Exercise-induced 3′-sialyllactose in breast milk is a critical mediator to improve metabolic health and cardiac function in mouse offspring

Poor maternal environments, such as under- or overnutrition, can increase the risk for the development of obesity, type 2 diabetes and cardiovascular disease in offspring 1 – 9 . Recent studies in animal models have shown that maternal exercise before and during pregnancy abolishes the age-related development of impaired glucose metabolism 10 – 15 , decreased cardiovascular function 16 and increased adiposity 11 , 15 ; however, the underlying mechanisms for maternal exercise to improve offspring’s health have not been identified. In the present study, we identify an exercise-induced increase in the oligosaccharide 3′-sialyllactose (3′-SL) in milk in humans and mice, and show that the beneficial effects of maternal exercise on mouse offspring’s metabolic health and cardiac function are mediated by 3′-SL. In global 3′-SL knockout mice ( 3 ′ -SL −/− ), maternal exercise training failed to improve offspring metabolic health or cardiac function in mice. There was no beneficial effect of maternal exercise on wild-type offspring who consumed milk from exercise-trained 3 ′ -SL −/− dams, whereas supplementing 3′-SL during lactation to wild-type mice improved metabolic health and cardiac function in offspring during adulthood. Importantly, supplementation of 3′-SL negated the detrimental effects of a high-fat diet on body composition and metabolism. The present study reveals a critical role for the oligosaccharide 3′-SL in milk to mediate the effects of maternal exercise on offspring’s health. 3′-SL supplementation is a potential therapeutic approach to combat the development of obesity, type 2 diabetes and cardiovascular disease. Maternal exercise, before and during pregnancy, has a beneficial effect on offspring. Harris et al. report that exercise-induced release of oligosaccharide 3′-sialyllactose in mouse breast milk mediates the metabolic health benefits of maternal exercise on offspring by improving glucose and insulin tolerance and cardiac function.