Drinking red wine does not increase the risk of developing prostate cancer, the most commonly diagnosed form of cancer among men living in the United States, according to a new study. However, the researchers found that red wine does not appear to offer any significant protection against the disease either.
"Red-wine consumption is unlikely to contribute appreciably to the etiology [or cause] of prostate cancer," wrote the authors of the study, a collaboration among researchers at Johns Hopkins Department of Epidemiology and the Harvard School of Public Health. Their work, which will be published in the April 1 issue of the International Journal of Cancer, may cast doubt on earlier findings on wine consumption and prostate cancer.
Prior research on prostate-cancer risk tended to focus on the impact of alcohol consumption overall, generally finding that the risk of cancer decreases along with consumption, but only up to moderate levels, and risk increases dramatically as consumption rises to heavy intake. But few studies examined wine separately from other beverages. Among those that did, some found that red wine had a protective effect: One study of cancer patients indicated that risk was reduced by half for some categories of red-wine drinkers but not for beer or spirits drinkers, and another lab study suggested that resveratrol, a chemical found in abundance in red wine, may help to turn off the genes associated with prostate-cancer development.
For the current study, the researchers pulled data on 45,433 of the more than 50,000 participants in the Health Professionals Follow-Up Study (HPFS), a Harvard-based examination of men's health and how diet relates to the incidence of serious illnesses. During the course of the HPFS, from 1986 to 2002, men working in several medical fields provided information on their eating, smoking and drinking habits, including the type of alcohol they preferred. During the study, 3,348 cases of prostate cancer were diagnosed among the 45,433 subjects chosen (those who were excluded had incomplete food and drink data or had been previously diagnosed with cancer).
The scientists found no "linear trend" when comparing the men's red-wine consumption habits and their rates of several forms of prostate cancer. The results were similar for beer drinkers and liquor drinkers, when their habits were examined separately.
Light consumption appeared to show a benefit since men who drank the smallest amounts of red wine had the lowest chances of developing prostate cancer. Those who drank one to three glasses per month had a 9 percent lower risk than all nondrinkers and other drinkers, those who had one glass per week had an 11 percent lower risk, and men who drank two to four glasses per week also had a 9 percent lower risk.
At higher consumption levels, the patterns of risk became inconsistent. Men who drank five to seven glasses per week showed a 12 percent increase in risk when compared to men who drink (but not red wine), as well as abstainers. But men who drank more than a glass a day showed only a 6 percent greater risk of prostate cancer.
Because the risk levels rose and fell as red-wine consumption increased, the researchers concluded that red-wine consumption has no correlation with prostate-cancer risk. "This pattern of association is difficult to explain biologically because protective levels of red-wine polyphenols, such as resveratrol, catechin and quercetin, would be much more likely to accumulate at higher levels of consumption than at levels as low as one to three glasses per month," the authors wrote.
Those three chemicals, all naturally occurring in red wine, have been the focus of numerous other studies that seek to unlock their potential health benefits. Resveratrol in particular has been the subject of many recent prominent reports on the chemical's potential for promising a longer, healthier life. Although less studied, cathechin, an antioxidant, shows potential as an anticancer agent. Scientists have also theorized that quercetin may be able to reduce the size of prostate-cancer cells.
"Based on the large number of epidemiologic studies conducted to date," said lead author Siobhan Sutcliffe, a post-doctoral fellow at the Department of Epidemiology at Johns Hopkins, "we do not recommend any changes in alcohol consumption for prostate-cancer prevention."