Caffeine 3
Many people feel that caffeine increases their mental alertness. Higher doses of caffeine can cause anxiety, dizziness, headaches, and the jitters. Caffeine can also interfere with normal sleep.
(the amount of caffeine that will produce an effect in someone) varies from person to person. On average, the smaller the person, the less caffeine needed to produce side effects.
Legend has it that coffee was "discovered" around 850 AD in upper Egypt by a goat herded named Khaldi. One night, Khaldi's goats did not return home. When he found his goats, Khaldi saw them dancing around a shrub with red berries (coffee beans). After Khaldi tried some of the berries, he started to dance too. Khaldi spoke with some monks who used the berries to make a drink and....coffee was born!
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Caffeine belongs to the xanthine chemical group. Adenosine is a naturally occurring xanthine in the brain that is used as a neurotransmitter at some synapses. One effect of caffeine is to interfere with adenosine at multiple sites in the brain including the reticular formation.
Caffeine also acts at other sites in the body to increase heart rate, constrict blood vessels, relax air passages to improve breathing and allow some muscles to contract more easily.
Caffeine may also cause the body to lose calcium, and that can lead to bone loss over time. Drinking caffeine-containing soft drinks and coffee instead of milk can have an even greater impact on bone density and the risk of developing osteoporosis.
Caffeine can aggravate certain heart problems. It may also interact with some medications or supplements. If you are stressed or anxious, caffeine can make these feelings worse.
In massive doses, caffeine is lethal. A fatal dose of caffeine has been calculated to be more than 10 grams (about 170 mg/kg body weight) - this is the same as drinking 80 to 100 cups of coffee in rapid succession
Caffeine enters the bloodstream through the stomach and small intestine and can have its effects as soon as 15 minutes after it is consumed. Once in the body, caffeine will stay around for hours: it takes about 6 hours for one half of the caffeine to be eliminated.
Caffeine sensitivity is most affected by the amount of caffeine a person has daily. People who regularly take in a lot of caffeine soon develop less sensitivity to it. This means they may need more caffeine to achieve the same effects.
Caffeine is a diuretic, meaning it causes a person to urinate (pee) more. It's not clear whether this causes dehydration or not. To be safe, it's probably a good idea to stay away from too much caffeine in hot weather, during long workouts, or in other situations where you might sweat a lot.
Caffeine is a drug that is naturally produced in the leaves and seeds of many plants. It's also produced artificially and added to certain foods.
Caffeine is defined as a drug because it stimulates the central nervous system, causing increased alertness. Caffeine gives most people a temporary energy boost and elevates mood.
In its natural form, caffeine tastes very bitter. But most caffeinated drinks have gone through enough processing to camouflage the bitter taste.
Caffeine is not stored in the body, but you may feel its effects for up to 6 hours.
Although caffeine is sometimes used to treat migraine headaches, it can make headaches worse for some people.
Caffeine is usually thought to be safe in moderate amounts. Experts consider 200-300 mg of caffeine a day to be a moderate amount for adults. But consuming as little as 100 mg of caffeine a day can lead a person to become "dependent" on caffeine.
This means that someone may develop withdrawal symptoms (like tiredness, irritability, and headaches) if he or she quits caffeine suddenly.
Try cutting your intake by replacing caffeinated sodas and coffee with noncaffeinated drinks. Options include water, decaffeinated coffee, caffeine-free sodas, and caffeine-free teas.