Two new studies have found that folic acid and B-vitamin supplements do not reduce the likelihood of heart attack and stroke in high-risk people.
The studies, published in yesterday’s issue of the New England Journal of Medicine, dispute speculations that a daily vitamin regimen high in concentrations of Vitamins B-6 and B-12 plus folic acid, a B-complex vitamin, offered such benefits by reducing blood levels of amino acids known as homocysteine. For decades, some doctors have held that high homocysteine levels are a dangerous risk factor for cardiovascular disease.
But the new research, conducted by separate Canadian teams involving more than 9,000 patients with cardiovascular disease found that lowering homocysteine levels through vitamin therapy did not decrease the risk of future problems in patients who have had previous heart attacks or other vascular disorders.
“Treatment with B vitamins did not lower the risk of recurrent cardiovascular disease after acute myocardial infarction [heart attack]. A harmful effect from combined B-vitamin treatment was suggested. Such treatment should, therefore, not be recommended,” Dr. Kaare Harald Bonaa and fellow investigators at the University of Toronto’s Institute of Medicine wrote in one report.
“Contrary to expectations, there was a trend toward an increased rate of [cardiovascular] events among patients receiving B vitamins, in particular, the combination of folic acid, Vitamin B-6 and Vitamin B-12,” said the researchers, whose study examined more than 3,700 Norwegian men and women, who had had heart attacks within a week of entering the trial.
Patients were followed for up to 3 years, and they experienced an overall 27 percent drop in homocysteine levels, but not their risk for future cardiovascular disease for death, the authors of the report said.
The second study, sponsored by the Canadian Institutes of Health Research and led by researchers at McMaster University in Hamilton, Ontario, examined approximately 5,500 men and women, 55 or older, who had either experienced heart disease or were diabetics.
Participants in that trial were randomly assigned to take either a daily regimen of folic acid and B vitamins or placebo and were followed for an average of five years.
The results found that 519 patients given the extra folic acid and B vitamins, or nearly 19 percent, either died of cardiovascular causes or had a heart attack or stroke. That compared with 547 patients, or nearly 20 percent, who were on placebo. The difference was not statistically significant.
“Clearly, there was no benefit” from these vitamin supplements, Dr. Robert Eckel, president of the American Heart Association, said yesterday in a telephone interview. “Yet, a significant minority of people who have cardiovascular disease or who consider themselves at risk for it take these vitamin supplements,” thinking they may help.