Folate and nutrition.

The main causes of nutritional folate deficiency are reviewed as well as the consequential effects of this vitamin deficiency; some are well defined such as hematological consequences, others are less known: possible effects on immune and non-immune systems, influence on the central and peripheral nervous system, on the outcome of pregnancy and newborns. This paper emphasizes at-risk physiological and pathological situations of deficiency: pregnancy, premature infants, elderly, alcoholics, patients admitted to intensive care units. In these high risk populations, the benefit of folic acid prophylaxis is raised.