Apart from calcium and iron requirements, nutrition in general (and vitamins in particular) has traditionally rated only a passing nod in medical school. Physicians in training are typically taught that a “balanced” diet is sufficient and that hardly anyone really needs vitamin supplements. Although frank vitamin deficiency is now uncommon in the United States, many investigators have long suspected that large segments of the US population are consuming suboptimal levels of several micronutrients; in recent years, compelling evidence has emerged that supports this contention. In national surveys, a substantial proportion of the US population consumes levels of several vitamins that are well below recommended intakes,1 and recent evidence strongly indicates that such low intakes are associated with serious health consequences. The most striking recent example is the finding that folic acid supplements can reduce the risk of neural tube defects by approximately 70%. That relationship
