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.
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.
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.”
These and other studies suggest that for people with NAFLD, or those at risk of this condition, coffee remains an option.
“Coffee is a healthy choice of drink,” said Yuan. However, “be mindful, avoiding added sugar and cream.”
Excess sugar and milk can contribute to weight gain and increase the risk of type 2 diabetes.
Also, because the study showed a benefit of metabolites related to caffeine as well as to other components of coffee, Yuan said people can feel comfortable choosing non-caffeinated coffee.
For caffeinated coffee, she recommends limiting consumption to 3 to 5 cups per day because excessive caffeine intake can have negative effects.
On top of this, Loomba said people can make other dietary changes to reduce the risk of NAFLD.
The number one, he said, is to reduce their alcohol consumption — not consuming more than one drink per day.
“If they have very advanced disease — such as cirrhosis or bridging fibrosis — they should absolutely abstain from alcohol,” he said, “because that’s known to be a risk factor for developing hepatocellular carcinoma.”
Also, they should stop smoking, which can increase the risk of both liver fibrosis worsening and heart disease.
In addition, Loomba recommends that people reduce their intake of added sugars and sugar-sweetened beverages, as well as exercise regularly. This will help them achieve a healthy weight and maintain muscle mass.
In particular, “the Mediterranean diet is helpful,” he said, “especially when you control the number of calories that you’re getting from that diet.”
Yuan said many aspects of the Mediterranean diet are healthy dietary choices for people with NAFLD: whole grains, high fiber, healthy fats (such as from nuts, olive oil, and avocado), lean protein from fish, and leafy vegetables.
“Building healthy dietary choices is fundamental to reducing the risk and progression of NAFLD,” she said, as well as “other complications of metabolic syndromes, such as cardiovascular diseases and vascular dementia.”
Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.
Current Version
Jan 13, 2023
Written By
Shawn Radcliffe
Edited By
Gillian Mohney
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