Effects of short-term folic acid and/or riboflavin supplementation on serum folate and plasma total homocysteine concentrations in young Japanese male subjects.

OBJECTIVE

To investigate the effects of short-term folic acid and/or riboflavin supplementation on serum folate and plasma plasma total homocysteine (tHcy) concentrations in young Japanese male subjects.

DESIGN

In a double blind, randomized controlled trial.

INTERVENTION

Subjects were randomly assigned to one of four groups and received a placebo (control group), 800 microg/day folic acid (FA group), 8.4 mg/day riboflavin (R group), or both (FAR group) for 2 weeks.

SETTING

Tokyo, Japan.

SUBJECTS

In total, 32 healthy male volunteers aged 20-29 years.

RESULTS

At the end of the 2 week supplementation period, the tHcy concentration decreased significantly in the FA group. Serum folate concentrations had increased between 2.7 and 2.0-fold in the FA and FAR groups, respectively, but the mean within-group changes in serum folate and plasma tHcy concentrations did not differ between these two groups. At the end of the study, alanine amino transferase was decreased in the R and FAR groups, while alanine amino transferase was increased in the FA group.

CONCLUSION

Supplementation with folic acid, 800 microg/day, for 2 weeks, increased the serum and red blood cell folate concentrations and decreased the plasma tHcy concentrations in healthy young male subjects. Riboflavin supplementation may have blunted the effect of folic acid, which resulted in a diminished reduction of tHcy in our subjects.