Heres news that might settle the nerves of heavy coffee drinkers: Two new studies suggest that high coffee consumption might be linked to reduced risks of the most aggressive form of breast cancer in women and lethal prostate cancer in men.
Some research has hinted at a protective benefit for coffee against breast cancer, but a 2010 analysis of more than 500 studies of coffee and cancer failed to support such a conclusion. Now scientists at Swedens Karolinska Institute may have found an explanation: Coffee may significantly reduce the risk of only one type of breast cancer-the most aggressive subtype, called ER-negative. This is a non-hormone responsive subtype, as opposed to the other major subtype, ER-positive, a hormone-responsive estrogen receptor form.
Jingmei Li, PhD, and colleagues drew on data from a population-based study of 2,818 Swedish breast-cancer patients, ages 50 to 74, and 3,111 healthy postmenopausal women matched by age. Overall, researchers found no evidence to support fears that coffee might increase breast-cancer risk; instead, coffee consumption was associated with a modest reduction in total risk.
But when Li and colleagues focused on ER-negative cancer, women who drank five or more cups of coffee a day were at 57% less risk compared to those drinking less than a cup a day. Calling the connection quite striking, researchers noted that it remained even after adjusting for known cancer risk factors. They also validated the findings in a similar German study of more than 10,000 women, although with less significant results.
The research was not designed to prove cause and effect, and scientists say they wouldnt recommend boosting coffee consumption until the biological mechanism for any protection is understood. Theyre now working on a new study to answer those questions.
Men who love their coffee, meanwhile, can perk up at a new study from the Harvard School of Public Health. Kathryn M. Wilson, ScD, and colleagues looked at data on 47,911 men in the Health Professionals Follow-Up Study who reported their coffee consumption every four years from 1986 to 2008. During the study period, 5,035 cases of prostate cancer were reported, including 642 fatal or metastatic cases.
Men who consumed the most coffee-six or more cups daily-had nearly a 20% lower risk of developing any form of prostate cancer. The inverse association with coffee was even stronger for aggressive prostate cancer: Men who drank the most coffee had a 60% lower risk of developing lethal prostate cancer, and even drinking one to three cups of coffee per day was associated with a 30% lower risk.
At present we lack an understanding of risk factors that can be changed or controlled to lower the risk of lethal prostate cancer, Wilson commented. If our findings are validated, coffee could represent one modifiable factor that may lower the risk of developing the most harmful form of prostate cancer.
The reductions in risk were seen whether the men drank decaffeinated or regular coffee. So researchers suggested that compounds in coffee besides caffeine, such as antioxidant polyphenols, appear to be responsible.
Jeffrey B. Blumberg, PhD, director of Tufts HNRCA Antioxidants Research Laboratory, says such a protective benefit from coffee polyphenols is plausible. Polyphenols from fruits and vegetables have been associated with chemoprevention in both experimental studies and observational cohorts, he points out. That polyphenols in coffee, such as chlorogenic acid, could have a similar action is coherent with our knowledge about polyphenols.
Blumberg cautions, though, against assuming that all such compounds in this diverse array of antioxidants act in the same way or are equally effective.
|Coffee Not Linked to High Blood Pressure
That morning cup of coffee-or three or five cups-probably doesnt boost your long-term blood pressure as it perks you up. A new review of six previous studies totaling more than 170,000 participants concludes that, overall, theres no difference in hypertension risk between those who drink the most coffee and people drinking little or none. Coffee consumption in the studies ranged from less than a cup a day to more than five, and participants were followed for up to 33 years. The analysis did find a slightly higher risk among people drinking one to three cups of coffee daily, which puzzled researchers. And scientists cautioned that coffee might affect people differently depending on genetic factors.
For coffee lovers already suffering high blood pressure, another new study says a few cups a day are OK for well-managed hypertension. In research presented at the American Society of Hypertension conference, an analysis of five prior trials found that, while coffee does boost blood pressure, the one- to three-hour spike is temporary. No long-term effect on blood pressure was found. The results do suggest, however, that you keep in mind your recent coffee consumption when getting your BP checked.
TO LEARN MORE: American Journal of Clinical Nutrition, June 2011; abstract at dx.doi.org/10.3945/ ajcn.110.004044.