This week as I was making the final tweaks to The Cancer Chronicles before the manuscript goes into the copyediting stage, my eyes were drawn to a new study, widely reported in the press, about multivitamins and cancer. According to a double-blind, randomized controlled trial — the state of the art in epidemiology — taking a daily multivitamin lowered overall cancer risk by 8 percent.
At first that sounded great. A scientist quoted in the New York Times put it like this:
It is a small overall effect, but from a public health standpoint, it could be of great importance. Other than quitting smoking, there’s not much else out there that has shown it will reduce your cancer risk by nearly 10 percent.”
Alas, when you dig into the numbers, the results are less impressive. The subjects who participated in the study were physicians. For every thousand of them taking the daily vitamins there were 17 cancer cases per year. For those taking the placebo, there were 18.3 cases. Rounding and converting to more familiar terms, that it is a risk of 1.7 percent versus 1.8 percent.
As the excellent Health News Review website noted, that is “barely outside of the range that would be considered statistical noise.”
That didn’t keep the vitamin makers from quickly seizing upon the commercial opportunity. The day after the study was reported on the main page of the Times online, an ad appeared there for Centrum Silver. Clicking it led to a message on Centrum’s website:
BIG NEWS: Centrum Silver
was part of the recently published
landmark study evaluating the
long-term benefits of multivitamins!”
No further details were provided.
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