The truth about caffeine

Caffeine: Most of us can't get through the day without it. Whether brewing a fresh pot of coffee in the morning, enjoying lunch with a refreshing can of cola, or recharging in the afternoon with an energy drink, we have many routines and food rituals revolving around this energizing substance. Found naturally in the leaves, seeds and fruits of more than 60 plants (including cocoa beans, kola nuts, guarana, yerba mate, green tea extract and tea leaves) and added to many other foods and beverages, caffeine is the world's most popular stimulant. In the US alone, more than 80% of adults consume it.

Like many commonly enjoyed foods and ingredients, we get mixed information about caffeine. Sometimes we hear it does a body good. Other times, we hear it's bad for us. Keep reading to uncover the truth about caffeine: how it works—and how it affects your health.

Why Caffeine Keeps You Charged
The brain produces a natural sedative called adenosine, which binds to the appropriate receptor sites in the brain, resulting in a drowsy feeling. Adenosine levels rise during daytime/waking hours, encouraging sleep in the evening. While sleeping, adenosine levels drop, so you awaken refreshed and raring to go.

Caffeine is similar in structure to adenosine. It temporarily binds to adenosine receptor sites in the brain.  This prevents adenosine from attaching itself to the sites and thus, wards off fatigue. If you regularly consume caffeine, you might also discover that you build up a tolerance because the brain makes more receptor sites as a result. Therefore, you need more caffeine to attach to these new sites and get the same results.

While caffeine is one of the most studied ingredients in food supply, there is still great confusion regarding its effects on health. For years caffeine has been included on the U.S. Food and Drug Administration's list of substances that are "generally recognized as safe" (GRAS) list. Extensive research has been conducted on numerous health aspects of caffeine consumption. Here is a synopsis of the findings regarding caffeine and health.
5 Health Benefits of Caffeine

• Dementia Risk: While it is too soon to tell about caffeine's role in the prevention of dementia in humans, there are some preliminary animal studies showing that it might help to protect against dementia.
   
• Headache Treatment: The blood vessels in the brain dilate (enlarge) during a headache. Caffeine constricts the blood vessels, which lessens the pain. It is also a mild pain reliever. This is why caffeine is found in headache medications like Excedrin Migraine (130 mg per 2 tablets), Midol Complete (120 mg per 2 tablets) and Anacin (64 mg per 2 tablets).
   
• Mental Stimulation and Problem Solving: Caffeine has been shown to speed up reaction time and improve processing skills, such as paying attention, solving arithmetic problems, typing and proofreading.
   
• Parkinson's Disease: Several preliminary studies have shown that higher caffeine intake can reduce one's risk for developing Parkinson's Disease. In fact, caffeine might help improve tremors and motor skills in people who already have the disease. However, the benefits could lessen as a person develops a tolerance to caffeine.
   
• Physical Performance: Low to moderate doses of caffeine (200-300 mg) have been shown to improve athletic performance in well-trained athletes, especially in endurance events like running. However, in sports that require short bursts of movement like weight lifting or sprints, caffeine is less effective. Caffeine might help with the burning of fat for energy after exhausting the carbohydrates stored in the muscles. Caffeine also helps reduce the feeling of muscle pain and tiredness, so one feels better while exercising

4 Health Risks of Caffeine Consumption

• Complex Tasks: Caffeine can worsen performance on complicated tasks, and with caffeine usage over time, the mental boost one gains from caffeine is reduced.
   
• Fertility and Pregnancy: The March of Dimes recommends that women who are pregnant or trying to get pregnant consume no more than 200 milligrams of caffeine per day due to possible adverse effects on fertility, miscarriage and fetal growth.
   
• Fibrocystic Breast Disease: While it does not cause this condition, caffeine can aggravate the symptoms in some women who already have the disease.
   
• Sleep: Consumed later in the day, caffeine can interfere with the onset of sleep and especially rapid eye movement (REM) sleep. Most people report difficulty falling asleep when consuming caffeine within six hours before going to bed. Your sensitivity will vary based on how quickly your body metabolizes caffeine, the amount you ingest and your regular consumption amount

As with anything in life, the key thing is 'moderation'. Do not abuse your caffeine intake.

culled from http://www.sparkpeople.com/resource/nutrition_articles.asp?id=1962&page=3