Women may be able to reduce their risk of heart disease dramatically by taking three to four times the recommended daily allowance of two vitamins, folate and B-6, a study suggests.
A survey of about 80,000 nurses found that those who consumed far more than the recommended daily allowance were about half as likely to develop heart disease as those who took in less than the RDA, researchers said in Wednesday's Journal of the American Medical Association.The women were tracked for 14 years, beginning in 1980.
Participants in the study got their folate and vitamin B-6 mostly through multiple vitamins and cereals. They also consumed orange juice, green leafy vegetables, broccoli and eggs, all of which are excellent sources of the two vitamins.
The women on high-vitamin diets got an average of 700 micrograms a day of folate, compared with the recommended daily allowance of 180. They got an average of 4.6 milligrams of B-6 a day, compared with the recommended allowance of 1.6.
The American Heart Association said the findings agree with earlier research linking folate to men's risk of heart disease, and with other evidence that low levels of folate and vitamin B-6 increase the risk.
But Dr. Ronald M. Krauss, chairman of the heart association's nutrition committee, said the study should be interpreted cautiously because it depended on participants' recollections, as recorded on mailed questionnaires.
"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," he said.
However, the heart association believes daily folate intake should be 400 micrograms - above the recommended daily allowance.
Women who had one or two drinks a day in addition to lots of folate had the very lowest heart risks, said the researchers, led by Eric B. Rimm, an assistant professor of epidemiology and nutrition at Harvard School of Public Health.
Previous studies have linked moderate alcohol consumption with protection against heart disease.
Dr. Robert S. Rosenson, director of preventive cardiology at Rush-Presbyterian-St. Luke's Medical Center in Chicago, said plenty of evidence exists to encourage people to increase their intake of folate and vitamin B-6. Multiple vitamins are an easy and safe way to get both, he said.
"Even though the study was performed among women, we would expect similar findings with men," Rosenson said.
To get 700 micrograms of folate from food, a person would need to drink 61/2 cups of orange juice, eat 61/2 cups of raw chopped spinach, down nine cups of cooked broccoli or put away 29 large eggs.
To get 4.6 milligrams of vitamin B-6 would require 21 cups of orange juice, 161/2 cups of spinach, 33 cups of broccoli or 66 eggs.