"A disclaimer: I do not own stock in
Starbucks nor, to my knowledge, in any other company that sells coffee or its
accouterments. I last wrote about America’s most popular beverage four years ago, and the latest and largest
study to date supports that earlier assessment of coffee’s health effects.
Although the new research, which
involved more than 400,000 people in a 14-year observational study, still
cannot prove cause and effect, the findings are consistent with other recent
large studies.
The findings were widely reported, but here’s the
bottom line: When smoking and many other factors known to
influence health and longevity were taken into account, coffee drinkers in the study were found to be living
somewhat longer than abstainers. Further, the more coffee consumed
each day — up to a point, at least — the greater the benefit to longevity.
The observed benefit of coffee
drinking was not enormous — a death rate among coffee drinkers that was 10
percent to 15 percent lower than among abstainers. But the findings are
certainly reassuring, and given how many Americans drink coffee, the numbers of
lives affected may be quite large.
Updating the Evidence
In decades past, experts repeatedly
warned that a coffee habit could harm health and shorten lives. And, indeed,
the new study did find that when the data were adjusted only for age, the risk
of death was greater among coffee drinkers.
But 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
to 71 and free of heart disease, cancer and stroke when the study began in
1995. By 2008, 52,515 had died. Dr. 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. But 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 to 10 ounces. The
gargantuan cups now often served would count as more than one cup, Dr. Freedman
said. Several of these extra-large cups can cause restlessness, irritability, sleeplessness and anxiety (and might enable me
to fly without an airplane).
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.
Effects on Health
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 70 milligrams in a shot of espresso to about 100 milligrams
in eight ounces of brewed coffee.
But 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 milligrams to 282
milligrams in an eight-ounce 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.
But 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 300 milligrams a day, but some studies have found
increased risk of low birth weight associated with consuming more than 150
milligrams a day.
Keep in mind, too, that caffeine is
a drug. Some medications, including Tagamet, Diflucan, Luvox, Mexitil,
estrogens and antibiotics like Cipro and Levaquin, interfere
with the metabolism of caffeine and can increase its effects.
In other cases, caffeine
can enhance the effect of drugs like aspirin and acetaminophen (a benefit for
pain relief). Caffeine can be toxic if used with prescribed"Source: NYTimes
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