Participants received a daily multivitamin or equivalent placebo. The primary measured outcome for the study was total cancer (excluding nonmelanoma skin cancer), with prostate, colorectal, and other site-specific cancers among the secondary end points. PHS II participants were followed for an average of 11.2 years.
Analysis of the data indicated that men taking a multivitamin had a modest 8 percent reduction in total cancer incidence. Men taking a multivitamin had a similar reduction in total epithelial cell cancer. Approximately half of all incident cancers were prostate cancer, many of which were early stage. The researchers found no effect of a multivitamin on prostate cancer, whereas a multivitamin significantly reduced the risk of total cancer excluding prostate cancer. There were no statistically significant reductions in individual site-specific cancers, including colorectal, lung, and bladder cancer, or in cancer mortality. [emphasis mine]
I wonder what value there is in this particular finding from the PHS…
At least the authors had the honesty to admit, "The role of a food-focused cancer prevention strategy such as targeted fruit and vegetable intake remains promising but unproven given the inconsistent epidemiologic evidence and lack of definitive trial data."
There is, after all, NO evidence in favour of "5 a day" — that was a marketing slogan. It started as the “National five-a-day for better health” program in 1991 as a public-private partnership between the National Cancer Institute (NCI) and the Produce for Better Health Foundation. The programme started in California, the sunshine state, and has become the world’s largest public-private nutrition education initiative. [Source, Zoe Harcombe's blog: http://www.zoeharcombe.com/2012/03/five-a-day-the-truth/]
And what about corrections for known associations with cancer, such as excessively high blood sugar, excessive omega-6 and other PUFAs, and wheat consumption?