Effect of riboflavin supplementation on plasma homocysteine in elderly people with low riboflavin status.
OBJECTIVE
To investigate the effect of riboflavin supplementation on plasma homocysteine (tHcy) concentrations in healthy elderly people with sub-optimal riboflavin status.


METHODS
A double-blind, randomized, placebo-controlled riboflavin supplementation trial.


METHODS
Community based study in Northern Ireland.


METHODS
From a screening sample of 101 healthy elderly people, 52 had sub-optimal riboflavin status (erythrocyte glutathione reductase activation coefficient, EGRAC>or=1.20) and were invited to participate in the study.


METHODS
The intervention had two parts. Part 1 was a 12 week randomized double blind, placebo-controlled intervention with riboflavin (1.6 mg/day). Following completion of part 1, the placebo group went on to part 2 of the study which involved supplementation with folic acid (400 micro g/day) for 6 weeks followed by folic acid and riboflavin (1.6 mg/day) for a further 12 weeks, with a 16 week washout period post-supplementation. The purpose of part 2 was: (a) to address the possibility that homocysteine-lowering in response to riboflavin may be obscured by a much greater effect of folate, and that, once folate status was optimized, a dependence of homocysteine on riboflavin might emerge; and (b) to demonstrate that these subjects had homocysteine concentrations which could be lowered by nutritional intervention.


RESULTS
Although riboflavin supplementation significantly improved riboflavin status in both parts 1 and 2 of the study (P<0.001 for each), tHcy concentrations were unaffected (P=0.719). In contrast, folic acid supplementation (study part 2) resulted in a homocysteine lowering of 19.6% (P=0.001).


CONCLUSIONS
Despite the metabolic dependency of tHcy on riboflavin, it did not prove to be an effective homocysteine-lowering agent, even in the face of sub-optimal riboflavin status.
McKinley
M C
MC
Northern Ireland Centre for Food and Health (NICHE), University of Ulster, Coleraine, Northern Ireland.
McNulty
H
H
McPartlin
J
J
Strain
J J
JJ
Scott
J M
JM
D000368:Aged; D000704:Analysis of Variance; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D009660:Northern Ireland; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012256:Riboflavin / Q000627:therapeutic use*; D012257:Riboflavin Deficiency / Q000178:diet therapy*; D014805:Vitamin B 12 / Q000097:blood
D017319:Photosensitizing Agents; D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12; D012256:Riboflavin