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December 8, 2015

Drinking coffee was associated with lower liver stiffness – a non-invasive measure used to estimate liver fibrosis – in people with hepatitis B, hepatitis C and non-alcoholic fatty liver disease (NAFLD), researchers reported at the 2015 AASLD Liver Meeting last week in San Francisco, USA. The study also showed a trend toward less liver fat build-up in people with NAFLD.

Over years or decades, chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection can lead to serious liver disease including cirrhosis (scarring), hepatocellular carcinoma (a type of liver cancer) and liver failure necessitating a transplant. NAFLD – fat in the liver not related to alcohol use – can lead to the same outcomes. As HBV vaccination and effective new treatments for hepatitis C reduce liver disease due to viral hepatitis, NAFLD is expected to become a major indication for liver transplantation, given rising rates of obesity.

Alexander Hodge of Monash Medical Centre in Melbourne, Australia, and colleagues conducted a retrospective, cross-sectional study to see whether coffee consumption leads to improvements in non-invasive markers of liver fibrosis and steatosis (fat accumulation).

In prior studies, coffee consumption has been linked to a wide range of health benefits including reduced risk of type 2 diabetes, metabolic syndrome and several types of cancer, the researchers noted as background. It may have a particularly beneficial effect on the liver, being associated with lower liver enzyme levels and reduced cirrhosis and liver cancer. It is not yet known whether these benefits are related to caffeine or other components of coffee such as antioxidants or other phytochemicals. Some studies suggest caffeine and other chemicals in coffee may dampen inflammation and reduce collagen production.

In this study, liver health was assessed using transient elastography or FibroScan. Although liver biopsy has traditionally been considered the ‘gold standard’ for determining the extent of liver injury, clinicians are increasingly using less expensive non-invasive methods.

Transient elastography uses shear waves to assess liver elasticity or ‘stiffness’. Higher liver stiffness scores (expressed in kiloPascals or kPa) indicate more extensive liver damage. A score below 6-7 kPa suggests absent or mild fibrosis (stage F0-F1) while a score above 13 to 14 kPa suggests cirrhosis (stage F4) in people with viral hepatitis.

Another transient elastography measure, the controlled attenuation parameter or CAP (expressed in decibels per meter or dB/m), is used to assess liver steatosis. Fat blocks propagation of ultrasound waves, so greater attenuation suggests more steatosis. Scores range from 100 to 400, with a score above 250 suggesting significant steatosis.

The researchers collected data on self-reported coffee and alcohol consumption – as well as the type of coffee (instant, espresso, filtered or boiled) – among all patients with hepatitis B, hepatitis C or NAFLD undergoing transient elastometry at their hospital clinic between May 2012 and November 2013. They also obtained information about demographic characteristics, weight and body mass index (BMI), smoking and alanine aminotransferase (ALT) liver enzyme levels.

Over 18 months, the researchers evaluated 1130 people, including 529 (47%) with hepatitis B, 434 (38%) with hepatitis C and 167 (15%) with NAFLD. Overall, 57% were men, the average age was 48 years and a quarter were smokers. The average BMI was 25.7 kg/m2 and the mean ALT level was 39 IU/L among people with available measurements.

Most participants reported that they consumed some coffee, with a median of one cup per day but ranging up to 20 cups daily; 72% reported drinking instant coffee and 24% drank espresso, with only a small number (1 to 2%) drinking filtered, boiled or decaf coffee. Average daily alcohol consumption was about 5 g/day.

The median liver stiffness score across all participants was 6.1 kPa, suggesting absent to mild fibrosis. However, people with HBV had lower scores than those with HCV or NAFLD (median 5.3, 7.1 and 7.4, respectively).

Among people with available controlled attenuation parameter data, the overall mean CAP score was 214 dB/m, rising above the steatosis threshold only for those with NAFLD (mean 201, 210 and 258, respectively).

People with hepatitis C who drank two or more cups of coffee daily had a 13% reduction in liver stiffness after taking into account confounding factors including age, sex, weight, alcohol consumption and smoking – a significant association. People with hepatitis B who drank four or more cups of coffee had a significant 18% reduction in liver stiffness in an adjusted analysis including ALT. There were no significant associations between coffee consumption and CAP scores among people with hepatitis B or C.

Among people with NAFLD, those who drank four or more cups of coffee daily had a 24% decrease in liver stiffness in an adjusted analysis. Greater coffee consumption showed a trend towards an association with lower CAP scores in people with NAFLD, but this fell short of statistical significance. Coffee consumption had no effect on CAP in people with hepatitis B or C.

Based on these findings, the researchers concluded that “coffee consumption is associated with less liver stiffness in patients with NAFLD, HCV and HBV, [and a] trend to less hepatic steatosis in [patients with] NAFLD.”

These findings, they said, “add to the growing body of evidence suggesting coffee may be a beneficial supplement in some liver diseases.”