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Zinc Supplementation Reduces Common Cold Duration among Healthy Adults: A Systematic Review of Randomized Controlled Trials with Dose-Response Analysis
Systematic review of RCTs in healthy adults: zinc supplementation as a single micronutrient was associated with a shorter common cold duration (pooled reduction about 2.25 days, 95% CI -3.39 to -1.12) while other micronutrients (except vitamin C) showed little preventive benefit on incidence or severity in this review's framing.
Design
- SR of RCTs in healthy adults; micronutrients provided singly orally
- Outcomes: cold incidence, duration, symptom severity
Zinc duration signal (abstract)
- Mean reduction in cold duration: 2.25 days (95% CI −3.39 to −1.12) when zinc is provided alone
Contextual nulls (abstract)
Review reports most other micronutrients (except vitamin C) did not clearly prevent incidence or reduce severity—read full text for vitamin C stratum decisions.
Evidence hygiene
Cold duration is patient-reported in many trials; dose/form (lozenge vs tablet) matters for tolerability and mucosal contact.
Publication
Wang MX, et al. Am J Trop Med Hyg. 2020 Jul;103(1):86-99. PMID 32342851.
Outcomes
- Pooled mean reduction in common cold duration with zinc monotherapy: 2.25 days (95% CI -3.39 to -1.12) per abstract.
- Review framed most micronutrients other than vitamin C as not clearly reducing cold incidence or severity; zinc singled out for duration benefit.