Evolving one's diet

I recently heard an interview of Dr. Steven Gundry over at Jimmy Moore's Livin' La Vida Low Carb site. Gundry said a few things that intrigued me, so I felt I should try and follow up by reading his book, "Dr. Gundry's Diet Evolution" [1].

Gundry's basic premise is that our diet affects which genes are turned on, and which off. That's not earth-shattering, the notion that environment shapes gene expression is pretty old hat. And most of what Gundry introduces in the first chapter is well supported stuff from the literature. But there's one thing that doesn't have any citations, and that's his notion that there is a genetic program designed to kill us off once we've served our purpose: transmitting our genes to the next generation. 

This "killer gene" program got my attention because there's a new hypothesis for the evolution of aging  in the evolutionary literature, and that is called the "programmed death" hypothesis. The basic idea is that our genes articulate a "use by" date, and once we're past it all sorts of things come unglued. In models at least, the advantage appears to be an increase in a lineage's ability to evolve [2]. There are species that do not age, and cell lineages that also don't age. 

Gundry's assertion is that once we've reproduced our genes prefer we get out of our offspring's way. He brings up a few interesting observations, like why do clots in our arteries form in the heart, brain and legs, but not say, in our noses and ears? It's almost as if they're targeting essential survival systems ... Gundry's idea is that our modern western diet, full of refined sugars and starches, is so good at getting us to reproduce quickly that our genes then quickly kill us off to reduce competition for our offspring. 

I'm willing to grant the programmed death idea as a hypothesis, but Gundry takes it to extremes. For example, he asserts that overeating until you are overweight also triggers the killer genes because "your genes percieve [this] as threatening the food supply of others." [page 16] That's just one example of how he has bought into a group selection argument for the existence of these killer genes. And convincing your genes that you're not a threat is the basis for phases 2 and 3 of his diet plan. 

Phase 1 of Gundry's plan is pretty standard -- drop the refined carbohydrates and starchy vegetables. Where he differs from a LCHF plan is by focusing on lean protein as the replacement for carbs, rather than fat. The logic is that you're trying to convince your body that "Winter's here", and animals would be lean in winter. There are a few little inconsistencies though. The key "Gundryism" here is "If it's white, out of sight", like sugar, flour and WHAT MAYONNAISE! There's no rationale for that, but in an earlier chapter he mentions that soybean oil (the main ingredient in commericial mayonnaise) should be avoided because of a high Omega-6 : Omega-3 ratio. OK, but then why is tofu listed as an acceptable protein? It's actually white too, now that I think about it. This "teardown" phase is supposed to last until your weight loss plateaus, and you're not showing signs of illness. 

In Phase 2, "Rebuilding", the main emphasis is on reducing the protein and increasing the green stuff. This is meant to imitate the diet of our pre-agricultural ancestors. He draws on the diet of a silver-back gorilla as inspiration -- lots of calorie sparse leaves*. The biological hypothesis in this section seems to be that eating protein raises metabolism, and a high metabolism is bad. So eat less protein, lower the heat, and you'll be better off for it. He also cites the China Study as support for this perspective. If you're still thinking that's a good idea, you should read the critiques by Denise Minger or Chris Masterjohn. Sorry Gundry, you're loosing me here.

In Phase 3, "Longevity", the goal is to keep those gene's from thinking you're a threat and providing a little bit of stress via plant toxins. Eat raw food, because that preserves those phytochemical toxins. Eat less, because that way you convince your genes you're not competing with your offspring. Calorie restriction is associated with longevity, at least in animal models, from the citations he provides. One thing that is slightly alarming here is that calorie restriction increases cortisol, and that's one mechanism that can increase fasting blood glucose levels. Which might be fine, if you're not insulin resistant.

To wrap up, I'm convinced that our genes matter and that our environment (including what we eat) influences which genes are on or off. But I was convinced of that before. I agree that programmed death is a valid hypothesis, but I don't see any evidence for the "competing with my offspring" as a trigger for killer genes. I agree that lots of low calorie vegies are good, but not sure about being able to get the majority of my protein from them without growing a gorilla sized colon. Eating less, check, as long as I'm not hungry. Back to the library with you, Gundry. 

[1] Steven R. Gundry. 2008. Dr. Gundry's diet evolution: turn off the genes that are killing you -- and your waistline -- and drop the weight for good. Crown Publishers, New York.

[2] Joshua Mittledorf and Andre Martins. 2014. Programmed Life Span in the Context of Evolvability. The American Naturalist, 184:289-302.

*But, but, gorillas have colons more than twice the size of a human which is why they can survive on calorie sparse food!

Go Gluten Free or Not?

Lots of people are going gluten free. In this post Fiona Willer argues that many people, especially young women, are doing so unnecessarily. In particular, she (and just about everyone else, like this guy) refer to a really neat study that experimentally isolated gluten and other components of grain, and determined that gluten was not responsible for intestinal symptoms. Instead, the culprits appear to be a group of short chain carbohydrates collectively known as "Fermentable, Oligo-, Di-, Mono-saccharides And Polyols.", or FODMAPs, that are poorly absorbed in the small intestine. However, it turns out that FODMAPs are found in things that also contain gluten (wheat, barley etc. as well as some fruits and vegetables). So if you avoid gluten ... In addition, restricting gluten containing foods will reduce your carbohydrate load, which helps with blood glucose control.

I found it interesting that Dr. Willer's argument for NOT avoiding gluten is that avoiding gluten might lead one to eat less wheat flour fortified with folate. Wait. You want me to eat wheat flour not for itself, but because it has something else added? I can take a multivitamin for that ... or you know, eat all sorts of real foods that naturally contain folate.

In 2012 I shifted my diet to reduce carbohydrates in response to being diagnosed as a Type 2 diabetic. Although this eliminated bread and beer, my 2 main sources of gluten containing carbohydrate, it did not eliminate gluten altogether. As a vegetarian, I was very keen on finding protein sources with relatively low carbohydrate, and many of those include wheat gluten as an ingredient. So, I reduced my consumption of lentils and chickpeas in favor of tofu and seitan, and processed foods containing soy and wheat protein. I lost ~25 pounds and brought my blood sugar back under control as a result.

Fast forward to spring 2014, and I finally got around to reading David Perlmutter's book "Grain Brain". Now that's a scary read. And although critics like Fiona Willer diss the book as "Alternative Medicine", I found the references to the scientific literature more compelling than that. As a result, I took a hard look at what I was eating, and went one step further, purging products containing wheat gluten from my diet. So, N=1 remember, and the plural of anecdote is not data! But here's my anecdote anyway. To borrow a phrase from the video linked above, my "satisfaction with stool consistency" dramatically improved, and more significantly, I felt better emotionally than I had in years. 

I had taken antidepressants for about 5 years, and I would occasionally forget to take my tablets in the morning. Typically I would start to feel withdrawal symptoms within a few hours of forgetting ("brain zaps"). A couple of months after I removed gluten from my diet I realized I was forgetting to take my antidepressant, and not experiencing any symptoms at all! With the support of my doctor, I began reducing the dosage of antidepressant, and 6 months later I've stopped altogether. And I feel great. 

So, I eliminated gluten, and coincidentally FODMAPs, and I feel good. Was there a cause and effect? I don't know. I'm not going to put gluten/FODMAPs back in my diet though. Your mileage may vary!

And here's a little (NSFW) light humor on Gluten courtesy of Southpark. It's not that bad. Really. It won't fly off. 

Hookahs and Anecdotes

From Andrew Gelman's Blog:

The evidence is certainly all around you pointing in the wrong direction - if you're willing to accept anecdotal evidence - there's always going to be an unlimited amount of evidence which won't tell you anything.

This is in the context of a panel of experts wondering if Hookahs cause lung cancer - one of the esteemed panelists used the fact that an uncle lived to 90 while smoking a hookah every day. I think there is an additional psychological mechanism involved in accepting this kind of anecdotal evidence - it is the direct experience of the person making the claim. Unfiltered by statistics, other people's attention to detail, and possibly dodgy methodology. It is particularly easy to accept anecdotal evidence when the process in question is impossible to experience directly - like the population level risk of cancer - or in my case, density dependent reductions in population vital rates. Even when faced with their own data, plotted in a different way to demonstrate the population consequences, people cling to their own experience. And unfortunately, density dependence isn't something you can experience directly.