A new study finds that exercise supports the treatment of non-alcoholic fatty liver disease by impacting several metabolic pathways.
Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, affecting approximately 25% of the world’s population. The disease may progress from the accumulation of fat in liver cells to liver inflammation and liver cirrhosis. The accumulation of fat in the liver can be reduced by weight loss and a health-promoting diet.
University of Eastern Finland researchers discovered that regular high-intensity interval training (HIIT) exercise over 12 weeks significantly decreased participants’ fasting glucose and waist circumference and improved their maximum oxygen consumption rate and maximum achieved workload.
The study was published in Scientific Reports.
Studying the effects of the exercise on non-alcoholic fatty liver disease
The researchers comprehensively examined the effects of exercise on metabolism in patients with non-alcoholic fatty liver disease. The randomised controlled intervention study involved 46 subjects diagnosed with the condition.
They divided the participants into an exercise intervention group that had a HIIT session twice a week, plus an independent training session once a week for 12 weeks, and a control group that did not increase exercise during the study. Neither of the groups sought to lose weight nor changed their dietary habits during the intervention.
In addition to conventional medical examination and laboratory tests performed at the onset and end of the study, the researchers also performed untargeted metabolomics analyses to identify various metabolites and their abundance in adipose tissue, plasma, urine, and stool samples. Based on the results, exercise affected metabolic pathways differently in different tissues.
What did the researchers find?
The researchers identified that exercise had a beneficial effect on fasting glucose concentrations, waist circumference, maximum oxygen consumption rate, and maximum achieved workload. These factors were also associated with many of the observed alterations in the abundance of various metabolites in the exercise intervention group.
Furthermore, the exercise intervention increased levels of amino acids, which are the building blocks of proteins, in adipose tissue. According to the researchers, their higher accumulations in adipose tissue may be associated with improved lipid and glucose metabolism, and reduced insulin resistance.
The levels of various gut microbial metabolites were altered as a result of exercise, which is suggestive of changes in the composition of gut microbes, or in their function. Amongst these metabolites, an increased amount of indoleacetic acid, for example, can strengthen the intestinal mucosa, immune defence, and glucose balance.
Therefore, the results indicate that exercise can have a beneficial effect on many factors contributing to disease in patients with non-alcoholic fatty liver disease, even without weight loss and dietary changes. The adipose tissue appears to play a key role in these effects. The research did indicate that abnormal blood lipid concentrations were not improved by exercise alone; their treatment does require attention to the quality of dietary fats.