Probiotic‐Mediated Vitamin D Supplementation Improves the Gut Microbiota and Vitamin D Receptor Composition in Obese Rats

Obesity is a complex disorder affecting metabolism and immunity, with gut microbiota and vitamin D metabolism playing key roles. This study aimed to evaluate the impact of vitamin D supplementation and probiotics on the vitamin D receptor (VDR) levels and the gut microbiota of rats given a high‐fat diet as an experimental model of obesity. In this study, experimental obese rat models were used to assess the impact of vitamin D and probiotic supplements on lipid profiles, inflammation, obesity, diabetes, VDR, and gut microbiota. 24 Wistar rats (4–6 weeks) were divided into four groups: control, high‐fat diet, high‐fat diet with probiotic supplementation (HFD + P), and high‐fat diet with probiotic and vitamin D supplementation (HFD + P + VD). Blood and fecal samples were collected from rats for analysis. Changes in BMI values, initial and final weights, and weight changes across all groups were found ( p = 0.018, p = 0.006, p = 0.023). HFD + P and HFD + P + VD showed lower levels of insulin, CRP, triglycerides, IL‐6, HOMA‐IR, and leptin. Supplementing probiotics and vitamin D reduced the phylum Bacteroidetes while increasing the phyla Proteobacteria, Firmicutes, and Actinobacteria. The findings suggest that probiotics combined with vitamin D supplementation may be a promising approach for supporting the management of obesity‐related metabolic disorders and microbiota. Furthermore, probiotics may enhance vitamin D's effectiveness by inducing VDR expression.