(HealthDay News) — Although some evidence suggests that zinc may prevent viral respiratory tract infections (RTIs) and shorten their duration, further research is needed, according to a review published online Nov. 1 in BMJ Open.
Jennifer Hunter, PhD, from Western Sydney University, and colleagues conducted a systematic review and meta-analysis to examine the benefits and risks of zinc formulations for prevention or treatment of acute viral RTIs in adults. Data were included from 28 randomized controlled trials (RCTs) with 5,446 participants; none were specific for severe acute respiratory syndrome coronavirus 2.
The researchers found that oral or intranasal zinc prevented 5 RTIs per 100 person-months compared with placebo (moderate certainty and quality of evidence). Following human rhinovirus inoculations, sublingual zinc did not prevent clinical colds (moderate certainty and quality of evidence). Symptoms resolved 2 days earlier, on average, with sublingual or intranasal zinc compared with placebo (very low certainty and quality of evidence); without zinc, 19 more adults per 100 were likely to remain symptomatic on day 7 (low certainty and quality of evidence).
Clinically significant reductions were seen in day 3 symptom severity scores, but not average daily symptom severity scores (low certainty and quality of evidence). A significant increase in nonserious adverse events (eg, nausea, mouth/nasal irritation) was seen (relative risk, 1.41; moderate certainty and quality of evidence). In the 25 RCTs that monitored them, there were no serious adverse events reported (low certainty and quality of evidence).
“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 nonspecific RTIs,” the authors write.
Several authors have received payment relating to traditional, complementary, and integrative medicine.