Fatty liver disease is becoming one of the fastest-growing health problems around the world, and new research suggests its impact may extend beyond the people who are diagnosed with it.
A large study from Sweden has found that close family members of people with fatty liver disease face a higher risk of developing serious liver conditions themselves, including liver cancer.
The condition is now known as metabolic-associated steatotic liver disease, or MASLD. It was previously called non-alcoholic fatty liver disease (NAFLD). MASLD develops when excess fat builds up inside the liver.
It is closely linked to obesity, type 2 diabetes, high blood pressure, and other metabolic health problems. Because these conditions have become increasingly common, the number of people living with fatty liver disease has risen sharply over the past few decades.
In its early stages, MASLD often causes no obvious symptoms. Many people do not realize they have the condition until it is discovered during routine medical tests. However, over time, the buildup of fat can trigger inflammation and scarring in the liver. In some people, this damage may eventually lead to cirrhosis, liver failure, or liver cancer.
Doctors have long known that people with MASLD face a greater risk of serious liver disease. What has been less clear is whether their family members also share some of that risk. To answer this question, researchers from Karolinska Institutet in Sweden carried out one of the largest and longest studies ever conducted on the topic.
The team used information from the Swedish ESPRESSO cohort, a nationwide database that contains records of liver biopsies performed in Sweden since 1965. A liver biopsy involves taking a small sample of liver tissue for examination and is considered one of the most reliable ways to confirm liver disease.
The researchers identified nearly 12,000 people whose MASLD had been confirmed through a liver biopsy. They then compared these patients with people from the general population who did not have the disease.
After that, they examined the health outcomes of almost 250,000 close family members, including parents, children, and siblings. They also studied more than 57,000 partners of both patients and comparison participants.
One of the strengths of the study was its long follow-up period. Participants were monitored for an average of 17.6 years, and some were followed for as long as 50 years. This allowed researchers to examine the long-term effects of having a family member with MASLD.
The results showed that close relatives of people with MASLD had an 80% higher risk of developing liver cancer compared with relatives of people who did not have the disease.
Although this sounds like a very large increase, the researchers noted that liver cancer remains relatively uncommon. Over a period of 20 years, the increased risk translated into approximately one additional case of liver cancer for every 900 family members.
Even so, the findings are important because MASLD is now so widespread. Small increases in risk can have a major impact when millions of people are affected.
One particularly interesting finding was that partners also faced a higher risk of serious liver disease. Since partners are not biologically related, this suggests that shared lifestyle habits play an important role.
People who live together often eat similar foods, have similar levels of physical activity, and may share other health-related behaviors. These factors can strongly influence liver health over many years.
The researchers believe the findings highlight the need for a broader approach to preventing liver disease. At present, doctors typically advise only the patient with MASLD to make lifestyle changes such as improving diet, exercising regularly, and losing weight if necessary.
However, the study suggests that family members may benefit from the same advice, especially if they already have risk factors such as obesity, diabetes, or high blood pressure.
The researchers also suggest that earlier screening of relatives who have metabolic risk factors could help identify liver problems before they become severe. Detecting liver disease early often provides more opportunities for treatment and prevention.
Experts say the study’s greatest strength is its use of a very large national database and decades of follow-up information. This provides strong evidence that fatty liver disease should not be viewed only as an individual health issue.
Instead, it may affect entire households and families through a combination of shared genes, shared environments, and shared lifestyle habits.
The findings add to growing evidence that preventing fatty liver disease requires more than treating one person at a time. Encouraging healthier eating habits, regular physical activity, weight management, and better awareness of metabolic health within families could help reduce the burden of liver disease in the future.
The study was published in the Journal of Hepatology and offers an important reminder that protecting liver health may be a family effort. By recognizing risks early and making healthy changes together, families may be able to lower their chances of developing serious liver disease and improve their long-term health.
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