How Things Work: Caffeine

Every day, millions of people all over the world consume caffeine in various forms, including coffee, tea, sports drinks, soft drinks, energy drinks, as the Food and Drug Administration notes. In fact, people have been using caffeine for centuries, chewing bark, seeds and leaves of many different plants for their mood-altering effects. Caffeine is one of the oldest and most widely used drugs on the planet. It affects your brain and body rapidly and distinctively and can be a real help in improving alertness; however, misusing it has been known to result in certain health issues.

Effects on the Brain

Caffeine is known under several other names, such as methyltheobromine, mateine, theine, guaranine and coffeine. A central nervous system stimulant with addictive properties, it is the world's most widely consumed psychoactive substance, the "New Scientist" reports.

Caffeine works by blocking adenosine receptors in your brain, which would otherwise normally receive signals to decrease the rate of cellular activity. It increases the release of dopamine and adrenaline, which serves to boost heart rate and blood pressure, and increases blood flow to muscles. This is why you feel more alert and energized after consuming caffeine. However, long-term use causes your body to develop a tolerance for caffeine's effects and greater sensitivity to adenosine.

Foods That Contain Caffeine

Many kinds of food naturally contain some amounts of caffeine. Around 60 different species of plants have caffeine in their seeds, leaves and fruits, including cocoa beans, kola nuts, coffee beans, tea leaves, yerba mate and guarana. Products such as chocolate, cocoa, tea, energy drinks and some types of soft drinks also contain caffeine. In addition, it is frequently added to medications such as appetite suppressants, pain relievers and cold medicines.

Foods That Contain Caffeine

Many kinds of food naturally contain some amounts of caffeine. Around 60 species of plants have caffeine in their seeds, leaves and fruits, including cocoa beans, kola nuts, coffee beans, tea leaves, yerba mate and guarana. Products such as chocolate, cocoa, tea, energy drinks and some types of soft drinks also contain caffeine. In addition, it is frequently added to medications such as appetite suppressants, pain relievers and cold medicines.

Side Effects

Excessive caffeine consumption, also known as caffeine intoxication, can lead to a wide variety of side effects, such as anxiety, tremors, sleeping difficulties, excessive urination, vomiting, nausea, restlessness and excessive urination, MedlinePlus explains. Aside from this, quitting caffeine "cold turkey" or abruptly ceasing consumption can lead to withdrawal symptoms, including headaches, irritability, drowsiness, vomiting and nausea. While it is safe for humans to consume, caffeine is toxic to certain animals such as dogs, parrots and horses.

Know Limits

Caffeine consumption, and drinking coffee in particular, plays a significant role in many people's daily or nightly routine. A moderate dose of caffeine, which is around 2 to 4 cups of brewed coffee each day, is not harmful. However, heavy caffeine users should still know their limits, MayoClinic.com advises. If you exceed 500 to 600 mg a day, or 4 cups and more, then you may already have experienced some of the symptoms listed above.

Some individuals are more sensitive, with symptoms appearing after just one cup. In addition, some antibiotics can actually amplify the effects of caffeine and delay its elimination from your system. If you notice that you're having difficulty getting seven to eight hours of sleep, you may want to gradually reduce your dependence on caffeine. Try to switch to decaf, shorten brew times, and check other products for the presence of caffeine.