Supplements for cold prevention

Compared by effect and evidence certainty. Cost is not currently assessed, and nothing here is sold to you.

Zincgrade Bmoderate certainty— zinc lozenges started early may modestly shorten cold duration

Safety: no modeled interaction found; coverage unknown, not proven safe. Cost: not assessed. Evidence gaps: population bounds not reported.

Vitamin Cstudied, no effectmoderate certainty— no reduction in cold incidence in the general population

Safety: no modeled interaction found; coverage unknown, not proven safe. Cost: not assessed. Evidence gaps: studied dose not reported; population bounds not reported; certainty or evidence strength remains limited.

Vitamin Dstudied, no effectmoderate certainty— Meta-analysis of 12 RCTs (41,552 participants) in older adults: vitamin D supplementation probably does NOT reduce the incidence of acute respiratory infections overall (RR 0.99, moderate certainty), with no significant subgroup effect by baseline vitamin D level, dose, or duration. A non-significant signal for benefit specifically in vitamin-D-deficient individuals was noted but not confirmed.

Safety: minor — Magnesium is a cofactor in vitamin D metabolism; the two are complementary.. Cost: not assessed. Evidence gaps: certainty or evidence strength remains limited.

1 paper with unavailable publication authority was omitted. Current findings are the verified subset of this bounded collection; this is not a complete literature search.