Epidemiology

Caffeine linked to reduced risk of liver damage

Last Updated: 2004-05-19 13:30:05 -0400 (Reuters Health)

By Karla Gale

NEW ORLEANS (Reuters Health) - Coffee and other caffeinated beverages may provide some protection from liver damage in people at increased risk for liver disease, according to research findings presented here at Digestive Disease Week.

Using data from the third US National Health and Nutrition Examination Survey, conducted between 1988 and 1994, Drs. James E. Everhart and Constance E. Ruhl extracted information regarding caffeinated beverage consumption, as well as risk factors for and evidence of liver disease, indicated by serum levels of alanine aminotransferase (ALT) > 43 U/L.

They identified nearly 6000 adults out of 16,000 total with such risk factors as viral hepatitis, obesity, diabetes, iron overload or heavy alcohol use, Dr. Everhart said during a press conference. Altogether, 8.7% of those at risk had elevated ALT levels.

Compared with subjects who did not drink coffee, the risk for high ALT levels was nearly halved among those who drank more than two cups per day (odds ratio 0.56, after adjusting for age, gender, race and smoking history).

For overall caffeine consumption, those in the highest quintile (> 373 mg/day), the adjusted odds ratio was 0.31 (p < 0.001) compared with those who abstained from drinks containing caffeine.

"In the lowest quintile, about 12% had high ALT levels, compared with about 45 among those in the fifth quintile," said Dr. Everhart, who is chief medical officer of the Epidemiology and Clinical Trials Division of Digestive Diseases and Nutrition at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

He noted that these findings are not sufficient for making recommendations regarding caffeine intake, especially since caffeine may have other deleterious effects, but "they should stimulate clinical trials."

As to a possible mechanism, he told Reuters Health, previous research has shown that one of caffeine's primary metabolic effects is blockade of adenosine receptors. The acute effect of this blockade is stimulation of the immune system that could protect the liver, "but we don't know what the chronic effects are," in terms of how caffeine affects liver function, he added.

Digestive Disease Week is jointly sponsored by the American Association for the Study of Liver Diseases, the American Gastroenterological Association, the American Society for Gastrointestinal Endoscopy, and the Society for Surgery of the Alimentary Tract.