Study: Multivitamins Reduce Cancer Among Men

| Thu Oct. 18, 2012 12:01 PM EDT

Have you been taking your multivitamins? Me neither. But a new study suggests that multivitamins can reduce the long-term risk of cancer in men. Aaron Carroll runs it down for us:

Here’s the gist. They rounded up more than 14,000 doctors 50 years or older in 1997 and randomized them to get a daily multivitamin or placebo, and then they followed them through June of 2011. Otherwise, they did nothing to these participants, so there’s every reason to believe they were otherwise treated similarly. They wanted to see if the two groups developed cancer at different rates. They did.

Men who took a daily multivitamin had a statistically significant lower rate of cancer than those who took the placebo (17.0 versus 18.3 events per 1000 person-years)....This was an extremely large study, well done, with amazing follow-up. You can’t dismiss it easily.

The chart below shows the difference in cancer rates for men with and without a baseline history of cancer. Technically, there was no statistically significant difference between the cancer and non-cancer groups because the sample size of the cancer group was fairly small. But statistics be damned. It sure looks to me that you should really think hard about taking a multivitamin if you have a previous history of cancer. The adjusted hazard ratio in this group was 27% lower than the placebo group. In the non-cancer group it was only 6% lower.

Also: if you have no parental history of cancer, multivitamins had a big effect. The hazard ratio in this group was 14% lower than in the placebo group.

As Aaron says, "Multivitamins are cheap. You can buy them by the barrel at Costco. There are few harms or side effects." In other words, there's probably no reason not to take them, and there might be a big benefit. The full study is here.