The questionnaire-based study, conducted on about 500 people and published in Clinical Gastroenterology and Hepatology, found lower levels of liver enzymes in the blood of caffeine and cigarette users, an effect that protected against the rare liver condition, primary sclerosing cholangitis (PSC).
PSC is a rare and severe condition that typically affects 30-40 year olds and is associated with cancer of the bile ducts.
The researchers from the Norwegian PSC Research Center at the Oslo University Hospital and the University of Oslo observed that 20% of the study patients reported daily cigarette smoking, compared with 43% of the healthy controls.
Similarly PSC patients drank less coffee in the present and past (2.7 vs 4 cups) than the healthy control group (which may have been healthier than ‘normal’ as they were all bone marrow donors).
Coffee drinking has been shown to protect against other liver conditions including liver cirrhosis and liver cancer.
“Of interest is that key substances in coffee and cigarette smoke (caffeine and nicotine, respectively) have similar effects; both are sympathomimetic and may increase the levels of intracellular cyclic adenosine monophosphate,” the researchers wrote.
Clinical Gastroenterology and Hepatology
Available online 25 September 2013
‘Effects of Coffee Consumption, Smoking, and Hormones on Risk for Primary Sclerosing Cholangitis’
Authors: Ina Marie Andersen, Guro Tengesdal, Benedicte Alexandra Lie, Kirsten Muri Boberg, Tom Hemming Karlsen, Johannes Roksund Hov