Yesterday, there were a lot of stories about a new AICR-supported study on coffee and prostate cancer. The study found that drinking six or more cups of coffee regularly reduced the risk of overall prostate cancer by 18 percent, and lethal prostate cancer by 60 percent.
The study was published in the Journal of the National Cancer Institute, and you can read more about it in yesterday’s post.
Julie Kasperzyk, PhD., an epidemiologist at the Harvard School of Public Health was one of the study authors. Julie’s research is partially supported by AICR. Here, she answers a few questions about the work.
Q: There have been other studies looking at coffee-prostate cancer risk that have found coffee does not have an effect, what is unique about this new study?
A: This is the first large, prospective study to look specifically at advanced and lethal prostate cancer. This is especially important because prostate cancer is such a heterogeneous disease, and we need to understand risk factors associated with more aggressive forms of the disease. In addition, most previous studies of coffee and prostate cancer are older and didn’t use modern methods of adjusting for possible confounders.
Q: Such as?
A: Smoking is particularly important to adjust for because it is positively associated with coffee intake, and it’s negative health effects can obscure any beneficial associations for coffee.
Q: Can you state the main message of your study? (6 cups a day is a lot of coffee! Is it fair to say that the study is not recommending men start drinking that much?)
A: We don’t recommend that anyone change their habits based on the result of this or any single study. I think the main message is that this adds to increasing evidence that coffee may have positive effects on long-term health, and at least does not seem to be harmful for long-term health.
Coffee has been consistently associated with a lower risk of type 2 diabetes, liver cancer, Parkinson’s disease, and gallstones. Prospective studies have also not found associations with increased risk of cardiovascular disease, which had been hypothesized. So there’s no evidence, from prostate cancer or other health outcomes, that suggests that men need to cut down on their coffee intake, or feel guilty about their coffee intake!
Additionally, regarding the amounts of coffee, note that we did see an inverse association between coffee intake and lethal prostate cancer even among men who drank 1-3 cups per day (30% lower risk). Also, the results were similar for both regular and decaf coffee, which is useful for those who prefer not to take in a lot of caffeine.
Q: What other dietary factors are you investigating that could potentially lower the risk of prostate cancer?
A: Most of my current studies address diet in relation to prostate cancer survival. Our group is investigating whether high intake of fish (with omega-3 fatty acids) and rye bread (with phytoestrogens) is inversely associated with prostate cancer mortality in a Swedish study of prostate cancer survivors. We previously showed in this Swedish cohort that high vitamin B6 intake and high zinc intake were associated with a reduction in prostate cancer-specific mortality.