Exposure to air pollution linked to higher risk of fatty liver disease

Long-term exposure to air pollution is associated with the development of fatty liver disease associated with metabolic dysfunction (MAFLD), especially in the presence of obesity and an unhealthy lifestyle, according to the results of a study published in the Journal of Hepatology.

Resulting from fatty accumulation in the liver, non-alcoholic fatty liver disease (NAFLD) and its more serious form, NASH, are responsible for an increasing proportion of advanced liver disease in the United States and around the world. In many cases, fatty liver disease is associated with obesity and diabetes, so it is sometimes referred to MAFLD. Fatty liver can lead to fibrosis, cirrhosis and even liver cancer. In the absence of effective approved medical therapies, disease management depends on lifestyle changes, such as weight loss and exercise.

While animal studies have shown that air pollution contributes to fatty liver disease, epidemiological research on the topic has been limited. Another study, presented at the 2021 AASLD Liver Meeting, reported a link between environmental pollutants and fatty liver disease as well as liver cancer, despite the absence of severe fibrosis.

“A growing number of studies suggest that ambient air pollution, which is the biggest environmental problem caused by industrialization, can increase the risk of metabolic disorders such as insulin resistance and dyslipidemia, and associated diseases such as type 2 diabetes mellitus and metabolic syndrome,” Xing Zhao, PhD, of Sichuan University in China, said in a .

Zhao and colleagues examined the link between air pollution and MAFLD in a Chinese population. They recruited 90,086 people between 2018 and 2019. MAFLD status was established based on liver fat determined by radiology as well as the presence of diabetes, overweight or obesity. The team conducted interviews with the participants to gather information on lifestyle, medical history, and demographic and social factors, and obtained biological samples and liver imaging.

High exposure to air pollution was strongly linked to a higher risk of MAFLD. This association was observed with particles of diameter ≤1, ≤2.5 and ≤10 micrometers (PM1, MP2.5 and PMten, respectively) as well as nitrogen dioxide (NO2).

“This study provides evidence that long-term exposure to ambient particulates1, MP2.5, MPten, and no2 may increase the odds of MAFLD in the real world,” the researchers wrote. “Our findings add to growing evidence of the adverse effects of ambient pollution on metabolic function and related organs.”

The researchers also noted that men, people who drank alcohol, current or past smokers, those on a high-fat diet, and those with abdominal obesity were more likely to be affected by exposure to long term to air pollution.

“[W]While physical activity combined with a healthy diet is an essential pillar in the fight against morbidities associated with metabolic syndrome, including MAFLD, findings that environmental pollution may exacerbate the risk of MAFLD may offer new clues for refine the counseling of these patients, for example by limiting the exposure of at-risk populations to outdoor environments with high pollution levels, as recommended for patients with severe asthma”, Massimo Colombo, MD, of San Raffaele Hospital in Italy, and Robert Barouki, MD, PhD, of the University of Paris, writes in a remark on the study.

Click here to read the study in the Journal of Hepatology.

Click here for more information on fatty liver disease.


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