Dec. 11, 2000 -- High levels of the amino acid homocysteine have been shown to cause harm by increasing clot formation in the blood vessels in the heart. Recent evidence suggests that vitamins B-12 and folic acid may help prevent heart disease by lowering the body's levels of homocysteine. But until clinical trials are completed in about four years, the jury is still out about not only the damaging effects of the amino acid but also the vitamins' potential benefit in preventing heart disease.
High levels of the harmful amino acid homocysteine may account for up to 10% of deaths from heart disease in men and 6% in women. But "may" is the operative word, and until the verdict is in, the authors of a study published in this week's Archives of Internal Medicine say using folic acid and vitamin B-12 to treat middle-aged people with high levels of homocysteine "may be a prudent option."
The researchers, from the University of Michigan in Ann Arbor, calculated whether it makes more sense to give multivitamins to everyone, or just to people with elevated homocysteine levels. They looked at patients taking 400 mcg of folic acid and 500 mcg of vitamin B-12 daily, and found that it would be most cost-effective if the supplements go to those whose blood tests show elevated levels of homocysteine.
Of course, those who are not necessarily "at-risk" can also benefit from the vitamins. Study author Brahmajee Nallamothu, MD, tells WebMD consumers should try to get enough folic acid and vitamin B-12 through their diets. Nallamothu is a fellow in the division of cardiovascular diseases at the University of Michigan Health System.
Clinical nutrition consultant Linda Rodriguez says the best food sources of folic acid are citrus fruits, tomatoes, vegetables, whole grain and fortified grain products, beans and lentils. Major sources of B-12 include meat, poultry, fish and dairy products. Rodriguez also recommends vitamin B-6, B-12 and folic acid supplements because of their probable effect on homocysteine levels and cardiac disease. Rodriguez is in private practice in Carmel, Calif.
But Robert H. Eckel, MD, tells WebMD, "we don't know enough yet" to recommend these vitamin supplements to prevent heart disease. He notes that in some people elevated homocysteine levels may be a sign of other significant health problem such as kidney disease.
"We think a healthy diet, including fruits, vegetables, whole grains, and fish, is really where people should be. In the opinion of the American Heart Association, vitamin supplements should not be encouraged until they are proven beneficial," he says. Eckel is the chair of the American Heart Association committee on nutrition and a professor of medicine and physiology at the University of Colorado Health Sciences Center in Denver.
Like Eckel, Charles Hennekens, MD, a visiting professor of medicine, epidemiology, and public health at the University of Miami (Fla.) School of Medicine, emphasizes that we are sure lifestyle changes can be effective in reducing heart disease risk, but the use of vitamin supplements is still under consideration. "We know people with higher homocysteine levels tend to have higher risk of heart disease. We also know if you give people folic acid it reduces homocysteine levels. Observational studies suggest that people who are taking folic acid have lower levels of heart disease but we don't have the evidence. Studies are needed to definitely show whether folic acid supplements do in fact lower heart disease risk."
Meanwhile, he also strongly recommends eating a diet rich in fruits, vegetables, and whole grains.