Drinking coffee may reduce the severity of nonalcoholic fatty liver disease (NAFLD) in people who are overweight and have type 2 diabetes, according to a new study.
NAFLD is a condition in which excess fat builds up in the liver. This is often a “silent” disease with few or no symptoms.
In the study, researchers surveyed 156 middle-aged people who were overweight about their coffee consumption. Of these, 98 people had type 2 diabetes.
Researchers also collected daily urine samples from participants. These were used to measure caffeine and non-caffeine metabolites — natural products that result from the body breaking down coffee.
People with higher coffee caffeine intake, as indicated by the metabolites, were less likely to have liver fibrosis, researchers reported.
In addition, people with higher levels of non-caffeine metabolites had lower fatty liver index scores. This score is a non-invasive way of estimating the accumulation of fat in the liver.
The results suggest that higher intake of coffee is associated with less severe NAFLD in people with type 2 diabetes who are overweight, the researchers write.
The study was published in the January issue of the journal Nutrients.
Funding came in part from The Institute for Scientific Information on Coffee (ISIC), whose members include six of the major European coffee companies.
The dangers of liver disease
About one-quarter of adults in the United States have NAFLD, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
Up to 6% of adults have the more severe form of NAFLD known as nonalcoholic steatohepatitis (NASH). People with this type also have inflammation of the liver and liver damage.
NASH can lead to scarring of the liver tissue (cirrhosis) and liver cancer (hepatocellular carcinoma).
NAFLD is more common in people with excess weight or obesity, type 2 diabetes, abnormal levels of fats in the blood, or metabolic syndrome. The latter is linked to obesity.
While genetics may increase a person’s risk of developing NAFLD, so may diets high in fructose, a sugar that is used to sweeten drinks and foods although it is primarily found in fruits.
The potential benefits of coffee
Dr. Liyun Yuan, a hepatologist with Keck Medicine of USC in Los Angeles, said the new study shows the potential benefits of coffee for reducing the severity of NAFLD in people with type 2 diabetes.
“Although the number of patients in the study is small, the results are significant,” she told Healthline.
In addition, while the researchers focused on people with type 2 diabetes, the results “could be expanded to the general population with NAFLD or with metabolic syndrome,” said Yuan, “since the coffee benefit in NAFLD has been shown in many population-based studies.”
Dr. Rohit Loomba, a professor in the Division of Gastroenterology at UC San Diego School of Medicine and director of hepatology at UC San Diego Health, cautioned that with studies like this, it is possible that some of the benefits may be due to factors related to the participants themselves rather than the coffee.
“A typical coffee drinker may be different than people who don’t drink coffee or who do not consume as much,” he told Healthline.
These other factors could affect the severity of NAFLD.
However, Loomba said other studies have found similar results as the new study, which adds to the evidence of the potential benefits of coffee for NAFLD.
For example, some research has found that consumption of coffee — and caffeine in coffee — may reduce fibrosis in people with NAFLD.
Overall, “it’s a decent work,” said Loomba, “and it gives you more understanding — based on the metabolites — of the impact of coffee on NAFLD.”
