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It’s not easy to get a handle on caffeine and health. One month scientists seem to say that it’s bad for you. The next month they say that a cup or two of coffee a day is harmless.
Trying to link our health to what we eat is always tough, but it’s especially complicated with caffeine, says Alan Leviton, a neuroepidemiologist at the Harvard Medical School.
That’s because we rarely consume caffeine by itself. We swallow it mixed with sugar or hundreds of other chemicals in coffee, tea, cocoa, and colas. And how much caffeine you get depends on the type of coffee or tea you drink, how it’s brewed, how big your mug is even the type of coffee maker you use. Researchers rarely have all those details.
To complicate the picture, decaf drinkers are more likely than other coffee drinkers to take care of themselves. They tend to take more vitamins, exercise more faithfully, and eat more cruciferous vegetables like broccoli. They’re even more likely to use seat belts when they drive.
And heavy-coffee-drinkers generally smoke more, drink more alcohol, and eat more fatty foods than non-coffee-drinkers.
Can caffeine soothe your migraine? Or lift your tennis game? Or help you lose weight? Here are some things it can and can’t do.
Alcohol. Caffeine may make a drunk wide awake, but it won’t make him sober, reports Stephen Braun, author of Buzz, a new book on caffeine and alcohol ($25.00, 1996, Oxford University Press, Oxford, England)
Athletic Performance. Low to moderate doses of caffeine, maybe two to three cups of coffee, improve performance, at least in well-trained athletes in the laboratory, says Lawrence Spriet, a researcher at the University of Guelph in Canada. That may be why the excessive use of caffeine is restricted in international competitions.
Will a couple of cups of coffee help the weekend athlete? When people ask me I just laugh and say no, says Spriet.
You’d get far more benefit from proper nutrition and running more often.
Blood Pressure. Caffeine may cause a slight, temporary rise. But cutting back doesn’t appear to reduce the risk of or help treat hypertension.
Caffeine Dependence. Yes. It’s true. Go cold turkey and that headache is for real. How do you know if you’re dependent? One clue: You want to cut back but can’t.
Headaches. Caffeine increases the power of aspirin and other painkillers by about 40 percent. That’s why it’s in products like Anacin and Excedrin. Caffeine also appears to work by itself. In a 1991 study, 65 mg of caffeine as just as effective as 648 mg of acetaminophen in alleviating non-migraine headache symptoms. And doctors often treat migraines by prescribing combinations of caffeine and other drugs that constrict blood vessels in the brain.
Premenstrual Syndrome and Breast Lumps. Can eliminating caffeine lessen the symptoms? Some women swear that it does, but the research isn’t clear.
Problem Solving. Caffeine speeds up reaction time and improves automatic processing skills like doing arithmetic problems and proofreading, says author Stephen Braun. But for more complicated tasks, like complex word problems, caffeine has also been shown to worsen performance.
Sleep. Caffeine can delay the onset of sleep. It can also interfere with rapid eye movement (REM) sleep, the stage when people dream. In a recent study, women in Iowa who routinely took caffeine-containing medications reported having more trouble falling asleep at night than women who took no caffeinated medications.
Weight-loss. In 1991, the FDA banned the use of caffeine in over-the-counter weight-loss aids because it has no long-term effect on weight. 
Caffeine can be hard on your bones. The more regular coffee a woman drinks, the more calcium is excreted in her urine, says Linda Massey, a bone researcher at Washington State University in Spokane. (While no one has studied men, there is no reason to think that they react any differently.)
The loss amounts to about five milligrams of calcium for every six ounces of coffee or two cans of cola, says Janet Barger-Lux of Creighton University’s Osteoporosis Research Unit in Omaha, Nebraska.
Two tablespoons of milk or yogurt for each cup of coffee you drink will replace the lost calcium, says Barger-Lux.
Massey recommends an easy rule of thumb to not only compensate for the lost calcium, but to help build bone. Drink a cup of milk for each cup of coffee, she says.
| Birth Defects & Miscarriages |
Cleft palates. Missing toes and fingers.
In laboratory animals, very large amounts of caffeine seem to cause females to bear young that are malformed.
And birth defects were reported in the children of three women who drank 8 to 25 cups of coffee a day. In 1980, based largely on the animal evidence, the Food and Drug Administration (FDA) advised pregnant women to avoid caffeine-containing foods and drugs, if possible, or consume them only sparingly.
To its credit, the FDA was erring on the side of caution. While birth defects were never really shown to occur in humans at the lower levels we consume, that doesn’t get caffeine off the hook.
The studies that were done in the early 1980s to see if caffeine caused birth defects in humans weren’t powerful enough to detect an effect, notes Michael Bracken, a Yale University epidemiologist.
There are so many different kinds of birth defects and so many different causes of them that it’s extremely difficult to implicate caffeine, particularly if its effect is subtle. In other words, it’s still uncertain whether caffeine matters.
But caffeine may matter in another way, as more than a half dozen studies have shown.
For example, among nearly 4,000 women who gave birth in New Haven, Connecticut, in the early 1980s, those who consumed between 150 and 300 milligrams of caffeine a day during their pregnancies had more than twice the risk of delivering underweight babies (less than about 5 pounds) than those who consumed less. The risk was almost five times greater for women who consumed more than 300 milligrams a day.
Lower birth weight is linked to an increased risk of dying in early infancy, notes Bracken.
Unfortunately, researchers haven’t been able to tell if it’s the caffeine, the coffee, or something else about women who consume them that’s causing the low-birth weight babies. A new study at Yale is designed to answer the question.
It should also help determine whether caffeine increases the risk of miscarriage.
In 1996, a study by Bracken showed more than double the risk of miscarriage in women who were consuming more than 300 mg a day of caffeine.
Trying to become pregnant? Then make your coffee decaf.
Among 104 heart women, those who drank just one cup of regular coffee a day were half as likely to become pregnant during any given menstrual cycle as those who drank less, according to a 1988 study by Allen Wilcox of the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina.
Most of the ten studies conducted since then have also found that caffeine impairs fertility, but usually only at three or more cups of regular coffee a day.
But the research is only as good or bad-as the women’s memories. For example, scientists at Johns Hopkins University recently found that among 2,500 women who were trying to become pregnant, consuming more than 300 milligrams of caffeine a day reduced their chances of succeeding in any given month by 17 percent. But those results were based on the amount of coffee and soft drinks the women could remember having consumed as many as ten years earlier.
Even so, it’s probably prudent for women who are trying to become pregnant, and especially for those having trouble, to cut back on caffeine, says Mark Klebanoff of the National Institute of Child Health and Human Development in Bethesda, Maryland.
Cafestol and kahweol. Odds are you’ve never heard of these two substances, which are found in the oils in ground coffee.
And, as long as you drink instant or filtered drip coffee (which most home coffee machines make and most restaurants and coffee houses serve), odds are they’re not raising your LDL (bad) cholesterol or your triglycerides.
That’s because filters remove most of the cafestol and kahweol. So does the processing that goes into making instant coffee. Good thing.
In a small study published last year, LDL rose 12 percent and triglycerides rose 58 percent in healthy men and women who, for three weeks, were given oils from the equivalent of four to eight cups of non-filtered coffee a day. That jibes with a study that has monitored 1,040 men since they were medical students as long as 44 years ago.
Men who drank five or more cups of coffee a day before 1975 were two and a half times more likely to develop heart disease than men who drank no coffee, says Michael Kiag, an epidemiologist at Johns Hopkins University in Baltimore. But men who drank that much coffee after 1975 seemed to have no greater risk than non-coffee-drinkers.
What changed in 1975? Drip coffee makers became popular about that time, speculates Kiag.
That may explain why most recent studies see no higher risk of heart disease in coffee drinkers.
We looked at it in the Nurses’ Health Study and the Health Professionals Follow-up Study with many heavy coffee drinkers, men and women, over a long period of time, and we don’t see any effect whatever after proper adjustment for cigarette smoking, says researcher Meir Stampfer of the Harvard School of Public Health.
There doesn’t seem to be any relation, even with five cups a day, and even for people who already have heart disease. To most, it’s basically a dead issue. |
