Coffee may taste good and get you going in the morning, but what will it do for your health?
- 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 the sake of science.
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 American, 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 the 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.
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