by Mark Jenkins, MD

This feature is a continuation of the "Performance Shop" column in the February 2002 issue of Runner Triathlete News. To get the full scoop on vitamins and other supplements, pick up a copy of the February issue of Runner Triathlete News.

Folic Acid Dosage range: 400 800 micrograms per day. Well documented benefit for women who are pregnant. Reduces the incidence of certain birth defects (neural-tube defects). All women who are pregnant or trying to get pregnant should take a folic acid supplement.

Alcohol interferes with folate absorption and metabolism, so those who consume alcohol on a regular basis should supplement with folic acid. Folate supplementation may also help reduce the risk of certain cancers and cardiovascular disease.

Vitamin C Despite the popularity there is very little evidence that vitamin C supplementation, above that provided in the diet, provides any benefit. The RDA (recommended daily allowance) is 90 mg for men and 75 mg for women (add 35 mg if you smoke). These amounts are easily met in the diet. For both general health and a variety of diseases (e.g., colds, hypertension) extra vitamin C has no demonstrable benefit. Similarly, there is no evidence that it helps treat or prevent overuse injuries.

Vitamin E Evidence is accumulating that supplemental vitamin E may reduce the risk of cardiovascular disease (e.g., heart attacks). Cardiovascular disease is a leading killer in the U.S. Thus, there is considerable interest in the potential benefit of vitamin E supplementation. Furthermore, this vitamin has shown promise in aiding recovery from high intensity, or high volume, exercise. A commonly recommended regimen is 400 IU per day and this dosage appears safe. A typical multivitamin (Centrum) contains 30 IU, which is 100% of the RDA. If you had to pick one single vitamin to "supplement" a multivitamin the best choice would be vitamin E (400 IU).

Multivitamins There are a bewildering array of multivitamins, so how does one choose the right one? As a rule a multivitamin should cover a broad range of established vitamins and minerals, and should not exceed 100% RDA, or percentage daily value. To reiterate, a multivitamin that boasts 800% RDA of several different vitamins is not better than one that provides100%. Stick with the well known names (e.g., Centrum), or generics, that provide 100% RDA or less. You achieve the best results possible and are less likely to get into trouble.