Excess drinking of coffee and tea may lead to addiction to caffeine as a stimulant, resulting in tension, headache, insomnia, racing heart and in severe cases, malnutrition through loss of appetite. Caffeine is used medically in tablet form as a stimulant, against headache and in certain cases for the treatment of asthma, but its abuse induces tolerance and mental dependence. Caffeine abuse, which is often coupled with nicotine abuse, may go unrecognized because coffee drinking is commonplace and socially acceptable; it is fully recognized as a drug problem.
Caffeine belongs to a group of drugs called methyxanthines which is found in over 63 plant species worldwide. It is found in coffee, tea, chocolate products, soft drinks, cough and cold remedies, pain relievers, diuretics and weight-control products. The caffeine content of these products varies. A can of cola, for instance, has 35 to 55 milligrams (mg) of caffeine - much less than a cup of drip coffee which has 110 - 150 mg or a cup or glass of tea which has have 45 - 75 mg. An cup of cocoa may contain up to 56 mg of caffeine; a chocolate bar has about four mg.
The caffeine content of coffee depends on preparation: 23 grams (8 ounces) provides up to 280 milligrams of caffeine; drip coffee contains between 88 and 280 mg; percolated contains between 27 and 64 mg.
As a drug, caffeine is not addicting but mildly habit-forming owing to its stimulating effect. It stimulates the heart and brain, causing improved performance, decreased fatigue, and increased alertness. Caffeine's stimulative effect on the central nervous system, the 'lift' one experiences from a caffeine-containing beverage, is a primary reason for its consumer popularity. Of course, not all people react positively to caffeine. In some, the drug causes irritability, nervousness, tremors, restlessness, headaches, insomnia, heartburn, diarrhea, and heart palpitations. These are the symptoms of caffeinism or coffee nerves and they usually occur with the consumption of 600 mg of caffeine.
Caffeine blocks the brain's receptors for adenosine, a molecular messenger that damps nerve cell activity. Hence the stimulant effect. Even those who consume only moderate amounts of caffeine may suffer withdrawal symptoms – headaches, fatigue, depression, poor concentration – after 18 to 24 hours of abstinence.
According to a 1991 FDA report, the average American consumes 200 mg of caffeine (2-3 cups of coffee) per day.
Caffeine, while recognized as a drug, is beneficial in moderation. Even when the body builds tolerance, caffeine consumption elevates mood, decreases fatigue, enables hard work, stimulates clear thinking and in some cases wards off depression. Although caffeine withdrawal may cause headache and fatigue, such symptoms last only a few days. Some suggest caffeine is not a drug but a food-additive.
Research reported in the New Scientist found that mice given caffeine survive otherwise lethal doses of radiation. The effect may be that caffeine – 1,3,7-trimethylxanthine – reacts with the hydroxyl radicals produced when cells are irradiated. thus protecting from cell damage.
There is little solid scientific evidence which indicates that a moderate intake of caffeine is a serious or even a minor health threat. Coffee nerves normally happen with the ingestion of about five to six cups of strong brewed coffee or 12 cans of caffeinated soft drinks – all taken in one sitting. Caffeine poisoning is also a threat to those who consume 10 grams of caffeine from 80 - 100 cups of brewed coffee or 200 cans of cola drinks. However, no one consumes that much caffeine in one sitting. The above figures don't represent the normal caffeine consumption patterns of both children and adults. This means that caffeine doesn't pose any health risk if taken in moderation. There has never been a case of caffeine poisoning from beverages since cola drinks were introduced in 1886.
The amount of caffeine in coffee helps the gallbladder contract, thus reducing stone formation. produce the same result. Researchers found that, out of 46,000 men, those who drank two to three cups of coffee daily cut their risk of developing gallstones by 40 percent.
Short-term administration of 200-250 mg caffeine to adults is known to increase alertness, stimulate attention and restore performance degraded by factors such as fatigue and boredom. When used in moderation by most people, the stimulative effect is transient and benign, according to members of the US Institute of Food Technologists (IFT) Expert Panel on Food Safety and Nutrition.