Folate requirements for health in different population groups.

Folate coenzymes are required for the transfer and utilisation of one-carbon units in essential reactions involving amino acid metabolism, and the synthesis of purines and pyrimidines. Much of our understanding of human folate requirement comes from the study of folate deficiency, as it progresses from early haematological changes to eventual clinical manifestations. In population studies folate status may be assessed during the early stages of negative balance, before functional and clinical changes occur, by means of both dietary evaluation and biochemical measurements. Sub-optimal folate status may arise as a result of a number of environmental, physiological or pathological factors which cause decreased availability, increased requirement, or both. Current reference values for folate apply to intakes in healthy population groups. New recommendations for folic acid in the prevention of both first occurrence and recurrence of neural tube defects have recently been published. Folate nutrition may also have a role in coronary heart disease and various cancers.