Decreased Coronary Artery Disease in Women with Increased Folate and Vitamin B6 Intake
July 1998; Volume 1: 81-82
ABSTRACT & COMMENTARY
Synopsis: During 14 years of follow-up, those women with low intakes of folate and B6 had higher cardiovascular risk. The opposite was also true; those with high intakes of folate and B6 had lower risk of coronary heart disease.
Source: Rimm EB, et al. JAMA 1998;279:359-364.
Rimm and colleagues conducted a prospective cohort study in 80,082 women from the Nurses' Health Study who had no previous history of cardiovascular disease, cancer, hypercholesterolemia, or diabetes. They analyzed their food frequency questionnaires, and they were able to derive the subjects' usual intake of folate and 6.
By then following these nurses' health over a 14-year period, they were able to calculate the incidence of nonfatal MIs and fatal coronary heart disease. With the 658 cases of nonfatal MI and the 281 cases of fatal coronary heart disease compared to folate and B6 intake, the authors were able to develop relative risk of quintiles of B6 and folate intake compared to incidence of coronary heart disease. They found that, at the lowest level of folate and B6 intake, there was significant coronary artery disease. At the highest level of intake (almost 4 times higher than the lowest quintile), they found half as much coronary heart disease.
Then, by further analyzing the data, they found that moderate amounts of alcohol intake strongly decreased the cardiovascular risk among the women with the highest folate and B6 intakes.
Rimm et al conclude that the current recommended dietary allowances of folate and B6 need to be raised to increase a primary prevention of coronary heart disease among women.
COMMENT BY LEN SCARPINATO, DO
As a primary care physician reading the medical literature, I was always interested in why there was so much excitement about homocystinuria and its relation to coronary disease. After all, how often does anybody see homocystinuria? Drawing a blood homocysteine level was not exactly a common test either.
Rimm et al have done a great service to providers by pointing out that folate and B6 are important cofactors for the homocysteine metabolism. By looking at nurses in the Nurses' Health Study who took different amounts of folate and B6, they found that high amounts had reduced the incidence of coronary heart disease. Because pregnant women who take adequate folate have fewer neural tube defects, we are already recommending higher amounts of both vitamins in primary care preconception counseling.
What is most fascinating about Rimm et al's study is that the protective effect with folate and B6 intake holds true for all ages at all levels after correcting for the other significant risk factors such as smoking or diabetes.
By comparing alcohol consumption in nondrinkers, mild drinkers, and moderate drinkers, the authors found that the relative risk of coronary heart disease was also reduced by alcohol across all folate and B6 intake levels. (It should be noted that only moderate amounts of alcohol were analyzed.)
In a related editorial by McCully, animal and bench data regarding the homocysteine theory of arteriosclerosis is discussed. Also mentioned are dietary data showing reduction of folate and B6 because of the increase of white flour, white rice, sugar, fats, and oils in our diet.
McCully also notes that moderate alcohol intake decreases cardiovascular risk among women, reflecting other studies that have been done about alcohol intake, and theorizes why this appears to be so.
Recommending a multivitamin with folate and B6 intake above the recommended dietary allowance may, in fact, reduce coronary heart disease among women. This would be additive to the effect of mild-to-moderate alcohol consumption.
Recommendations
· There's no benefit in getting a homocysteine level measured-yet.
· 400 mcg of folate is twice the RDA, and probably what women need.
· Refined flours and their products-breads, pasta, polenta-are all to be fortified with folate this year.
· Women need 1.6 mg B6, and men need 2 mg; this is the RDA.
· Leafy greens, whole grains, fortified cereals, and beans are great folate and B6 sources.
Dr. Scarpinato is Associate Professor, Medical College of Wisconsin, and Program Director, Racine (WI) Family Practice Residency.
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