Report from the Journal of the American Medical Association (Feb. 4, 1998) A study of 80,082 female nurses over a 14-year period has indicated that increased intake of two vitamins, folate and vitamin B-6, is predictive of reduced risk of coronary heart disease (heart attack or death from coronary heart disease).
These results are consistent with earlier data indicating a relationship of folate intake with coronary disease risk in men, and with other evidence that low blood levels of folate and vitamin B-6 are indicative of increased heart disease risk.
Although the present study did not include measurements of blood homocysteine, an amino acid that has been linked to increased heart and vascular disease risk, it is known that both folate and vitamin B-6 consumption can lower blood homocysteine levels. The study, authored by Eric B. Rimm, Sc.D., and colleagues from the Harvard School of Public Health, Boston, suggests that reduced homocysteine may account for a major portion of the apparent protection from heart disease afforded by folate and vitamin B-6.
Notably, the findings suggest a benefit for intake of both vitamins at levels beyond those currently recommended for the general population. The current recommended dietary allowance (RDA) for folate is 180 micrograms (mcg) for women and 200 mcg for men per day. For vitamin B-6, the RDA is 1.6 milligrams (mg) for women and 2 mg for men. A diet, rich in green leafy vegetables, citrus fruits, legumes, lean cuts of meat and poultry and fortified cereals could provide an individual with these amounts of folate and vitamin B-6. However, for most individuals, achieving intakes associated with the lowest heart disease risk for women in the JAMA study (400 mcg per day of folate and 3mg/day of vitamin B-6) would require the use of supplements.
Speaking on behalf of the American Heart Association, Ronald M. Krauss, M.D., chairman of the AHA's Nutrition Committee, says the results are "intriguing, and should prompt further research." Krauss is also a senior scientist and head of the Molecular Medicine Department at the Lawrence Berkeley National Laboratory of the University of California, Berkeley.
"However, we urge caution before we consider the results of this study conclusive, since the data were collected by mailed questionnaires of medical history and lifestyle. Although this method of study is valuable, the accuracy of the dietary information is based on the unverified reporting of participants," he says. "It will be important in future studies to determine whether supplementation of the diet with folate and vitamin B-6 beyond the current RDAs for these nutrients will directly benefit heart disease risk."
Women who drank a moderate amount of alcohol appeared to have the greatest reduction in heart disease risk with high folate intake. "This points to the need to better understand how the effects of folate and other nutrients are affected by overall diet and other lifestyle factors," says Krauss. At present AHA recommends an intake of folic acid of 400 mcg/day. It encourages that this level of intake, as well as the RDAs for vitamin B-6 and other vitamins, be achieved through dietary means. Individuals that cannot achieve these intakes, or who are at increased risk for heart disease, may be advised to use vitamin supplements.