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Caffeine is the world’s most widely consumed legal psychoactive drug. It is a naturally occurring chemical stimulant found in food such as chocolate and in caffeinated beverages such as soft drinks, tea, coffee, and energy drinks. It is most commonly taken orally to improve mental alertness and alleviate tiredness. It can also be found in over-the-counter and prescription medicines to treat drowsiness, and is used in conjunction with pain relievers to treat migraines.
For healthy adults, the US Food and Drug Administration recommends an intake of no more than 400 milligrams of caffeine a day, around four to five cups of coffee. It says that drinking this amount isn’t associated with any dangerous, negative side effects.
What does caffeine do to your body?
Caffeine is rapidly absorbed into the body and crosses cell membranes into the central nervous system. It blocks the uptake of adenosine, the neurotransmitter responsible for relaxing your brain and regulating fatigue. It also increases blood adrenaline levels and increases the amount of dopamine in your brain. This causes the alert feeling commonly associated with caffeinated drinks.
Other effects of caffeine can be beneficial, too. Caffeine has been used to treat asthma because it acts as a mild bronchodilator, meaning it relaxes the muscles in the lungs that tighten your airways, allowing more air in. Studies suggest that regular coffee drinkers may have a lower risk of developing Alzheimer’s, dementia and liver disease. Caffeine has even been associated with a lower risk of suicide. Another study found that the caffeine in coffee may influence the activity of our genes via epigenetic changes.
Although caffeine is useful as a natural stimulant, there are many negative effects of excessive consumption to the body and it is therefore advisable to limit it. A toxic dose is generally considered to be over 10 grams of caffeine per day, 25 times the recommended maximum daily intake.
Excessive doses of caffeine can cause a fast heartbeat, which is especially harmful to those with pre-existing heart conditions like arrhythmia. It can also cause a variety of long-term health problems, like fertility issues, high blood pressure and, as caffeine inhibits calcium intake into your bones, increased risk of osteoporosis.
Is caffeine a drug?
Anyone who drinks caffeine regularly could experience caffeine withdrawal symptoms if they suddenly stop – this is considered a mild form of drug dependence. The symptoms include headaches, tiredness, irritability, nausea and muscle pain. It is therefore recommended to gradually decrease your intake, rather than stopping abruptly.
Although an overdose is very rare, it has been reported as the cause of 92 deaths. Most were the result of an overdose of caffeine tablets or purified caffeine powder. Extreme levels of caffeine in the blood cause ventricular fibrillation – when the lower chambers of the heart vibrate rather than contracting regularly, causing a heart attack.
Read more at New Scientist