A naturally occurring substance found in the leaves, seeds, fruits, and some plants including tea leaves, kola nuts, and various herbal supplements such as guarana and mate. The amount of caffeine in products varies depending on the serving size, type of product, and preparation method. It acts as a mild stimulant to the central nervous system. Also slightly increases water loss through urination.
Caffeine can increase slightly the amount of calcium lost through the digestive and urinary tracts.
Moderate consumption of caffeine can increase feelings of alertness, reduce fatigue and drowsiness and temporarily improve mental alertness. For some people, caffeine can actually enhance physical performance. The U.S. Food and Drug Administration advises pregnant women to consume caffeine in moderation. Pregnant women should always consult with their physician before considering use of any kind of stimulant. There hasn't been any scientific evidence linking moderate caffeine intake to any health risks, including cancer, cardiovascular disease, fibrocystic breast disease, osteoporosis, or birth defects.