Safe use of high intakes of folic acid: research challenges and paths forward.
Adequate folic acid intake is an effective dietary-based prevention tool for reducing the risk of neural tube defects. Achieving adequate intake for the prevention of neural tube defects frequently requires the consumption of foods fortified with folic acid and/or the use of folic acid-containing dietary supplements. To date, research on the potential for adverse effects of high intakes of folic acid has been limited. Without such research, it is difficult to define a value for high intake. In May 2015, an expert panel was tasked with examining the available scientific literature and making research recommendations within 4 general categories of potential folate-related adverse health effects: cancer, cognition in conjunction with vitamin B12 deficiency, hypersensitivity-related outcomes, and thyroid and diabetes-related disorders. This article summarizes the expert panel's conclusions, outlines the challenges faced when reviewing the literature, and examines some of the panel's recommendations for research.
A.L. Boyles and K.A. Thayer are with the Office of Health Assessment and Translation, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Durham, North Carolina, USA. E.A. Yetley and P.M. Coates are with the Office of Dietary Supplements, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA. abee.boyles@nih.gov.
Abee L
AL
Boyles
A.L. Boyles and K.A. Thayer are with the Office of Health Assessment and Translation, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Durham, North Carolina, USA. E.A. Yetley and P.M. Coates are with the Office of Dietary Supplements, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA.
Elizabeth A
EA
Yetley
A.L. Boyles and K.A. Thayer are with the Office of Health Assessment and Translation, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Durham, North Carolina, USA. E.A. Yetley and P.M. Coates are with the Office of Dietary Supplements, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA.
Kristina A
KA
Thayer
A.L. Boyles and K.A. Thayer are with the Office of Health Assessment and Translation, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Durham, North Carolina, USA. E.A. Yetley and P.M. Coates are with the Office of Dietary Supplements, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA.
Paul M
PM
Coates
D003071:Cognition / Q000187:drug effects; D048909:Diabetes Complications; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000009:adverse effects*; D005527:Food, Fortified; D006801:Humans; D009369:Neoplasms; D009436:Neural Tube Defects / Q000517:prevention & control; D012106:Research; D013959:Thyroid Diseases; D014806:Vitamin B 12 Deficiency
D005492:Folic Acid
folic acid; high vitamin intake; research recommendations; safety.