Vitamin D

Immune Effects#

Antimicrobial peptides: Vitamin D induces cathelicidin (LL-37) and defensin production—direct antimicrobial effectors at mucosal surfaces. Treg support: Vitamin D promotes Treg differentiation and IL-10 production, counterbalancing Th17 responses. Th17 suppression: Calcitriol directly inhibits IL-17 production by Th17 cells.

Microbiome Interactions#

Vitamin D supplementation alters Gut Microbiome composition—increases Bacteroidetes, modulates Firmicutes:Bacteroidetes ratio. VDR expression in the gut epithelium regulates barrier integrity and antimicrobial peptide production.

Vitamin D + probiotic: Combined supplementation (vitamin D + Lactobacillus/Bifidobacterium) improved metabolic parameters in schizophrenia RCT.^{[1]Clinical and Metabolic Response to Vitamin D Plus Probiotic in Schizophrenia PatientsGhaderi A, Banafshe HR, Mirhosseini N et al. · 2019Open reference 1 ↓}

Disease Relevance#

MS: Low vitamin D is the strongest environmental risk factor; supplementation reduces relapse rate.^{[2]The immunology of multiple sclerosisKathrine E. Attfield, Lise Torp Jensen, Max Kaufmann et al. · 2022Open reference 2 ↓[3]Gut Microbiome-Modulated Dietary Strategies in EAE and Multiple SclerosisHoffman K, Doyle WJ, Schumacher SM et al. · 2023Open reference 3 ↓}

T1D: Vitamin D deficiency associated with beta-cell autoimmunity.^{[4]Bi 2017 — Omega-3 Polyunsaturated Fatty Acids Ameliorate Type 1 Diabetes and AutoimmunityXinyun Bi, Fanghong Li, Shanshan Liu et al. · 2017Open reference 4 ↓} Hashimoto's: Part of nutritional prevention strategy.^{[5]Role of Food and Nutrition in Pathogenesis and Prevention of Hashimoto's ThyroiditisPuszkarz I, Guty E, Stefaniak I et al. · 2018Open reference 5 ↓} Schizophrenia: Vitamin D + probiotic RCT evidence.^{[1]Clinical and Metabolic Response to Vitamin D Plus Probiotic in Schizophrenia PatientsGhaderi A, Banafshe HR, Mirhosseini N et al. · 2019Open reference 1 ↓}