Evidence check: VDR in the context of gut health

The vitamin D receptor (VDR) mediates the effects of vitamin D on immune cells and gut epithelium. Genetic variants in the VDR gene (e.g., rs2228570, rs1544410) have been associated in observational studies with a modestly increased risk of inflammatory bowel disease (IBD) and shifts in gut microbiota composition. However, effect sizes are small, and findings are not consistent enough to guide clinical decisions. A direct-to-consumer genetic test cannot predict gut disease or justify specific supplementation. Measuring actual serum vitamin D levels is more actionable; deficiency should be corrected regardless of genotype. Evidence is based on association studies (human-moderate). Caveat: Many studies are underpowered or unreplicated; causal links to gut health remain unproven. For chronic digestive issues, consult a gastroenterologist rather than relying on genetic results.