Higher personal UVR exposure was significantly associated with lower BMI z-score in preschool children, with this association partially mediated by changes in gut microbiota diversity, particularly Lactobacillus, Lachnospira, Coprococcus, and Bifidobacterium.
Higher personal solar UV radiation exposure was significantly associated with lower BMI z-score in preschool children.
Structural equation modeling indicated that UVR exposure was positively related to microbial diversity and inversely associated with BMI z-score.
Lactobacillus exhibited the most substantial mediating effect in the relationship between UVR exposure and BMI z-score, followed by Lachnospira, Coprococcus, and Bifidobacterium.
The study highlights UVR exposure's potential as a natural and non-invasive intervention for children with overweight or obesity.
This research suggests that preschool children in China who are exposed to more sunlight (specifically ultraviolet radiation, or UV rays) tend to have lower body mass index (BMI) scores, a common measure used to assess whether a child's weight is healthy for their age and sex. The study followed 405 young children across three Chinese cities, measuring their personal UV exposure through a modeling approach and analyzing their gut bacteria using stool samples. Children with higher UV exposure appeared to have more diverse communities of gut bacteria, and this greater diversity was linked to lower BMI scores. The study also found that specific types of gut bacteria — particularly Lactobacillus, followed by Lachnospira, Coprococcus, and Bifidobacterium — appear to play a role in connecting UV exposure to BMI. In other words, sunlight may partly influence a child's weight by changing the makeup of the bacteria living in their digestive system. This is known as a mediation effect, and it was identified using a statistical technique called mediation analysis alongside structural equation modeling. This research suggests that encouraging safe, age-appropriate sunlight exposure in young children could potentially support healthy weight development, in part by promoting a healthier gut microbiome. However, because this was a cross-sectional study (a snapshot in time rather than a long-term follow-up), it cannot prove that UV exposure directly causes lower BMI or healthier gut bacteria. The authors emphasize the need for future research to understand the long-term effects and the biological mechanisms involved before these findings can inform public health recommendations.
Liang J, Ke D, Shao M, Li Y, He G, Liu Y. (2026). Associations of personal solar UV exposure with gut microbiota diversity and BMI among preschool children in China.. Journal of pediatric endocrinology & metabolism : JPEM. https://doi.org/10.1515/jpem-2025-0631