COMMENTARY

Can Coffee Treat Liver Disease?

Rowen K. Zetterman, MD

Disclosures

April 14, 2014

In This Article

Coffee and Mortality

More than 2.25 billion cups of coffee are consumed each day throughout the world. This requires harvesting and roasting 7 million tons of coffee beans every year.[1] Although coffee consumption varies from country to country, most Americans drink coffee daily. Despite early concerns about the deleterious effects of coffee on health, contemporary studies suggest that coffee is beneficial for many medical disorders, including Parkinson disease, diabetes mellitus, symptomatic gallbladder disease, stroke, and chronic liver diseases.[2]

Coffee contains caffeine, a methylxanthine that is also found in tea and other plants. The quantity of caffeine present in each cup of coffee varies depending on how the coffee is prepared, the type of coffee brewed, and whether it is ground or instant coffee. In general, from each cup of coffee, approximately 85 mg of caffeine[3] is absorbed in the stomach and small bowel and metabolized in the liver by cytochrome P450. The half-life of caffeine is 4-6 hours.

Current studies suggest that caffeine binds to adenosine receptors and reduces the development of hepatic fibrosis from liver injury by limiting stellate cell activation and the secretion of connective-tissue growth factors and collagen.[4] The diterpenes cafestol and kahweol present in coffee can increase cholesterol formation, but cafestol and kahweol are retained on paper filters during coffee brewing.

Coffee appears to have a significant effect on all-cause mortality. The National Institutes of Health-American Association of Retired Persons Diet and Health Study involving 229,119 men and 173,141 women demonstrated an inverse relationship between coffee consumption and mortality.[5] In other words, coffee drinkers had a reduction in mortality compared with non-coffee drinkers.

The men and women in the study were aged 50-71 years at baseline and were followed until death or the study end point. It was observed that coffee drinkers were also more likely to smoke cigarettes, a finding that has been documented in other studies. The inverse relationship of coffee consumption to overall mortality was dose-dependent and resulted in reduced deaths from heart disease, respiratory disease, stroke, injuries and accidents, diabetes mellitus, and infections. Cancer deaths were not reduced by coffee.

Coffee's Effect on Liver Tests

Alcohol (ethanol) consumption and cigarette smoking can increase gamma-glutamyl transferase (GGT) levels.[6] Coffee appears to reduce circulating levels of GGT.[7] When a Japanese study involving 12,687 general health examinees (7398 men and 5289 women) with no evidence of liver disease or elevated aminotransferase levels were surveyed for coffee consumption, a significant reduction in serum GGT activity was observed in men (P < .001), whereas a similar reduction of GGT in women was only weakly evident.[8] Men who were heavy consumers of alcohol-containing beverages had a reduction of GGT with coffee intake, whereas non-alcohol drinkers did not. Serum aminotransferase levels were also reduced in alcohol-consuming patients who drank coffee.[8,9] Green tea had no effect on GGT levels.

Another study of 1176 male office workers aged 40-59 years with no history of liver disease or abnormal aminotransferase levels[10] also had reduced circulating GGT levels from coffee intake. Elevated GGT levels were associated with increased body mass index, alcohol intake, cigarette smoking, and snacking between meals. Similar findings have been observed by others.[11]

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