Oslo: A Norwegian study of around 4,000 heart attack survivors who were given high doses of vitamins B6, B12 and folic acid increased their risk of a second attack or stroke, it has been found.
B vitamins are one of the most popular health products on the market and taken by many to boost health and immune system. They are also thought to be helpful with premenstrual syndrome and other female problems. The Bs are also recommended to reduce homocysteine a substance found in the blood and linked to a number of health problems including heart disease, stroke and Alzheimer’s disease.
But the Norwegian study found no clear benefit, even after three years of treatment. Volunteers who took all three supplements faced a considerably higher risk of further heart attacks or strokes.
For those who took the full trio of supplements, the risk was 22 per cent higher, compared to a rise of up to 14 per cent for those who took vitamin B6 alone or a combination of B12 and folic acid.
Professor Kaare Harald Bonaa, of the University of Tromso, told a medical conference in Atlanta that some doctors were treating patients with B vitamins despite a paucity of supporting evidence.
‘Such therapy may even be harmful and should not be recommended,’ he said.
His conclusions were strengthened by a second study on the B vitamins also presented at the conference. A team of Canadian researchers gave more than 5,500 volunteers from 13 countries either a placebo or supplements of vitamin B6, B12 and folic acid.
The supplements in both studies were in doses at least double that available over the counter.
Although the vitamins in the Canadian study reduced levels of homocysteine, they did not cut the risk of heart attacks and strokes. In some cases, the supplements seemed to aggravate other health problems, lead researcher Dr Eva Lonn, of McMaster University in Ontario, said. Homocysteine is an amino acid produced by the body and found in the blood.
It was thought it could cause fatal blockages in the heart and brain by damaging the lining of the arteries and making blood more likely to clot.
But following the latest research – which will appear in the New England Journal of Medicine later this week – scientists believe it may be a sign, rather than a cause, of heart disease.