Are breast milk and serum irisin levels affected by the BMI and nutritional status? A prospective observational study

• This is the first study to evaluate the association between maternal BMI, nutritional status, and both breast milk and serum irisin levels. • Overweight and obese mothers exhibit lower breast milk irisin but higher serum irisin levels, and maternal intake of fiber, fat, folate, vitamin B12, and zinc is significantly associated with irisin levels.