Coffee drinkers, rejoice!
The heavenly brew, once deemed harmful to health, is turning out to be, if not quite a health food, at least a low-risk drink, and in many ways a beneficial one. It could protect against diabetes, liver cancer, cirrhosis, and Parkinson's disease.
What happened? New research - lots of it - and the recognition that older, negative studies often failed to tease apart the effects of coffee and those of smoking because so many coffee drinkers were also smokers.
"Coffee was seen as very unhealthy," said Rob van Dam, a coffee researcher and epidemiologist at the Harvard School of Public Health. "Now we have a more balanced view. We're not telling people to drink it for health. But it is a good beverage choice."
As you digest the news on coffee, keep in mind that coffee and caffeine are not the same thing. In fact, "they are vastly different," said coffee researcher Terry Graham, chair of Human Health and Nutritional Sciences at the University of Guelph in Ontario, Canada. One can be good for you; the other, less so.
"Coffee is a complex beverage with hundreds, if not thousands, of bioactive ingredients," he said. "A cup of coffee is 2 percent caffeine, 98 percent other stuff."
Before we rhapsodize further, a few caveats:
Caffeine - whether in coffee, tea, soft drinks, or pills - can make you jittery and anxious and, in some people, can trigger insomnia. Data are mixed on whether pregnant women who consume caffeine are more likely to miscarry. In general, 200 milligrams a day - the amount in one normal-size cup of coffee - is believed safe for pregnant women, said van Dam.
For people with hard-to-control hypertension, a sudden, big dose of caffeine may boost blood pressure because caffeine constricts blood vessels. But decaf is fine. And even caffeinated coffee doesn't increase blood pressure much once you drink it for a week or so, said van Dam.
In fact, the caffeine in coffee seems to have less of an effect on blood pressure than the caffeine in colas because there are so many other substances in coffee that have the opposite effect physiologically from caffeine.
One final caveat: The new research heralding coffee's health benefits is not perfect. Most of the studies are observational, that is, they followed people over time and correlated health outcomes with coffee drinking - based on people's recollections of how much coffee they consumed. The studies don't prove that coffee was the cause of improved health outcomes.
Still, the sheer volume of the research, and the fact that the conclusions line up so neatly, make it reasonably credible, researchers say.