The investigators caution that the quality of the evidence is variable and an optimal formulation or dose remains unknown.
Zinc supplements may help to reduce the symptoms of a respiratory tract infection and reduce the duration of the illness, according to a pooled analysis of available evidence published in BMJ Open. The investigators caution that the quality of the evidence is variable and an optimal formulation or dose remains unknown.
Zinc plays a key role in immunity, inflammation, tissue injury, blood pressure, and tissue responses to lack of oxygen, which has resulted in speculation that it may be an effective treatment for COVID-19 infection. The investigators sought to appraise the available evidence for whether zinc could be used for the prevention and treatment of SARS-CoV-2.
The review evaluated 28 clinical trials with a total of 5446 participants, none of which specifically examined the use of zinc for the prevention or treatment of COVID-19. Doses and delivery methods varied considerably between studies, with the most common formulations being lozenges, nasal sprays, and gels containing either zinc acetate or gluconate salts.
The pooled results of 25 studies demonstrated that zinc lozenges or nasal spray prevented 5 respiratory tract infections in 100 people per month, according to the investigators. Three studies suggested that zinc was effective in curbing the risk of severe symptoms, including fever and influenza-like illness.
On average, symptoms of respiratory infection cleared 2 days earlier for patients using a zinc nasal spray or liquid formulation than those using placebo, according to the study. However, sublingual zinc did not reduce the risk of infection or cold symptoms for patients inoculated with human rhinovirus, nor were there differences in illness duration compared to placebo.
“The marginal benefits, strain specificity, drug resistance and potential risks of other over-the-counter and prescription medications makes zinc a viable ‘natural’ alternative for the self-management of non-specific [respiratory tract infections],” the investigators said in a prepared statement. “[Zinc] also provides clinicians with a management option for patients who are desperate for faster recovery times and might be seeking an unnecessary antibiotic prescription. However, clinicians and consumers need to be aware that considerable uncertainty remains regarding the clinical efficacy of different zinc formulations, doses and administration routes, and the extent to which efficacy might be influenced by the ever-changing epidemiology of the viruses that cause [respiratory tract infections].”
Adverse events (AEs) were approximately 40% more likely among patients using zinc, but no serious AEs were reported across the 25 trials monitoring them.
Zinc might help to stave off respiratory infection symptoms and cut illness duration [news release]. EurekAlert; November 1, 2021. Accessed November 2, 2021. https://www.eurekalert.org/news-releases/933197