The vitamin folic acid appears so valuable in preventing heart disease that clinical trials are urgently needed to confirm its life-saving potential, say researchers who analyzed 38 previous studies.
Folic acid, also called folate, reduces levels of an amino acid in the blood called homocysteine. Elevated levels of homocysteine are believed to damage the lining of blood-vessel walls, the researchers said.
“High homocysteine levels can cause arteriosclerosis - thickening of the arteries - which can result in heart attacks, strokes and premature death,” said principal investigator Shirley A.A. Beresford, an epidemiologist at the University of Washington in Seattle.
Beresford’s team combined and analyzed findings from 38 studies: 27 related homocysteine to arteriosclerosis and 11 explored the effects of folic acid on homocysteine levels.
The analysis found a higher risk of heart disease, blood-vessel disease and strokes among people with higher homocysteine levels. It also found higher levels of folic acid in the diet were associated with lower levels of homocysteine in the blood.
Up to 10 percent of deaths from coronary artery disease in U.S. men over 45 - about 35,000 deaths per year - are attributable to high homocysteine levels, the researchers estimated in today’s issue of The Journal of the American Medical Association.
“Clinical trials are urgently needed” to test whether dietary supplements of folic acid can reduce the incidence of blood-vessel disease in men and women, they said.
Other researchers previously have estimated that folic acid deficiencies could trigger 30 percent to 40 percent of the heart attacks and strokes suffered by American men each year. They also said more research is needed.
Folic acid is found in green leafy vegetables such as brussels sprouts, spinach and lettuce, and in many fruits, including apples and oranges. It is also available in most common multiple vitamin supplements.
The researchers listed three ways to increase folic acid in the American diet: adding two to three servings of fruits and vegetables a day; taking 400 micrograms of folic acid in supplements a day for people not already taking supplements; and fortifying the food supply, such as grains, with folic acid.
Citing Beresford’s study, the March of Dimes called for fortifying the nation’s food supply with folic acid, noting the well-established role the vitamin plays in prevention of serious birth defects of the brain and spine.
The current recommended daily allowance for folic acid is 200 micrograms a day for adult males and 180 micrograms for adult females.