Moderate coffee drinking is safe
Moderate coffee drinking is safe, and three to four cups a day may have some health benefits, according to a large review of previous studies, in the BMJ.
It found a lower risk of liver disease and some cancers, and a lower risk of dying from stroke - but researchers could not prove coffee was the cause.
Too much coffee during pregnancy could be harmful, the review confirmed.
Experts said people should not start drinking coffee for health reasons or to prevent disease.
The University of Southampton researchers collected data on the impact of coffee on all aspects of the human body, taking into account more than 200 studies - most of which were observational.
Was it the coffee?
Compared with non-coffee drinkers, those who drank about three cups of coffee a day appeared to reduce their risk of getting heart problems or dying from them.
The strongest benefits of coffee consumption were seen in reduced risks of liver disease, including cancer.
But Prof Paul Roderick, co-author of the study, said the review could not say if coffee intake had made the difference.
"Factors such as age, whether people smoked or not and how much exercise they took could all have had an effect," he said.
The findings back up other recent reviews and studies of coffee drinking so, overall, his message on coffee was reassuring.
"There is a balance of risks in life, and the benefits of moderate consumption of coffee seem to outweigh the risks," he said.
The NHS recommends pregnant women have no more than 200mg of caffeine a day - two mugs of instant coffee - because too much can increase the risk of miscarriage.
This review suggests women at risk of fractures should also cut back on coffee.
For other adults, moderate caffeine intake equates to 400mg or less per day - or three to four cups.
one mug of instant coffee: 100mg
one mug of filter coffee: 140mg
one mug of tea: 75mg
one can of cola: 40mg
one 250ml can of energy drink: up to 80mg
bar of plain chocolate: less than 25mg
bar of milk chocolate: less than 10mg
The researchers say coffee drinkers should stick to "healthy coffees" - which avoid extra sugar, milk or cream, or a fatty snack on the side.
And they are calling for rigorous clinical trials on coffee intake to find out more about the potential benefits to health.
At present, the researchers said pinning down exactly how coffee might have a positive impact on health was "difficult".