby survive in a time of food scarcity would cause things like obesity and diabetes and heart disease today.
