People with metabolic dysfunction-associated steatotic liver disease (MASLD) commonly show lower levels of irisin, a protein that supports metabolism. In new research published in Nutrients, researchers in South Korea and the USA found that an increase in participants’ irisin levels was associated with a reduction in liver fat, indicating that irisin could be a key biomarker for assessing improvements in liver health due to lifestyle interventions.
“Our results provide novel evidence of the association between changes in irisin levels and hepatic fat content,” they wrote.
What is irisin?
First identified and described in 2012 by a research team at Harvard Medical School, irisin demonstrated a molecular link between exercise and metabolic health. Its name originates from the Greek goddess Iris, who was a messenger of good news, reflecting irisin’s role as a chemical messenger that transmits the beneficial effects of exercise to fat and other tissues.
Irisin is a myokine, a hormone-like protein, and is produced by skeletal muscle during exercise. One of its key functions is regulating thermogenesis, helping to convert white fat into brown fat in a process known as browning. White fat stores energy, whereas brown fat burns it, so the metabolic effect of irisin is an increase in energy expenditure and potentially improved insulin sensitivity.
Because of its metabolic benefits, irisin has been studied as a therapeutic tool to manage obesity and metabolic syndrome. The current study noted that irisin also “reduces the production of reactive oxygen species (ROS) through multiple mechanisms, such as upregulating autophagy while downregulating endoplasmic reticulum stress, inflammasome activation, and cell death,” thereby protecting liver cells from damage due to oxidative stress.
Study details
For the 4-week study, the researchers randomly assigned 30 adults with MASLD who hadn’t exercised in the previous 3 months into 3 groups: calorie restriction (CR), CR with resistance exercise, and CR with resistance exercise and whey protein.
Participants received three boxed meals per day, resulting in a 30% calorie deficit. Those in the whey protein group received powdered supplementation corresponding to 0.7 g of protein per kg of body weight.
The resistance exercise was performed five times a week at 50% to 75% of the participant’s one-repetition maximum. The researchers used controlled attenuation parameter (CAP) to assess liver fat content and measured plasma irisin and body composition before and after the intervention.
The results showed that plasma irisin levels significantly increased in the CR with exercise and CR with exercise and whey protein groups, but not in the CR alone group.
“Furthermore, a stronger increasing trend in the plasma irisin levels was observed with whey protein supplementation,” the researchers noted.
Muscle mass increased only in the exercise plus protein group, and the CAP decreased in all groups.
The researchers observed that an increase in irisin levels was significantly associated with reduced liver fat, “suggesting that irisin may serve as a biomarker reflecting improvements in hepatic steatosis following lifestyle intervention.”
They acknowledged the small sample size and called for research with larger cohorts to validate their observed trends.
Source: Nutrients; doi: 10.3390/nu18081272; “Effects of Resistance Exercise and Whey Protein Supplementation on Irisin Levels in Patients with MASLD Under a Calorie-Restricted Diet.” Authors: F-R Zhang et al.
