Effect of folic acid and vitamin C supplementation on folate status and homocysteine level: a randomised controlled trial in Italian smoker-blood donors.

BACKGROUND: This trial sought to examine the effects of high dosage of folic acid and vitamin C supplementation on red blood cell folate (RCF), serum folate (SF) and homocysteine (Hcy) levels in subjects who smoke more than 15 cigarettes per day. METHODS: A prospective study of 100 Italian repeat blood donors was undertaken to measure RCF, SF and Hcy levels before and after 45 days of vitamin supplementation. All subjects were randomised into four groups: [A] folic acid (FA) 5 mg/day, [B] vitamin C 500 mg/day, [C] FA 5 mg/day plus vitamin C 500 mg/day [D] no supplementation. RESULTS: Before supplementation the median RCF, SF and Hcy levels were similar in the four groups; 32 (40%) subjects had an RCF level below 340 nmol/l, 15 (18.8%) had an SF level below 6.8 nmol/l and 21 (26.3%) had an Hcy level above 16 micromol/l. After 45 days the median RCF and SF levels were significantly (P<0.01) increased in all supplemented subjects. The median Hcy level was significantly (P=0.008) reduced in subjects supplemented with FA and significantly (P=0.01) increased in those supplemented with vitamin C alone. CONCLUSION: The supplementation with 5 FA mg/day is able to increase significantly both RCF and SF levels and reduce Hcy level in Italian smoker-blood donors.