PARIS - Vitamin B, while harmless, does not help prevent a repeat occurrence of strokes or heart attacks, according to a study released Wednesday.
The findings, based on first-ever clinical trials, suggest that vitamin B supplements should no longer be recommended for patients who have suffered severe vascular events, the researchers said.
Previous research has shown a link between an increase of amino acid in the blood -- a condition known as homocysteine -- and a higher risk of stroke and cardiovascular disease.
At the same time, other studies have shown that a daily dose of B vitamins can reduce abnormal amino acid levels.
What remained unknown was whether the supplements would also help cut the risk of repeat heart attacks or strokes, fatal or non-fatal.
To find out, an international consortium of doctors and scientists in 20 countries conducted a clinical trial with more than 8,000 patients who had recently had a serious heart or vascular problem.
Half the participants were given a daily dose of B vitamins -- a mix of folic acid, B6 and B12 -- while the other half swallowed lookalike placebos.
During a follow-up period that averaged 3.4 years, there was no statistically significant difference in the outcome: 15% of the vitamin B group experienced a major vascular event, compared to 17% for the control group.
At the same time, the vitamins did not cause any unwanted side effects.
The results were published in the British medical journal The Lancet.