Zinc vs Vitamin D
for immune function
Stronger evidence: tie
Stronger effect: Vitamin D
Safety: Vitamin D carries a minor interaction; Zinc has none recorded.
For immune function, the two are evidence-matched; the difference is in effect and safety.
Vitamin D
grade C low certainty
modest reduction in acute respiratory infection risk, concentrated in deficient people
1000–2000 IU/day, adults
sources: PMID:00000024 · PMID:20000105