From the Mayo Clinic:
Newer studies have also shown that coffee may have benefits, such as protecting against Parkinson's disease, type 2 diabetes and liver cancer. And it has a high content of antioxidants. But this doesn't mean you should disregard the old maxim "Everything in moderation." Although coffee may not be very harmful, other beverages such as milk and juice contain nutrients that coffee does not. Also, keep in mind that coffee accompaniments such as cream and sugar add fat and calories to your diet. Finally, heavy caffeine use — on the order of four to seven cups of coffee a day — can cause problems such as restlessness, anxiety, irritability and sleeplessness, particularly in susceptible individuals.
Enjoy your coffe in moderation.