Social bonds and health: exploring the impact of social relations on oxytocin and brain–gut communication in shaping obesity

Social relationships play a crucial role in shaping health. To better understand the underlying mechanisms, we explored the independent and interactive effects of perceived emotional support (PES) and marital status on body mass index (BMI), eating behaviors, brain reactivity to food images, plasma oxytocin, and alterations in the brain-gut microbiome (BGM) system. Brain responses to food stimuli, fecal metabolites, and plasma oxytocin levels were measured in 94 participants. Structural equation modeling was used to determine the integrated pathways linking social factors to obesity-related outcomes. Marital status and PES interact and independently influence lower BMI, healthier eating behaviors, increased oxytocin levels, food-cue reactivity in frontal brain regions involved in craving inhibition and executive control, and tryptophan-pathway metabolites related to inflammation, immune regulation, and energy homeostasis. These findings suggest that supportive human relationships, particularly high-quality marital bonds, may regulate obesity risk through oxytocin-mediated alterations in brain and gut pathways.