Wednesday, 8 September 2010

Adaptation to Neolithic diet: C282Y and H63D

Vegatarians and vegans often use arcane methods of food preparation or supplementation to make sure their diet is complete. This is clearly an unnatuaral way to make the supposedly natural plant based diet to work. WAPF adherents can also go to extreme to make grains lose most of its toxicity.

But sometimes the meat eating Paleo crowd uses a simillar method to make sure that the unsuitable diet is tolerable: they suggest bloodletting for iron overload. Indeed, giving blood is effective for haemochormatosis and is also laudable, but I doubt it is natural on a regular basis. Perhaps the meat rich diet is just as "unnatural" for sime people as vegetarian or vegan one is in others?

I took a closer look at heamochromatosis. It appears that about a quarter of people of European heritage are carriers of C282Y or H63D mutations which markedly increase the risk of iron overload. These mutations most likely occured some 60 generations ago as a response to grain-based diet, associated in turn with risk of iron deffciency. The mutations occured in Celtic and/or Viking tribes and spread across Europe. Apparently the Southern farmers did not have this trait due to vegetarian sources of iron (or they were not "lucky" enough to mutate). The mutated genes were selected for during the Bubonic plague as low iron in macrophages (due to rapid storing in tissues) offered protection against Yersinia pestis.

All this means that about a quarter of Europeans (more in Ireland, Scotland and Scandinavia than in Southern Italy or Greece) should worry about iron overload, and perhaps stay clear from too much meat.

I suppose they can still be Paleo, eating seafood, snails and other invertebrates, but possibly they would also be more adapted to grains?

One way to find out is to do the tests for Total Iron Binding Capacity (TIBC), Serum Iron (SI) and Serum Ferritin (SF), as apparently genetic testing is unreliable - typically ony those two genes are tested while 40 mutations can lead to iron overload - and expensive.

To me it looks like those people are stuck. Going back to meat-based Paleo is risky, but grains are without doubt suboptimal, even if some adaptation occured. What if there are some other mutations responsible for other metabolic pathways which helped our ancestors adapt to Neolithic diets, but with serious side effects in chronic diseases and decreased longevity? Saturated fat can be a good example. Or gluconeogenesis. Or glucose transport?

What if those genes can be modified epigenetically and our grain eating grandmother had greater impact on expression of our metabolic enzymes than hundreds of thousands of Paleolithic evolution?

I am worried that the Paleo community is starting to become as dogmatic as the entrenched vegetarians, who know better and do not even engage in constructive discussion.

In science the only way to move ahead is to constantly question our hypothesis, try to falsify it. I failed as a vegetarian scientist, but this time I am going to be more careful.

4 comments:

  1. The Chapter in Eades' book Protein Power on iron and iron overload has always had me curious, as far as the application to the general public, and those NOT afflicted with hemochromatosis.

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  2. I have two comments.

    One, do you think paleolithic man had more or less blood sucking parasites than modern man? Do you think his lifestyle had more or less incidents of blood loss due to trauma? Giving blood may be the modern equivalent of having parasites and injuring yourself frequently.

    The genetic mutation is interesting, especially as it is in about a quarter of the people of European descent.

    But, I think we may be assigning too much "intelligence" to evolution. The mutation happened, and spread within that particular people-group because it was passed to progeny. Travel being much more restricted in that time, it is reasonable to assume that the mutation would spread only as far as that gene pool spread. That's what we know from the facts you presented. But can we really assign diet as the cause of the mutation? Or parasites, as I have done above?

    Unless the problem of too much iron struck down people before they reached reproductive age, or affected fertility some other way, I doubt that the mutation is in response to environmental pressure.

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  3. Paleo Diet is basically what our ancestor used to eat millions of years ago,
    before agriculture came into existence . It is also referred as “Hunter’s Food” as they used to gather it from here and
    there by hunting animals or collecting from plants and trees paleo diet

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