- Dietary counseling to increase natural folate intake: a randomized, placebo-controlled trial in free-living subjects to assess effects on serum folate and plasma total homocysteine. Venn, B.J., Mann, J.I., Williams, S.M., Riddell, L.J., Chisholm, A., Harper, M.J., Aitken, W. Am. J. Clin. Nutr. (2002)