The warning is based on a survey of more than 100 studies on the association between homocysteine and cardiovascular disease by Dr. David Wald, a specialist registrar in cardiology at Southamptom General Hospital. Those studies show that "homocysteine is a cause of cardiovascular disease such as heart attack and stroke," Wald says. It is a view that differs from that of the American Heart Association and other authorities, who say that a cause-and-effect relationship between high homocysteine levels and heart risk has not yet been established.
Wald's survey, appearing in the Nov. 23 issue of the British Medical Journal, included two different kinds of studies. One of them looked at the incidence of cardiovascular disease in people with a genetic condition that causes them to have high homocysteine levels. The other looked at the incidence of artery problems in people with a normal genetic makeup but who had high homocysteine levels.
Both kinds of studies point to the same conclusion, Wald says -- reducing homocysteine levels by taking folic acid can reduce the risk of heart disease by 16 percent, of stroke by 24 percent, and of deep-vein blockages by 25 percent.
Wald's finding is a new contribution to a simmering debate about the role of homocysteine in heart disease. His view is in sharp contrast to the American Heart Association position. The association's Web site says, "We don't recommend widespread use of folic acid and B vitamin supplements to reduce the risk of heart disease and stroke." The heart association has just concluded its yearly scientific meeting and Darby Stitz, a spokeswoman, says none of the presentations at that meeting would lead to a change in that cautious approach.
Wrong, wrong, wrong, Wald says. He says that some of his earlier work indicates that taking 800 micrograms a day of folic acid will effectively reduce the risk caused by elevated levels of homocysteine. B vitamins can also help, he says, but "their effect is much more modest. Folic acid is far and away more effective."
Bread and other grain products are fortified with folic acid in the United States to reduce the risk of the birth defect spina bifida. Folic acid is also found in beans and peas, nuts, orange juice, green leafy vegetables, and liver. The folic acid levels in foods, even those that are fortified, are not enough to provide optimum protection against heart disease and stroke, Wald says, and he is recommending widespread use of supplements.
"All people stand to benefit from taking folic acid, but the people who will benefit the most are those who already have cardiovascular disease, those who have had a heart attack, a stroke, or deep vein thrombosis," Wald says. "And the risk increases after age 55, and we are advising all people to take folic acid after that age."
The Food and Drug Administration limits the amount of folic acid in nutritional supplements to 400 micrograms, the recommended daily allowance, so a doctor's prescription is necessary for preparations containing higher amounts.
Wald is aware of the Heart Association's doubting opinion. "This work may well help influence them" in making a change, he says.
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