With the publication of a very large, very long and very thorough scientific study of nearly 15,000 physicians published in the American medical journal JAMA, now documents that a daily multivitamin can prevent cancer.
Since 1999, a group of researchers from Harvard Medical School have followed 14,641 male doctors who were over 50 years at baseline. The investigation that has lasted approx. 12 years is a double-blind, placebo-controlled randomized study called the Physicians' Health Study II. It is a sequel to an earlier study in which they tested the hypothesis that vitamin C and vitamin E can prevent cardiovascular disease and cancer.
In the new study, the doctors were randomly assigned to receive either a daily multivitamin or a placebo tablet (dummy). The study showed that participants who received a daily multivitamin had 8% lower risk of getting cancer. The result was statistically significant. Another result, as demonstrated by this study is that the participants who had previously had cancer reduced their risk of dying from cancer by as much as 27%. This result was almost statistically significant (marginally).
For some, an 8% reduction in cancer mortality doesn't sound as much but translated into human lives and reduced health care costs, this figure is however of great importance. We should also take into account that the participants were American doctors who are likely to eat fairly healthy and varied. In addition, the multivitamin they took wasn't state of the art. The minerals were low-dose, inorganic and with low bioavailability, the vitamins were synthetic, only the content of vitamin B12 was extraordinarily high. It can not be excluded that a multivitamin in a better quality and/or a worse nourished target group would have given a much better result.
The jury is still out on this question.
Ref. Gaziano JM, et al. Multivitamins in the Prevention of Cancer in Men. The Physicians' Health Study II Randomized Controlled Trial. JAMA 2012. E-pub ahead of print.