Zinc and Viral Respiratory tract infections.

 

Does Zinc Really Help Treat Viral Respiratory Tract Infections (RTIs) / Colds?

Judy Stone, MD

November 08, 2021

A new study published 2021 in BMJ Open adds to the evidence that zinc is effective against viral respiratory infections, such as colds.

 

Jennifer Hunter, PhD, BMed, of Western Sydney University's NICM Health Research Institute, New South Wales, Australia, and colleagues conducted a meta-analysis of 28 randomized controlled trials (RCTs). They searched 17 English and Chinese databases to identify the trials and then used the Cochrane rapid review technique for the analysis.

The trials included 5446 adults who had received zinc in a variety of formulations and routes — oral, sublingual, and nasal spray. The researchers separately analyzed whether zinc prevented or treated respiratory tract infections (RTIs)

Oral or intranasal zinc prevented five RTIs per 100 person-months (95% CI, 1 – 8; numbers needed to treat, 20). There was a 32% lower relative risk (RR) of developing mild to moderate symptoms consistent with a viral RTI.

Use of zinc was also associated with an 87% lower risk of developing moderately severe symptoms (incidence rate ratio, 0.13; 95% CI, 0.04 – 0.38) and a 28% lower risk of developing milder symptoms. The largest reductions in RR were for moderately severe symptoms consistent with an influenza-like illness.

Symptoms resolved 2 days earlier with sublingual or intranasal zinc compared with placebo (95% CI, 0.61 – 3.50; very low-certainty quality of evidence). There were clinically significant reductions in day 3 symptom severity scores (mean difference, -1.20 points; 95% CI, -0.66 to -1.74; low-certainty quality of evidence) but not in overall symptom severity. Participants who used sublingual or topical nasal zinc early in the course of illness were 1.8 times more likely to recover before those who used a placebo.

However, the investigators found no benefit of zinc when patients were inoculated with rhinovirus; there was no reduction in the risk of developing a cold. Asked about this disparity, Hunter said, "It might well be that when inoculating people to make sure they get infected, you give them a really high dose of the virus. [This] doesn't really mimic what happens in the real world.”

BMJ Open. DOI: 10.1136/bmjopen-2020-047474.

Read attached link for full document/research paper. 

https://bmjopen.bmj.com/content/bmjopen/11/11/e047474.full.pdf