Regular consumption of unsweetened coffee — whether regular or decaffeinated — reduces the risk of liver disease. It also has a beneficial effect on the microbiota, positively influencing mood.

Coffee consumption, including decaffeinated coffee, is associated with a lower risk of liver disease and related mortality: these are the findings of a study conducted by researchers at the Cedars-Sinai Medical Center in Los Angeles and published in the scientific journal Clinical Gastroenterology & Hepatology.

The researchers monitored more than 350,000 people over 13 years: at the start of the study, none of the participants suffered from cirrhosis or liver cancer. Coffee consumption habits — including the type of coffee and the use of sugar or sweeteners — were tracked through questionnaires. Blood tests and MRI scans were also carried out.

According to the study's findings, as the number of cups of coffee consumed increased, the risk of liver disease progressively decreased. Among those who drank five or more cups of coffee per day, researchers observed a 32 per cent reduction in the risk of developing liver cirrhosis, a 47 per cent reduction in the risk of contracting liver cancer, and a 42 per cent reduction in liver-related mortality. Coffee intake was also associated with physical indicators of a healthier liver: lower fat accumulation in the liver (steatosis), lower levels of hepatic iron, and a reduced presence of fibroinflammation.

These benefits are hypothesised to stem from higher levels of proteins linked to hepatic synthesis and proper immune system functioning, as well as lower levels of markers associated with scarring of liver tissue and chronic inflammatory activation.

The benefits proved to be entirely similar for both regular and decaffeinated coffee, suggesting that the protective effect is attributable to other antioxidant substances and compounds found in the plant itself, rather than to caffeine per se. The addition of sugar or artificial sweeteners, while not eliminating the benefits altogether, did slightly attenuate the positive effects on inflammation.

"Our findings support moderate coffee consumption for people who already enjoy it and tolerate it well," said Ju Dong Yang, one of the study's authors. This does not mean that starting to drink coffee solely to protect the liver is being recommended, but it does suggest that consuming unsweetened coffee — even in moderate amounts, such as three cups a day to balance any cardiovascular sensitivities, and as part of a balanced diet — can be a simple and effective strategy for preventing the progression of liver disease.

For regular coffee drinkers, the benefits extend to mood and the management of anxiety and stress as well: a study conducted by University College Cork and the University of Parma, published in Nature Communications, investigated the biological mechanisms by which coffee consumption influences the microbiota-gut-brain axis, seeking to understand what depends on caffeine and what, instead, on other substances present in the coffee bean. The observation involved 31 consumers (those who drink between three and five cups a day) and 31 non-consumers, whose psychological tests, food diaries, caffeine intake, and stool and urine samples were all analysed.

According to the results, coffee consumption would significantly improve mood, regardless of caffeine content. Coffee consumers were found to have a greater abundance of bacteria in the microbiota, particularly those associated with positive emotions in women. A notable improvement in learning and memory was observed only in those who consumed decaffeinated coffee, suggesting that components other than caffeine — such as polyphenols — are responsible for these cognitive benefits. However, in this study the researchers found that only caffeinated coffee was associated with a reduction in anxiety, as well as improvements in alertness and attention. Caffeine was also linked to a reduced risk of inflammation.

The researchers suggest that coffee is a complex dietary factor that interacts with our gut microbiota, our metabolism, and even our emotional wellbeing — and that, whether caffeinated or decaffeinated, it can influence health in distinct but complementary ways.