Vitamin B-6 and folate supplementation provides optimal homocysteine-lowering

Even mild elevations of homocysteine are associated with increased risk of cerebrovascular and cardiovascular disease (CVD), especially in elderly persons. In a study appearing in the American Journal of Clinical Nutrition, McKinley et al. investigated the homocysteine-lowering effect of vitamin B-6, which was found in previous studies to have uncertain benefit when used alone as a supplement.

The 22 elderly participants in the study, aged 63-80, were recruited from the community surrounding the University of Ulster; none were currently taking B-vitamin supplements. Before starting the vitamin B-6 intervention, all subjects achieved repletion in riboflavin and folic acid, first receiving riboflavin (1.6 mg/d) for 12 weeks, followed by a combination of folic acid (400 µg/d) and riboflavin (1.6 g/d) for an additional 6 weeks. Riboflavin and folate supplementation continued throughout the vitamin B-6 phase of the study. Baseline analysis of the subjects’ nutritional status had shown that 10 of the 22 subjects had deficient or suboptimal serum concentrations of vitamin B-6. In a randomized, double-blind trial, they were assigned to receive either vitamin B-6 (1.6 mg/d) supplementation, or a placebo for 12 weeks. Dietary intake and compliance with the vitamin B-6 supplementation were closely monitored throughout the study.

As anticipated, the initial folate supplementation produced a significant decline in serum homocysteine levels. The participants had reached a "folate plateau" prior to the start of the B-6 intervention, as evidenced by a lack of any change in homocysteine in the placebo group. In response to vitamin B-6 alone, homocysteine concentrations were reduced by an additional 7.5%. The authors suggest that the effect of vitamin B-6 may have been missed in previous studies due to suboptimal folate status in the study population. If this hypothesis is correct, the effect of vitamin B-6 supplementation may be significant only after accounting for the homocysteine-lowering response to folate. As part of a public health strategy aimed at preventing CVD, the lowest effective dose of a combination of B-vitamins will result in the greatest reductions in homocysteine levels.

McKinley, Michelle C., et al. Low-dose vitamin B-6 effectively lowers fasting plasma homocysteine in healthy elderly persons who are folate and riboflavin replete. Am J Clin Nutr 2001;73:759-64.

This media release is provided by The American Society for Clinical Nutrition, Inc., to provide current information on nutrition-related research. This information should not be construed as medical advice. If you have a medical concern, consult your doctor. To see the complete text of this article, please go to: http://faseb.org/ajcn/April/11654-McNulty.pdf

For more information please contact: h.mcnulty@ulst.ac.uk