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Coffee And Your Health
Say it's so, Joe: The potential health benefits and
drawbacks of coffee
By Neil Osterweil
WebMD Feature
Coffee may taste good and get you going in the
morning, but what will it do for your health?
A
growing body of research shows that coffee drinkers,
compared to non-drinkers, are less likely to have
type 2 diabetes, Parkinson's disease, and dementia
have fewer cases of certain cancers, heart rhythm
problems, and strokes.
“There is certainly much more good news than bad
news, in terms of coffee and health,” says Frank Hu,
MD, MPH, PhD, nutrition and epidemiology professor
at the Harvard School of Public Health.
But
(you knew there would be a “but,” didn’t you?)
coffee isn't proven to prevent those conditions.
Researchers don't ask people to drink or skip coffee
for science's sake. Instead, they ask them about
their coffee habits. Those studies can't show cause
and effect. It's possible that coffee drinkers have
other advantages, such as better diets, more
exercise, or protective genes.
So
there isn't solid proof. But there are signs of
potential health perks -- and a few cautions.
If
you're like the average person, who downed 416
8-ounce cups of coffee in 2009 (by the World
Resources Institute's estimates), you might want to
know what all that java is doing for you, or to you.
Here
is a condition-by-condition look at the research.
Type 2 Diabetes
Hu
calls the data on coffee and [type 2] diabetes
"pretty solid," based on more than 15 published
studies.
"The
vast majority of those studies have shown a benefit
of coffee on the prevention of diabetes. And now
there is also evidence that decaffeinated coffee may
have the same benefit as regular coffee,” Hu tells
WebMD.
In
2005, Hu's team reviewed nine studies on coffee and
type 2 diabetes. Of more than 193,000 people, those
who said they drank more than six or seven cups
daily were 35% less likely to have type 2 diabetes
than people who drank fewer than two cups daily.
There was a smaller perk -- a 28% lower risk -- for
people who drank 4-6 cups a day. The findings held
regardless of sex, weight, or geographic location
(U.S. or Europe).
More
recently, Australian researchers looked at 18
studies of nearly 458,000 people. They found a 7%
drop in the odds of having type 2 diabetes for every
additional cup of coffee drunk daily. There were
similar risk reductions for decaf coffee drinkers
and tea drinkers. But the researchers cautioned that
data from some of the smaller studies they reviewed
may be less reliable. So it's possible that they
overestimated the strength of link between heavy
coffee drinking and diabetes.
How might coffee keep diabetes at
bay?
“It’s the whole package,” Hu says. He points to
antioxidants -- nutrients that help prevent tissue
damage caused by molecules called oxygen-free
radicals. “We know that coffee has a very strong
antioxidant capacity," Hu says.
Coffee also contains minerals such as magnesium and
chromium, which help the body use the hormone
insulin, which controls blood sugar (glucose). In
type 2 diabetes, the body loses its ability to use
insulin and regulate blood sugar effectively.
It's
probably not the caffeine, though. Based on studies
of decaf coffee, “I think we can safely say that the
benefits are not likely to be due to caffeine," Hu
says.
Hold the Caffeine?
Just
because coffee contains good stuff, it does not
necessarily follow that it’s good for us, says James
D. Lane, PhD, professor of medical psychology and
behavioral medicine at Duke University Medical
Center in Durham, N.C.
“It
has not really been shown that coffee drinking leads
to an increase in antioxidants in the body,” Lane
tells WebMD. “We know that there are antioxidants in
large quantities in coffee itself, especially when
it’s freshly brewed, but we don’t know whether those
antioxidants appear in the bloodstream and in the
body when the person drinks it. Those studies have
not been done.”
Regular coffee, of course, also contains caffeine.
Caffeine can raise blood pressure, as well as blood
levels of the fight-or-flight chemical epinephrine
(also called adrenaline), Lane says.
Heart Disease and Stroke
Coffee may counter several risk factors for heart
attack and stroke.
First, there's the potential effect on type 2
diabetes risk. Type 2 diabetes makes heart disease
and stroke more likely.
Besides that, coffee has been linked to lower risks
for heart rhythm disturbances (another heart attack
and stroke risk factor) in men and women, and lower
risk for strokes in women.
In a
study of about 130,000 Kaiser Permanente health plan
members, people who reported drinking 1-3 cups of
coffee per day were 20% less likely to be
hospitalized for abnormal heart rhythms
(arrhythmias) than non-drinkers, regardless of other
risk factors.
And,
for women, coffee may mean a lower risk of stroke.
In
2009, a study of 83,700 nurses enrolled in the
long-term Nurses' Health Study showed a 20% lower
risk of stroke in those who reported drinking two or
more cups of coffee daily, compared to women who
drank less coffee or none at all. That pattern held
regardless of whether the women had high blood
pressure, high cholesterol levels, and type 2
diabetes.
Parkinson’s and Alzheimer's Diseases.
“For
Parkinson’s disease, the data have always been very
consistent: higher consumption of coffee is
associated with decreased risk of Parkinson’s,” Hu
tells WebMD. That seems to be due to caffeine,
though exactly how that works isn't clear, Hu notes.
Coffee has also been linked to lower risk of
dementia, including Alzheimer’s disease. A 2009
study from Finland and Sweden showed that, out of
1,400 people followed for about 20 years; those who
reported drinking 3-5 cups of coffee daily were 65%
less likely to develop dementia and Alzheimer’s
disease, compared with non-drinkers or occasional
coffee drinkers.
Cancer
The
evidence of a cancer protection effect of coffee is
weaker than that for type 2 diabetes. But “for liver
cancer, I think that the data are very consistent,”
Hu says.
“All
of the studies have shown that high coffee
consumption is associated with decreased risk of
liver cirrhosis and liver cancer,” he says. That's a
"very interesting finding," Hu says, but again, it's
not clear how it might work.
Again, this research shows a possible association,
but like most studies on coffee and health, does not
show cause and effect.
Pregnancy
In
August 2010, the American College of Obstetricians
and Gynaecologists (ACOG) stated that moderate
caffeine drinking – less than 200 mg per day or
about the amount in 12 ounces of coffee – doesn't
appear to have any major effects on causing
miscarriage, premature delivery, or fetal growth.
But
the effects of larger caffeine doses are unknown,
and other research shows that pregnant women who
drink many cups of coffee daily may be at greater
risk for miscarriage than non-drinkers or moderate
drinkers. Again, it's not clear whether the coffee
was responsible for that.
Calories, Heartburn, and Urine
You
won't break your calorie budget on coffee -- until
you start adding the trimmings.
According to the web site
myfoodapedia.gov, a 6-ounce cup of black coffee
contains just 7 calories. Add some half & half and
you'll get 46 calories. If you favor a liquid
non-dairy creamer that will set you back 48
calories. A teaspoon of sugar will add about 23
calories.
Drink a lot of coffee and you may head to the
bathroom more often. Caffeine is a mild diuretic –
that is, it makes you urinate more than you would
without it. Decaffeinated coffee has about the same
effect on urine production as water.
Both
regular and decaffeinated coffee contains acids that
can make heartburn worse.
©
WebMD. All rights reserved.
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“There is certainly much more
good news than bad news, in terms of coffee and
health.” |
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