Both vitamin B12 and folic acid are involved in red blood cell formation and DNA synthesis.2,3 Vitamin B12 and folic acid are also required for the conversion of homocysteine to methionine, which is necessary for the production of S-adenosyl-methionine, the methyl donor involved in nearly all methylation reactions. Research demonstrates that daily supplementation with 400 mcg of folic acid during the first trimester helps to decrease neural tube defects by approximately 50%. In a randomized, placebo-controlled trial involving 119 pregnant women, continued supplementation with 400 mcg of folic acid daily into the second and third trimesters significantly increased maternal and cord blood folate status. Folic acid intake also better maintained homocysteine levels in the late stages of pregnancy, which may be associated with appropriate methyl transfer activity.