A multivitamin tablet a day will not keep the doctor away, according to the latest study to question the value of supplements.

Taking the pills for a year appears to have no effect on over-65s, say Aberdeen University researchers. At least a quarter of older people are thought to take nutritional supplements.

Researchers divided 910 men and women who did not normally take supplements into two groups - one taking a combined multivitamin and multimineral tablet each day, the other dummy pills.

They report in today's British Medical Journal that 12 months later there had been no significant difference in visits to GPs, reported infections or quality of life.

The study focused on people living at home rather than in residential care in the Grampian region of Scotland, and aimed to resolve uncertainty about whether supplements could help protect people at risk of infection.

The authors admit that intakes in the daily supplements may not have been high enough to affect the immune system. It also remains to be settled whether older people living in care would benefit from a vitamin regime, since some studies have suggested supplementation may improve their immune system.

However several other studies have now cast doubts on the efficacy of vitamin supplements for most people.

In an accompanying editorial Salah Gariballa, clinical senior lecturer at Sheffield University, says: "Evidence is increasing for a holistic approach to improving diet rather than focusing too closely on the effects of individual nutrients on risk factors and preventing disease.

"If combined with physical activity, which can increase appetite and enable a diet of marginal nutrient density to become adequate, a better diet can make a substantial impact on population health, particularly of older people."