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