Monday, June 23, 2014

The Problem of Paleo Diet Arguements

Excepts taken from Chris Kresser's Interview of Mat Lalonde (from here)

Mat Lalonde PHd Chemical and Chemical Biology:

Invalid Inference 1: Our Paleolithic ancestors ate Paleo this way and they were free of disease

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.  

Invalid Inference 2: We haven’t evolved enough to thrive on modern agriculture

Mat Lalonde:  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.
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. 

Invalid Inference 3: We should live like our ancestors because we’re still genetically the same

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.

What is the best scientifically backed argument for Paleo?

Mat Lalonde:  There has been insufficient time and evolutionally pressure for complete adaptation to seed consumption arise in homosapiens.  And I think about that today, and I’m like, well, you know, people might think that there could be complete adaptation.  Let’s say you were to take a population and give them only wheat to eat, but unfortunately I don’t think that’s the case, because all evolution cares about is getting to the next generation. And eating these foods will allow you to reach reproductive age.  There are certain types of insects that live only long enough to reproduce, and then they die off, and then the next generation takes over. That’s right, so the challenge right now is that we are trying to live for a very long time and very well and healthy, so we’re pushing the boundaries.
<<So that we’ve evolved some what might be called “shallow” adaptations or mutations, and some examples of this kind of rapid genetic change are the evolution of light skin in response to humans moving into northern climates or the changes in some genes or gene expression that regulate insulin metabolism in response to a higher carbohydrate diet.  But those are relatively simple mutations.  They’re not complex adaptations, which are characteristics that involve coordinated actions of many different genes together. >>
When you think about these two statements, what I like about it is that it’s pinpointing what think is a fact in that people who are adapted to grains and legumes or who not necessarily thrive, but survive on these foods are probably the minority.  Now, that’s very different than saying, well, nobody should eat this because we’ve never eaten these foods in the past.  And it is a very different statement, and it forces people to think about themselves, which is what you do all the time.  It’s like, OK, where do I sit on this spectrum?  What do I tolerate and what do I not tolerate?
It all goes back to a personal responsibility argument.  Robb Wolf always says, make changes and see how you look, feel, perform and rank in important disease markers.  In other words, keep an eye on the science, but I put a disproportionate weight into personal experience.