“What I tell patients is, if you like coffee, go ahead and drink as much as you want and can,” says Dr. Peter Martin, director of the Institute for Coffee Studies at Vanderbilt University. He’s even developed a metric for monitoring your dosage: If you are having trouble sleeping, cut back on your last cup of the day. From there, he says, “If you drink that much, it’s not going to do you any harm, and it might actually help you. A lot.”
Officially, the American Medical Association recommends conservatively that “moderate tea or coffee drinking likely has no negative effect on health, as long as you live an otherwise healthy lifestyle.” That is a lackluster endorsement in light of so much recent glowing research. [my emphasis]
via Prof. Reynolds.