Caffeine: the inside scoop.
A well-timed mug of coffee, cup of tea, or can of cola can lift the curtains on a groggy mine or buy a few more hours of alertness.
"I probably even owe my life to coffee, because it kept me alert during World War II," confesses cancer researcher John Weisburger of the American Health Foundation. like millions of others, Weisburger doesn't drink regular coffee in the afternoon. "If I do, it disturbs my sleep," he says. You can thank caffeine for that...and for the wonderful sense of well-being that comes from a steaming cup of coffee.
But if you're a woman who's worried about brittle bones or who's trying to become pregnant, you may want to say "no thanks."
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.(1)
And heavy-coffee-drinkers generally smoke more, drink more alcohol, and eat more fatty foods than non-coffee-drinkers.(2)
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.(3) 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, Co 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 1/2 pounds) than those who consumed less. The risk was almost five times greater for women who consumed more than 300 milligrams a day.(4)
"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.(5)
Trying to become pregnant? Then make your coffee decaf.
Among 104 healthy 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.(6)
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 woman 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.(7) 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.
RELATED ARTICLE: Wish Upon a Starbucks
Watching your caffeine? Then watch out for Starbucks.
According to the "Coffee and Caffeine" brochure that's available at every outlet, "a typical cup of regular Starbucks might contain 100 milligrams of caffeine."
Might? The only way it might is if it weren't a typical cup of regular Starbucks coffee.
According to the company's own lab analyses, the smallest size coffee you can get, an 8-oz. "short," contains a whopping 250 milligrams of caffeine. A 16-oz. "grande" has a nervebusting 550 milligrams.
Compare that with the 110 milligrams of caffeine in an 8-oz. cup of Maxwell House.
Why is Starbucks so caffeine-rich?
To start with, the company's "darker" roasting drives more moisture out of the 3 beans. That means more coffee in each tablespoon. Then, to create its "signature" flavor, Starbucks uses twice the usual amount of grounds-about 2 2/3 tablespoons per 8-oz. cup.
"So our caffeine content will be higher," admitted a company spokesperson.
Of course, anybody reading Starbucks's "Coffee and Caffeine" brochure would think just the opposite: "The best advice for those wishing to enjoy full-flavored coffee with lower caffeine content," it says, "is to avoid bland, caffeine-rich commercial blends...and enjoy your Starbucks in moderation."
Maybe it's time for a new brochure.
RELATED ARTICLE: Coffee and....
Most of the caffeine we consume comes from coffee. Is there anything else in that cup of java we should worry about?
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 11 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.(1)
That jibes with a study that has monitored 1,040 men since they were medical students as long as 44 years ago.(2)
"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 Klag, 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 Klag.
That may explain why most recent studies see no higher risk of heart disease in coffee drinkers.(3)
"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.(4,5)
"There doesn't seem to be any relation, even with five cups a day, and even for people who already have heart disease. To my mind, it's basically a dead issue."
The connection between coffee and cancer was seared into the American health psyche in 1981, when a study published in the prestigious New England Journal of Medicine concluded that "coffee use might account for a substantial proportion of the cases of [pancreatic cancer] in the United States"(6)
But most studies since then have come up empty.(7)
"Coffee is not likely to be causing pancreatic cancer," concludes Debra Silverman, an epidemiologist at the National Cancer Institute in Bethesda, Maryland. "Smoking is clearly a risk factor, and once you take that into account, most studies show that coffee drinking doesn't seem to be associated with an increased risk."
As for cancers of the bladder, breast, colon, lung, or prostate, "there's no good evidence that coffee has any role in their development," says John Weisburger of the American Health Foundation.
(1) J. Internal Med. 237: 543, 1995. (2) Annals of Epidem. 4: 425, 1994. (3) British Heart Journal 72: 269,1994. (4) J. Am. Med. Assoc. 275: 458, 1996. (5) New Eng. J Med. 323: 1026, 1990. (6) New Eng. J Med. 304: 630, 1981. (7) Pancreas II: 223, 1995.
RELATED ARTICLE: The Good, The Bad...and the Myths
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.(1) 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 was just as effective as 648 mg of acetaminophen in relieving non-migraine headache symptoms.(2) 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.(3)
* 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.
(1) J. Amer. Med. Assoc. 251: 1711, 1984. (2) Pain 44: 151, 1991. (3) J. Amer. Geriatric Soc. 43: 860, 1995.
RELATED ARTICLE: THE BOOTOM LINE
* To build bone, women should drink one cup of (skim or 1%) milk for every cup of regular coffee.
* The caffeine in three or more daily cups of regular coffee may lessen a woman's chance of becoming pregnant.
* To reduce the risk of miscarriage, birth defects, and underweight babies, pregnant women should consume as little caffeine as possible.
RELATED ARTICLE: The Caffeine Corner
* Caffeine is similar in structure to adenosine, a chemical found in the brain that slows down its activity. Since the two compete, the more caffeine you drink, the less adenosine is available...up to a point. That's why caffeine temporarily heightens concentration and wards off fatigue.
* Within 30 to 60 minutes of drinking a cup of coffee, caffeine reaches peak concentrations in the bloodstream. It typically takes four to six hours for its effects to wear off.
* Smokers remove caffeine from their blood twice as fast as nonsmokers. That may be why smokers tend to drink more coffee.
* The average American adult consumes about 200 milligrams (mg) of caffeine a day, and the top ten percent consume an average of 400 ma, according to John J. Barone, who tracks caffeine consumption at The Coca-Cola Company in Atlanta.
* As little as 200 mg of caffeine is enough to make some people feel nervous and anxious. It might take even less for cola-guzzling kids.
* The typical American drinks about two cups of coffee a day. In 1962, when coffee consumption hit its peak, three cups was typical.
* Coffee accounts for about three-quarters of the caffeine we consume. Tea makes up about 15 percent, soft drinks about ten percent, and chocolate about two percent. Here are average caffeine levels of popular beverages, foods, and drugs (rounded to the nearest 5 milligrams):
Coffee grande (16 oz.) Starbucks 550 Coffee, tall (12 oz.), Starbucks 375 Coffee short (8 oz.), Starbucks 250 NoDoz, Maximum Strength (1), or Vivarin (1) 200 7-Eleven Big Gulp cola (64 oz.) 190 Coffee, non-gourmet (8 oz.) 135(*) Excedrin (2) 130 Maxwell House (8 oz.) 110 Caffe Americano, grande (16 oz.) Starbucks 105 NoDoz, Regular Strength (1) 100 Coffee instant (8 oz.) 95(*) Caffe Americano, tall (12 oz.), Starbucks 70 Caffe Latte or Cappuccino grande (16 oz.) Starbucks 70 Caffe Mocha, grande (16 oz.), Starbucks 70 Espresso double (2 oz.) Starbucks 70 Water, caffeinated ([Edge.sup.2]O) (8 oz.) 70 Anacin (2) 65 Cola (20 oz.) 60(*) Mountain Dew (12 oz.) 55 Cola (16 oz.) 50(*) Tea, leaf or bag (8 OZ.) 50 Caffe Americano, short (8 oz.), Starbucks 35 Caffe Latte, short (8 oz.) or tall (12 oz.), Starbucks 35 Caffe Mocha, short (8 oz.) or tall (12 oz.), Starbucks 35 Cappuccino, short (8 oz.) or tall (12 oz.), Starbucks 35 Cola (12 oz.) 35(*) Espresso (1 oz), Starbucks 35 Tea, green or instant (8 oz.) 30(*) Chocolate, dark, bittersweet or semi-sweet (1 oz.) 20(*) Coffee, decaf, grande (16 oz.) Starbucks 15 Tea, bottled (12 oz.) or from instant mix (8 oz.) 15(*) Coffee, decaf, short (8 oz.) or tall (12 oz.) Starbucks 10 Chocolate, milk (1 oz.) 5(*) Cocoa or hot chocolate (8 oz.) 5(*) Coffee, decaf, non-gourmet (8 oz.) 5(*) Espresso decaf (1 oz.) Starbucks 5 Tea, decaf (8 oz.) 5(*)
(*) = typical value. Sources: National Coffee Association, National Soft Drink Association, Tea Council of the USA, Starbucks Coffee Company, package labels, and Food Chemistry and Toxicology 43:119, 1996.
(1) Epidemiology 5: 537, 1994. (2) Ecol. Food Nutr. 31: 285, 1994. (3) Lancet 1:415, 1981. (4) Amer J. Epidem. 126: 813, 1987. (5) Epidemiology 7: 250, 1996. (6) Lancet 2: 1453, 1988. (7) Amen J. Epidem. 142: 1322, 1995.
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|Title Annotation:||includes related information on caffeine content and health aspects of coffee, health aspects of caffeine and other sources of caffeine|
|Publication:||Nutrition Action Healthletter|
|Article Type:||Cover Story|
|Date:||Dec 1, 1996|
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