Caffeine exists naturally in tea, coffee, and cocoa.

The Beverage Guidance Panel found tea and coffee—preferably without creamer or sweetener—tied as the number-two healthiest beverages, second only to water.

Studies have shown many potential benefits to coffee consumption. For Hepatitis C patients, for example, drinking coffee may reduce DNA damage, increase the clearance of virus-infected cells, and slow the scarring process, which may help explain coffee’s apparent role in reducing liver disease progression risk.

Coffee consumption seems to be associated with about one-third lower risk for Parkinson’s, and giving Parkinson’s patients the caffeine equivalent of two daily cups of coffee significantly improved movement symptoms within three weeks. Caffeine appears to be the key ingredient, since tea also seems protective while decaf coffee doesn’t.

The National Institutes of Health–AARP Diet and Health Study found that people who drank six or more daily cups of coffee had a 10 to 15 percent lower mortality rate due to fewer deaths from heart disease, respiratory disease, stroke, injuries, accidents, diabetes, and infections. However, when a study looked at people 55 and younger, the opposite effect was found: Drinking more than six cups of coffee daily was found to increase the risk of death. The bottom line? Based on all the best studies to date, coffee consumption may be associated with a small reduction in mortality, on the order of a 3 percent lower risk of premature death for each cup of coffee consumed daily.

We used to think caffeine might increase the risk of atrial fibrillation, an irregular heart rhythm, but studies dispelled that myth. Moreover, “low-dose” caffeine, defined as drinking fewer than about six cups of coffee a day, may even have a protective effect on heart rhythm.

Coffee is not for everyone, though. People with glaucoma, epilepsy, and gastroesophageal reflux disease (GERD) may want to stay away from caffeinated coffee.

The information on this page has been compiled from Dr. Greger’s research. Sources for each video listed can be found by going to the video’s page and clicking on the Sources Cited tab. References may also be found at the back of his books.

Image Credit: Tyler Nix / Unsplash. This image has been modified.