Drinking a cup or two of coffee a day may benefit liver health, according to a new study. In particular, people who drank about three to four cups daily showed significantly lower risks of cirrhosis and liver cancer, as well as death from liver disease.
According to the medical community Wednesday, a research team led by Professor Hyun-seok Kim of Cedars-Sinai Medical Center in the United States published its findings in the latest issue of the international journal Clinical Gastroenterology and Hepatology. The team tracked 354,957 adults registered in the UK Biobank over an average of 13 years. The study subjects were adults who had no liver disease, such as cirrhosis or liver cancer, at the start of the survey.
The analysis found that coffee drinkers had lower liver disease risks overall. Those who drank one to two cups a day had a 20% lower risk of cirrhosis, a 24% lower risk of liver cancer, and a 31% lower risk of dying from liver disease compared with those who did not drink coffee.
Among those who drank three to four cups, the risks of cirrhosis and liver cancer fell by 35% each, while the risk of liver disease-related death dropped by 41%. The group that drank five or more cups a day also showed a 32% lower risk of cirrhosis, a 47% lower risk of liver cancer, and a 42% lower risk of liver disease death.
Additional analysis of data from about 29,000 people who underwent MRI scans yielded similar results. The more frequently people drank coffee, the less fat and iron accumulated in their livers, and their cT1 values, which indicate the degree of liver fibrosis and inflammation, were also lower.
In addition, a proteomic analysis of about 44,600 people confirmed a tendency for proteins related to liver cell function to increase, while proteins that induce inflammation and fibrosis decreased.
Interestingly, similar effects appeared with decaffeinated coffee. The researchers analyzed that, in addition to caffeine, antioxidant components such as polyphenols and various bioactive substances may have contributed to the liver-protective effect.
By contrast, coffee with sugar, artificial sweeteners, or highly processed creamer showed somewhat weaker effects. In particular, people who drank coffee with additives had relatively higher liver inflammation markers than those who drank black coffee. The researchers advised that if you drink coffee, reducing additives as much as possible may help.
However, the researchers stressed that because this was an observational study, it cannot be concluded that coffee directly prevents liver disease. Since coffee consumption was also surveyed based on participants' self-reported questionnaires, there is a possibility that memory errors were involved.
Professor Kim said, "Coffee can be a health habit that is relatively easy to practice," but noted that excessive caffeine intake can cause elevated blood pressure or increased heart rate, advising that "around three cups of unsweetened coffee a day is an appropriate level when considering both liver health and overall safety."
He added that while there are individual differences, for a good night's sleep it is generally "advisable to reduce coffee intake after 3 p.m."
