DrinkToYourHealth:StudyLinksDailyCoffeeHabitTo
LongevitybyAllisonAubreyNPR
If you have a daily coffee habit, here's something to buzz about: A new study finds those
cups of joe may help boost longevity. "In our study, we found people who drank three to
five cups of coffee per day had about a 15 percent lower [risk of premature] mortality
compared to people who didn't drink coffee," says one of the study authors, nutrition
researcher Walter Willett of the Harvard School of Public Health. Decaf drinkers also
saw benefits.
The findings, published in the journal Circulation, build on a body of evidence linking a
coffee habit to potential health benefits.
As we've reported, previous research has pointed to a decreased risk of stroke. And,
there's some evidence that a coffee habit cuts the risk of Type 2 diabetes, too.
Now, of course, it's possible to overdo it with caffeine. Research has shown that
consuming more than 400 milligrams of caffeine can interfere with sleep and create
feelings of unease. And some of us are even more sensitive. (I feel jittery if I have more
than one strong cup!)
One study found that 200 milligrams of caffeine (the equivalent of about two cups of
coffee) is an optimal amount to enhance cognitive function and mood among sleepdeprived people. But we don't all metabolize caffeine the same way.
As we've reported, the caffeine amounts in coffee vary wildly. One analysis, conducted
by Bruce Goldberger, found a 16-ounce cup of caffeinated coffee from Starbucks could
contain anywhere from 250 milligrams to more than 500 milligrams of caffeine.
"Not everyone reacts to coffee in the same way," says Andrew Maynard, who studies risk
assessment at Arizona State University. He summarizes the benefits documented in this
study as "small."
He says this study does not prove cause and effect between drinking coffee and living
longer. Rather, it points to an association. "There are a lot of unknowns as to what [may
explain] the increase in life expectancy," Maynard says.
Got more questions? So did we. Here's our conversation about the findings with study
co-author Walter Willett, edited for length and clarity.
So, what do you think might explain this association? In the study, you
point to compounds in coffee — such as lignans, quinides and magnesium —
that may help reduce insulin resistance and inflammation. Prior studies
have pointed to these as well.
We're not sure exactly how coffee is [linked] to all these benefits. The coffee bean itself is
loaded with many different nutrients and phytochemicals. And my guess is that they're
working together to have some of these benefits.
We [see] similar benefits from caffeinated and decaffeinated coffee. That's important,
because it suggests that caffeine is not responsible for [the benefit].
So this may be welcome news to people who drink decaf?
Yes, because too much [caffeinated] coffee can cause insomnia and loss of sleep, and
that's not a good thing!
The reduced risk of death was not seen among the coffee drinkers in your
study who were smokers or former smokers.
Definitely. It's extremely important to disentangle the effects of coffee from the effects of
cigarette smoking.
So, what's the take-home here? Is it that coffee can be part of a healthy
lifestyle?
I think if people like coffee, it's fine to include it [as part of your daily habit]. So,
certainly, [people] should not feel guilty about moderate coffee consumption. It
definitely can be part of a healthy lifestyle.
I wouldn't suggest that someone who doesn't like coffee go out and drink it.
Are you a coffee drinker? Are these findings likely to influence your own
behaviors?
Well, I really like a good cup of coffee. But if I have more than two cups a day, I really
don't sleep as well. So, I've been switching more toward decaf or half decaf/half regular.
In this study, you also analyzed how coffee influenced the risk of specific
diseases — or categories of diseases. What did you find?
We went beyond total mortality and looked at specific causes of death. And we found
that people who drink moderate amounts of coffee have lower risk of [death] from
cardiovascular disease, diabetes, neurologic disease [such as Parkinson's] and suicide.
Your findings come from data from two Nurses' Health Studies, which
included about 167,000 women. And it also looked at the 40,000 men in the
Health Professionals Follow-up Study.
As you point out, the participants in these studies are about 95 percent
white, largely middle-class and well-educated. Can you extrapolate to other
populations?
Yes, I'm quite sure these findings would apply to other populations. This is a biological
relationship. And we basically have a common biology.
Original publication: “Association of Coffee Consumption with Total and Causespecific Mortality in Three Large Prospective Cohorts,” Ming Ding, Ambika Satija,
Shilpa N. Bhupathiraju, Yang Hu, Qi Sun, Walter Willett, Rob M. van Dam, Frank B.
Hu, Circulation, online November 16, 2015.