Evolutionary Psychiatry

The hunt for evolutionary solutions to contemporary mental health problems.

Zombieland

Do zombies one-up us when it comes to optimal nutrition?

Zombie
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Back in the day we ate a lot of brains. Stands to reason. All animals come with one, after all. And we certainly wouldn't leave behind such a great source of important fat. You don't think we just took the skinless boneless chicken breast and left the rest behind, did you?  In fact, anthropologic data suggests that the opposite is true - we preferentially grabbed the fatty bits (marrow, organ meats, fatty meat), and that we would also seek to hunt for particular animals in season when they were fattiest.  In fact if you were fastidious and ate only the lean meat, you might succumb to so-called "rabbit starvation," where you have plenty of protein but suffer from malnutrition and hunger. Humans cannot live on protein alone.

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Have you seen the movie Zombieland? I highly recommend it if you are into a bit of gore and fun, and while the dietary advice isn't necessarily paleo, the exercise discussions take a functional fitness turn… (that last link is not entirely "safe for work," as they say, due to some foul language).

Zombies might be lacking in variety with their chosen food, but they certainly wouldn't be lacking in micronutrients and omega 3s! Brains are also an especially rich source of phospholipids, one of which, phosphatidylserine, was mentioned by a commenter on my other blog. She seems to have had luck with it helping her joint pain and fatigue. Terrific! But why?

Well, phospholipids are found in many foods, but the highest concentrations are in brains, seafood, and some organ meats. When one looks back at different hunter-gatherers roaming the world, they would tend to eat a lot of seafood, or they ate a lot of large land-roving mammals, or both. It would make sense that today we might have a lot less phospholipid intake compared to our evolutionary past. In fact, today's foods contain about 1/3 the amount of phospholipids they did even at the beginning of the 20th century (1).

Research in phospholipids was heating up in the 80s and 90s, but then a little illness came along called mad cow disease, and since the major source of phospholipids for supplements was cow brain, things slowed down for a while until an alternative soy source was found. Not surprisingly, the soy sourced supplement is somewhat different than the animal sourced one, but looks like from perusing pubmed that almost all the latest research was done with the soy version. If you are not fond of soy, krill oil combines omega 3 and phospholipids, and since krill (or the algae they eat) are the food for marine animals from which many ancient humans got their phospholipids, it would certainly be a more evolutionarily pedigreed source than soy. Not keen on krill or pills in general? Eggs and chicken and beef heart have tons of choline, the precursor of the phospholipid phosphatidylcholine.

Phospholipids are necessary to form cell membranes and to form the particles that carry cholesterol around in the blood stream.  Who cares?  Well, if we don't have enough of the precursors to make the phospholipids, the fat will get stuck in our livers, leading to the aptly named fatty liver.  Lack of choline, for example, has been associated with both fatty liver and the development of diabetes.  You might be interested to know that women eating the standard American diet have insufficient choline intake, and that the small percentage eating enough choline get it from eating an unusually high number of eggs.

But what does the research show about our brains and muscles? Do we suffer as human beings because we've greatly reduced our phospholipid intake, especially in the last century? Well, in sports performance studies, phospholipids can help reduce pain and speed up recovery. And supplementation can result in a statistically significant improvement in your golf shot (2). A study of memory and cognition in the elderly didn't show any improvement using the soy-derived versions (3), though other earlier studies showed positive effects. But the most intriguing part of the research is when you find out that ingestion of phospholipids has been found to reduce increases in ACTH and cortisol in response to stress (4).  That is remarkable - it would imply that having plenty of phospholipids on board would diminish our total hormonal stress response, and decrease the damaging effects of chronic stress along the way.  Effects that would include an increased vulnerability to depression, anxiety, diabetes, and heart disease.

I've always wondered why we modern humans are considered so "stressed." I mean, sure, we are probably way more stressed than the majority of our ancestors who worked obtaining food 17 hours a week and otherwise hung out and told stories and played games. But the most accepted pathophysiologic model for major depressive disorder and other mental illness is the stress diathesis model. Meaning stress combined with genetic vulnerability changes your brain and causes your symptoms. There's a lot of research support for this model and it makes a great deal of sense. BUT. Mental illness has been increasing over the 20th and 21st centuries, especially depression. Maurizio Fava MD said in a lecture it is increasing on the order of 10% in each generation since the 1950s. That is HUGE. We know this (in America at least) from epidemiological catchment studies (5) done since the beginning of the 20th century.

But are we really more and more stressed? In the first 50 years of the 20th century, there were two world wars. Millions of people died from flu epidemics, and when my mother was a child, there was still constant fear of polio. By the 60s we were worried about global nuclear annihilation. Sure, now I have to remember 40 different passwords and traffic is pretty rotten, and we worry about terrorism and natural disasters and relatives with chronic illness, and men and women are still fighting wars, but is that more stressful than what families faced in the last century? Ot the centuries before, also ridden with war, plague, and famine?

I don't think stress has changed so much, at least in recent history. Agricultural humans have always been unhealthy and stressed, and I don't see how increases in cardiovascular disease and mental illness over the past 100 years could be explained *strictly* by a stress (cortisol) model.

I contend (as many do) that the MAJOR change in the last 100 years has been our industrialized diets. Agriculture is one thing, and not good for human health (though it did beef up human fertility). But industrialization of the food supply, I believe, is the primary causative factor in our modern physical diseases and our modern decline in mental health.

And here we have a bit of evidence that may bring diet and stress together at last. Phospholipid supplementation, in a few studies, decreases our stress response, especially to emotional stress. Imagine day after day of munching on mammal brains or atlantic herring, rich in phospholipids, and thus (if one believes the research) having a blunted hormonal response to emotional and physical stressors, compared to our relatively phospholipid deficient diets of today. Modern disease pathology is all about the cortisol, as much as it is all about the insulin.

We are built for eating brains and/or seafood (or eggs).  Ancestral migration patterns would seem to suggest that is the case. The farther we stray from achieving the micronutrient richness of our ancestral diets, the more we seem to suffer.

migration patterns

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Copyright Emily Deans M.D.

 

Emily Deans, M.D., is a psychiatrist with a practice in Massachusetts.

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