Vitamin D supplementation may lower the risk of autoimmune diseases

A Mendelian randomization analysis published in Seminars in Arthritis and Rheumatism has revealed genetic evidence indicating a relationship between vitamin D and psoriasis and systemic lupus erythematosus (SLE).  

The study conducted by Dr. Zhao and the team collected information from 332,984 UK Biobank individuals, 23,089 of whom had at least one autoimmune condition identified by ICD code or self-report. Additionally, diseases were examined separately in mechanistic subgroups driven by ‘autoimmunity’ (n=12,774) or ‘autoinflammation’ (n=11,164). To create a weighted genetic score, the researchers used certain genetic variations within gene regions linked to the biology of vitamin D. 

The researchers found a significant association between genetically predicted vitamin D and a reduced risk of diseases in the autoinflammation group (95% CI 0.91-0.99; P=0.03). However, the association was not observed in the autoimmunity group (OR 0.99; 95% CI 0.95-1.03; P=0.64). Furthermore, a significant association was found between genetically predicted vitamin D and a lower risk of SLE (OR 0.84; 95% CI 0.69-1.02; P=0.08) and psoriasis (OR 0.91; 95% CI 0.85-0.97; P =0.005). 

The VITAL randomized controlled trial, which followed 25,871 participants for approximately five years, revealed that supplementing with vitamin D and omega-3 fatty acids decreased the incidence of autoimmune illness compared to not supplementing. Omega-3 fatty acid supplementation, with or without vitamin D, reduced the incidence of autoimmune illness by 15%, whereas vitamin D supplementation alone decreased the rate of autoimmune disease by 22% over the five-year period. 

The research conducted by Dr. Zhao and colleagues highlights the potential of vitamin D supplementation in reducing disease susceptibility among individuals at risk for psoriasis or SLE, even though a definitive threshold level has yet to be established. The research sets the stage for more focused and evidence-based approaches to improve public health. 


  1. Zhao SS, Mason A, Gjekmarkaj E, Yanaoka H, Burgess S. Associations between vitamin D and autoimmune diseases: Mendelian randomization analysis. Semin Arthritis Rheum. 2023 Jun 30;62:152238. 
  2. Hahn J, Cook NR, Alexander EK, Friedman S, Walter J, Bubes V, et al. Vitamin D and marine omega 3 fatty acid supplementation and incident autoimmune disease: VITAL randomized controlled trial. BMJ. 2022 Jan 26;376:e066452.