Some other benefits of coffee:
- It may reduce the risk of Alzheimer's and dementia. A caffeine habit in your 40s and 50s — three to five cups daily of the high-octane stuff, not decaf — seems to reduce by up to 70 percent the risk of Alzheimer's and dementia in your 70s, a 2009 University of Florida study found. Other studies have found that regular caffeine consumption may help slow the rate of cognitive decline in older adults.
- Coffee cuts suicide risk. A 2013 study by Harvard's School of Public Health found that those who drank two to three cups of caffeinated coffee a day cut their suicide risk by 45 percent — possibly because caffeine's stimulant effect helps boost people's moods.
- It lowers the risk of oral cancers. Older adults who drank four or more 8-ounce cups of regular coffee daily were half as likely to die of mouth and upper throat cancer. Decaf had a weaker effect, while no protection was found with tea.
- Coffee lowers the risk of stroke for older women. A 2009 U.S. study and a 2011 Swedish study both found that older women who drink more than a cup of caffeinated coffee daily have a 20 to 25 percent lower risk of stroke. A 2008 Swedish study found a similar result in older men.
Caffeine aside, coffee can be considered a healthy drink, judging by the preponderance of research suggesting it may protect against a variety of diseases and help us live longer. Keep in mind that these studies found an association between better health and coffee drinking, but researchers haven't yet found exactly what causes these benefits. It could be, for example, that coffee drinkers are more active and social. Or it could be that one of the more than 1,000 compounds that coffee naturally contains boosts our health. We don't know.
Some of the benefits you might be getting from your favorite cup of joe
- A longer life. The largest study to date, a joint project last year by the NIH's National Cancer Institute and AARP that followed 400,000 men and women ages 50 to 71 for more than 10 years, found that those who regularly drank coffee — either decaf or regular — had a lower risk of overall death than did nondrinkers. In particular, the coffee drinkers were less likely to die from heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections.
- Protection against a number of cancers. A 2010 overview of major studies on coffee consumption and cancer by the University of California, Los Angeles, found a strong protective association between coffee and endometrial (also called uterine) cancer and some protection from colon cancer; other recent studies have found that drinking coffee may protect against prostate and liver cancer.
- Reduced risk of type 2 diabetes. "Studies from around the world consistently show that high consumption of caffeinated or decaffeinated coffee is associated with low risk of type 2 diabetes," says Harvard's van Dam. That's true even though coffee may raise blood glucose levels in people with diabetes, at least on a short-term basis. His recommendation: Switch to decaf because some research shows it has less of an effect on blood sugar.
Bottom line: It's all about you. People have different reactions to caffeine. Some can drink six cups of coffee a day and feel fine, others need to switch to decaf or herbal tea by noon or they'll be up all night.
If you need to cut back on your caffeine consumption, do it slowly over several weeks, gradually adding more decaf to your regular brew. And don't forget: That big cup of soda and your favorite chocolate bar also contain caffeine.
Candy Sagon is an editor and health writer for AARP Media.