A Role for Multivitamins in Infection?

Millions of Americans take multivitamin and mineral supplements hoping to promote good health, but few studies have documented the benefits (1). The strongest evidence supports use of folate supplements to reduce birth defects; less compelling but suggestive evidence supports multivitamin use for prevention of chronic disease, especially coronary disease and cancer. Despite fortification of the U.S. food supply with folate, homocysteine levels could be further reduced with optimal intake of folate, vitamin B₆, and vitamin B₁₂. Moreover, although many elderly adults produce insufficient gastric acid to liberate vitamin B₁₂ from food, causing subclinical insufficiency, acid is not required to absorb vitamin B₁₂ from supplements. A recent randomized trial among postangioplasty patients showed that homocysteine-lowering vitamin therapy reduced major adverse outcomes by one third compared with placebo (2).

Ames and Wakimoto (3) have summarized several lines of evidence suggesting that insufficient micronutrient intake may increase cancer risk. Giovannucci and colleagues (4) found that folate intake was related to reduced risk for colon cancer, but the association was largely limited to persons who had taken folate supplements of adequate dosage (400 µg/d) for 15 years or more. This finding underscores the difficulties in designing trials to test these hypotheses, particularly in well-nourished populations. This finding and other evidence provide a reasonable …