2009-12-12 / Columnists

Maintaining Your Health on Mackinac

Caffeine Is the Most Commonly Consumed Stimulant Drug
By Yvan Silva, M.D.

Caffeine is a stimulant. It is methylxanthine, a substance that, when ingested, rapidly traverses the blood-brain barrier to diminish neuro-chemical transmission at brain receptor sites for adenosine. This transmission normally induces sleepiness. Thus the biologic effect of caffeine temporarily induces wakefulness, improves cognitive function, and may boost athletic performance. Initially, caffeine elevates the blood pressure and increases stomach secretions, urine production, and other biological substances in the blood. Caffeine is present in coffee, tea, caffeinated soda beverages, chocolate, and many prescriptions and over-the-counter drugs; it is, by far, the most commonly consumed stimulant drug.

The most commonly used vehicle for caffeine is coffee, which also contains other chemicals that may have other biological actions. There are more than 170 million regular coffee drinkers in the United States. Coffee consumption is a selfpropagating behavior. Coffee dependency and addiction are common in some types of work groups and some lifestyles. Physical dependence is variable among individuals, and while most people believe that coffee is a mild stimulant, many do not know that abrupt cessation can produce unpleasant withdrawal symptoms. Several studies have shown that at least half of regular caffeine users would experience withdrawal symptoms. This, of course, is related to the type of products and the amount of caffeine used daily. Some health authorities believe that many coffee drinkers may use it more to prevent the ill effects of withdrawal symptoms rather than to really enjoy the experience of a cup of coffee.

An eight-ounce cup of regular coffee contains 80 to 150 milligrams (mg) of caffeine. A typical consumer is said to drink two to three cups of coffee a day, providing 200 to 300 mg of caffeine. The highest boost occurs one hour after ingestion and the effects can last up to eight hours. U.S. military medical authorities recommend that fighter pilots and combat soldiers may occasionally take 100 to 600 mg of caffeine when needed as a boost to stay awake. The exact safe limit of dietary intake of caffeine has not been established, and one well-known authority reports that more than five cups of coffee is too much. Another believes that some people who ingest as little as 100 mg of caffeine per day may acquire a physical dependence that could result in withdrawal symptoms. Clearly, there is a good deal of variability.

Intake of too much caffeine can result in jitters, stomach pains, and diarrhea. Several studies have shown that half of regular caffeine users would experience symptoms if they stopped. Symptoms would occur regardless of the type of caffeine product used. About 13% of those who get clinically ill from withdrawal have severe symptoms. The spectrum of symptoms includes difficulty concentrating, headache, irritability or depression, and a flu-like syndrome with fatigue and drowsiness. Other withdrawal symptoms include tremors, heart palpitations, cramps, and insomnia. The onset of symptoms occurs within 12 to 24 hours after cessation; peak symptoms occur in this time period and some withdrawal symptoms can last up to nine days. In severe cases, there may be time lost at work or users’ taking to bed with what is thought to be a bad case of flu.

There has been an exponential explosion of caffeine containing products in the U.S. markets during this decade, and it’s growing. Marketing surveys show that 55% to 90% of the U.S. population consumes caffeine in some form every day, and this is influenced by demographics. Caffeine is used to spike so-called energy drinks.

The phenomenal growth of Starbucks, with thousands of outlets in the U.S. and several other countries, is evidence of the growing trend of consumption of coffee drinks formulated into an elaborate menu of choices. This trend is now spreading through major fast food chains. Red Bull energy drinks have the highest popular profile of caffeine spiked drinks, and caffeine is being added to a variety of products, seductively packaged and widely sold – mints (30 mg), energy gum (40mg), lip balm, beer, candy, and interestingly, soap (200 mg per shower; the caffeine is absorbed through your skin). Fixx, an energy drink, contains 500 mg per 20- ounce bottle. Blow (the name making a pun on an illegal substance) is a legal, white caffeinebased powder that is actually sold in vials. This can be stirred into water or other types of drinks to deliver caffeine. Several soft drinks contain 80 mg to 150 mg of per can, while “energy” drinks vary from 75 mg to 300 mg per container. Sales containing caffeinated drinks went up 55% last year, a figure published by Beverage Digest.

The popularity of super-caffeinated drinks continues to soar. With names like Monster, Amp, and Full Throttle, in addition to Red Bull and many other caffeine containing beverages, are believed to add up to about $3 billion in annual sales. In one survey, one-third of 12- to 24- year-olds claimed they regularly consume energy drinks. Recent events involving high school students who drank Spike Shooter and middle school students who went to the emergency room after drinking Redline have educational authorities concerned that this, in addition to caffeine buzz or withdrawal, is indicative of risktaking behavior. Research has shown that high consumption of high-energy drinks is associated with a trend toward additional risk taking like unprotected sex, substance abuse, and violence. A collaborative study of college students at 10 universities recently showed that students who mixed energy drinks with alcohol got drunk twice as often as those who drank alcohol only. Aggressive sexual behavior was more likely in those who mixed drinks. As usual, manufacturers offer statements advising consumers to enjoy the products responsibly.

Research studies have linked coffee and caffeine to many illnesses, but have not been consistently validated, and several questions remain about the long term ill-effects on health. In average doses, it doesn’t seem to increase the risk of abnormal heart rhythm, but people with heart disease are advised to drink de-caffeinated beverages. Caffeine in dietary amounts causes increases in blood pressure. In one study of 85 men and women who abstained for one week and then took measured doses of coffee three times a day, persistent, mild elevations of blood pressure occurred daily in some of these habitual coffee drinkers.

Overall, the consumption of coffee has been decreasing markedly in the U.S. over the past two decades in some groups, especially because of increasing health consciousness. Those in the older age groups have moved to non-caffeinated beverages, yet there is a sizeable younger population for whom daily caffeine is a way of life. Extensive research has not shown that caffeine leads to any serious health problems. Clearly, there are limits, and those with heart disease, high blood pressure, and stomach problems should consult their doctors regarding their individual use of caffeine. Coffee and tea can be a pleasure when used safely. There are no rehabilitation centers in the United States solely for coffee dependence or addiction, but high-energy caffeinated beverage consumption is being seen more frequently in younger people, with multiple substance and drug use.

Dr. Silva is a professor of surgery at Wayne State University and a resident of Woodbluff on Mackinac Island.

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