The results of a new study have concluded that tea and coffee consumption can do wonders for liver health.
Chronic liver disease currently ranks as the 12th leading cause of death in the U.S., with almost 32,000 people dying from it every year.
Liver-related death is often the result of cirrhosis. Although a large number of cirrhosis cases are caused by long-term alcohol consumption, non-alcoholic fatty liver disease (NAFLD) can also lead to cirrhosis.
Fortunately, there are quite a few things that we can do to protect our liver. Apart from avoiding alcohol, maintaining an active, healthy lifestyle may ward off obesity, which is a risk factor for a fatty liver.
New research, published in the Journal of Hepatology, adds a couple of new preventive factors to the list: tea and coffee. A team of scientists led by Sarwa Darwish Murad, Ph.D., a hepatologist at the Erasmus MC University Medical Center in Rotterdam in the Netherlands, set out to examine the impact of coffee and tea consumption on liver health.
Dr. Murad explains the motivation behind the research:
"There is quite some epidemiological, but also experimental data suggesting that coffee has health benefits on liver enzyme elevations, viral hepatitis, NAFLD, cirrhosis, and liver cancer. [...] We were curious to find out whether coffee consumption would have a similar effect on liver stiffness measurements in individuals without chronic liver disease."
Studying the link between tea, coffee, and liver health
Dr. Murad and team examined the data available on 2,424 participants from a large cohort study called the Rotterdam Study. The study participants were 45 years old and above, and they lived in Rotterdam.
As part of the study, each participant underwent a full physical checkup, which included anthropometric measurements such as body mass index (BMI), height, blood tests, and abdominal scans for examining the liver.
The liver imaging was used to look for liver "stiffness," a measurement that is high when the liver is scarred. Liver scarring, also known as progressive fibrosis, can ultimately lead to cirrhosis if left untreated.
The participants' food and drinking habits were assessed using a food frequency questionnaire comprising 389 questions, including detailed items about tea and coffee intake.
Participants were divided into three categories according to their coffee and tea drinking patterns: no consumption, moderate tea and coffee consumption (defined as up to three cups per day), and frequent consumption (defined as three or more cups each day). Tea was divided into green, black, and herbal.
Dr. Murad and colleagues applied regression analysis to study the link between coffee and tea consumption and liver fibrosis. They also accounted for a variety of possible confounding factors, including age, gender, BMI, smoking, and alcohol consumption, as well as physical activity and healthy eating patterns.
The study revealed that frequent coffee and herbal tea consumption consistently correlated with a significantly lower risk of liver stiffness. These results were independent of lifestyle factors or BMI.
Additionally, the researchers found that the beneficial effect of coffee on liver stiffness could be seen both in participants who had a fatty liver and those who did not. This indicated to the authors that frequent coffee and tea intake may prevent liver fibrosis long before the signs of liver disease start to appear.
Dr. Louise J. M. Alferink, of the Department of Gastroenterology and Hepatology at Erasmus MC University Medical Centre and lead author of the study, explains the significance of the findings in the context of the so-called Western diet:
"This [diet] is typically rich in unhealthy foods including processed foods lacking nutrients and artificial sugars. [...] In this context, examining accessible and inexpensive lifestyle strategies that have potential health benefits, such as coffee and tea consumption, is a viable approach to finding ways to halt the rapid increase of liver disease in developed countries."
More studies are needed to understand the mechanisms responsible for this association, the authors caution.