Caffeine can affect the body in a variety of ways. Factors that determine how an individual will react to caffeine include a person's size, age, tolerance or sensitivity to caffeine, how much is consumed and physical condition.
What is Caffeine?
Caffeine is a natural substance found in leaves, seeds and fruits that acts as a stimulant to the body's central nervous and cardiovascular systems.
Foods and Drugs
Found in more than 60 plant varieties, the most common foods containing caffeine are coffee beans, tea leaves and cocoa. Caffeine levels in a brewed 8-ounce cup of coffee average 85 milligrams, and an 8-ounce cup of brewed tea contains approximately 47 milligrams. Levels can vary depending on the type of coffee bean or tea leaf.
A 12-ounce can of soda averages 35 milligrams of caffeine; 1 ounce of milk chocolate averages 1 to 15 milligrams; and an 8-½ ounce can of energy drink averages 50 to 200 milligrams. About 300 milligrams of caffeine per day is considered a moderate, average intake for adults. Children should consume less than 300 milligrams.
Caffeine is used in prescription and over-the-counter drugs such as aspirin, cold medicines and pain relievers. Packaging must disclose caffeine as an ingredient.
Caffeine's ability to be absorbed quickly into the body results in increased alertness and elevated mood within an hour of consuming it. Caffeine also increases the heart rate and blood flow for several hours.
Caffeine increases metabolism and calorie burning effectiveness for up to three hours after it is consumed. It can also increase endurance and speed in certain athletic situations. Moderate intakes of caffeine during pregnancy carry no adverse health risks and are important for a healthy pregnancy. Caffeine is a hydration fluid and counts toward the recommended daily water intake of 80 ounces.
Children are affected easily by stimulants such as caffeine. However, limited caffeine intake is considered safe for children.
Caffeine is absorbed directly into the stomach lining, so stomach ulcers may occur with excessive consumption. Another side effect is sleeping disorders precipitated by too much caffeine intake throughout the day.
Abruptly discontinuing the use of caffeine can result in mild depression, fatigue and headaches. It is recommended that caffeine be gradually reduced over time to minimize these effects. Excessive caffeine doses of 600 milligrams or more a day, approximately six cups of coffee, can cause nausea, sweating, anxiety and insomnia.
Moderate caffeine use does not pose any long-term health effects. According to the International Food Information Council, the U.S. Food and Drug Administration in 1958 and in 1987 classified caffeine as Generally Recognized As Safe and produced no increased health risks. Both the American Medical Association and American Cancer Society agree that moderate caffeine use is safe.
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