Impact of Vitamin D on Gut Microbiome

Originally published online at https://arbonahealthhub.com/2025/04/23/impact-of-vitamin-d-on-gut-microbiome/ Iranis N. Hernández González provides an overview of how vitamin D supports and modulates the gut microbiome. Hernández González begins by defining vitamin D as a fat-soluble prohormone sourced from diet (e.g., fish oil, egg yolk) and synthesized in skin upon UV exposure; it requires hepatic and renal hydroxylation to become active, and malabsorption conditions (e.g., celiac disease) or liver/kidney dysfunction can impair its status. She then describes the gut microbiome—a complex ecosystem of bacteria, fungi, archaea, and viruses essential for nutrient metabolism, immune defense, and intestinal barrier integrity—and explains that disturbances to this community contribute to diseases such as inflammatory bowel disease and colorectal cancer. The heart of her piece details the vitamin D–vitamin D receptor (VDR) axis: in the gut, VDR–vitamin D complexes upregulate tight-junction proteins to strengthen the mucosal barrier, stimulate anti-inflammatory signaling, and induce antimicrobial peptides to inhibit pathogens. Moreover, vitamin D may foster VDR expression in gut cells and promote the growth of beneficial bacterial taxa. Conversely, vitamin D deficiency compromises barrier function and host defenses, heightening susceptibility to gastrointestinal disorders. Hernández González concludes that while current evidence supports vitamin D’s role in maintaining gut health, additional clinical research is needed to determine optimal dosing and to explore vitamin D supplementation as supportive or preventive therapy for conditions like inflammatory bowel disease.