There are a few hypotheses behind these benefits, Hu said, but ultimately more research is needed to determine the exact mechanisms at work. “Coffee contains not just caffeine, but numerous bioactive compounds like polyphenols, which may have health benefits,” Hu said. “Coffee contains not just caffeine, but numerous bioactive compounds like polyphenols, which may have health benefits.” For otherwise healthy adults, the AHA suggests consuming no more than a maximum of 400 milligrams of caffeine a day. “And we have found that if you add too much sugar and cream, you can dilute the health benefits of coffee.