Digestive Diseases News Spring 2010
Coffee Consumption Linked to Decreased Rate of Hepatitis C Disease Progression
A data analysis from the Hepatitis C Antiviral Long-term Treatment against Cirrhosis (HALT-C) Trial Group found that drinking 3 or more cups of coffee per day reduced the risk of liver disease progression among people with chronic hepatitis C by 53 percent. The study, however, found no association between liver disease progression and tea consumption.
“Laboratory studies suggest that several components of coffee, including caffeine, diterpenes, and polyphenols, may have beneficial effects on the liver,” wrote Neal D. Freedman, Ph.D., M.P.H., an investigator at the National Cancer Institute's Division of Cancer Epidemiology and Genetics, and colleagues for the HALT-C Trial Group in their report in the July 13 online issue of Hepatology. “Increasing coffee consumption has been inversely associated with liver enzyme concentrations,” the researchers added.
An estimated 3 million Americans and an estimated 170 million people worldwide have chronic hepatitis C. The hepatitis C virus is transmitted through contact with infected blood, often from an infected mother to her child during birth, through intravenous drug use, or through a blood transfusion received before 1992. Hepatitis C infection often becomes chronic; over time, it can lead to liver failure and liver cancer. The best available treatment for chronic hepatitis C includes daily doses of ribavirin and weekly injections of peginterferon for up to 48 weeks, but this treatment is effective for only half of those treated.
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) funded the HALT-C trial to determine whether long-term peginterferon treatment would reduce the rate of disease progression among patients whose infection did not resolve after the initial 48-week treatment.
The HALT-C trial included participants with advanced liver fibrosis—as determined by liver biopsy—with no history of liver cancer or liver disease unrelated to hepatitis C. Patients in the study's treatment arm received weekly injections of peginterferon for an average of 3.5 years. During the study, participants gave blood every 3 months for liver enzyme analysis and were evaluated by ultrasound at least once per year for liver cancer. Primary outcomes measured were liver disease-related death, liver decompensation, liver cancer, or a significant increase in liver fibrosis as measured by the Ishak fibrosis scale.
Although long-term peginterferon treatment reduced hepatitis C virus levels, it failed to slow disease progression.
At the study's start and again 13 months later, participants completed a questionnaire about the variety and quantity of food and beverages they consumed, including coffee and tea. For analysis, the researchers classified participants' coffee consumption as never, more than 0 but less than 1 cup per day, more than 1 cup but less than 3 cups per day, or 3 or more cups per day. Tea consumption was classified as never, more than 0 but less than 1 cup per day, more than 1 cup but less than 2 cups per day, or 2 or more cups per day.
At the study's conclusion, about 36 percent of HALT-C participants included in the analysis had experienced at least one primary clinical outcome or a 2-point increase in fibrosis score. Participants who drank more than 1 cup of coffee per day on average experienced significantly fewer outcomes and less liver disease progression than participants who never drank coffee. Researchers found no risk reduction, however, associated with tea consumption.
Participants who drank the most coffee experienced the least disease progression. Those who drank 3 or more cups per day had a 53 percent reduction in risk, relative to participants who never drank coffee. Risk reduction was similar for participants in the treatment and control groups and was unaffected by initial liver disease severity, gender, or use of alcohol or tobacco.
The researchers offered potential explanations for coffee's protective effect, including studies showing an association between coffee consumption and decreased risk of type 2 diabetes, which has been linked to liver disease. Additionally, they cited studies that have demonstrated coffee's anti-inflammatory properties: “Coffee intake,” wrote the authors, “could also act by reducing inflammation, because the inflammatory response to liver injury is thought to cause fibrosis and cirrhosis.”
Coffee contains more than 1,000 chemical compounds. Studies have associated caffeine with levels of alanine aminotransferase—a liver enzyme that when high indicates liver disease. In laboratory experiments, caffeine and the diterpenes cafestol and kahweol, which are also abundant in coffee, have been shown to inhibit liver cancer in rats.
Coffee, according to the authors, might also reduce oxidative stress—a build-up of metabolic byproducts known as free radicals, which are toxic to liver cells.
In light of their findings and the limitations of current chronic hepatitis C therapies, the authors urged additional research of coffee and its constituent compounds: “Future work is needed to identify bioactive components in coffee and determine their effects in vivo.”
For more information about hepatitis C and other kinds of hepatitis, visit the National Digestive Diseases Information Clearinghouse at www.digestive.niddk.nih.gov.
NIH Publication No. 10–4552