According to Brown University, most American adults consume an average of 200 mg of caffeine each day, an amount that is considered moderate and safe for most people, and well above the 64 mg you might get from a cup of coffee or tea. Like some other drugs, however, caffeine is mildly addictive and, when consumed in large amounts, can have unpleasant side effects and cause health complications. Pregnant women and people with certain medical conditions should limit the amount of caffeine they consume.
Caffeine
Caffeine is a drug that stimulates the central nervous system. In the brain, caffeine increases nerve cell firing, which stimulates the production of the brain chemicals adrenaline and dopamine. The stimulating effects of caffeine vary from person to person, depending on age and body size. In pregnant women, caffeine passes through the placenta and breast milk to the baby. A review of available studies on caffeine and health, published in "Food Additives and Contaminants," found that adult men and non-pregnant women can safely consume up to 400 mg of caffeine each day, while pregnant women should consume less than 300 mg a day.
Dietary Sources of Caffeine
Caffeine is found in coffee, tea, chocolate, hot cocoa and cola drinks. Some prescription and nonprescription medications also contain caffeine. Five oz. of regular, brewed coffee contains anywhere from 60 to 150 mg of caffeine, compared with decaffeinated coffee, which contains only 2 to 5 mg per 5 oz. serving. Five oz. of tea contains up to 80 mg of caffeine, while an equal amount of hot cocoa contains up to 8 mg. Milk chocolate contains up to 15 mg of caffeine per ounce, while bittersweet chocolate contains up to 35 mg per ounce. Cola and other caffeine-containing soft drinks contain up to 100 mg of caffeine per 12 oz. serving.
Caffeine Side Effects
Too much caffeine can cause headaches and make you feel restless. It acts as a diuretic, causing frequent urination that can lead to dehydration. Excess caffeine also can keep you up at night, even if you consumed it much earlier in the day. If you drink coffee regularly and then stop, you might experience withdrawal symptoms such as bad headaches, temporary feelings of depression and irritability. The Food and Drug Administration suggests avoiding caffeine altogether if you have a heart condition or suffer from anxiety.
Caffeine Supplements
A study published in a 2007 issue of "Analytical and Biolytical Chemistry" found that the caffeine content of supplements commonly purchased in the United States ranges from 1 mg to more than 800 mg a day when taken at recommended doses. In some cases, caffeine is not listed as an ingredient on the label but is coming from botanical ingredients such as guarana, yerba mate, kola nut and tea extract.
References
- Brown University: Caffeine
- U.S. Food and Drug Administration: Caffeine and Your Body
- "Food Additives and Contaminants"; Effects of Caffeine on Human Health; Nawrot, P. et al; January 2003
- "Analytical and Bioanalytical Chemistry"; The Caffeine Content of Dietary Supplements Commonly Purchased in the US; Andrews, KW et al; 2007
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