Host Richard Hentschel talks more with Dru Banks, Nutrition and Wellness educator on the Dietary Guidelines and our coffee drinking habits. Americans drink lots of coffee. Moderate coffee consumption is ok for healthy adults. That is about 400 milligrams of caffeine in total during the day. Think 3 8 oz cups a day if that is the only source of caffeine. Too much caffeine can mean upset stomachs, nerviness and insomnia. Your heartbeat can be elevated as well. Caffeine may have some positive impact too. Some teas can provide caffeine depending on how long they are brewed.