Men who eat multivitamins more than seven times a week (heavy users) double their chance of developing a deadly prostate cancer to be. An insanely huge diet and health study, involving 300,000 men, has found a link between fatal prostate cancer and heavy use of vitamin supplements.

Government scientists turned to a study tracking the diet and health of almost 300,000 men. 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.

Heavy multivitamin users were almost twice as likely to get fatal prostate cancer as men who never took the pills, concludes the study in Wednesday’s Journal of the National Cancer Institute.

Here’s the twist: Overall, the researchers found no link between multivitamin use and early-stage prostate cancer.

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

Source: Vitamins tied to prostate cancer