Caffeine is consumed in at least one beverage each day by 80% of Americans. It is found in various beverages as well as chocolate. The following chart breaks down the caffeine content for a few products: (on average)

• 5 oz. Brewed Coffee, drip method = 115 mg
• 2 oz. Espresso Coffee = 100 mg
• 5 oz. Brewed Tea = 40 mg
• 12 oz. Soft Drink = 35 mg
• 1 oz. Milk Chocolate = 5 mg

Caffeine is a mild stimulant that dehydrates the body—causing tremors, heart palpitations, and headaches in some. It also causes the body to absorb iron at a lower rate, as well as having an adverse effect on calcium balance. Some athletes use caffeine during training for its ability to enhance mobilization of fatty acids and conserve glycogen. However, the International Olympic Committee restricts the use of caffeine in the amount equivalent to 4-5 cups of coffee in an average-size man.