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Diane Dew
Reprinted from The Covington News, 3/2/95
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Caffeine is America's drug of choice. Thirty percent of North Americans consume an average of 550 mg (the equivalent of six cups of coffee) per day. Ten percent ingest more than 1,000. Since medical science has determined that 650 mg of caffeine daily can cause serious health effects, many of us may be jeopardizing our health with java.
Although sanctioned by society as a stimulant, numerous clinical and laboratory studies have named caffeine as the culprit in many an unsolved medical case. Whatever its form – coffee, tea, cola, chocolate or prescription drugs – caffeine is still a drug.
Excessive caffeine consumption has been found to be a contributing factor in such varying conditions as osteoporosis, spontaneous abortion, reduced fertility, even an increase in the plasma level of total cholesterol. Tachycardia (rapid heart beat), involuntary muscle contractions, and ventricular fibrillation have also been attributed, at times, to excessive caffeine use – although the results of some studies have been contradictory.
Caffeine remains in the body from four to 12 hours, depending on the individual's rate of metabolism. It reaches its peak effect between 30 and 60 minutes after ingestion. However, smoking, liver disease, and the use of oral contraceptives, among other factors, affect the rate at which the substance is metabolized. (Nicotine shortens caffeine's effect; oral contraceptives increase it.)
Reduced bone density
Excessive caffeine consumption has been linked to decreased bone density, causing osteoporosis – especially among women. In old age, osteoporosis (a condition resulting in bone loss and embrittlement) increases the risk of hip fracture. This association is particularly pronounced when the diet is deficient in calcium.
However, sufficient calcium intake can adequately counterbalance caffeine's effect on calcium, according to a study by the Department of Family and Preventive Medicine at the University of California, San Diego.
Reduced fertility
Excessive caffeine consumption also interferes with fertility and can double or triple a woman's risk of miscarriage, a study by the National Institute of Health (NIH) indicates. This confirms a 1980 advisory by the Food and Drug Administration that pregnant women should restrict their use of caffeine. The toxic effect of caffeine upon the fetus is even more risky when the unborn child is also subjected to nicotine.
Stillbirth and growth retardation have also been linked to caffeine use in pregnancy, animal studies have shown.
Nevertheless, at least 75 percent of pregnant women drink caffeinated beverages.
Taken before and during pregnancy, caffeine has been attributed to miscarriage and reduced fertility, according to a study by Claire Infante-Rivard of the University of Montreal in Quebec, Canada. The more caffeine ingested, the more the risk of spontaneous abortion, the study showed.
For every five-ounce cup of coffee (or two cans of soda) consumed daily during pregnancy, the study showed, the risk of miscarriage increased by 122 percent. Caffeine consumed prior to the pregnancy had a lessened effect upon the fetus.
Use of caffeine has also been associated with difficulty conceiving, according to a study by epidemiologists Elizabeth Hatch, of the National Cancer Institute in Rockville, Md., and Michael Bracken of the Yale University School of Medicine. Women who consumed three cups of coffee (six cans of cola) daily were 27 percent less likely to conceive during each menstrual cycle, they found.
Some scientific studies also have discovered that caffeine, consumed in excess, can interfere with DNA duplication, causing mutations in cell reproduction, which results in genetic defects, cancers and tumors .
Addiction, withdrawal
A psychoactive drug (one that alters mood and behavior), caffeine is the most popular drug in the world. Annual world consumption is 120,000 tons.) Nevertheless, society does not view caffeine with the same criticism as it does other psychoactive drugs: heroin, marijuana, nicotine, cocaine and alcohol.
Popular for its brain-stimulating effects, caffeine may cause behavioral problems: restlessness, difficulty concentrating, increased stress, and insomnia. Its use has also been found to exacerbate existing anxiety disorders, and may be the cause of some panic attacks.
As with other drugs, caffeine produces in its subjects a level of tolerance, or acquired insensitivity to the drug. Although dependence upon caffeine in itself is not dangerous, an increased tolerance level often leads to increased usage, which, if dramatic, can cause serious effects. Physical dependence upon caffeine may result with a daily intake of 350 milligrams – the amount consumed by 20 percent of North Americans.
Excessive caffeine consumption (300 milligrams or more) has also been found to be a contributing factor in many psychiatric conditions, including depression, anxiety, tension and chronic insomnia.
Symptoms of caffeine withdrawal – headaches, drowsiness, fatigue, runny nose, depression, leg pains – occur within several hours after discontinued use, even by moderate coffee drinkers, and persist for 36 hours.
Benefits
Used in moderation, caffeine has no detrimental effects upon human health. In some uses it has proven beneficial. In newborns suffering from apnea (breathing failure), for example, caffeine has been used to induce breathing.
In the process of en vitro ferilization, caffeine improves the fertility rate by increasing the motility of sperm, researchers at the University of Pennsylvania School of Medicine have discovered. And the drug's ability to increase both mental alertness and physical endurance is helpful in many occupations in which physical endurance, rather than fine motor coordination, is required.
Despite the beneficial uses of caffeine, however, America's dependence upon the drug, and its many side-effects, should certainly be, as the title of one JAMA article described it, "grounds for concern."
Copyright © 1995 by Diane S. Dew
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Little-Known
Facts
on Caffeine
- Caffeine remains in a newborn's system up to 85 hours after birth. Unless the child is breast-fed (and thus continuing to receive the drug via the mother's milk), the baby may suffer breathing problems as a complication of withdrawal.
- Although tea, by weight, contains twice the caffeine of coffee beans, brewed coffee contains twice the caffeine of tea – because more water is added to tea.
- The caffeine content of a cup of coffee varies between 29 and 176 mg (tea contains between 8 and 91 mg), depending on its strength, the quality of the bean (or leaf, in the case of tea) and the size of the "cup."
- The US has the 12th highest per capita coffee consumption in the world.
- Worldwide, coffee is an annual $15 billion trade. It is the top agricultural import of North America, where caffeine consumption exceeds three times the world average.
Blood pressure
After conducting a detailed review of eleven earlier studies on the effects
of coffee drinking, Johns Hopkins public health researchers have found that
people with normal blood pressure consuming an average of five cups a day
for two months experienced an increase in systolic blood pressure by an average
of 2 millimeters, and diastolic blood pressure by an average of 1 millimeter.
The effect upon those with high blood pressure may be even greater.
Coffee still contributes much less to high blood pressure than either alcohol or sodium, however.
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