Coffee consumption link to reduced cirrhosis risk

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Drinking more coffee might help reduce the kind of liver damage that's associated with overindulging in food and alcohol, a review of existing studies suggests. Reuters Health reports that researchers analysed data from nine previously published studies with a total of more than 430,000 participants and found that drinking two additional cups of coffee a day was linked to a 44% lower risk of developing liver cirrhosis.

"Cirrhosis is potentially fatal and there is no cure as such," said lead study author Dr Oliver Kennedy of Southampton University in the UK. "Therefore, it is significant that the risk of developing cirrhosis may be reduced by consumption of coffee, a cheap, ubiquitous and well-tolerated beverage," Kennedy added.

The report says cirrhosis kills more than 1m people every year worldwide. It can be caused by hepatitis infections, excessive alcohol consumption, immune disorders, and fatty liver disease, which is tied to obesity and diabetes.

Kennedy and colleagues did a pooled analysis of average coffee consumption across earlier studies to see how much adding two additional cups each day might influence the odds of liver disease. Combined, the studies included 1,990 patients with cirrhosis.

In eight of the nine studies analysed, increasing coffee consumption by two cups a day was associated with a significant reduction in the risk of cirrhosis. In all but one study, the risk of cirrhosis continued to decline as daily cups of coffee climbed.

Compared to no coffee consumption, researchers estimated one cup a day was tied to a 22% lower risk of cirrhosis. With two cups, the risk dropped by 43%, while it declined 57% for three cups and 65% with four cups.

But the, the report says, results still leave some unresolved questions. One study, for example, found a stronger link between coffee consumption and reduced cirrhosis risk with filtered coffee than with boiled coffee. And, while the studies accounted for alcohol consumption, not all them accounted for other cirrhosis risk factors like obesity and diabetes, the authors note.

But patients also shouldn't take the findings to mean loading up on frothy caramel lattes packed with sugar and topped with whipped cream is a good way to prevent liver disease, the report says Kennedy cautioned. It's also not clear exactly how coffee might lead to a healthier liver, or whether the type of beans or brewing method matter.

"Coffee is a complex mixture containing hundreds of chemical compounds, and it is unknown which of these is responsible for protecting the liver," Kennedy said.

Summary
Background
Liver cirrhosis is a large burden on global health, causing over one million deaths per year. Observational studies have reported an inverse association between coffee and cirrhosis.
Aims
To perform a systematic review and meta-analysis to characterise the relationship between coffee consumption and cirrhosis.
Methods
We searched for studies published until July 2015 that reported odds ratios, relative risks (RR) or hazard ratios for cirrhosis stratified by coffee consumption. We calculated RRs of cirrhosis for an increase in daily coffee consumption of two cups for each study and overall. We performed analyses by study design, type of cirrhosis and mortality. We assessed the risk of bias in each study and the overall quality of evidence for the effect of coffee on cirrhosis.
Results
We identified five cohort studies and four case–control studies involving 1990 cases and 432 133 participants. We observed a dose–response in most studies and overall. The pooled RR of cirrhosis for a daily increase in coffee consumption of two cups was 0.56 (95% CI 0.44–0.68; I2 83.3%). The RR pooled from cohort studies for a daily increase of two cups was 0.58 (95% CI 0.41–0.76; I2 91.1%) and from case–control studies it was 0.52 (95% CI 0.40–0.63; I2 0.0%). The pooled RR of alcoholic cirrhosis for a daily increase of two cups was 0.62 (95% CI 0.51–0.73; I2 0%) and of death from cirrhosis it was 0.55 (95% CI 0.35–0.74; I2 90.3%).
Conclusion
This meta-analysis suggests that increasing coffee consumption may substantially reduce the risk of cirrhosis.

Full Reuters Health report Alimentary Pharmacology Therapeutics article summary

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