Immunity / Common Cold (URTI) Support
Adults seeking evidence-based adjuncts; NOT a substitute for vaccination/medical care.
immunity
URTI
reduce risk (limited) and/or duration of URTI
Core stack
Vitamin D (status-based)
B → C (updated evidence mixed)
Dose: 1000–2000 IU/day (or per clinician to correct deficiency)
Daily with fat-containing meal
Ongoing during low-sun months
Why: Earlier IPD meta-analysis suggested modest protection; recent updates show attenuated/neutral effects overall—benefit most plausible in deficient individuals.
Adjuncts
Zinc lozenges (acetate/gluconate)
B
Dose: 75–90 mg elemental/day divided (onset of symptoms)
Start within 24 h of cold symptoms; limit to ≤14 days
Notes: May shorten duration by ~2 days; taste/GI side-effects common; avoid intranasal zinc.
Sources
Probiotics (selected strains)
B (low–moderate certainty overall)
Dose: 1–10 billion CFU/day (strain-dependent)
Notes: Some strains reduce risk and/or shorten URTIs; effects are strain- and context-specific.
Not recommended
- Megadose vitamin C/Echinacea for prevention: Heterogeneous/weak evidence; side-effects possible.
Monitoring
- Adverse effects (nausea, taste changes)
- Total daily zinc to avoid copper deficiency with prolonged use