Coffee drinkers had a lower risk of chronic liver disease and death due to chronic liver disease compared to non-coffee drinkers, U.K. researchers found in a large observational study.
Compared to non-coffee drinkers, coffee drinkers had a 49% reduced risk of death from chronic liver disease (HR 0.51 95% CI 0.39-0.67), and a 20% to 21% reduced risk of incident chronic liver disease (HR 0.79, 95% CI 0.72-0.86) and incident chronic liver disease or steatosis (HR 0.80, 95% CI 0.75-0.86), reported Oliver J. Kennedy, MD, PhD, of the University of Southampton in England, and colleagues.
However, the association between coffee consumption and hepatocellular carcinoma was non-significant (HR 0.80, 95% CI 0.54-1.19), the authors wrote in BMC Public Health.
“The idea that drinking coffee decreases the adverse risks of chronic liver disease has been brewing (excuse the pun) for some time now,” Craig Gluckman, MD, a gastroenterologist at UCLA Health in West Hills, California, told MedPage Today.
“There is a major burden of disease from chronic liver disease due to alcohol, viral hepatitis, fatty liver, etc., so any potential protective mechanism must be taken seriously,” added Gluckman, who was not involved in the study.
Chronic liver disease can lead to fibrosis, cirrhosis, liver failure, or death, and treatment options are often limited in lower-to-middle income countries, where incidence remains high, noted Kennedy and colleagues.
Previous studies found greater consumption of coffee provided lower risks of chronic liver disease and studies also linked coffee with protecting against hepatocellular carcinoma. The authors noted that the current study was the first large cohort to investigate all coffee types including decaffeinated, ground, instant coffee, and found all types reduced the onset and progression of chronic liver disease.
“Caffeine is a non-selective antagonist of the A2A receptor, activation of which stimulates collagen production by hepatic stellate cells, the primary mediators of fibrosis,” they wrote. “Given the protective effects of the different coffee types with varying composition, there may be a complex relationship involving more than one active ingredient.”
This study analyzed data from 494,585 individuals from 22 U.K. Biobank centers who had medical or death records for statistical analysis. Among them, 78% were coffee-drinkers.
The main outcomes included incidence of chronic liver disease, hepatocellular carcinoma, or death caused by chronic liver disease in relation to all types of coffee consumption. The incidence of chronic liver disease or steatosis was also assessed.
Participants had an average age of 58. Average daily coffee consumption was 2 cups per day. Non-coffee drinkers were more likely to be non-smokers and non-drinkers, but also more likely to have cases of obesity and diabetes than coffee drinkers.
Coffee drinkers who ranked highest in daily consumption (5 cups or more per day) were more likely to be male, to be smokers, and were more likely to be overweight.
Instant coffee was the most popular type (55%), followed by ground coffee (23%) and decaffeinated coffee (19%).
From 2006 to 2019, researchers found 5,439 individuals developed chronic liver disease or steatosis and 3,600 participants developed chronic liver disease. Furthermore, during an average follow-up of 10.7 years, there were 184 participants who developed hepatocellular carcinoma and 301 participants died due to chronic liver disease.
Andrew Talal, MD, from the University of Buffalo in New York, noted that while the authors claim the findings could be applicable to middle- and low-income countries, “a few words of caution are worthwhile,” he told MedPage Today.
Specifically, Talal cited the study’s shorter follow-up period as being “roughly half of two other studies that evaluated similar effects of coffee.”
While Kennedy’s group found protective effects for coffee drinkers were limited to those who consumed around 3-4 cups of coffee per day, additional cups did not show added benefits.
“People should be cautioned about not drinking too much coffee as a result of the findings of this study with the idea that excess coffee drinking is totally safe,” said Gluckman. “Something else important to point out is that other modifiable risk factors must be addressed such as weight loss and limiting alcohol intake, and that drinking coffee is not a substitute for this.”
Talal added that the present study evaluated coffee association at a single point in time, so “causation could not be established.”
“In addition, it is worthwhile to note that caffeine should not be used in children and should be used cautiously in those with sleep disorders, or during pregnancy,” Talal said. “The finding that decaffeinated coffee has a protective effect may be useful to consider in situations in which caffeine administration should be used cautiously.”
Additional limitations noted by Kennedy and colleagues were the observational design, that coffee cup sizes are subjective and could have been misclassified, and that ex-coffee drinkers were also excluded.
The demographic makeup of participants was largely older and white, and the majority of participants were from a higher socioeconomic status. They also noted the possibility of medical coding errors to have occurred in the data, which could have misreported liver disease classifications, such as non-alcoholic fatty liver disease versus steatosis.
The authors declared no competitive interests.