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Coffee Consumption May Protect Liver from Alcohol
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By Peggy Peck, Managing Editor, MedPage Today
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
June 12, 2006
www.medpage.com
......while this study suggests that coffee consumption is associated with a reduced risk of alcoholic cirrhosis, the observational nature of the data limits any attempt to establish a causal link.
.....In this study the benefit of coffee was seen only among those who were at risk for alcoholic cirrhosis.
Review
OAKLAND, Calif. June 12 - Coffee may help protect the livers of heavy alcohol drinkers.
In a cohort study of Kaiser Permanente members, drinking one to three cups of coffee a day was associated with a 40% decrease in the risk of alcoholic cirrhosis versus drinking less than one cup (P<0.001), according to a report in the June 13 issue of the Archives of Internal Medicine.
Moreover, Arthur L. Klatsky, M.D., and colleagues at the Kaiser Permanente Division of Research wrote that this protective effect appears to be dose-dependent. Those who drank four or more cups of coffee had an 80% decrease in the relative risk of alcoholic cirrhosis (95% CI 0.1-0.4, P<0.001).
Among subgroups of patients with nonalcoholic cirrhosis, coffee had a similar, weak, nonstatistically significant inverse relation to risk of either viral hepatitis-associated cirrhosis or to miscellaneous other cirrhosis.
Tea drinking, on the other hand, was unrelated to the risk of either alcoholic or nonalcoholic cirrhosis.
Dr. Klatzky and colleagues studied data from 129,580 Kaiser Permanente members who completed baseline background health questionnaires and an alcohol questionnaire between 1978 and 1985. By 2001, 330 of these patients developed cirrhosis-199 were diagnosed with alcoholic cirrhosis and 131 with nonalcoholic cirrhosis.
Sixty-five percent of patients with alcoholic cirrhosis and 54% of patients with non-alcoholic cirrhosis were men, and in both groups about half of the patients were 50 or younger.
The risk of cirrhosis, both alcoholic and nonalcoholic, increased with age, male sex, and obesity, but education was protective-cirrhosis risk declined as years of education increased.
Among the findings:
* Coffee drinking was positively correlated with smoking and alcohol drinking.
* As expected mean blood levels of AST and ALT increased as alcohol consumption increased.
* In a cross-sectional analysis coffee drinking was inversely related to AST and ALT levels, people who drank four or more cups of coffee daily reduced the risk of elevated AST by 50% (95% CI, 0.4-0.6; P <0.001) and for elevated ALT by 40% (95% CI 0.6-0.7; P<0.001).
Additionally, the inverse relationship between liver enzyme elevations and coffee consumption was strongest among heavy drinkers.
The authors noted a number of limitations to their study, including the fact that smoking, drinking, and coffee consumption are often related habits, which makes it "difficult to rule out residual confounding by alcohol amount or drinking pattern." Nonetheless, they argued that smoking "may prolong the persistent of caffeine in the body. Thus, any residual confounding related to coffee drinking would tend to produce an inverse smoking-cirrhosis relation, not the positive one we obtained."
The study was also limited by its reliance on baseline ascertainment of habits and incomplete follow-up of the cohort.
Finally, the "observational nature of the data and the absence of an established mechanism limit a causal interpretation." The data suggested that the need for "research about hepatic coffee-ethanol interactions is warranted, but we should keep in mind that coffee might represent only one of a number of potential cirrhosis risk modulators."
Primary source: Archives of Internal Medicine
Source reference:
Klatsky, AL et al "Coffee, Cirrhosis, and Transaminase Enzymes" Arch Intern Med 2006;166:1190-1195
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