Common wisdom meets pseudo-science

For some asinine reason, people have gotten the idea that any food or food habit chosen by early man or primitive tribes that have never run afoul of a white missionary, has got to be superior to any food or food habit that North Americans choose. As is usually the case when common wisdom meets pseudo-science, this conclusion is sometimes and somewhat off the mark. Oh sure, many cultures have stumbled onto nutritionally whammo combinations--beans and rice, macaroni and cheese--which is why they flourished, but often this was sheer happenstance.
Take the case of two African tribes living in close proximity, one experiencing a high incidence of xeropthalmia (a potentially blinding eye condition brought on by vitamin A deficiency), the other tribe virtually free of the disease. Nutritional anthropologists investigating the situation discovered that the disease-free group gathered seedling shoots (rich in vitamin A) in the early morning when there was just enough dampness from dew to produce them; after a few hours the seedlings withered. The neighbouring tribe was out of luck, high and dry, almost blind. Talk about the early bird getting the worm.
Analysis of primitive diets often reveal considerable wisdom--or luck--in the food choices of native peoples. The ancient Aztec custom of soaking maize in a solution of lime (calcium carbonate) before pounding it into meal has been shown not only to add dietary calcium but also to convert the niacin content of the corn into a biologically available form, thus preventing the niacin-deficiency disease of pellagra.By contrast, in the late nineteenth and early twentieth century, poor folks in the southern U.S. relied heavily on untreated corn as a staple in their diets (a grits-driven culture) and pellagra was rampant. Some decrepit mental institutions still exist there as monuments to major dietary blundering.

In South Africa, certain Zulu tribes had a strong taboo against drinking milk from cows that didn't belong to their own families. The upshot of that, of course, was that women who went to live with their husband's families drank no milk. The U.N.'s Food and Agriculture Organization (F.A,O.) had the brilliant idea of introducing powdered milk, which couldn't be identified as coming from any particular family's cows. While this could have had the unintended consequence of nobody in the tribe drinking milk because the origin couldn't be identified, common sense ultimately prevailed and "foreign" brides were soon drinking milk. In short order, and bucking the notion that new and processed is inferior to old and traditional, the nutritional status of many women and breast-feeding infants was greatly improved.

In present-day Colombia there is a problem that has nothing to do with drugs or dictators...it stems from the dietary custom of fava bean consumption. Fava beans. as it happens, are a very nutritional food, but contain a substance that is innocent enough on its own, but combines with the high nitrate content of the bean to make a carcinogenic compound. Colombians tend to eat fava beans several times a day; stomach cancer is quite common among these people. Another area of the world with a high incidence of stomach cancer is Japan, the home of a culture whose diet North Americans are encouraged to emulate. The culprit in this case is thought to be a high intake of smoked and cured vegetables and similarly treated fish.

Seasonal variations in the diets of different cultures often occur. The San bushmen are hunter-gatherers of the Kalahari desert of southern Africa. Great seasonal differences in rainfall and temperature lead to sharp fluctuations in the natural food supply. In the dry season people lose as much as six percent of their body weight and fertility drops markedly in San women. Birth data for neighbouring tribes on diets supplemented with cultivated food show a more even distribution of fertility. It's therefore been hypothesized that the diminished food intake of San women in the dry season sharply reduces production of the steroid hormones that maintain fertility. The seasonal fluctuation of the natural food supply provides a natural cyclical method of population control, while introduction of supplemental food resources may contribute to an increase in birth rates. Whether or not this is a good thing is subject to debate.

From a nutritional standpoint, it's simply bad policy to embrace a dietary practice based on the fact that it was the custom of dear old granddad, cro-magnon man, or a Tibetan monk. Nutrition is an evolving science and some day we may know with certainty the ideal diet. Till that day comes, you can't do better than your country's food guide.