The Paleo Diet - Loren Cordain [32]
Vitamin B deficiency is another problem. Many people believe that whole-grain cereals are rich sources of B vitamins. They’re mistaken. Compared to lean meats, fruits, and vegetables, calorie for calorie, cereals are vitamin B lightweights. Even worse, as I mentioned earlier, whole grains and legumes contain antinutrients that block the absorption of B vitamins in the intestines. For instance, antinutrients called “pyridoxine glucosides” can prevent your body from getting as much as two-thirds of the vitamin B6 you eat. In a study of vegetarian women from Nepal, Dr. Robert Reynolds, of the USDA Human Nutrition Research Center, linked the low vitamin B6 levels in these women to the high levels of pyridoxine glucosides in their grain- and legume-heavy diets. In contrast, the availability of vitamin B6 in lean meats is nearly 100 percent.
Another B vitamin that’s poorly absorbed when you eat whole grains is biotin. Experiments by my colleague Dr. Bruce Watkins from Purdue University have shown that wheat and other whole grains impair the body’s ability to get enough biotin. Biotin deficiencies result in dry, brittle fingernails and hair. Research by Dr. Richard K. Scher and colleagues at Columbia University has shown that biotin supplements reduce fingernail brittleness and vertical “ridging” in nails. But you won’t need to supplement your diet if you get enough biotin (or any other vitamin or mineral) the old-fashioned way—by eating the right foods. The availability of biotin from animal foods is almost 100 percent.
Pellagra and beriberi are two of the most devastating and widespread B vitamin deficiency diseases that have ever plagued human-kind. They are caused exclusively by excessive consumption of cereals. Pellagra is a serious, often fatal, disease caused by a lack of the B vitamin niacin and the essential amino acid tryptophan. In a sad chapter of U.S. history, between 1906 and 1940 there was an epidemic of pellagra in the South. An estimated 3 million people developed it, and at least 100,000 of them died. Similar outbreaks have occurred in Europe and India, and pellagra is still common in parts of Africa.
Underlying every worldwide pellagra epidemic was excessive consumption of corn. Corn has low levels of both niacin and tryptophan, and the tiny amounts of niacin that are present are poorly absorbed. Pellagra could never have happened in the Paleolithic era, because lean meats are excellent sources of both niacin and tryptophan. Invariably, whenever we stray from the lean meats, fruits, and vegetables that we are genetically adapted to eat, ill health is the result.
Beriberi, caused by a deficiency of vitamin B1 (thiamin), ultiately causes paralysis of the leg muscles. This disease was virtually unknown until the introduction of polished rice in the late 1800s. In parts of Japan and Southeast Asia, where rice was the staple food, beriberi became epidemic as people replaced their traditional brown rice with white rice. Eventually, scientists discovered that removing the thiamin-containing bran during the polishing process was largely responsible for this disease. Beriberi has been mostly eliminated with the introduction of “enriched” rice, to which vitamin B1 is added. However, the message should be clear: If we have to add 1 a vitamin to a food to prevent it from causing ill health and disease, we shouldn’t be eating it in the first place.
Vitamin B Deficiency and Heart Disease
In North America, we enrich our refined cereal grains with vitamin B1 and niacin—which means you will never have to worry about pellagra or beriberi. But it doesn’t mean that these foods are good for you. Far from it. Within the past twenty years, a major risk factor for heart disease has surfaced. It has been found that