Scientists first extracted caffeine from green coffee beans in 1820, and it was later found in more than 60 plants. Caffeine is a central nervous system stimulant that belongs to the xanthine chemical group. It inhibits adenosine reception at multiple sites in the brain, increasing alertness and warding off fatigue. Because caffeine is hydrophobic, or water-fearing, it easily diffuses, or passes through, the mucosa lining of the small intestine, which is where absorption occurs.
About Caffeine
The U.S. Food and Drug Administration, or FDA, considers caffeine a food additive and a drug. It naturally develops in plants and can be found in tea leaves, cacao pods and coffee beans. Approximately 80 percent of adult Americans consume an estimated 200 mg. of caffeine daily through the consumption of foods and beverages, such as chocolate and sodas, and medications and dietary supplements like headache medications and weight-loss aids. According to Dr. Eric Chudler, a neuroscientist at the University of Washington Engineered Biomaterials, the International Olympic Committee, or IOC, imposed a caffeine ban years ago that prohibited athletes who tested positive for 12 mcg or more of caffeine per milliliter of urine from participating in future Olympic Games. The IOC lifted this ban in 2004.
Digestion and Physiology
The digestive tract begins with your mouth, ends with your anus and is approximately 20 feet long. When you ingest a caffeinated item, it passes through the esophagus and into the stomach where it's stored, mixed with gastric juices and passed into the small intestine. Microvilli and villi, which are finger-like projections that aid the movement of microscopic particles, help caffeine pass through the folds of the mucosa lining into the bloodstream. Approximately 15 minutes after consumption, caffeine elicits temporary physiological changes, including but not limited to an increased heart rate and urination frequency. One hour after absorption, caffeine concentration levels peak.
Side Effects
Caffeine is addictive and can be fatal if taken in large doses. The FDA has reported its knowledge of a 19-year-old student who overdosed on caffeine tablets in an effort to stay awake. Depending on the brand and manufacturer, caffeine tablets may contain as much caffeine as one to three 5 oz. cups of coffee. Caffeine may increase the heart rate, cause jitters, dehydration, increased blood pressure, heart palpitations or arrhythmias, sleeplessness and gastrointestinal upset. It triggers the release of excess hydrochloric acid, or stomach acid, which can cause indigestion.
Benefits of Caffeine Use
According to the August 2007 issue of "Neurology," caffeine may offer neurological protection. A study conducted at the University of Paris in France found that women age 65 or older with no clinical diagnosis of dementia who drank three cups of coffee daily exhibited reduced rates of cognitive decline. Caffeine also eases headache pain by constricting blood vessels in the brain, which alleviates pressure. It suppresses appetite, and under a doctor's supervision, may be used as part of a weight-loss regimen.
Suggestions
Because caffeine is found in many products, you may find it difficult to track your caffeine intake. Log anything you ingest that contains caffeine, its caffeine content and the amount of the item you consumed. If you find that your caffeine intake exceeds the FDA's recommendation of 100 to 200 mg daily, which is approximately one to two 5 oz. cups of coffee, consider opting for caffeine-free sodas, decaffeinated teas and coffees and reduce your chocolate intake.
References
- University of Washington Egineered Biomaterials; Neuroscience for Kids: Caffeine; Dr. Eric Chudler
- U.S. Food and Drug Administration; Medicines in My Home: Caffeine and Your Body; 2007
- National Drug and Alcohol Research Centre: Caffeine Fact Sheet
- National Sleep Foundation: Caffeine and Sleep
- "Neurology"; The Neuroprotective Effects of Caffeine; K. Ritchie et al.; August 2007
- National Digestive Diseases Information Clearinghouse; Your Digestive System and How it Works; April 2008
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