Pros and cons at the soda machine

Caffeine: Its possible dangers -- as well as benefits -- are under study and debate

Health & Fitness

January 05, 2003|By Jamie Talan | By Jamie Talan,Special to the Sun

The smell of coffee does it for me -- every morning, every day. It's a strong lure, but one tempered by another force: After one cup, my brain responds that I've had enough, for the sheer pleasure in that first serving will turn into the jitters with a second.

The act of balancing caffeine's pleasure vs. its harm is one every coffee or tea drinker knows well. But scientists have taken the discussion in new directions -- to an examination of the impact of caffeine on health, far beyond the jitters.

Researchers have spent decades putting caffeine -- the ingredient in coffee, tea and cola -- under the microscope. So far, their efforts have yielded mixed results.

So what's a coffee drinker to do? Interviews with half a dozen researchers yielded sage advice: that two to three cups of caffeine-filled coffee, tea or cola a day is probably safe.

About two cups of a caffeinated beverage -- around 300 milligrams -- can nudge the brain's arousal system and bring on alertness, scientists say.

Thousands of studies have examined the effects of caffeine. Recent findings have been the result of the most popular research method on humans: asking them to recall how much they drink. And because memories can be faulty, the results don't represent science at its most definitive.

Among the recent studies are findings suggesting that four or more cups a day may have value. The study with the most dramatic conclusion reported that such consumption over time had improved the memory of women.

Scientists at the University of California in San Diego studied 1,500 people over age 50, asking about coffee-drinking habits over their lifetimes. Volunteers who said they drank six or more cups a day performed better on six of the 12 tests gauging their ability to think and react, compared with those who drank less coffee. But the effect was found only for women, and one subset performed the best: elderly women (over 80) with a long, sturdy history of coffee-drinking. They outperformed the others on 11 of the 12 tests.

The interpretation, according to scientists, is that coffee "may have a protective effect on the cognitive decline associated with aging." But why only for women?

As a mild stimulant, caffeine works on the brain chemical acetylcholine, which is involved with attention and memory. It's possible, the investigators reason, that the female brain, known to be more vulnerable to Alzheimer's, may be aided by caffeine's role on the brain system that regulates the chemical.

Another study concluded that coffee may reduce the risk of gallstones, this time in men and women. Other research has hinted at possible benefits at protecting against Parkinson's disease and diabetes.

Caffeine has also been linked to miscarriages, infertility, cancer, birth defects and heart disease.

But the scientific evidence isn't strong, according to Dr. Herbert Muncie, a professor and chair of family medicine at the University of Maryland.

"Caffeine is the most researched chemical in the world," said Muncie, "but people keep raising questions."

Michael Jacobson, executive director of the Center for Science in the Public Interest, has followed the food additive world for decades, "and one that stuck out like a sore thumb is caffeine because it caused birth defects in animals." He published a report in the British medical journal Lancet about three women who said that they drank more than 14 cups of coffee a day during pregnancy; each gave birth to children with missing digits.

Since the late 1970s, the Food and Drug Administration has advised women to cut down on caffeine during pregnancy -- no more than two cups a day. A few years ago, federal scientists found that women who consume six or more cups of coffee or tea during pregnancy have double the risk of miscarriage.

The effect on gallstones -- cholesterol-filled nuggets that lead to surgery for 800,000 Americans a year -- came from the continuing Nurses' Health Study, in which almost 81,000 women have been filling out lifestyle and health questionnaires since 1976. In 1980, the scientists began asking questions about diet.

Women who drank four or more cups of coffee or tea a day throughout the two decades had a 25 percent lower risk of having gallbladder disease that resulted in surgery.

The diabetes finding came from a study in which adults who consume seven cups of coffee daily were 50 percent less likely to develop Type 2 diabetes compared with those who drank two cups or less.

Why does caffeine appear to play a protective role against Parkinson's, diabetes and gallstones, as well as enhance women's memories and mental alertness? Even more studies will be necessary before scientists can close in on the answers.

Jamie Talan is a reporter for Newsday, a Tribune Publishing newspaper.

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