Taking vitamin B or folic acid supplements does not prevent death in patients with heart disease, a study has shown.

The research is the latest to demonstrate that money spent on vitamins is often wasted. But it also suggests that fortifying bread with folic acid — a measure under consideration in Britain to prevent birth defects — would not have the additional advantage of protecting the nation's hearts.

Earlier work suggested that folic acid, either alone or combined with vitamins B12 and B6, reduced levels in the blood of homocysteine, an amino acid linked to a higher risk of heart attack. Proponents of vitamin supplements argued that lowering homocysteine levels through supplements would also reduce heart attacks. But the new study seems to disprove that.

While homocysteine levels did fall by 30 per cent after a year of treatment with folic acid and B12, there was no corresponding fall in heart attacks or strokes. In the group given folic acid, there was a decline in strokes, but an increase in cancer, though neither was significant.

The study, published in the Journal of the American Medical Association, involved more than 3,000 patients in two Norwegian hospitals between 1999 and 2006. Patients were given folic acid plus vitamin B12 and vitamin B6, or folic acid plus B12, B6 alone, or a placebo.

“Our findings do not support the use of B vitamins as secondary prevention in patients with coronary artery disease,” the team concluded.

Since folic acid fortification of flour began in the US and Canada ten years ago, deaths from stroke have fallen faster than in England and Wales, where fortification has been discussed endlessly but never implemented.

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