Zinc and the common cold
Zinc supplements (frequently zinc acetate or zinc gluconate lozenges) are a group of dietary supplements that are commonly used in an attempt to treat the common cold.[1] Evidence of any benefit is weak, but it seems zinc may not prevent colds, but possibly reduce their length while not reducing the severity of the symptoms.[2] Adverse effects with zinc supplements by mouth include bad taste and nausea.[1][3] The intranasal use of zinc-containing nasal sprays has been associated with the loss of the sense of smell;[1] consequently, in June 2009, the United States Food and Drug Administration (USFDA) warned consumers to stop using intranasal zinc.[1]
The human rhinovirus – the most common viral pathogen in humans – is the predominant cause of the common cold.[4] The hypothesized mechanism of action by which zinc reduces the severity and/or duration of cold symptoms is the suppression of nasal inflammation and the direct inhibition of rhinoviral receptor binding and rhinoviral replication in the nasal mucosa.[1]
Effectiveness
[edit]Evidence around the effect of zinc on the common cold is weak, and insufficient to provide a basis for clinic decision making. What evidence there is, suggests zinc might not help prevent colds, does not make them less severe, but might reduce their length.[2]
Interactions
[edit]Some lozenge formulations do not contain enough zinc to effectively reduce the lengths of colds; some of them contain ingredients that bind zinc, like citric acid, which prevent the zinc from working.[5]
Safety
[edit]There have been several cases of people using zinc nasal sprays and suffering a loss of sense of smell.[1] In 2009 the US Food and Drug Administration issued a warning that people should not use nasal sprays containing zinc.[1]
Excessive zinc intake may result in an unpleasant taste and/or nausea.[1][6]
Mechanism of action
[edit]The hypothesized mechanism of action by which zinc reduces the severity and/or duration of cold symptoms is the suppression of nasal inflammation and the direct inhibition of rhinoviral receptor binding and rhinoviral replication in the nasal mucosa.[1] Zinc has been known for many years to have an effect on cold viruses in the laboratory.[7] In the arteriviridae and coronaviridae families of virus that also cause the common cold, in vitro studies found that zinc ionophores block the replication of those viruses in cell culture.[8]
References
[edit]- ^ a b c d e f g h i "Zinc – Fact Sheet for Health Professionals". Office of Dietary Supplements, US National Institutes of Health. February 11, 2016. Retrieved January 7, 2018.
- ^ a b Nault D, Machingo TA, Shipper AG, Antiporta DA, Hamel C, Nourouzpour S, Konstantinidis M, Phillips E, Lipski EA, Wieland LS (May 2024). "Zinc for prevention and treatment of the common cold". Cochrane Database Syst Rev (Systematic review). 2024 (5): CD014914. doi:10.1002/14651858.CD014914.pub2. PMC 11078591. PMID 38719213.
- ^ Science M, Johnstone J, Roth DE, Guyatt G, Loeb M (July 2012). "Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials". CMAJ. 184 (10): E551-61. doi:10.1503/cmaj.111990. PMC 3394849. PMID 22566526.
- ^ "Common Cold and Runny Nose". United States Centers for Disease Control and Prevention. September 26, 2017. Retrieved January 7, 2018.
- ^ Hemilä H, Petrus EJ, Fitzgerald JT, Prasad A (November 2016). "Zinc acetate lozenges for treating the common cold: an individual patient data meta-analysis". British Journal of Clinical Pharmacology. 82 (5): 1393–1398. doi:10.1111/bcp.13057. PMC 5061795. PMID 27378206.
- ^ Singh M, Das RR (June 2013). Singh M (ed.). "Zinc for the common cold". The Cochrane Database of Systematic Reviews (6): CD001364. doi:10.1002/14651858.CD001364.pub4. PMID 23775705. (Retracted, see doi:10.1002/14651858.CD001364.pub5, PMID 25924708, Retraction Watch)
- ^ "Zinc 'can cut length of common cold'". NHS Choices. May 8, 2012. Archived from the original on June 12, 2017. Retrieved January 7, 2018.
- ^ te Velthuis, Aartjan J. W.; van den Worm, Sjoerd H. E.; Sims, Amy C.; Baric, Ralph S.; Snijder, Eric J.; van Hemert, Martijn J. (November 4, 2010). "Zn2+ Inhibits Coronavirus and Arterivirus RNA Polymerase Activity In Vitro and Zinc Ionophores Block the Replication of These Viruses in Cell Culture". PLOS Pathogens. 6 (11): e1001176. doi:10.1371/journal.ppat.1001176. PMC 2973827. PMID 21079686.