Vitamin D and Anxiety
Anxiety disorders — generalised anxiety, panic disorder, social anxiety — show a modest deficiency association with vitamin D in cohort studies. Small supplementation trials in deficient anxious adults report GAD-7 score improvements. Evidence is weaker than for depression but the intervention is safe and cheap.
Observational data
Cross-sectional studies find lower mean 25(OH)D in adults with anxiety disorders vs matched controls (Bicikova 2015 and others). The correlation is smaller than for depression. Mendelian randomisation studies have not convincingly supported causation for anxiety.
Small supplementation trials
Fazelian 2019 and others show modest GAD-7 reduction in deficient anxious adults given vitamin D vs placebo for 8-12 weeks. Effect sizes are small (0.5-1.5 point improvement on GAD-7). Larger definitive trials are lacking.
Practical approach
- Test 25(OH)D in patients with persistent anxiety symptoms.
- Correct any deficiency with 2,000 IU/day cholecalciferol.
- Continue evidence-based anxiety management — CBT, SSRI/SNRI, mindfulness.
- Don't stop or delay effective anxiety treatment for a vitamin trial.