B vitamins and folic acid don't cut the risk of further heart attacks

Mar 13 2006

Scientists have found that levels of the amino acid homocysteine may be high in people destined for a heart attack or stroke, and some studies in the past have linked homocysteine to an increased risk of heart disease.

But according to two new studies, it seems lowering homocysteine levels with B vitamins and folic acid does not reduce the risk of recurrent cardiovascular disease after a heart attack.

They both also found a harmful effect from the combined B vitamin treatment was suggested and say such treatment should not be recommended.

In one study, Eva Lonn of McMaster University in Ontario and her colleagues looked at people over 54 with diabetes or who were at risk of heart disease.

They gave 5,522 volunteers from 13 countries either a placebo or supplements of vitamin B6, B12 and folic acid.

In the group that received the supplements, homocysteine levels did drop but the risk of stroke, heart attack, or death from any heart-related cause did not.

It appears the rate of heart problems or stroke was 18.8 percent for volunteers getting the supplements and 19.8 percent for the placebo recipients.

Lonn's team found that even when they thought they might be seeing some benefit from folic acid or B vitamins, that was counteracted by an increased risk of another health problem.

The risk of stroke seem to fall by 25 percent for supplement recipients, but 24 percent more ended up being hospitalized for unstable angina, which can quickly lead to a heart attack.

The second smaller trial examined 3,749 Norwegian men and women who had had a heart attack up to seven days before and were given either supplements or a placebo to take.

The team led by Kaare Bonaa of the University of Tromso, also found no clear benefit after about three years of treatment.

Volunteers who took folic acid and the two B vitamins actually seemed to face a higher risk of a stroke, heart attack or death from any heart-related cause.

Bonaa's team also concluded that such therapy may be harmful to people who have just survived a heart attack or had a stent implanted to prevent another heart attack and should therefore not be recommended.

Lonn's team says that because homocysteine levels are related to kidney problems, smoking, high blood pressure and other factors that increase the risk of heart disease, homocysteine may be a marker rather than a cause of vascular disease.