An update on folates and folic acid: contribution of MAFF‐funded research

Abstract

SummaryThe Ministry of Agriculture, Fisheries and Food (MAFF) recently commissioned the British Nutrition Foundation to review critically its Optimal Nutrition Status programme and identify future research requirements. MAFF describes two main scientific objectives for this programme: (a) to understand the links between optimal nutrition status and the maintenance of good health, and (b) to develop accurate measures of bioavailability of micronutrients from foods. Five projects funded under this programme have been concerned with folates and folic acid.The B vitamin folate/folic acid occurs in food as folic acid (the synthetic form used for fortification and dietary supplements) and a range of naturally occurring folate vitamers (folates). Measurement of folates in foods and biological samples has been difficult because of the different natural forms of folate. Several MAFF‐funded projects have addressed this difficulty and new assays for food folates and folates in biological samples have been developed.There is good evidence that the synthetic form of the vitamin, folic acid, in its free form as in supplements, is stable and more bioavailable than the naturally occurring folates at typical intake levels, but its bioavailability from fortified foods is less well established. Understanding of the bioavailability of endogenous food folates is also incomplete, and it is not possible at this time to predict the bioavailability for a given diet. Stable isotopic methods, as used in some of the MAFF‐funded projects, show great promise for the determination of folate bioavailability in whole diets, fortified foods and dietary supplements.An understanding of the function and metabolism of folates/folic acid is critical in identifying indicators of status. Recent and current research (some funded by MAFF), especially that relating to plasma homocysteine as a functional marker, is described in this paper. Human intervention studies that are being used to determine dose response of both natural food folates, and folic acid in fortified foods and supplements are also described.As yet there is insufficient evidence to determine functional markers of optimal nutrition status of folates/folic acid in population groups and hence to be in a position to review the Dietary Reference Values. Further research requirements were identified in the review and refined at a workshop of experts. These are set out under individual MAFF programme objectives in a table at the end of the paper.