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Caffeine: Good or Bad?
After googling “caffeine effects,” the page comes up with 382,000 hits. I checked out a few to see what they were claiming about caffeine and what type of websites they were. The website Go Ask Alice! is sponsored by Columbia University, where Alice is the name of Columbia’s Health Education program. The website’s main purpose is to answer medical questions sent in (http://www.chinamist.com/knowledge/health/caffeine/-effects.htm). One other website that discusses caffeine is The Vaults of Erowid, which is devoted to the legalizing of all psychoactive drugs, drugs that alter the mind or mood (http://www.erowid.org/chemicals/caffeine/caffeine_effects.shtml). The McKinley Health Center of the University of Illinois at Urbana-Champaign supports a site that answers health-related questions (http://www.mckinley.uiuc.edu/health-info/drug-alc/caffeine.html). Theresa Daley of Saint Anselm University devoted a website to the effects of caffeine on athletes (http://www.anselm.edu/academic/psychology/tdaley/-effects.htm). Health World online is a site that discusses all forms of alternative medicine and sells many products, like Anti-aging cream and energy drinks. Lastly, China Mist is a website put on by the China Mist Tea Company, a multi-million dollar corporation selling teas and coffees (http://www.chinamist.com/knowledge/health/caffeine/-effects.htm). Already there are many websites discussing caffeine with competing interests: some are simply publishing medical questions and answers, some are vendors of caffeine, and some are vendors of caffeine alternatives. All these different sources of information can confuse the average person.
What is caffeine?
First, what is caffeine? It’s a drug commonly found in coffees, teas, some prescription and nonprescription drugs, and chocolate. The websites all agree that caffeine is a stimulant, though they may differ in their descriptions of how it works or the extent that it works. The McKinley website describes caffeine as a mild stimulant of the central nervous system, which can be habit-forming but is not addictive. Go Ask Alice! states that caffeine belongs to a group of stimulants called xanthines and is mildly addictive. These sites go farther in proclaiming the benefits of caffeine. Erowid reports that caffeine gives people a “lift,” making them feel less fatigued and more able to have rapid thinking and improved performance in some manual tasks. Theresa Daley in the Anselm website reports that in low doses around 20-200 mg of caffeine people have feelings of well-being and alertness. They have enhanced vigilance, sharper thinking, and improved speed and endurance.
The China Mist Tea Company describes how caffeine works in detail. To paraphrase, caffeine binds to adenosine receptors in the brain instead of adenosine binding (which can tire you and slow you down), and activity to cells increases and the blood vessels in the brain constrict. The brain thinks all this activity indicates danger and the pituitary gland tells the adrenal gland to produce adrenaline. This adrenaline makes the heart rate increase and the liver releases more sugar, supplying the person with more energy. The Erowid website states that caffeine increases heartbeat, basal metabolic rate, respiration, and the production of urine and stomach acid, while relaxing the bronchial muscles and other smooth muscles.
All this information leads to the question: “What are the side effects of caffeine?” The side effects alone might be enough to determine if caffeine is harmful. Go Ask Alice! claims that too much caffeine (more than eight eight-ounce cups) could give the side effects of anxious, dizzy, restless, irritable, unable to concentrate, having gastrointestinal aches, and headaches. Withdrawal is discussed on the McKinley website, where a person could have headaches and fatigue when stopping the intake of caffeine. Erowid reports that studies show that caffeine can decrease reaction time to visual and auditory stimuli. Health World claims that caffeine crosses the blood-brain barrier easily, and higher doses of caffeine can cause nervousness, tremors, insomnia, and heightened sensitivity. Most of the websites also state that caffeine is a diuretic, which increases the flow of urine. This could cause a person to become dehydrated.
The most controversial issue concerning caffeine seems to be the more specific health effects of the drug. No website quite agreed with another on the serious health impacts caffeine may have. The McKinley site states there is NO evidence that caffeine consumption is associated with heart disease, high cholesterol, osteoporosis, or hypertension. Go Ask Alice! states that too much caffeine could increase a person’s chances of osteoporosis. As a diuretic, caffeine produces more urine and more calcium can be lost in the urine. There are also claims that caffeine could cause an increased risk for miscarriages and low birthweight babies. Health World lists a slew of health problems caused by caffeine: blood pressure rises, caffeine consumers are more likely to have heart disease, peptic ulcers can form due to caffeinated beverages being acidic, and can be implicated as a risk factor for cancer, difficult pregnancies, and fibrocystic breasts. Since each website has its own spin on caffeine, how does one know what to believe?
Studies published in medical journals report the findings of psychologists who have examined the effects of caffeine to investigate some of the claims concerning it. Here are some examples of their findings:
Withdrawal: People have claimed to go through withdrawal after stopping caffeine consumption. Bernstein et al (1998) studied the effects of caffeine withdrawal on young children. Thirty kids were tested, the experimenters looking first at the regular caffeine diet, then specifically on 120-145 mg of caffeine a day, then with no caffeine for two weeks, then back to normal caffeine consumption. Being tested on attention, memory, and motor performance, Bernstein et all found performance on memory tasks to be worse during the withdrawal tasks, specifically with worse reaction times. Bernstein et al also report another study done on adults and caffeine withdrawal by Griffiths et al (1986) where nine heavy coffee drinkers switch to decaffeinated coffee for ten days and withdrawal symptoms such as headaches, fatigue, and decreased activity occurred within one day and lasted around six days.
Effects on Blood Pressure: Savoca et at (2004) studied the effects caffeinated beverages can have on blood pressure on adolescents. In this study, 159 white and black kids had a three-day controlled diet, with caffeine intake falling into three categories, 0-50 mg,
>50-100 mg, and >100 mg a day. The more caffeine the adolescent consumed, the more likely he was to have high blood pressure, especially in the case of black adolescents. This could be seen as a confirmation that caffeine increases the risk of hypertension.
Caffeine and calcium loss: A study done by Massey and Sutton (2004) is based on the fact that caffeine increases urinary calcium excretion. Their study looked at caffeine’s effect on the urine of calcium kidney stone formers. Thirty-nine stone-forming patients were tested, and each subject, both in the experiment group and the control group, had increased urinary calcium, and raised the Tiselus risk index for stone formation in both the stone-former group and the non-stone-former group.
Decreased insulin sensitivity: This is a study done by Keijzers et al (2002) on decreased insulin sensitivity, which also helps define how caffeine works. They report caffeine to work by releasing catecholamines and antagonizing adenosine receptors. Twelve healthy participants were given either caffeine or placebo, and glucose clamps were used to watch their insulin sensitivities, and caffeine was found to decrease insulin sensitivity by 15 %. Also, free fatty acids increased in the caffeine group. Plasma epinephrine and blood pressure were also raised in the caffeine group.
In some ways, the websites were helpful in understanding caffeine effects. Though differing on specifics, caffeine is believed to enhance vigilance and alertness, allowing you to have better attention when you are tired than without caffeine. Caffeine does not enhance all performances, and has many side effects. Withdrawal from the drug can occur in a period of sudden decrease in caffeine input, including side effects like fatigue, dizziness, irritability and so forth. The real issue remains on the physical effects caffeine may have on your health. Studies have shown that caffeine raises blood pressure, which can raise risk to hypertension, causes loss of calcium in urine, which can raise the risk of osteoporosis later in life, and can decrease insulin sensitivity. Some questions about caffeine remain unanswered. Many studies have looked at the effects caffeine has had on women who become pregnant, but conflicting evidence leaves the question of the effect caffeine has unanswered. Likewise, high intake of caffeine could go along with a stressful lifestyle, which could account for things like higher blood pressure. Even with
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Bernstein, Gail A. MD; Carroll, Marilyn E. PhD; Dean, Nicole Walters BA; Crosby,
Ross D. PhD; Perwien, Amy R. BA; Benowitz, Neal L. MD (1998) Caffeine withdrawal in normal school-age children. Journal of the American Academy of Child & Adolescent Psychiatry, 37(8):858-865.
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C R. 1; Hawley, J A. Facsm 1 (2001) Effect of different caffeine intake protocols on metabolism and performance of prolonged cycling. Medicine & Science in Sports & Exercise, 33(5) Supplement 1:S43.
Keijzers, Gerben B. MD 1; De Galan, Bastiaan E. MD 1; Tack, Cees J. MD 1; Smits,
Paul MD 1,2 Caffeine Can Decrease Insulin Sensitivity in Humans. Diabetes Care. 25(2):364-369.
Massey, Linda K. *; Sutton, Roger A. L. (2004) Acute caffeine effectson urine
composition and calcium kidney stone risk in calcium stone formers. Journal of Urology. 172(2):555-558.
Savoca, Margaret R. PhD; Evans, Conner D. BA; Wilson, Martha E. MA; Harshfield,
Gregory A. PhD; Ludwig, David A. PhD (2004) The Association of Caffeinated Beverages With Blood Pressure in Adolescents. Archives of Pediatrics & Adolescent Medicine. 158(5):473-477.
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