Can Coffee Help Prevent Liver Fibrosis?

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There is good evidence that coffee has a beneficial effect in people at risk for liver fibrosis and there are plausible biological mechanisms to explain why, according to an editorial in the January 27 advance online edition of Hepatology. However, the amount needed to see such an effect may be too high for many people to tolerate, they cautioned.

A growing body of research suggests that drinking coffee -- and perhaps consuming caffeine more generally -- is associated with reduced progression or even improvement in liver fibrosis among people with chronic liver problems including hepatitis C and fatty liver disease.

"The published epidemiological data demonstrating an inverse relationship between coffee (and potentially other caffeinated beverage) consumption and liver fibrosis and its downstream complications are weighty and rapidly accumulating," wrote Jonathan Dranoff from the University of Arkansas for Medical Sciences and colleagues.

One strong study, for example, found that people in the highest 20% of coffee consumers had less than one-third the risk of ALT elevation -- indicating liver inflammation, which over time promotes fibrosis -- compared with the bottom 20%. Another study showed that the odds of liver cirrhosis decreased in a step-wise manner with increasing daily coffee consumption.

There are several plausible biological mechanisms that could contribute to this association, according to the authors. One possible mechanism is that the caffeine in coffee interferes with adenosine signaling in hepatic stellate cells in the liver, which can act as myofibroblasts that produce collagen and other components of scar tissue. In addition, they suggested, anti-oxidant and anti-inflammatory properties of various coffee constituents may also play a role.

There is not yet enough evidence to say whether caffeine or other components underlie the anti-fibrotic effect of coffee. Some animal studies have found that caffeine in non-coffee forms is also beneficial, while others have seen benefits with decaffeinated coffee.

"Taken together, it appears that there are noteworthy holes in the animal liver fibrosis literature; there are simply not enough data to make firm conclusions about the relative importance of coffee caffeine content," Dranoff and colleagues wrote. "At present, while it is premature to assume that the major effect of coffee is mediated by caffeine, the preponderance of evidence would suggest that this is the case."

"The number of North American and European patients with chronic liver disease is increasing, primarily due to steady levels of hepatitis C infection but rapidly expanding levels of fatty liver disease (primarily non-alcoholic)," the authors summarized. "Thus, identification of simple measures that can slow fibrosis and prevent cirrhosis in at-risk patients is critical. Since coffee consumption appears to have salutary effects on human health overall, coffee is an attractive lifestyle measure that patients can take."

Coffee is an attractive "prescription" because many people enjoy it, it appears to have other health benefits besides reducing fibrosis, and it does not have "profound adverse effects." However, they added, "the most potent observed effects of coffee require the equivalent of four or more cups per day" -- a quantity that many people would likely not easily tolerated.

"Hopefully, the most important effect gained by the observations reviewed here is not the use of coffee as a drug, but rather the generation of testable hypotheses as to the pathogenesis, prevention, and treatment of liver fibrosis and cirrhosis," they concluded.

2/7/14

Reference

JA Dranoff, JJ Feld, EG Lavoie, M Fausther. How Does Coffee Prevent Liver Fibrosis? Biological Plausibility for Recent Epidemiological Observations. Hepatology. January 27, 2014 (Epub ahead of print).