Being physically active helps prevent NAFLD

Physical activity (PA) is associated with a lower prevalence of nonalcoholic fatty liver disease (NAFLD), with greater benefits for higher PA intensities, reveals a study. Better metabolic health, particularly lower waist circumference and insulin resistance, mediates this association.

“Although we observed strongest associations for vigorous PA, additional benefits were objectified for both moderate and light PAs,” the researchers said. “This is especially relevant for those unable to reach vigorous PA and indicates that increasing time spent in lower intensities of PA may already be beneficial in achieving or maintaining good liver health.”

Cross-sectional analyses were carried out within the population-based Rotterdam Study cohort. The researchers collected abdominal ultrasound and accelerometry data between 2009 and 2014 from 667 participants (mean age 63.3 years, 53 percent female). Accelerometry data was categorized into sedentary time and light, moderate, and vigorous PA.

NAFLD was defined as hepatic steatosis diagnosed by ultrasound, in the absence of secondary causes for steatosis, namely viral hepatitis, steatogenic drugs, and excessive alcohol.

Of the participants, 34.3 percent had NAFLD. Total PA inversely correlated with NAFLD prevalence, adjusted for lifestyle, demographic, and socioeconomic factors (odds ratio [OR], 0.958 per 10 min/d, 95 percent confidence interval [CI], 0.929‒0.986). [Am J Gastroenterol 2022;117:311-318]

Of note, a more intensive PA resulted in much lower NAFLD prevalence: light (OR, 0.931 per 10 min/d, 95 percent CI, 0.882‒0.982), moderate (OR, 0.891 per 10 min/d, 95 percent CI, 0.820‒0.967), and vigorous PA (OR, 0.740 per 10 min/d, 95 percent CI, 0.600‒0.906).

Such associations were driven by metabolic health, specifically homeostatic model assessment of insulin resistance (proportion mediated, 0.59; p<0.001) and waist circumference (proportion mediated, 1.08; p<0.001). No direct effect could be shown beyond this indirect effect (p=0.282‒0.827).

Disease management and prevention

Earlier studies also demonstrated that the association between PA and NAFLD eased after adjusting for changes in anthropometrics and glucose management. [Aliment Pharmacol Ther 2012;36:772-781; Liver Int 2017;37:919-926; Am J Gastroenterol 2011;106:460-469]

“Thus, these results support that the association of PA with liver health is not only a matter of weight or waist circumference but is also affected and mediated by other metabolic health parameters, particularly glucose management,” the researchers said.

“We recommend incorporating PA to its full extent in NAFLD disease management and prevention,” they added.

To improve current guidelines for disease management and prevention programs, it is necessary to show evidence for the effects of PA at different intensities on NAFLD, according to the researchers.

For instance, a 2009 study among NAFLD patients reported how three individually tailored counselling sessions to increase low-to-moderate PA led to a 1 hr/wk increase of PA in >60 percent of participants and to improvements in glucose management and alanine aminotransferase levels. [Hepatology 2009;50:68-76]

“Additional studies are needed to investigate lasting effects, NAFLD regression rates, impact on fibrosis or liver stiffness, feasibility of implementation on a large scale in NAFLD patients, and how more vigorous activity could be incorporated best,” the researchers said.

“However, supported by our results, it seems feasible with a small intervention to achieve health benefits in patients with NAFLD focusing on PA,” they added.