Fatty liver disease, now officially known as metabolic dysfunction-associated steatotic liver disease, affects a third of the world's adult population, and the numbers keep rising, according to Spanish liver specialists.
The condition is a complex disease caused by a combination of genetic, metabolic and environmental factors that lead fat to accumulate in the liver. Specialists at the Hospital Clínic de Barcelona explained that this fat deposit can damage liver cells and trigger a process of inflammation and repair in which liver cells are replaced by scar tissue, known as fibrosis. Over time, the buildup of fibrosis and the distortion of the liver's normal shape and structure lead to cirrhosis, a chronic condition that causes insufficient liver function.
The main risk factors for the disease fall under what is known as metabolic syndrome, particularly obesity and type 2 diabetes, but also high cholesterol, high triglycerides or elevated blood pressure. The Hospital Clínic specialists said these factors promote excess synthesis of lipids and their transfer from fatty tissue to the liver, which overwhelms the liver's ability to clear them.
The disease can also appear in people without any of these risk factors. In those cases it is usually caused by genetic factors, with the genetic variants identified directly affecting the pathways the body uses to produce or eliminate lipids, making it easier for fat to build up in the liver.
Ethnic groups more affected
Although the disease affects a large share of the world's population, its distribution is not uniform, and some ethnic groups are more affected than others. Several epidemiological studies carried out in the United States, where the population is highly diverse, found that people of Hispanic origin, and Mexicans in particular, had the highest prevalence, at 58 percent, followed by white patients at 44 percent and Black patients at 35 percent. The figures come from researchers Raúl Bernal Reyes, Daniel Bernal Serrano and Almudena Laris González in an article published in the journal Clínicas de Gastroenterología de México.
One of the biggest challenges of the disease is that it can remain hidden for years, which is why it is often referred to as the silent epidemic. As with other liver diseases, it produces almost no symptoms for much of its progression, so many people do not know they have it until it has reached an advanced stage. Tests commonly used to detect liver disease, such as transaminase levels, can also stay within normal ranges even when the disease is present, which can delay diagnosis.
Social factors
Beyond biological factors such as obesity, type 2 diabetes or genetics, social conditions play a decisive role in both the risk of developing the disease and its severity. Javier Crespo, a specialist in digestive medicine and hepatology and a member of the Spanish Society of Digestive Pathology, said there is a saying that postal code matters more than genetic code when it comes to the disease. That is not entirely true, he said, but it does hold some truth.
People with greater socioeconomic vulnerability more often develop obesity, type 2 diabetes and the liver disease itself. Crespo pointed to several contributing factors, including difficulty accessing quality health information, greater exposure to ultra-processed, low-quality food, and living environments that encourage a sedentary lifestyle.
New drug treatments
Paula Iruzubieta, a specialist in digestive medicine and hepatology at the Hospital Marqués de Valdecilla in Santander and a member of the Spanish Society of Digestive Pathology, said that until recently, advice on healthy eating, weight loss and physical activity was practically the only tool available to slow the disease's progression.
That has changed with the arrival of the first drug treatments specifically aimed at the most advanced forms of the disease. Iruzubieta said these treatments have shown for the first time that they can resolve the liver inflammation characteristic of the disease and improve fibrosis, opening the door to changing its natural course and reducing the risk of serious complications.
Not every patient needs the same treatment, however. In the early stages of the disease, the outlook is mainly shaped by cardiovascular and metabolic complications, so lifestyle changes remain the most effective and cost-efficient approach. But once significant, advanced fibrosis develops, the risk of the liver disease progressing rises considerably, and that is when the new drug treatments can offer the greatest benefit.
Iruzubieta said it is precisely in that window that targeted drug treatment becomes most relevant, and where the approved use of these medicines is concentrated. She added that, alongside these advances, there has been unprecedented development of new drugs, with multiple molecules currently in advanced stages of research along with new combination therapy strategies. The future, she said, is very promising.
