US researchers have claimed that taking a daily multivitamin pill may lower the risk of developing cancer in men.

Their study followed nearly 15,000 men, aged over 50, for more than a decade.

The findings, published in the Journal of the American Medical Association, reported a small reduction in cancer cases in men taking vitamin pills.

But experts warned that other studies had found the opposite effect and that eating a diet packed with fruit and vegetables was a safer bet.

Vitamin supplements are recommended for some groups of people, such as vitamin D in the over 65s.

However, the benefits of multivitamins on general health have been mixed. Some studies suggest they cause more harm than good when taken by healthy people while others have shown no benefit in cancer.

Doctors at the Brigham and Women’s Hospital and Harvard Medical School analyzed data from men who were given either a multivitamin or a sugar pill every day.

There were 17 cancers per 1,000 people taking multivitamins per year compared with 18 cancers per 1,000 people taking the dummy pills per year.

One of the researchers, Dr. Howard Sesso said: “Many studies have suggested that eating a nutritious diet may reduce a man’s risk of developing cancer.

“Now we know that taking a daily multivitamin, in addition to addressing vitamin and mineral deficiencies, may also be considered in the prevention of cancer in middle-aged and older men.”

The researchers do not know if a similar effect would be seen in women or in younger men.