Swallowing a daily multivitamin can reduce the risk of cancer by at least eight per cent in middle-aged and older men and appears to have no dangerous side effects, according to the first large-scale, randomised study on the subject.

Landmark study suggests balanced vitamin intake better than high doses

The protective effect of the daily pill was described as “modest” by the trial investig-ators, who emphasised that the primary use of vitamins was to prevent nutritional deficiencies. The findings were published in the Journal of the American Medical Association and presented at a meeting of the American Association for Cancer Research in Anaheim, California.

“This is indeed a landmark study,” said Cory Abate-Shen, a professor of urological oncology at Columbia University Medical Centre, who was not involved in the trial. “It suggests that a balanced multivitamin approach is probably more beneficial than increasing to high levels of any one vitamin.”

About half of US adults take at least one daily dietary supplement – the most popular being a multivitamin, according to the US Centres for Disease Control and Prevention.

The US Physicians Health Study II included nearly 50,000 male participants aged 50 and older and spanned more than 10 years. They were randomly assigned to a multivitamin – Pfizer’s Centrum Silver – or a placebo.

The research was sponsored by the National Institutes of Health. Several previous studies, many relying on self-reported use of specific vitamins or supplements, have generated mixed results in terms of cancer outcomes.

“There have been some other trials that have tested combinations, often at high doses, of certain vitamins and minerals,” said Howard Sesso, one of the study’s authors and an associate epidemiologist at Brigham and Women’s Hospital in Boston. “Our trial took a very commonly-used multivitamin that has basically low levels of all the essential vitamins and minerals.”

The findings of the study suggest that the biggest health benefit may come from a broad combination of dietary supplements, he added.

Last year, the questionnaire-based Iowa Women’s Health Study found that older women who take multivitamins have slightly-increased death rates compared to those who don’t.

A study examining whether vitamin E and selenium could reduce the risk of prostate cancer was stopped prematurely in 2008 after men taking 400 international units (IU) of the vitamin showed an increased risk of developing the cancer. Over-the-counter multivitamins typically contain 15 to 25 IU of vitamin E.

The newly-released Physicians Health Study showed an eight per cent reduction in total cancer occurrence for participants taking a multivitamin, but no benefit was seen for rates of prostate cancer, the most common cancer seen among the participants in the study.

Excluding prostate cancer, researchers found about a 12 per cent reduction in overall cancer occurrence and said the protect-ive effect seemed to be greater in people who had previously battled cancer.They also saw a 12 per cent reduction in the risk of death from cancer, although those findings also were not statistically significant in themselves.

Researchers said they planned to continue to follow the study group to monitor the effect of vitamin intake over time, and said additional studies would be needed to see if there were similar benefits for women or younger men.

“It doesn’t seem like there is any particular risk associated with taking a vitamin and there might be a small benefit,” said David Weinberg, chief of the department of medicine at Fox Chase Cancer Centre in Philadelphia. He was not involved in the study.

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