BEIJING, May 16 (Xinhuanet) -- Men who take too many vitamins may increase the risk of dying from prostate cancer, according to researchers at the U.S. National Cancer Institute Wednesday.

    The researchers found that men who exceeded the recommended dose -- taking more than seven multivitamins a week -- increased the risk of advanced cancer by about 30 percent.

    The study tracked the diet and health of almost 300,000 men over five years to see if there was a link between multivitamin use and prostate cancer.

    About a third reported taking a daily multivitamin, and 5 percent were heavy users, swallowing the pills more than seven times a week.

    Within five years of the study's start, 10,241 men had been diagnosed with prostate cancer. Some 1,476 had advanced cancer; 179 died

    Overall, the researchers found no link between multivitamin use and early-stage prostate cancer.

    "We didn't see any relationship with overall prostate cancer," said Dr. Michael Leitzmann, a National Cancer Institute investigator who worked on the study.

    He said the increased risk from overuse of multivitamins was linked to more aggressive cancer that has spread beyond the prostate gland or cancer that proved fatal.

    The researchers speculated that perhaps high-dose vitamins had little effect until a tumor appeared, and then could spur its growth.

    While similar but smaller studies have suggested a link too, more rigorous research is needed, cautioned the researchers. This newest study involved men who voluntarily took vitamins, and those most at risk -- perhaps because they had a family history of the disease - may have been more likely to take the pills in hopes of avoiding their fate.

    (Agencies)