Lower levels of coffee consumption are associated with primary sclerosing cholangitis (PSC), but not primary biliary cirrhosis (PBC), researchers report in the September issue of Clinical Gastroenterology and Hepatology.
Coffee is considered to be a medically beneficial beverage—consumption has been associated with reductions in metabolic syndrome, cardiovascular disease, and weight gain, as well as total and cause-specific mortality. Furthermore, many studies have reported that coffee consumption reduces the risk of liver diseases such as alcoholic liver disease, cirrhosis, and hepatocellular carcinoma.
Craig Lammert et al. therefore investigated associations between coffee consumption and cholestatic liver disorders. PBC and PSC are chronic autoimmune liver diseases characterized by biliary inflammation that leads to biliary fibrosis, cirrhosis, and liver transplantation or death.
The authors collected answers from questionnaires about lifetime coffee drinking from 606 patients with PBC, 480 patients with PSC, and 564 healthy volunteers (controls).
Only about 16% of patients with PBC and controls never drank coffee. However, 24% of patients with PSC reported never drinking coffee, and only 67% were current coffee drinkers, compared with 77% of controls. These differences were found to be significant.
Patients with PSC also consumed fewer lifetime cups per month (45 vs 47 for controls) and spent a smaller percentage of their lifetime drinking coffee (46.6% vs 66.7% for controls). Among patients with PSC and concurrent ulcerative colitis, coffee protected against proctocolectomy.
The observation of reduced coffee consumption in PSC remained statistically significant after adjustments for subjects’ age, sex, higher education, and significant history of smoking.
Lammert et al. propose that coffee might modify genetic or environmental risks for PSC, or affect immune regulation or progression of fibrosis. Coffee consumption has been reported to alter intestinal microbiota, and changes in the relationship between the gut and liver have been proposed to contribute to pathogenesis of PSC.
Although this study included a large number of subjects, it has limitations. Patient self-reporting of coffee consumption is subject to memory bias, and subjects are likely to have different definitions of coffee or cups of coffee. Lammert et al. admit that they were unable to compare differences in brands, preparations, or additives, or consumption of other products with bioactive substances.
However, the authors state that despite classification of PBC and PSC as autoimmune cholestatic liver disorders, coffee consumption represents another key disparity between them. Prospective studies are needed to assess the effects of coffee on outcomes and survival of patients with PSC.