Heavy drinking can damage the liver, but not everyone who drinks the same amount develops serious liver disease.
New research suggests that a person’s existing health problems may help explain why alcohol causes much more harm in some people than in others.
The study was led by researchers at Keck Medicine of USC and was published in the journal Clinical Gastroenterology and Hepatology.
The team found that diabetes, high blood pressure, and a large waist size were linked to a much greater risk of serious liver scarring among heavy drinkers.
The liver performs hundreds of important jobs, including processing nutrients, removing harmful substances from the blood, and breaking down alcohol. Drinking too much over time can injure liver cells and cause inflammation, fat buildup, and eventually permanent scarring.
This scarring is known as fibrosis. When it becomes severe, it can develop into cirrhosis, a condition in which healthy liver tissue is replaced by scar tissue and the liver can no longer work normally.
Researchers wanted to understand why some heavy drinkers appear especially vulnerable. They examined information from a large national health survey involving more than 40,000 people and focused on participants who reported heavy alcohol use.
In the study, heavy drinking was defined as more than 1.5 alcoholic drinks per day for women and more than two drinks per day for men. The researchers then looked at several common health problems that are connected with metabolism and cardiovascular health.
Heavy drinkers with diabetes or a large waist were about 2.4 times more likely to have advanced liver fibrosis than heavy drinkers without those conditions. High blood pressure was also important, with affected drinkers having about 1.8 times the risk.
A large waist can be a sign of excess fat stored around the abdominal organs. This type of body fat is strongly connected with problems involving blood sugar, insulin, inflammation, and fat accumulation in the liver.
Diabetes, high blood pressure, and abdominal obesity are also associated with metabolic dysfunction-associated steatotic liver disease, or MASLD. In this condition, too much fat builds up in the liver and can eventually cause inflammation and scarring.
Dr. Brian P. Lee, a liver specialist at Keck Medicine and the study’s lead researcher, suggested that alcohol and these existing metabolic problems may combine to place extra stress on the liver. In other words, a liver already affected by excess fat or poor metabolic health may be less able to tolerate heavy alcohol use.
Not every metabolic risk factor showed the same connection. High levels of triglycerides, a type of fat found in the blood, and low levels of HDL, often called good cholesterol, were not as strongly associated with advanced liver disease in the heavy drinkers studied.
The researchers did not prove exactly why the three strongest risk factors increased liver damage. The study was observational, meaning it found relationships between health conditions and liver disease but could not show that one directly caused the other.
Still, the findings could help doctors identify people who may need closer monitoring. Heavy drinkers who also have diabetes, high blood pressure, or excess abdominal fat may benefit from earlier checks for liver damage before symptoms appear.
This is important because liver fibrosis can develop quietly. People may feel well for years while damage is progressing, and serious symptoms may not appear until liver disease has become advanced.
The findings also do not suggest that heavy drinking is safe for people who do not have these health problems. Alcohol itself can harm the liver, and individual risk also depends on factors such as drinking patterns, genetics, age, nutrition, medications, and other medical conditions.
The study adds to evidence that liver health depends on more than alcohol consumption alone. Improving blood pressure, blood sugar, weight, and other aspects of metabolic health while reducing alcohol intake may be especially important for people who face several risks at the same time.
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