"We should learn the lessons from the randomized trials in Finland and the United States testing the seemingly compelling hypothesis that beta-carotene would reduce the lung cancer and cardiovascular disease incident rates. Those trials found that participants taking this vitamin instead had increased lung cancer incidence and cardiovascular disease mortality rates. Associations should not be described as effects." The Cleveland study, part of a European Concerted Action Project, examined 750 people with atherosclerosis or blockages in the blood vessels of the heart, brain and leg. The individuals were younger than 60 and about 200 of them were women. The study also included 800 healthy individuals of similar age and sex.
The project, which involved 19 centers in nine European countries, showed that people with atherosclerosis or blockages who had lower folic acid levels may also be more likely to have heart disease and stroke.
The association of vitamin B-6 and folic acid deficiency with heart disease and stroke may be connected to their effects on homocysteine metabolism. Homocysteine, a natural byproduct of the body's metabolism of meat and dairy foods, has been shown in earlier research to damage the lining of blood vessels.
Low levels of vitamin B-6 can lead to elevations in homocysteine. Regarding the surprising finding about normal levels of homocysteine in people with low B-6 and increased risk for cardiovascular disease, Robinson says, "There's something else going on that vitamin B-6 is doing. Even if you take homocysteine levels into account, low B-6 marks out people with heart disease and stroke." That "something" remains a mystery, but in other studies animals given a vitamin B-6-deficient diet have developed disease, he says.
The mechanism for the blood vessel damage is unclear, although other research has suggested that vitamin B-6 deficiency, in
Contact: Carol Bullock
American Heart Association