Coffee is a complex combination of chemicals such as phenolic chlorogenic acid, di terpenes and caffeine, which is a natural alkaloid that can be found in large amounts more in coffee than in any other dietary products. Coffee is also composed of many other constituents such as potassium, niacin, magnesium, and antioxidant substances, like tocopherols, that may play a role in its biological activity. Coffee is a beverage that can have different caffeine concentrations, depending on the methodology of beverage preparation and type of coffee. The annual amount of coffee consumed per person is about 4 kg in USA and about 3 kg in United Kingdom. In the last few years several studies have pointed out that the consumption of coffee can bring health benefits by influencing on many biological systems; for instance it has been shown that people who drink coffee regularly have lower risks of developing type 2 diabetes, colon cancer, liver cirrhosis and gallstones. Because the benefits of coffee on health seem to exceed the negative effects, coffee can be regarded as a functional food.