Effects of polymorphisms in endothelial nitric oxide synthase and folate metabolizing genes on the concentration of serum nitrate, folate, and plasma total homocysteine after folic acid supplementation: a double-blind crossover study.

•This was a double-blind crossover study with folic acid supplementation (800 μg/d) over 2 wk.•We examined whether genetic polymorphisms in endothelial nitric oxide synthase and genes involved in folate metabolism affect the concentration of serum nitrate, serum folate, and plasma total homocysteine in healthy individuals after folic acid supplementation.•Polymorphisms in endothelial nitric oxide synthase and folate genes affect the concentration of serum folate and plasma total homocysteine but do not have any effect on the concentration of NO3.