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Study Finds Link Between Metabolic Syndrome and Alcohol-Induced Liver Disease

A new study from Keck Medicine of USC has identified metabolic syndrome as a factor in why certain patients develop liver disease due to heavy alcohol intake.

Metabolic syndrome is a cluster of conditions that together raise the risk of coronary heart disease, diabetes, stroke and other serious complications. The syndrome, which affects more than 1 in 3 Americans, is characterized by symptoms such as abdominal fat, high blood pressure, high cholesterol and high blood sugar.

“Our research suggests that metabolic syndrome and alcohol interact in such a way that they multiply the effect of alcohol on the liver, more than doubling the risk of advanced liver disease among heavy drinkers,” said Brian P. Lee, MD, MAS, a hepatologist and liver transplant specialist at Keck Medicine who is the leader author on the study.

“Drinking is harmful to the liver, but especially so for this segment of the population.”

The study, published in the Annals of Internal Medicine, defined heavy alcohol use as two drinks (a total of 12 fluid ounces) a day for women and three drinks (a total of 18 fluid ounces) per day for men.

Alcohol’s rising role in liver disease

Lee and his colleagues were motivated to research a connection between advanced liver disease, alcohol use and metabolic syndrome after noticing that between 2009 and 2018, deaths from alcohol-associated liver disease surged in the United States by more than 30%, while alcohol use, including heavy drinking, remained stable or declined.

During the last 20 years, the number of Americans with metabolic syndrome increased significantly. Previous research has shown that metabolic syndrome can cause liver abnormalities.

“We therefore hypothesized that metabolic syndrome could be an important contributor to this unexplained surge in advanced liver disease,” Lee said.

For the study, Lee and his fellow researchers used data from the National Health and Nutrition Examination Survey, which assesses the health and nutritional status of adults and children in the United States, pulling together samples representing the U.S. population 20 years or older between 1999 and 2018.

While the data revealed a slight increase in advanced liver disease with heavy alcohol use without metabolic syndrome, the greatest increase in advanced liver disease was found in those with combined heavy alcohol use and metabolic syndrome.

A call for awareness, action

Lee believes that the increased risk of liver damage from drinking is a result of an increase in the amount of fat in the liver. A healthy liver contains less than 5% fat; any more than that can lead to inflammation and cirrhosis of the liver, liver cancer and liver failure.

“Both metabolic syndrome and drinking increase liver fat, and we think that the combination of the two accelerates the accumulation of fat in the liver and fuels inflammation, resulting in a greater chance of liver disease,” Lee said.

He hopes the study will encourage physicians who screen and diagnose patients with metabolic syndrome to also ask about alcohol use and look for liver disease.

Additionally, physicians may advise patients with metabolic syndrome that they may be at increased likelihood of advanced liver disease, and to monitor their drinking accordingly.

“Our study indicates that these conditions may often coexist, and it is in patients’ best interest to address both issues,” Lee said.