If you ask 100 people what a vitamin is, at least 100 of them will get it wrong. They will have some vague ideas: everyone should take them, they are derived from natural sources and the more you take, the healthier you will be. All of this is wrong.
The definition is actually rather simple: vitamins are nutrients required in very small amounts to promote many of the thousands of chemical reactions that make life possible. Most vitamins function as catalysts — substances typically used in miniscule quantities to promote these reactions that would otherwise not take place or would do so millions of times more slowly. Vitamins must be consumed because (with few exceptions) they are not produced within the body.
The quantity of vitamins actually needed is unexpectedly small. If you add up the total weight of all vitamins in the Recommended Daily Allowance (RDA) you come up with 150 milligrams, roughly equivalent to 5 grains of uncooked rice. This tiny amount is sufficient to support a wide-ranging array of biochemical reactions that generate energy, synthesize proteins and regulate hormone levels, just to mention a few.
Surprisingly, nearly all vitamin supplements come from synthetic rather than natural sources. The two forms are chemically identical and your body cannot tell them apart, so the source is immaterial. Even vitamin C, which could easily be extracted from fruits or vegetables, is man-made in vitamin pills.
More surprisingly, large doses of vitamins can be harmful and even fatal. Vitamins are divided into two classes: water-soluble and fat-soluble. Each group behaves differently when taken in large quantities. Water-soluble (B and C) vitamins are less toxic, since they are rapidly excreted in the urine, where they nourish the life forms in your sewer at the expense of your wallet. By contrast, fat-soluble vitamins (A, D, E, and K) are stored in body fat, and they are eliminated much more slowly, making them more dangerous. Indeed, numerous studies have shown that large doses of vitamin E are associated with cardiotoxicity and early death. Excess vitamin A causes liver toxicity, anemia and hair loss, and is especially dangerous for the fetuses of pregnant women. It is chemically related to the acne drug Retin A, which can cause serious birth defects.
Vitamin C is possibly the most controversial of all because of claims regarding its utility for prevention of many diseases, especially colds. Dr. David S. Seres, director of medical nutrition at New York-Presbyterian Hospital Columbia University Medical Center, says these claims are unproven. “Most studies, except in extreme athletes, have failed to show any benefit from supplemental vitamin C. Furthermore, mega-doses of any vitamin may cause toxicity.” Vitamin C is also touted as an antioxidant (which functions to prevent DNA damage); however it can also function in reverse — as an oxidant. One study found that people taking as little as 200 milligrams per day of supplemental vitamin C had more DNA damage within their white blood cells than people not taking a supplement.
A more fundamental question is whether Americans should be taking vitamins at all. Although almost heretical, the answer is usually no. We get them in a normal diet, even an imperfect one. According to Dr. Seres, there are “no data that vitamin supplements are of any help, except in very specific instances (vitamin D supplementation of milk and possibly folic acid in pregnant women).”
So, why do so many of us take vitamins? The answer is Very Effective Marketing. It has become part of the American psyche that vitamins are good, that they will protect us from all sorts of diseases and that we don’t get enough of them in our diets. And how can anything shaped like Fred Flintstone be bad? But the risk of taking supplemental vitamins is actually real and the benefit small. Quoting Dr. Seres, “there has never been a study showing that taking a multivitamin has any health benefits in the general population.” I threw mine away years ago.
Dr. Bloom is an organic chemist and has worked in the pharmaceutical industry for over two decades.
