HDCA Supplementation During Maternal High-Fat Diet Exposure Is Associated with Offspring Gut Microbiota at Weaning and Adult Metabolic Phenotypes in a Mouse Model

Background/Objective: Maternal diet is an important determinant of gut microbiota composition in dams and offspring. This study investigated whether HDCA supplementation during maternal high-fat diet (HFD) exposure was associated with gut microbiota composition in dams and offspring and with selected obesity-related phenotypes. Methods: Nineteen C57BL/6J female mice were assigned to a control diet group (CON), a high-fat diet group (HFD), and a high-fat diet supplemented with 0.5% hyodeoxycholic acid group (HFD+HDCA). Fecal samples were collected from the dams before mating, following 8 weeks of dietary intervention, and from the offspring at weaning. All samples were analyzed using 5R 16S rRNA gene sequencing. Body weight was monitored in both dams and offspring, and liver histology was assessed by hematoxylin and eosin staining. Results: HFD exposure was associated with obesity-related phenotypes in dams and offspring, including increased maternal body weight and greater hepatic lipid accumulation and visceral adiposity in offspring. LEfSe and ANCOM-BC2 analyses identified concordant microbial changes between dams and offspring under corresponding dietary conditions. Lachnospiraceae_Unknown_genus3261 and Coprococcus increased with HFD exposure in both dams and offspring, whereas Bifidobacterium, Coprococcus, and Allobaculum decreased following HDCA supplementation. These findings indicate maternal–offspring concordance in microbiota responses to HFD and HDCA, without establishing direct vertical transmission. PICRUSt2 analysis suggested group association differences in predicted functional potential for pathways annotated to propionate, pyruvate, and β-alanine metabolism. Conclusions: HDCA supplementation during maternal HFD exposure was associated with differences in offspring gut microbiota at weaning and with attenuation of selected obesity-related phenotypes. These findings suggest a potential role of the gut microbiota–bile acid axis in mediating intergenerational dietary effects. However, the study does not establish direct microbial transmission, altered metabolic activity, or causality; these findings require confirmation in litter-aware and mechanistic studies.