Researchers found that an additional two cups of coffee per day was linked with a 44% reduction of developing cirrhosis of the liver and a 50% reduction in death from the disease.
Cirrhosis is a disease that replaces the healthy tissue of the liver with scar tissue, stopping it from maintaining proper function. Researchers said it has a large burden on public health, with more than 1m people affected by the disease each year.
Method of the study and what they found
Many observational studies have reported an inverse association between coffee and cirrhosis. Researchers said their aim was to perform a systemic review and meta-analysis of the relationship to see if this correlation holds true.
Researchers looked for studies through July 15, 2015, that reported hazard ratios, relative risks or odds ratios for cirrhosis that is stratified by consumption.
“We calculated RRs of cirrhosis for an increase in daily coffee consumption of two cups for each study and overall,” researchers wrote. “We performed analyses by study design, type of cirrhosis and mortality. We assessed the risk of bias in each study and the overall quality of evidence for the effect of coffee on cirrhosis.”
After looking through 1,990 cases with more than 430,000 participants, researchers said they “observed a dose–response in most studies and overall”.
“This meta-analysis suggests that increasing coffee consumption may substantially reduce the risk of cirrhosis,” researchers said.
Coffee’s various benefits
Researchers wrote in the study that it is “biologically plausible” that coffee also protects against the fibrotic and inflammatory process that lead to cirrhosis. It may also suppress oxidative stress and inhibit tumor necrosis, researchers wrote.
“The protective effect of coffee against cirrhosis may also involve indirect mechanisms that modify risk factors,” they wrote in the study. “Laboratory studies have shown that various constituents of coffee inhibit the activities of hepatitis B and C viruses. In addition, and of even greater significance to public health, is the inverse association between coffee (both caffeinated and decaffeinated) and type 2 diabetes mellitus.”
In the discussion portion of the study, the researchers stopped short of recommending an increase in coffee consumption, writing that the wider effects need to be considered. There have been associations between coffee and certain types of cancer, for example. However, they said it “generally well tolerated and has an excellent safety profile.”
“The findings of this meta-analysis are important given the high incidence of severe liver disease, the positive interaction between alcohol and obesity for liver disease risk and the lack of specific treatments to prevent liver disease due to these factors,” researchers wrote, adding that the next steps must include developing interventions with patients and increasing their consumption of coffee to fight this illness.
Source: Alimentary Pharmacology & Therapeutics
Systematic review with meta-analysis: coffee consumption and the risk of cirrhosis
O. J. Kennedy, P. Roderick, R. Buchanan, J. A. Fallowfield, P. C. Hayes and J. Parkes