The American journal of clinical nutrition
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The implementation of folic acid fortification in the United States has resulted in unprecedented amounts of this synthetic form of folate in the American diet. Folic acid in circulation may be a useful measure of physiologic exposure to synthetic folic acid, and there is a potential for elevated concentrations after fortification and the possibility of adverse effects. ⋯ Folic acid fortification has resulted in increased exposure to circulating folic acid. The biochemical and physiologic consequences of this are unknown, but these findings highlight the need to understand the effects of chronic exposure to circulating folic acid.