Vitamin D for Immune Function
Verdict: Published with Warning
Across 6 PubMed studies, the evidence for Vitamin D in Immune Function grades Tier B — preliminary evidence. Effective, but with safety or population caveats.
B 🟡 B Preliminary Evidence Published with Warning
Why this grade7-layer evidence engine
⚖️
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditableRaw score 0.51
D
C
B
A
S
← counter-evidence / ineffectiveeffective / strong evidence →
Final grade
B · Published with Warning
Confidence
87%
Highly consistent evidence
Evidence level
E2
Multiple high-quality MAs (≥2 independent, consistent)
▸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 = 0.512
- 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 > 1 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status
PubMed studies (6)L2 · primary research & systematic reviews
Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data
Finding: Vitamin D supplementation modestly reduced ARI risk overall (adjusted OR 0.88, 95% CI 0.81-0.96), with much larger benefit in those with baseline 25(OH)D <25 nmol/L (aOR 0.30, 0.17-0.53) and only when given daily/weekly rather than as bolus doses.
View on PubMed Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trials
Finding: Across 46 RCTs vitamin D produced a small protective effect (OR 0.92, 95% CI 0.86-0.99), strongest with daily dosing of 400-1000 IU (OR 0.78, 0.65-0.94) for <=12 months; the absolute effect was small and heterogeneity high.
View on PubMed Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate data
Finding: With six new RCTs added (49 studies), the protective effect was no longer statistically significant (OR 0.94, 95% CI 0.88-1.00, p=0.057), and pre-specified subgroups showed NO effect modification by baseline vitamin D status, age, dose, or dosing frequency.
View on PubMed Vitamin D supplementation for prevention of acute respiratory infections in older adults: A systematic review and meta-analysis
Finding: Pooling 12 RCTs in older adults, vitamin D supplementation probably results in little to no difference in ARI incidence (RR 0.99, 95% CI 0.97-1.02; moderate-certainty GRADE).
View on PubMed Preventive Vitamin D Supplementation and Risk for COVID-19 Infection: A Systematic Review and Meta-Analysis
Finding: Across 16 publications vitamin D was associated with lower COVID-19 risk, with a stronger effect in the RCT subset (OR 0.403, 95% CI 0.218-0.747) than in observational studies (OR 0.592, 0.476-0.736); pooling RCTs with observational data and a small RCT subset limits reliability.
View on PubMed Infections and Autoimmunity-The Immune System and Vitamin D: A Systematic Review
Finding: This narrative systematic review reports no pooled effect estimate and concludes that maintaining serum 25(OH)D >50 ng/mL is associated with significant risk reduction from infections and autoimmunity - an association based largely on observational serum-level data rather than supplementation RCT endpoints.
View on PubMed Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …
L4a US FDA
Supportive
Vitamin D-3 is recognized as GRAS source↗
L4b EU EFSA
Supportive
cause and effect relationship has been established source↗
L4c UK NHS
Supportive
everyone should consider taking a daily vitamin D supplement during the autumn and winter source↗
L4d TW TFDA / 衛福部
Supportive
每日維生素D攝取量需達10微克 source↗
L4e WHO
Cautious
not recommended for all pregnant women source↗
L5a NIH Office of Dietary Supplements
Supportive
Vitamin D is a fat-soluble vitamin source↗
L5b Mayo Clinic
Supportive
Vitamin D helps keep your muscles, nerves and immune system healthy. Vitamin D supplementation may help shape how the immune system responds to gut bacteria in people with inflammatory bowel disease (IBD). source↗
L5c Cleveland Clinic
Supportive
Vitamin D has been shown to help regulate the immune system, and having adequate levels helps prevent infections. Having low vitamin D levels is associated with a higher risk of infections, especially those that affect the respiratory system. source↗
L5d Harvard Health
Cautious
While there is also evidence that vitamin D may have positive effects on immune function, a specific antiviral effect remains unproven. source↗
L5e Specialty Society (condition-mapped)
Cautious
Your immune system needs vitamin D to fight off invading bacteria and viruses. Vitamin D has roles in the body including reduction of inflammation as well as modulation of such processes as cell growth, neuromuscular and immune function, and glucose metabolism. However, meta-analyses of vitamin D supplementation studies have drawn inconsistent conclusions regarding effects on immune function an… source↗