People who drink three to four cups of coffee a day are more likely to see health benefits than problems, experiencing lower risks of premature death and heart disease than those who abstain, scientists have said.
The research, which collated evidence from more than 200 previous studies, also found coffee consumption was linked to lower risks of diabetes, liver disease, dementia and some cancers.
Three or four cups a day confer the greatest benefit, the scientists said, except for women who are pregnant or who have a higher risk of suffering fractures.
Coffee is one of the most commonly consumed drinks worldwide. To better understand its effects on health, Robin Poole, a public health specialist at Britain’s University of Southampton, led a research team in an “umbrella review” of 201 studies based on observational research and 17 studies based on clinical trials across all countries and all settings.
“Umbrella reviews” synthesise previous pooled analyses to give a clearer summary of diverse research on a particular topic.
“Coffee drinking appears safe within usual patterns of consumption,” Pool’s team concluded in their research, published in the BMJ British medical journal on Wednesday.
Drinking coffee was consistently linked with a lower risk of death from all causes and from heart disease. The largest reduction in relative risk of premature death is seen in people consuming three cups a day, compared with non-coffee drinkers.
Drinking more than three cups a day was not linked to harm, but the beneficial effects were less pronounced.
Coffee was also associated with a lower risk of several cancers, including prostate, endometrial, skin and liver cancer, as well as type-2 diabetes, gallstones and gout, the researchers said. The greatest benefit was seen for liver conditions such as cirrhosis of the liver.
In a linked editorial, Professor Eliseo Guallar from the Johns Hopkins Bloomberg school of public health in Maryland wrote that “coffee is safe, but hold the cake”.
He argued that the latest study showed that “coffee consumption seems generally safe”, but added: “Coffee is often consumed with products rich in refined sugars and unhealthy fats, and these may independently contribute to adverse health outcomes ...
“Does coffee prevent chronic disease and reduce mortality? We simply do not know. Should doctors recommend drinking coffee to prevent disease? Should people start drinking coffee for health reasons? The answer to both questions is ‘no’.”
Poole’s team noted that because their review included mainly observational data, no firm conclusions could be drawn about cause and effect. But they said their findings support other recent reviews and studies of coffee intake.
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