Folate Supplementation: Is It Safe and Effective?

Letter to the Editor

Sir: In the September 2008 issue of the Journal, Stahl reviews
L-methylfolate as a possibly helpful adjunctive antidepressant
agent,1 and Mischoulon and Fava briefly review the
evidence that folates, including folic acid, a stable synthetic
substance, could be useful augmenting antidepressant agents.
However, there is some evidence of possibly harmful or, at the
least, disappointing effects of folate supplementation.

1. There has long been a concern that folate supplementation
   might mask, or even worsen, the manifestations
   of B12-deficiency anemia. L-Methylfolate may be less
   likely to do this than folic acid.