Ginseng integrative supplementation for seasonal acute upper respiratory infections: A systematic review and meta-analysis

Abstract

Background: The aim of the review was to assess whether ginseng can be a useful supplementation for seasonal acute upper respiratory infections (SAURIs).

Methods: All clinical studies investigating ginseng efficacy for the treatment or prevention of SAURIs were included in the review. Medline, EMBASE, Web of Science, Scopus, Cochrane Library, Google Scholar were systematically screened for relevant articles up to May 26th, 2020. The risk of bias was assessed with the Cochrane tool (RoB 2).

Results: Nine articles (describing ten trials about P. ginseng or P. quinquefolius) were included in the review. Evidence globally indicated some useful activity of intervention when administered in adjunct to influenza vaccination. The results of our quantitative synthesis suggested a significant effect on SAURIs incidence (RR = 0.69 [95 % C.I. 0.52 to 0.90], p < 0.05), as well as a significant reduction of their duration if only studies with healthy individuals were included in the analysis (MD=-3.11 [95 % C.I.-5.81 to -0.40], p < 0.05). However, the risk of bias was high-to-unclear for most included trials, and publication bias couldn't be excluded.

Discussion: Limitations of existing evidence don't allow to draw conclusions on the topic. Nevertheless, it is not excluded that ginseng supplementation in adjunct to influenza vaccination and standard care might be useful for SAURIs prevention and management in healthy adult subjects, but further high-quality trials are needed to support this hypothesis.

Other: This research was not funded. The protocol was registered in PROSPERO under the following code: CRD42020156235.

Keywords: Cold; Complementary medicine; Flu; Ginseng; Meta-analysis; Systematic review.

Fig. 1

PRISMA flow diagram describing the process of article screening and selection. Caption: The structure of the flowchart was adapted from Moher et al., 2009. doi:10.1371/journal.pmed1000097

Fig. 2

Risk-of-bias assessment of included trials. Caption: The risk of bias of included studies was assessed with the Cochrane’s tool (RoB 2). Analyzed domains were the randomization process, deviations from the intended interventions, missing outcome data, measurement of the outcome, selection of the reported result, and the overall risk of bias. Standard conventional symbols were used to indicate low, unclear or high risk of bias, as described in the figure.

Fig. 3

L'Abbé plot referred to the first meta-analysis: risk for developing a respiratory infection. Caption: The first meta-analysis aimed to assess the relative risk for developing a seasonal acute upper respiratory infection at least once during the study period (winter seasons). Intervention was defined as taking ginseng and all trials were placebo-controlled. Each point represented a study included in the quantitative synthesis (red: P. ginseng; blue: P. quinquefolius). The X axis indicated the event rate in the control group, whereas the Y axis displayed the event rate in the experimental intervention group.

Fig. 4

Forest plot representing the second meta-analysis: duration of symptoms. Caption: Forest plot referred to the meta-analysis about the duration of symptoms (measured in days) of seasonal acute upper respiratory infections. Means and standard deviations were reported in columns and a random-effect model was adopted to better estimate overall size effects. Experimental intervention was represented by taking ginseng extracts, and control by taking placebo pills.