Folic acid fights heart risk factor.

High concentrations of the amino acid homocysteine in the blood may join the ranks of high cholesterol, obesity, and smoking as risk factors for heart attacks, say researchers from the University of Utah School of Medicine in Salt Lake City.

But the news isn't all bad. The scientists also discovered that the B vitamin folic acid--commonly found in green leafy vegetables, fruits, and legumes--appears to lower homocysteine in the blood and may protect the heart.

"We had found before that high homocysteine is associated with early coronary artery disease and plays a role in 12 percent of all early familial cases," says study investigator Paul N. Hopkins. "In this study, we found that the strongest indicator of homocysteine levels was folic acid."

Homocysteine is derived from methionine, another amino acid. Folic acid exerts its protective effect by helping an enzyme convert homocysteine back into methionine. Previous animal research found that high homocysteine concentrations damage the interior layer of blood vessels. In trying to repair the damage, the vessels clog.

The Utah team studied 120 men and 42 women who had suffered a heart attack, undergone angioplasty, or had coronary bypass surgery--before the age of 55, if they were men, and before age 65, if they were women. All participants also had siblings who suffered from early coronary artery disease. Eighty-five men and 70 women who didn't suffer from coronary artery disease served as a comparison group.

Among participants with the highest homocysteine, men were 14 times more likely to have heart disease, and women 13 times more likely, than people with the lowest concentrations. The researchers report their findings in the September Arteriosclerosis, Thrombosis and Vascular Biology.

When the researchers evaluated folic acid circulating in the blood, they found that the higher the folic acid concentration, the lower the homocysteine concentration. "This finding suggests that if you would raise the folic acid levels among coronary artery disease patients you could almost eliminate homocysteine levels as a risk factor," says Hopkins.

Hopkins notes that because processing and cooking destroy folic acid, it is the most commonly deficient vitamin in U.S. diets. However, the exact amount required has been a bone of contention. Before 1989, the Food and Nutrition Board of the National Academy of Sciences recommended that each adult get 400 micrograms ([mu]g) of folic acid per day. But in 1989, the board cut that amount in half (SN: 10/28/89, p.277). Other researchers have found that homocysteine increases when people drop below 400 [mu]g per day, says Hopkins.

University of Washington researchers combined the results of 38 studies of homocysteine and reported in the Oct. 4 Journal of the American Medical Association that 10 percent of the nation's heart disease results from high homocysteine. The group recommends that clinical trials be conducted to test folic acid's ability to stop heart disease.

In response to the recent findings, the chairman of the American Heart Association's nutrition committee, Ronald Krauss, says there is no direct evidence that folic acid deficiency leads to heart disease.

However, the Council for Responsible Nutrition, a lobbying association for the nutritional supplement industry, intends to petition the Food and Drug Administration to label folic acid as a heart disease preventive; it is already known to prevent certain birth defects. The group also plans to urge NAS to return the recommended allowance to 400 [mu]g.

Hopkins maintains that appropriate amounts can be achieved through a healthful diet but that taking vitamins at the recommended levels is an appropriate alternative. He hopes that a clinical trial can determine appropriate folic acid concentrations to prevent heart disease.