They found that coffee drinkers seemed a little more likely to live longer than folks who drink no coffee at all. Regular or decaf didn't matter.
That's reassuring because a few studies in the past suggested coffee might be harmful. Results of the latest study are published in Thursday's New England Journal of Medicine.
WHY THE FUZZY RESEARCH?
Older studies weren't wrong: Coffee can raise cholesterol and blood pressure in the short term, which in turn can raise the risk of heart disease.
But few studies have looked at coffee and the risk of dying of any cause, let alone specific diseases. Some of those that have involved too few deaths to make firm comparisons.
CAN WE TRUST THIS ONE?
No study is perfect, and like most diet studies, this one is just based on observing people's habits and resulting health. So it can't prove coffee lengthens lives. But experts say it's the best look yet at this issue.
It involved more than 400,000 people and was done by the National Institutes of Health and AARP.
Researchers also took into account smoking, drinking alcohol, exercise and other things that can skew results.
HOW MUCH DIFFERENCE DID COFFEE MAKE?
Very little, especially in relation to bigger factors such as smoking.
Compared with those who drank no coffee, men who had two or three cups a day were 10 per cent less likely to die at any age. For women, it was 13 per cent.
A single cup a day lowered risk a tiny bit: 6 per cent in men and 5 per cent in women. The strongest effect was in women who had four or five cups a day — they had a 16 per cent lower risk of death.
SO IT'S OK TO DRINK ALL I WANT?
Watch the sugar and cream. Extra calories and fat could negate any good from drinking coffee.
Doctors also suggest drinking filtered coffee — that removes the compounds that raise LDL or bad cholesterol.