Yesterday was a good morning to wake up and smell the coffee. The New England Journal of Medicine published outcomes from the the NIH-AARP Diet and Health Study, which found drinking coffee was associated with living longer in both men and women. This is not only the largest study ever to look into this question, NIH-AARP is one of the largest prospective (forward-looking) studies ever performed on nutrition and disease, following more than a half million people for a dozen years.
This follows on the heels of an editorial published last month in the American Journal of Clinical Nutrition entitled "Coffee Consumption and Risk of Chronic Diseases: Changing Our Views," which reviewed the growing evidence that for most people, the benefits of drinking coffee likely outweigh the risks. Though the study published today found no significant relationship between coffee consumption and cancer, a recent analysis of the best studies published to date suggests coffee consumption may lead to a modest reduction in overall cancer incidence. Each daily cup o' joe was associated with about a 3% reduced risk of cancers, especially bladder, breast, mouth, colorectal, endometrial, esophageal, liver, leukemic, pancreatic, and prostate cancers.
One of the reasons it's so difficult to study the relationship between diet and disease is because many dietary behaviors are associated with non-dietary behaviors. For example, people who drink coffee may be more likely to have a cigarette in the other hand, which can lead to spurious conclusions. When these considerations are factored in, though, the best available evidence suggests that coffee consumption is generally health-promoting.