The observed benefit of coffee drinking was not enormous -- a death rate among coffee drinkers that was 10-15% lower than among abstainers. However, the findings are certainly reassuring, and given how many Americans drink coffee, the numbers of lives affected may be quite large.
In decades past, experts repeatedly warned that a coffee habit could harm health and shorten lives. Indeed, the new study did find that when the data were adjusted only for age, the risk of death was greater among coffee drinkers.
However, when the researchers took into account other health-related characteristics among the participants, like smoking, alcohol use, meat consumption, physical activity and body mass index, those who regularly drank coffee lived longer.
“Coffee drinkers shouldn’t be worried,” said Neal Freedman, an epidemiologist at the National Cancer Institute who directed the study. “Their risk is quite similar to that of nondrinkers.”
Coffee drinkers who were relatively healthy when the study began were less likely than nondrinkers to die of heart disease, respiratory disease, stroke, diabetes, infections, injuries and accidents.
The study, published in May in The New England Journal of Medicine, examined data on 402,260 adults in the National Institutes of Health-AARP Diet and Health Study. They were ages 50-71 and free of heart disease, cancer and stroke when the study began in 1995. By 2008, 52,515 had died. Freedman and his co-authors examined why they died in relation to how much coffee they said they drank when the study began.
The risk of death gradually dropped as the number of cups the participants drank increased to four or five. At six cups or more each day, there was a slight rise in death risk, compared with that at four or five cups. However, the chances of death remained lower than among people who drank no coffee.
Reflecting practices of the mid-1990s, the researchers considered a cup of coffee to be 8-10oz. The gargantuan cups now often served would count as more than one cup, Freedman said. Several of these extra-large cups can cause restlessness, irritability, sleeplessness and anxiety.
Contrary to previous belief, at usual levels of consumption, coffee is not any more of a diuretic than the equivalent amount of water. Up to six cups a day can be counted toward one’s recommended liquid intake.
Coffee is a complex substance that contains more than 1,000 compounds that may affect health. Caffeine, a stimulant, is the most studied and sought after. The amounts in coffee can vary greatly, from about 70mg in a shot of espresso to about 100mg in 8oz. of brewed coffee.
However, there can be wide variability in caffeine levels, even in similar beverages. As Jane V. Higdon and Balz Frei of Oregon State University reported in Critical Reviews in Food Science and Nutrition, when the same type of coffee was purchased from the same store on six different days, the caffeine content varied from 130-282mg in an 8oz. cup.
Nor is caffeine is the only compound in coffee important to health. In the new study, little or no difference was found in death rates among those who drank predominantly caffeinated coffee or decaffeinated coffee. Other substances -- like antioxidants and polyphenols -- probably also play a health-related role, the researchers noted.
Their findings should reassure people concerned about possible harm from substances long used to remove caffeine from coffee. Fear of these chemicals prompted many manufacturers to switch to the Swiss water method for removing caffeine.
How coffee is brewed can make a health difference. Two prominent chemicals in coffee beans, cafestol and kahweol, are known to raise blood levels of cholesterol and especially artery-damaging LDL cholesterol. These substances are removed when coffee is prepared through a filter, but remain in espresso, French press and boiled coffee. Single-serving coffee pods, like those used in a Keurig, contain filters.
Even though coffee can cause a temporary rise in blood pressure, the new study, like those before it, found the risk of heart disease to be lower among otherwise healthy coffee drinkers. Other benefits suggested by recent studies include a reduced risk of type 2 diabetes, liver disease and Parkinson’s disease. Some research has found a reduced risk of depression, dementia and Alzheimer’s disease among coffee drinkers.
People who engage in strenuous physical activities can also benefit, but only if their coffee contains caffeine, which helps muscles use fatty acids for energy and blunts the effect of adenosine, extending the time before muscles fatigue. Post-exercise soreness is also reduced and recovery time shortened.
Whether coffee poses a risk to pregnant women remains controversial. A causal relationship between coffee consumption and miscarriage has not been demonstrated at caffeine intakes of less than 300mg a day, but some studies have found increased risk of low birth weight associated with consuming more than 150mg a day.
From the July 2, 2012, Prepared Foods Daily News