Vitamin D for Depression
Vitamin D earns a weak evidence grade for depression: it does not prevent depression in the general population, and any benefit appears limited to people who are deficient or already depressed, where it may modestly ease symptoms as an add-on. It is not a substitute for proven treatment.
Why this grade7-layer evidence engine
The grade lands at weak (C) because the evidence is genuinely split. Four recent meta-analyses (PMID 39552387, n=24,189; PMID 40821024; PMID 37852593; PMID 36716601, n=1,980) report small-to-moderate symptom improvement (SMD roughly -0.15 to -0.49), but the effect is driven by subgroups who were vitamin D-deficient or already depressed rather than the general public.
Crucially, the largest and most rigorous trial pulls the other way: VITAL-DEP (PMID 32749491), a 5-year double-blind RCT in 18,353 adults given 2,000 IU/day, found no reduction in depression risk or mood scores. So the strongest single study shows no benefit for prevention, which is why the grade is not higher.
Clinical and regulatory bodies mirror this caution. Harvard Health notes VITAL 'found no effect,' Mayo Clinic only links low vitamin D and depression as a correlation, and the ADAA/APA call it 'unclear whether these supplements improve the symptoms of SAD.' The FDA, EFSA and NHS endorse vitamin D for bone and immune health, but none approve a depression claim. Bottom line: correct a deficiency if present, but do not rely on it to prevent or treat clinical depression.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.456
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status