http://en.wikipedia.org/wiki/Decaffinated_Coff ee
Health and pharmacology of coffee
Main article: Coffee and health
Many studies have been performed on the relationship between coffee consumption and many medical conditions, ranging from diabetes and cardiovascular disease to cancer and cirrhosis. Studies are contradictory as to whether coffee has any specific health benefits, and results are similarly conflicting with respect to negative effects of coffee consumption.[19] In addition, it is often unclear whether these risks or benefits are linked to caffeine or whether they are to be attributed to other chemical substances found in coffee (and whether decaffeinated coffee carries the same benefits or risks).[citation needed]
One fairly consistent finding has been the reduction of diabetes mellitus type 2 in coffee consumers, an association that cannot be explained by the caffeine content alone and indeed may be stronger in decaffeinated coffee.[20]
Recently, coffee was found to reduce the chances of developing cirrhosis of the liver: the consumption of 1 cup a day was found to reduce the chances by 20%, and 4 cups a day reduced the chances by 80%.