Grant: Project Grant

Folic acid and vitamin B12 have crucial effects on human health but the effects differ for different conditions, so the optimal amount of each vitamin is unclear. Internationally, the optimal intakes of folic acid and vitamin B12 are still regarded as unsettled issues, with a large variety of recommendations across many countries based on evidence about which there is considerable uncertainty. Recently, there has been a move to base advice on assessment of evidence for the role played by specific food components in causing or preventing chronic diseases. Our team includes leaders in national assessment programs in Africa, N. America, Asia and Europe. Our goal is to develop an approach that can be used to help the individual assessment programs target key areas for refinement of advice. Because the investigation of the part nutrients play in causing or preventing disease is frustrated by problems of measuring nutritional intake and status, we propose to bring together different strands of evidence on the health effects of folic acid and vitamin B12. These stands of evidence include relationships between health states and (1) diet, (2) supplement use, (3) blood levels, (4) genes variants that alter blood levels, and (5) combinations of gene variants and intake of folic acid and vitamin B12. We will combine the available evidence on folic acid and vitamin B12 to understand better the volume, credibility and risk of bias of the associations with diverse health outcomes. In addition, we will develop a map of government policy interventions relating to these vitamins, and undertake a review of their effectiveness. This will provide insight into both the strengths and limitations of existing policy interventions, be the basis of recommendations as to possible modifications to consider the rapidly changing environment of food production, emerging dietary patterns which vary between populations and within them, and so inform best practice for policy development.