Although Americans commonly use caffeine, few people could be called dependent; few people experience problems socially and occupationally because of the habit. Nevertheless, the American Psychiatric Association recognizes caffeine intoxication as a diagnosable condition, along with caffeine-induced anxiety and sleep disorder, and caffeine withdrawal.
Many foods contain caffeine, including coffee, tea, chocolate, and carbonated beverages. So do over-the-counter medicines—pain relievers, appetite suppressants, and cold medicines. Caffeine functions as a central nervous system stimulant and also a diuretic. It is a myth that coffee will sober up an inebriated person; instead, it causes agitation. And never give caffeine to a frostbite or hypothermia victim. Caffeine, a stimulant, can cause the heart to beat faster and hasten the effects of cold temperatures on the body.
How much caffeine is there in the foods and beverages we commonly associate with it?
Caffeine is absorbed and distributed quickly. After absorption, it passes into the brain. Caffeine does not accumulate in the bloodstream nor is it stored in the body. It is excreted in the urine many hours after it has been consumed. Caffeine will not reduce the effects of alcohol. Caffeine may be used as a treatment for migraine headaches and in temporarily relieving fatigue or drowsiness.
Excessive intake of caffeine can lead to a fast heart rate, excessive urination, nausea and vomiting, diarrhea, restlessness, anxiety, depression, tremors, irregular heartbeat, flushed face, rambling talk and thinking, and difficulty sleeping.
The effects of caffeine on health have been widely studied—in particular, its effects on fibrocystic breast disease, conditions of the heart and blood vessels, birth defects, reproductive function, and behavior in children. The American Medical Association Council on Scientific Affairs concludes, "Moderate tea or coffee drinkers probably have no concern for their health relative to their caffeine consumption provided other lifestyle habits (diet, alcohol consumption) are moderate as well."
Abrupt withdrawal of caffeine may cause headaches, drowsiness, irritability, nausea, vomiting, and other symptoms. Reduce caffeine intake gradually to prevent symptoms of withdrawal.
About 250 to 300 milligrams of caffeine per day is considered a moderate amount. This is roughly equivalent to three cups of coffee. More than ten 8 ounce cups per day is excessive. Caffeine poisoning from excess amounts does occur.
There is no human requirement for caffeine in the diet. Moderate caffeine intake, however, does not pose a health risk.
A child's caffeine consumption, however, should be closely monitored. Caffeinated beverages may be replacing nutrient-dense foods such as milk. It can interfere with the absorption of certain nutrients such as calcium and iron. A child may also eat less, because caffeine acts as an appetite suppressant. Since there is no nutritional value in caffeine, it is probably best that children avoid it. For a hyperactive child, in fact, it's imperative to eliminate caffeine from the diet, as it acts as a stimulant.
Pregnant women and people with coronary heart disease or peptic ulcers may be advised by their health care provider to restrict or avoid using caffeine.
Many drugs interact with caffeine. Consult your health care provider or pharmacist about potential interactions whenever you take medications.
In case of caffeine overdose, call your local Poison Control to see if hospitalization is necessary.