Folate and homocysteine - Cardiovascular Risk Reduction

Nutrition Research Newsletter, Nov, 2002 by B Venn, J Mann, S Williams, L Riddell, A Chisholm, M Harper, W Aitken

The association of moderately elevated concentrations of plasma total homocysteine (tHcy) with vascular disease has led to research on ways of decreasing tHcy concentrations. Many studies have shown that folic acid, given either as a supplement or through fortification, is effective in decreasing tHcy concentrations; fewer studies have examined the possibility of decreasing tHcy concentrations by increasing the intake of foods that are naturally rich in folate. The potential of dietary change rather than fortification or supplementation is an important issue because changes in dietary habits may well result in additional health benefits and because some concerns remain, especially in the elderly, regarding high levels of folic acid fortification. In this randomized, placebo-controlled study, the researchers advised free-living individuals to increase their consumption of foods rich in bioavailable folate to examine the effects on serum folate and tHcy concentrations.

Thirty-four subjects were randomly assigned to either the dietary group or the control group. At recruitment, two weeks before the start of intervention, a registered dietitian instructed participants to follow the recommendation for healthy eating prescribed in the National Heart Foundation of New Zealand's Food Guide. Participants were advised to avoid eating foods fortified with folic acid and were provided with a list of unfortified brands. At the start of the study, subjects in the dietary group received individual instruction on ways to increase their dietary folate intake to reach a target of 600 micrograms of folate per day. Subjects were recommended to consume two glasses of orange juice per day and one serving of legumes per day and then self-select items from a list of folate-rich foods for the next four weeks. The control group was given unfortified breakfast cereal and instructed to weigh and eat 20 g of cereal per day (providing 16 micrograms of folate per day). Serum folate and tHcy concentrations in both groups were measured before and after the intervention period, and the concentrations in the dietary group were also measured 17 weeks after the intervention period.

During the four-week intervention, mean dietary folate intake in the dietary group increased from 263 to 618 [micro]g/d, resulting in a mean increase in serum folate of 37% and a decrease in tHcy from 12.0 to 11.3 [micro]mol/L. A further decrease in tHcy occurred in the dietary group during follow-up, with a final tHcy concentration of 9.7 [micro]mol/L. Therefore, increasing natural folate intake was found to improve folate status and decrease tHcy concentrations to an extent that might significantly reduce the risk of vascular disease. Dietary modification may have advantages over folic acid fortification because the altered food-consumption patterns lead to increased intakes of several vitamins and minerals and decreased intakes of saturated fatty acids.

B Venn, J Mann, S Williams, L Riddell, A Chisholm, M Harper, W Aitken. 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. Am J Clin Nutr 76(4):758-765 (October 2002) [Correspondence: BJ Venn, Department of Human Nutrition, University, of Otago. PO Box 56, Dunedin, New Zealand. E-mail: abab@es.co.nz]