FOR those of us who wake up to the aroma and flavor of that morning brew, the evidence is in: Coffee, in moderation, is not bad for you after all. In fact, some studies indicate it may even have some health benefits.
For years the public was warned of the dangers of coffee, the main source of caffeine. In one well-publicized New England Journal of Medicine study released in 1981, researchers found a link between coffee and pancreatic cancer. But when at least seven other studies failed to back up that finding, those results had to be retracted.
Now, more than 19,000 dietary caffeine studies have been done, and many experts agree that moderate daily caffeine intake – 300 to 400 milligrams, about 3 to 4 cups of coffee – is not harmful. Here are the latest findings on what coffee does to the body and mind. Just a note though: the information discussed here are for educational purposes only.
Coffee and heart
The idea that coffee is bad for your heart pops up periodically. A Finnish study found that even those people who averaged 5 to 6 cups of coffee per day were not at a higher risk for developing heart disease than non-coffee drinkers. On the other hand, a Harvard study of 45,589 men, published in 1990, found no link between excessive coffee drinking and heart disease.
Research has also shown that regular, moderate drinking does not dangerously raise blood pressure. And studies have failed to substantiate fears that coffee might trigger abnormal heart rhythms (arrhythmias) in healthy people.
“For heart disease, I think the issue is closed,” says Dr. Meir Stampfer, an epidemiologist at Harvard who has studied many aspects of coffee and health. “Coffee drinking at reasonable levels is unrelated to heart risk.”
What about cancer?
Until recently, there is no conclusive evidence that caffeine or coffee is a risk factor for the development of human cancer. In 1990, the International Agency for Research on Cancer held a monograph on “Coffee, Caffeine, Tea & Maté,” the latter being a beverage unique to South American countries. The purpose of this monograph was to assess whether these beverages should be classified as being cancer causing (carcinogenic). Coffee was cleared in all areas with the exception of bladder cancer where there was insufficient evidence available at that time, though several studies have since been published that clearly show no link between coffee consumption and bladder cancer.
Thousands of research projects have been carried out to investigate any links between coffee consumption and the development of cancer in the human body. In 1997, the World Cancer Research Fund published a comprehensive review of diet and cancer. In regard to coffee it stated that, “Most evidence suggests that regular coffee consumption of coffee and/or tea has no significant relationship with the risk of cancer at any site.”
Parkinson’s disease (PD) is a progressive nervous disease that destroys dopamine-producing brain cells. The resulting symptoms are tremor, a slowing of movement, weakness and facial paralysis. In the past 30 years, nine studies have shown that regular coffee consumption over time may reduce the risk of PD. The coffee element that appears most likely to produce this effect is caffeine. Six retrospective studies found that people who drank coffee on a regular basis were 50 to 80 percent less likely to develop PD than those who did not consume coffee. Three of the studies showed a dose-response relationship – strong support that the more one consumes coffee, the less likely the risk of developing PD.
If regular coffee consumption over decades seems to protect against PD, how does it do so? One of the characteristics of PD patients is the reduced amount of dopamine in certain areas of the brain. Mice whose brain dopamine content has been depleted exhibit some symptoms of PD. In a 1991 study, caffeine given to these mice prevented the development of Parkinson symptoms. In a 2001 study, mice were given a chemical that depletes dopamine in important areas of the brain. Levels of caffeine intake comparable to human consumption reduced the amount of dopamine depleted in the brain as well as the physical symptoms typical of PD in humans—providing a molecular explanation for the neuroprotective effect of caffeine against PD.
Osteoporosis is a condition in which the bones are weakened, which in turn can lead to an increased risk of fractures occurring. Osteoporosis may be caused by many different factors, which collectively result in a weakening of the bones to such a degree that they break easily. Cigarette smoking, lack of exercise and poor nutrition are all well established as playing a role in the development of this condition.
Coffee drinking has been implicated because it has been suggested that caffeine, which is naturally occurring in tea, coffee, and chocolate and added to cola and some energy type beverages, causes calcium excretion which in turn results in weakened bones. However, a UK Government report on Nutrition and Bone Health which looked at all the available evidence concluded that concerns about loss of calcium in the urine due to caffeine intake, “are not well founded.”
The National Osteoporosis Society in the UK state that, “We have yet to see any conclusive evidence that moderate coffee consumption is a significant risk factor in the development of osteoporosis.” On the other hand, the Osteoporosis Society of Canada says that two or three cups of coffee are not harmful if you get enough calcium in your daily diet. “As long as women consume adequate calcium (1,000 to 1,200 milligrams per day) caffeine is not a significant risk factor for osteoporosis,” says one expert.
Caffeine and pregnancy
In 1980, pregnant women were first warned to avoid drinking coffee due to concerns that caffeine could result in low-birth-weight and miscarriages—caffeine easily crosses the placenta, and fetuses and newborns don’t have enough of the enzymes needed to metabolize it.
But the low-birth-weight theory has been difficult to prove since maternal smoking, a known cause of low birth weight, can confuse the results of studies.
The association between caffeine and miscarriages continues to be researched, however. Studies have found that while caffeine intake before and during pregnancy appears to be associated with increased miscarriages, several factors could cause a false association, including effects of morning sickness or nausea, the number of cigarettes smoked and amount of alcohol consumed.
The Motherisk program at The Toronto Hospital for Sick Children analyzed a large number of studies and concluded that there is “a small but statistically significant increase in risk of spontaneous abortion and low-birth-weight babies in pregnant women consuming more than 150 milligrams of caffeine a day,” or more than one to two cups a day, depending on the coffee’s strength.
Meanwhile, the US Food and Drug Administration classified caffeine as “generally recognized as safe.” The American Medical Association stated that “moderate tea or coffee drinkers probably need have no concern for their health relative to their caffeine consumption provided other lifestyle habits like diet, alcohol consumption are moderate as well.”