Depending on the type of coffee and method of preparation the caffeine content of an average cup of coffee can vary greatly. However, on average for a 7oz cup of coffee the following amounts of caffeine can be expected:

• Drip: 115-175 mg
• Espresso: 100 mg (serving size 1.5-2 oz)
• Brewed: 80-135 mg
• Instant: 65-100 mg
• Decaf, brewed: 3-4 mg
• Decaf, instant: 2-3 mg

Coffee contains caffeine, a mild stimulant. Drinking coffee results in an increase of the heart rate of the drinker, increased blood flow to the muscles, and an increase in blood pressure and it causes a decrease in blood flow to the skin and to the inner organs. Most importantly for many drinkers, the level of dopamine in the brain increases. Coffee is often consumed because of its stimulating properties, as an aid to beginning one's day by reducing the aftereffects of sleep or as a way to ward off fatigue in general.

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. 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).

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.

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%.

Health of Coffee