Data collected across 10 European countries, found that while three or more cups of coffee a day may reduce risk of death by between 8% and 18% from circulatory and digestive-related conditions, a higher intake correlated to a higher cancer mortality amongst women.
“We found that higher coffee consumption was associated with a lower risk of death from any cause, and specifically for circulatory diseases, and digestive diseases,” said lead author Dr Marc Gunter of the International Agency for Research on Cancer (IARC) and formerly of Imperial College London.
“Importantly, these results were similar across all of the 10 European countries, with variable coffee drinking habits and customs. Our study also offers important insights into the possible mechanisms for the beneficial health effects of coffee.”
This study, along with a similar multi-ethnic cohort study carried out in the US, is in keeping with previous evidence, which generally identify death rates to be slightly lower in coffee drinkers than in non-coffee drinkers.
‘Coffee’s protective health effect’
Despite their findings, the authors, from IARC and Imperial College London were unable to establish cause and effect, for overall death or specific causes of death (e.g. cancer, heart disease).
In their concluding remarks, they added though that coffee drinking was unlikely to be harmful.
“These findings add to a growing body of evidence which indicates that drinking coffee not only is safe, but it may actually have a protective health effect for people,” said Professor Elio Riboli, head of the School of Public Health at Imperial and study author.
“While further research is needed, we can be confident that the results from a large European study confirm previous findings seen around the world.”
Using information gathered from the European Prospective Investigation into Cancer and Nutrition (EPIC) study, the team’s findings involved over 520,000 people, 35 years and over from 10 EU countries, including the UK, France, Denmark and Italy.
Their dietary habits were evaluated using questionnaires and interviews, with the highest level of coffee consumption (by volume) identified in Denmark (900 millilitres (ml) per day). Italy was the lowest with around 92ml per day.
Those who drank more coffee were also more likely to be younger, to be smokers, drinkers, eat more meat and less fruit and veg.
Around 42,000 people died during a follow-up period of 16 years, from a number of conditions including cancer, circulatory diseases, heart failure and stroke.
By adjusting for lifestyle factors, the researchers found that for men and women with the highest coffee consumption had a lower risk for all-causes of death, compared to those who did not drink coffee.
Among women, high consumption of coffee was linked to a lower risk of death from circulatory disease and cerebrovascular disease mortality.
The study found a positive association between higher coffee consumption and a higher risk of death from ovarian cancer.
Further findings in a subset of 14,000 people found a higher coffee consumption was associated with a healthier metabolic biomarker profile.
This included lower serum alkaline phosphatase; alanine aminotransferase; aspartate aminotransferase; γ-glutamyltransferase;
In women, this meant lower C-reactive protein, lipoprotein(a), and glycated hemoglobin levels.
“We found that drinking more coffee was associated with a more favourable liver function profile and immune response,” explained Dr Gunter.
“This, along with the consistency of the results with other studies in the U.S. and Japan gives us greater confidence that coffee may have beneficial health effects.”
Population-wide findings
Dr Tim Chico, reader in cardiovascular medicine and consultant cardiologist based at the University of Sheffield added that both studies had the advantage of observing thousands of people from many different countries and ethnic backgrounds, and the association between coffee drinking and mortality seems to be the same across all these populations.
However, he added that neither study took into account the income of the people involved.
“Since coffee isn’t cheap it is possible that non-coffee drinkers are less well off, which would be a potential explanation for some of the differences seen.”
Professor Kevin McConway, emeritus professor of applied statistics at The Open University, added that it was worth noting that coffee consumption was not well defined.
“In the European study, this shows up in the amount of coffee (in in millilitres) that defined the group who drank the most coffee. In Italy, you had to drink only 138ml a day to be in that group, while the limit for that group was 750ml in the Netherlands (and 488ml in the UK). “
“Doubtless that has something to do with the type and strength of coffee that is drunk in different countries – Italian coffee cups are typically very small and very strong.
“But maybe other effects are at play. Perhaps there is some social aspect of drinking several cups of coffee a day that has a protective effect on health, regardless of what is actually in the coffee? These studies can’t tell us.”