Vitamins and Your Health

People can be confused about how to get all of the vitamins that they need in their diet, largely because "the experts" differ on the amounts that they say we need. The traditional philosophy reminds us that vitamins are, by definition, nutrients that we need in very small amounts. You may have heard the phrase, "Americans have the most expensive urine in the world!" because the supplements we buy are ultimately flushed out of our bodies by the kidneys, presumably as excess. A newer philosophy reminds us that the the same thing happens to penicillin — but it can help the body, before it is filtered out.

The RDA, Recommended Daily Allowance, for each vitamin is determined by seeing how much vitamin is needed before a deficiency disease develops, and then multiplying this number many times over for a daily recommendation. A well balanced diet will usually provide these amounts, although a diet full of snacks and processed foods doesn't guarantee that your daily needs will be met without supplements.

Some new research shows that vitamin doses greater than the RDA can help prevent or treat many conditions. Nobel laureate Linus Pauling was the first to claim that large doses of vitamin C (up to 2000 mg a day) can help prevent colds — although, despite popular usage he didn't claim that it could treat a cold once you had one. The acidity of vitamin C can prevent urinary tract infections, much as cranberry juice does, although chewable vitamin C can cause dental cavities for the same reason. Vitamin E in larger than RDA doses has been shown to improve the immune response in elderly people, and such research suggests that it may reduce the risk of heart attacks. It may also improve fertility in sub-fertile couples. Vitamins A, C and E are antioxidents, which can theoretically help the immune system fight infections, cancer, and perhaps the aging process. There are many B vitamins, which have traditionally been used in supplemental doses to do everything from prevent migraines to ward off mosquitoes. Vitamin B is used to treat fatigue, PMS, and menstrual cramps, with varying success. Risk factors for heart disease have also been improved with the use of several B vitamins. Folic acid, or folate, has recently been shown to clearly reduce birth defects and the incidence of cervical cancer in women.

There are, however, drawbacks to taking mega-doses of vitamins and people should be careful. Too much vitamin C may increase the risk for kidney stones, a very painful condition. Vitamins A, D, E, and K should especially be taken in moderation, as excesses are stored in the body, rather than excreted. An overdose of vitamin A can cause liver disease, and while a megadose can treat acne, it can also cause severe birth defects. Even too many minerals in a supplement can cause problems, overdosing on iron supplements is a major cause of poisoning in children and can also cause liver failure. There are some vitamins that are so common in our diets that supplements are unlikely to be helpful. Others like vitamin K, are made in large quantities by bacteria in our digestive system, eliminating any need for supplements.

Taking a multi-vitamin a day is good idea for most people, especially those who are dieting, smoking, or not eating properly. Some studies show benefits can be attained from eating foods high in vitamins, but no benefit from taking the supplements themselves. This just emphasizes the primary role of a good diet in supplying your vitamin needs.

Dr. Richard Jacobi is board certified in family medicine. He joined Longmont Clinic in December 1994.