Trending Science: Three cups of coffee a day keeps an early death away… maybe

Around 2.5 billion cups of coffee are consumed every single day, with caffeine now being the most popularly-used drug in the world, which stimulates the central nervous system, reducing tiredness and increasing alertness. 90% of us drink coffee daily and many of us simply feel that we can’t function without our early morning Cup of Joe (your writer included).

For years, there have been claims that regardless of its stimulating nature, coffee has wider health benefits and now two completely independent studies, one based in the UK and the other in the US, have made the connection a little clearer. However, rather than the caffeine itself, the researchers believe that it’s the antioxidant plant compounds in coffee are responsible for the benefits, rather than caffeine. Most interestingly, they found that even those who drank decaffeinated coffee were also protected.

The first study, led by the University of Southern California, looked at coffee consumption amongst 185 000 white and non-white participants, recruited in the early 1990s and followed up for an average of over 16 years. The results revealed that individuals who drink one cup of coffee per day was linked to a 12% lower risk of death at any age, from any cause, whilst those drinking two or three cups per day had an 18% lower risk, with the association not linked to ethnicity.

‘We found that coffee drinkers had a reduced risk of death from heart disease, from cancer, stroke, respiratory disease, diabetes and kidney disease,’ commented Veronica Setiawan, associate professor of preventive medicine, a co-author of the American study.

The European study, led by Imperial College London and the UN International Agency for Research on Cancer, tracked 520 000 people over the age of 35 in ten EU countries for an average of 16 years. ‘We felt this analysis would capture some [the] variation in coffee preparation methods and drinking habits,’ said Marc Gunter, a co-author of this study.

When taking into account a range of factors including age, smoking status, physical activity and education, those who drank three cups or more a day were found to have an 18 % lower risk of death for men, and an 8% lower risk of death for women of any age, compared to those who don’t indulge in the black gold. Importantly, the benefits were found to hold up regardless of any particular country, although coffee consumption was not linked to a lower risk of death for all types of cancer.

Looking at a sub-set of 14 800 participants, the research team found that coffee-drinkers had better results on many biological markers, including liver enzymes and glucose control. ‘We know many of these biological factors are related to different health outcomes, so it is another piece of the puzzle,’ says Gunter.

However, frustratingly for coffee addicts, the two research teams have warned that their results do not show that drinking coffee, in itself, is behind the overall lower risk. The studies did not look at socio-economic factors, such as how much coffee-drinkers earned compared to non-coffee drinkers. Possibly, it might be that people who drink three or more cups a day are richer with a good disposable income that may help them to stay healthier. Or people who drink three cups a day may socialise more, which adds to their wellbeing.