Coffee Consumption ‘More Likely to Benefit Health Than To Harm It’

Drinking three to four cups of coffee a day is associated with a lower risk of mortality and getting heart disease compared with drinking no coffee, according to an umbrella review of over 200 previous studies, published in the journal BMJ.

According to the scientists, coffee consumption is generally safe, but doctors should not recommend drinking coffee to prevent disease — and people should not start drinking coffee for health reasons. Image credit: Myriams Fotos.

Coffee is one of the most commonly consumed beverages worldwide. As such, even small individual health effects could be important on a population scale.

But existing evidence is of lower quality from observational research and randomized controlled trials are needed to strengthen the evidence of benefits.

To better understand the effects of coffee consumption on health, University of Southampton researcher Dr. Robin Poole and co-authors carried out a review of 201 studies that had aggregated data from observational research and 17 studies that had aggregated data from clinical trials across all countries and all settings.

Drinking coffee was consistently associated with a lower risk of mortality from all causes and from heart disease, with the largest reduction in relative risk of mortality at three cups a day, compared with non-coffee drinkers.

Increasing consumption to above three cups a day was not associated with harm, but the beneficial effect was 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 greatest benefit was seen for liver conditions, such as cirrhosis of the liver.

Finally, there seemed to be beneficial associations between coffee consumption and Parkinson’s disease, depression and Alzheimer’s disease.

There was less evidence for the effects of drinking decaffeinated coffee but it had similar benefits for a number of outcomes.

“However, drinking coffee in pregnancy may be associated with harms, and may be linked to a very small increased risk of fracture in women,” the authors said.

“Excluding pregnancy and women at risk of fracture, coffee drinking appears safe within usual patterns of consumption,” they concluded.

“We call for robust randomized controlled trials to understand whether the key observed associations are causal.”

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Robin Poole et al. Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes. BMJ 2017 (359): j5024; doi: 10.1136/bmj.j5024