11 Jul 2017 --- People who drink around three cups of coffee a day may live longer than non-coffee drinkers, according to a study in which scientists analyzed data on coffee consumption from more than half a million people across ten European countries. In a subset of 14,000 people, the researchers also analyzed metabolic biomarkers, and found that coffee drinkers may have healthier livers overall and better glucose control than non-coffee drinkers.

Researchers from the International Agency for Research on Cancer (IARC) and Imperial College London found that higher levels of coffee consumption were associated with a reduced risk of death from all causes, particularly from circulatory diseases and diseases related to the digestive tract.

Although previous studies on coffee consumption and health outcomes have yielded conflicting results, studies in both the US and Japan have since revealed a potential beneficial effect of drinking coffee on risk of death from all causes.

In the latest study, published in the journal Annals of Internal Medicine, researchers have carried out the largest analysis of the effects of coffee-drinking in a European population and found a similar association between consumption and mortality, with a lower risk of death from any cause, and specifically for circulatory diseases and digestive diseases.

“Importantly, these results were similar across all of the ten European countries, with variable coffee drinking habits and customs,” says lead author Dr. Marc Gunter of the IARC and formerly at Imperial’s School of Public Health.

Using data from the EPIC study (European Prospective Investigation into Cancer and Nutrition), the group analyzed data from 521,330 people from over the age of 35 from ten EU countries, including the UK, France, Denmark and Italy.

The highest level of coffee consumption (by volume) was reported in Denmark (900 mL per day) and the lowest in Italy (approximately 92 mL per day). The data also showed that those who drank more coffee were also more likely to be younger, to be smokers, drinkers, eat more meat and less fruit and vegetables.

After 16 years of follow-up, almost 42,000 people in the study had died from a range of conditions including cancer, circulatory diseases, heart failure and stroke. Following statistical adjustments for lifestyle factors such as diet and smoking, the researchers found that the group with the highest consumption of coffee had a lower risk for all causes of death, compared to those who did not drink coffee. They found that decaffeinated coffee had a similar effect.

However, consumption of caffeinated and decaffeinated coffee is not simple to separate, as they could not exclude that decaffeinated coffee drinkers may have been consuming caffeinated coffee as well in different periods of their life.

“We found that drinking more coffee was associated with a more favorable liver function profile and immune response,” explained Dr. Gunter. “This, along with the consistency of the results with other studies in the US and Japan gives us greater confidence that coffee may have beneficial health effects.”

According to the group, more research is needed to find out which of the compounds in coffee may be giving a protective effect or potentially benefiting health.

Still, Professor Elio Riboli, Head of the School of Public Health at Imperial, who established the EPIC study, states that these findings add to a growing body of evidence which indicates that drinking coffee not only is safe, but may well have a protective health effect for people.

“Due to the limitations of observational research, we are not at the stage of recommending people to drink more or less coffee. That said, our results suggest that moderate coffee drinking – up to around three cups per day – is not detrimental to your health and that incorporating coffee into your diet could have health benefits,” Dr. Gunter adds.

In related news, a study published last month in the Journal of Hepatology found that drinking coffee and herbal tea may protect against liver fibrosis, i.e. scarring of the liver resulting from chronic inflammation.