"In this large-scale, randomized, placebo-controlled trial among middle-aged and older men, long-term daily multivitamin use had a modest but statistically significant reduction in the primary end point of total cancer after more than a decade of treatment and follow-up."
"In this large-scale randomized trial of 14 641 middle-aged and older men, a daily multivitamin supplement significantly but modestly reduced the risk of total cancer during a mean of 11 years of treatment and follow-up. Although the main reason to take multivitamins is to prevent nutritional deficiency, these data provide support for the potential use of multivitamin supplements in the prevention of cancer in middle-aged and older men."
Multivitamins in the Prevention of Cancer in Men:
The Physicians' Health Study II Randomized Controlled Trial
JAMA. 2012;():1-10. doi:10.1001/jama.2012.14641.