(Reuters Health) - 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.
Researchers analyzed 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 U.K.
"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 by email.
Cirrhosis kills more than one million 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 analyzed, 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.
7 different types of coffee drinks explained:
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But the 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 in the journal Alimentary Pharmacology and Therapeutics, online January 25.
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, 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.
It's also important to note that coffee isn't powerful enough to counteract lifestyle choices that can severely damage the liver, said Samantha Heller, a senior clinical nutritionist at New York University Langone Medical Center in New York who wasn't involved in the study.
"Unfortunately, although coffee contains compounds that have antioxidant effects and anti-inflammatory properties, drinking a few cups of coffee a day cannot undo the systematic damage that is the result of being overweight or obese, sedentary, excessive alcohol consumption or drastically mitigate an unhealthy diet," Heller said by email.