Has mandatory folic acid supplementation of foods increased the risk of asthma and allergic disease?

摘要

Folate (the naturally occurring form) and folk acid are forms of a water-soluble B vitamin (B9) that were first synthesized in 1945. Folate functions as an important cofactor in the transfer and use of 1-carbon moieties, primarily methyl groups. An important advance in understanding subclinical folate deficiency came in 1991 with the demonstration that folic acid supplementation before and during pregnancy dramatically reduced the risk of neural-tube defects in newborns. Folate supplementation of women before and during the first trimester of pregnancy has a dose-response effect in preventing neural-tube defects, ranging from a 23% reduction with 200 mug to an 85% reduction with 5000 mug of folic acid per day. The strong evidence demonstrating reduced risks of neural-tube defects led to mandatory folic acid fortification of cereal grain products in the United States by January 1, 1998. Fortification of foods with folic acid in the United States costs about dollar1,000 per neural-tube defect prevented.3 Even with all the information on the benefits of folate, many studies show inadequate folate intake among young women. Adequate folate levels have also been associated with reduced risks of coronary artery disease, colorectal cancer, and dementia.