All Things in Moderation
As the saying goes, all things are OK in moderation, and that includes coffee. Moderate doses of caffeine, equal to about 200 to 300 milligrams per day, is safe for adults, according to Michigan State University. However, even up to six cups a day hasn’t been proved to be harmful, Harvard Medical School states. Caffeine is an addictive substance, though, so cutting back might lead to withdrawal symptoms such as extreme fatigue or headaches.