"Multivitamins = Increased Prostate Cancer Risk" - Study

Vitamins are generally associated with better health and life, but heavy dosage of these can put men at a significant risk of prostate cancer, says a recent study.

According to the study conducted by US researchers at the National Cancer Institute (NCI), overdosing on vitamins can increase men’s risk of dying from prostate cancer. Men who took multivitamins more than seven times a week, researchers considered them “heavy multivitamin users”.

To validate their findings, Dr Karia Lawson and colleagues from the NCI in Bethesda, Maryland investigated the impact of vitamin use on cancer in 295,344 men enrolled in a national diet and health study. Of the total participants, about a third reported taking a daily multivitamin, and 5 percent were heavy users, consuming the pills more than seven times a week.

After tracking the diet and health of the study subjects for more than five years, the researchers found men who exceeded the recommended dose, taking more than seven multivitamins a week, increased the risk of the deadliest forms of prostate cancer by about 30 percent.

Within five years of the study’s start, a total of 10,241 of the men studied were diagnosed with prostate cancer. Of these, 8,765 had localised cancers and 1,476 advanced cancers. And, during a separate follow-up period of six years, 179 men died from the disease.

Heavy multivitamin users were almost twice as likely to get fatal prostate cancer as men who never took the pills, the study concludes.

However, the researchers did not find a link between high-dose multivitamins and the early stage prostate cancer. The link was strongest for men with a family history of the disease, and who also took selenium, beta-carotene or zinc supplements, according to the study, published Wednesday in the Journal of the National Cancer Institute.

No similar correlation was seen between heavy multivitamin consumption and localized 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.

The government researchers speculate mega-dose vitamins perhaps not have much of an effect until a tumor appears, and then it could stimulate its growth.

In their report, Dr Lawson wrote: “Because multivitamin supplements consist of a combination of several vitamins, and men using high levels of multivitamins were also more likely to take a variety of individual supplements, we were unable to identify or quantify individual components responsible for the associations that we observed.”

Although, the newest study suggest a markedly increased prostate cancer risk among men using multivitamin supplements, still more rigorous research is needed, Dr Lawson said.

For decades people have been taking vitamin supplements for health benefits. However, NCI says that there is little evidence to suggest any advantage to multivitamin use.

“Millions of Americans take multivitamins because of a belief in their potential health benefits, even though there is limited scientific evidence that they prevent chronic disease,” NCI said in a statement.

In February this year, scientists from Copenhagen University Hospital in Denmark found that vitamin A, C and vitamin E and beta carotene taken singly or with other supplements don’t provide long-life benefits rather "significantly increase mortality". The study linked the supplements with overall 5 per cent increased risk of mortality.