For years, coffee consumption has been linked to health benefits, but a new large-scale study now provides additional evidence that it may reduce the risk of liver disease. Researchers found that the more coffee participants drank, the lower their risk of liver cirrhosis, liver cancer and death from liver disease. The protective effect was also observed among people who drank decaffeinated coffee, suggesting that caffeine alone is not responsible for the health benefits.
The study, published in the journal Clinical Gastroenterology and Hepatology and covered by CNN, included 354,957 participants from the UK Biobank who were followed for a median of 13 years. None had liver cirrhosis or liver cancer at the start of the study.
Researchers divided participants into four groups: those who did not drink coffee, those who drank one to two cups a day, three to four cups a day and five or more cups a day. They also examined whether participants drank regular or decaffeinated coffee and whether they added sugar or artificial sweeteners.
Compared with people who did not drink coffee, consuming one to two cups a day was associated with a 20% lower risk of liver cirrhosis, a 24% lower risk of liver cancer and a 31% lower risk of death from liver disease. Among those who drank three to four cups a day, the risk of both liver cirrhosis and liver cancer fell by 35%, while the risk of death from liver disease declined by 41%. Participants who drank five or more cups a day had a 32% lower risk of liver cirrhosis, a 47% lower risk of liver cancer and a 42% lower risk of death from liver disease.
According to Prof. Nathan Gluck, a gastroenterology specialist at Assuta Medical Centers, one of the study's main strengths is its design.
"This is a prospective study, meaning the data were collected over time rather than retrospectively, and that type of study is considered more reliable," he said. "In addition, it is based on an enormous database of hundreds of thousands of participants. One of the most convincing findings is the clear dose-response relationship: the higher the coffee consumption, the lower the risk of liver cirrhosis, liver cancer and death from liver disease."
Decaffeinated coffee also linked to benefits
One of the study's standout findings was that the protective effect was similar among people who drank regular and decaffeinated coffee. According to Gluck, this provides an important clue about how coffee works.
Prof. Nathan GluckPhoto: Courtesy"If there is no difference between caffeinated and decaffeinated coffee, then caffeine is probably not the main factor. Instead, other compounds found in coffee beans are likely responsible. Coffee contains biologically active compounds, including polyphenols, antioxidants and substances with anti-inflammatory and anti-fibrotic properties that may reduce oxidative damage and inflammation in the liver."
The study did not stop at tracking disease and mortality. About 29,000 participants also underwent liver MRI scans, allowing researchers to assess liver fat, iron content and the degree of inflammation and scarring. They found that higher coffee consumption was associated with less liver fat, less iron accumulation and fewer signs of inflammation and fibrosis.
"That is one of the study's strengths," Gluck said. "The researchers did not simply track who developed disease and who did not. They also examined what was happening inside the liver itself. They found that higher coffee consumption was associated with less fat accumulation and less iron buildup, which is also considered a marker of liver health."
In addition, blood samples from more than 44,000 participants were analyzed, measuring nearly 3,000 different proteins. Researchers identified 74 proteins associated with both coffee consumption and the risk of liver cirrhosis. Coffee drinkers had higher levels of proteins linked to healthy liver function and lower levels of proteins associated with inflammation, immune system activation and liver scarring.
According to Gluck, these biological findings further strengthen the overall picture.
Researchers found that the more coffee participants drank, the lower their risk of liver cirrhosis, liver cancer and death from liver disease
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"The researchers found that proteins known to protect the liver and support its regeneration were present at higher levels among coffee drinkers. By contrast, proteins associated with immune activation, inflammation and liver fibrosis were found at lower levels. Simply put, the 'good' proteins went up and the 'bad' proteins went down."
According to the researchers, the combination of the clinical findings, MRI results and molecular analyses provides a consistent picture supporting the hypothesis that coffee may have a protective effect on the liver.
Should people start drinking more coffee?
The association between coffee consumption and a lower risk of liver disease remained even among participants who added sugar or artificial sweeteners, although those additions appeared to weaken some of coffee's beneficial effects. MRI scans showed more signs of inflammation and liver scarring among participants who added sugar or sweeteners compared with those who drank their coffee plain.
"These additions appear to reduce some of coffee's beneficial effects," Gluck said.
However, he emphasized that the findings do not mean the benefits continue to increase indefinitely with greater coffee consumption.
"Although participants who drank five or more cups a day had the lowest levels of liver fat, there was no meaningful advantage over those who drank three to four cups a day in the other measures."
According to Gluck, the takeaway is not that people should drink as much coffee as possible, but that the overall evidence supports recommending coffee, preferably without added sugar, as part of a healthy lifestyle for people with chronic liver disease.
"When you combine the clinical data, the MRI findings and the biological analyses, you get a consistent picture supporting the idea that coffee, especially without added sugar, may help prevent liver disease."
The researchers also stressed that this was an observational study and therefore cannot prove cause and effect. Even so, they concluded that the overall findings — from the long-term follow-up to the MRI scans and blood protein analyses — strengthen the hypothesis that drinking coffee, particularly without added sugar, may be a simple, accessible and inexpensive way to reduce the risk of liver disease.