To understand how zinc therapy impacts a cold, it helps to first understand what is actually causing the illness. The common cold is the result of a respiratory viral infection.
Viruses are simple, non-living particles that are strictly parasitic and very focused on a single objective – making more viruses. In order to increase in number, a virus must first infect a cell. The viruses that cause colds specifically infect cells of the human nasal cavity and upper throat.
Does Zinc Really Help Cure a Cold?
Due to different experimental designs and use of a variety of zinc formulations, early scientific studies on zinc’s effectiveness in combating the common cold were somewhat conflicting and confusing, but the publication of a 2004 review of all research to date has set the record straight.
Zinc lozenges, such as Cold-Eeze, were some of the first zinc therapies on the scene, but these oral formulations didn’t taste good and caused stomach upset in some patients. Even so, the majority of data showed oral formulations of zinc (lozenges and oral sprays) to be effective in reducing the duration and severity of cold symptoms if administered within 24 hours of the onset of symptoms.
More recent studies of zinc gluconate administered as a nasal gel (such as Zycam gel swabs) present even more good news for cold sufferers. The latest studies have support and expand on original findings, showing that zinc treatment can reduce cold symptoms even when used in patients with established illness (i.e. when not used within the first 24 hours of a cold).
How Does Zinc Cure a Cold?
When a virus collides with a cell that it can infect, receptors on the virus and receptors on the host cell match up in a way that allows the virus to enter the cell and begin the infection. Zinc physically binds to receptors on the surface of the virus, preventing the virus from binding to the host cell. Once zinc is introduced, the viruses can’t infect new cells and the infection doesn’t escalate.
Why Doesn’t Zinc Work to Alleviate Every Cold?
Zinc only blocks the receptors of Rhinoviruses, the genus of virus responsible for most, but not all, colds. There are other types of viruses that can also cause colds, including coronaviruses, adenoviruses, enteroviruses, parainfluenza viruses, metapneumoviruses, and human respiratory syncytial virus. Zinc does not block the receptors of these varieities of cold-causing viruses, and therefore will not alleviate cold symptoms. Bottom line, if a cold is the result of a Rhinovirus infection (and most are) zinc therapy will help.
Al-Nakiba, W. et al. (1987) “Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges.” Journal of Antimicrobial Chemotherapy, 20, 893-901.
Bauman, R. (2004) Microbiology. Pearson Benjamin Cummings.
Hirt M, Nobel S, Barron E (2000) “Zinc nasal gel for the treatment of common cold symptoms: a double blind placebo- controlled trial.” Ear Nose & Throat Journal 79(10): 778- 780.
Hulisz, D. (2004). “Efficacy of Zinc Against Common Cold Viruses: An Overview.” Journal of the American Pharmacists Association.