Limitations include 24-hour time frame
The findings were limited by several factors, including the use of 24-hour urine sample, which may not represent an individual’s habitual coffee consumption, the researchers noted. The urine metabolites measured also may be derived from foods and beverages other than coffee. In addition, the assessment of NAFLD was based on serum markers and ultrasound/elastography, which are less precise than liver biopsy and magnetic resonance spectroscopy.
However, the study is the first known to use urine data to examine coffee’s protective effect against NAFLD and suggests that both caffeine and noncaffeine metabolites are associated with less severe disease, they concluded.
Findings intriguing but not ready for prime time
“The bottom line is that we have a major epidemic of NAFLD in the United States,” Victor L. Roberts, MD, professor of internal medicine at the University of Central Florida, Orlando, said in an interview. NAFLD has become the most common cause of chronic liver disease worldwide, and will become one of the leading causes of cirrhosis – surpassing infections as the main driver of end-stage liver disease.
“In this country, the epidemic of obesity compounds the problem, and risks for NAFLD include obesity and type 2 diabetes,” said Dr. Roberts.
The concept of coffee as beneficial is not new, but data suggest that the effects vary with insulin resistance, he said. If liver disease is advanced, coffee and its components may not have much benefit, but early on, it might have a role.
The likely mechanism of action for the benefits of coffee on the reduction in liver fibrosis is through a complex set of metabolic steps that interrupt the promotion of collagen production and reduce liver stiffness, said Dr. Roberts.
The current study authors were up front about the limitations, mainly the use of self-reports, although including the urine collection provided more scientific data, he said. More studies are needed in other populations, but the findings are interesting enough to merit additional research.
The take-home message for primary care, however, is that drinking coffee – regular or decaf – does not replace standard of care, Dr. Roberts emphasized.
“If a patient is a coffee drinker and they have NAFLD or are at risk, they could be encouraged to continue drinking coffee,” in reasonable amounts, said Dr. Roberts. “Anywhere from 1-3 cups a day is unlikely to be a problem, and there is some hope and interest in this area,” but the findings of the current study “should not be taken as gospel or advocacy as a solution for people with NAFLD.”
Instead, clinicians should focus on the standard of care for management of patients at risk for NAFLD, promoting lifestyle changes such as weight loss, diet, and exercise (challenging as that may be), and prescribing appropriate medications, he said.
The study was supported by the Institute for Scientific Information on Coffee, and the researchers received funding from the ISIC to conduct the study. Dr. Roberts had no financial conflicts to disclose, but he serves on the editorial advisory board of Internal Medicine News.