β -Glucan Improves Protective Qi Status in Adults with Protective Qi Deficiency—A Randomized, Placebo-Controlled, and Double-Blinded Trial

Objective To test the hypothesis that β -glucan enhances protective qi (PQi), an important Chinese medicine (CM) concept which stipulates that a protective force circulates throughout the body surface and works as the first line of defense against “external pernicious influences”. Methods A total of 138 participants with PQi deficiency (PQD) were randomized to receive β -glucan (200 mg daily) or placebo for 12 weeks. Participants’ PQi status was assessed every 2 weeks via conventional diagnosis and a standardized protocol from which a PQD severity and risk score was derived. Indices of participants’ immune and general health status were also monitored, including upper respiratory tract infection (URTI), saliva secretory IgA (sIgA), and self-reported measures of physical and mental health (PROMIS). Results PQi status was not significantly different between the β -glucan and placebo treatment groups at baseline but improved significantly in the β -glucan ( vs. placebo) group in a time-dependent manner. The intergroup differences [95% confidence interval (CI)] in severity score (scale: 1–5), risk score (scale: 0–1), and proportion of PQD participants (%) at finish line was 0.49 (0.35–0.62), 0.48 (0.35–0.61), and 0.36 (0.25–0.47), respectively. Additionally, β -glucan improved URTI symptom (scale: 1–9) and PROMIS physical (scale: 16.2–67.7) and mental (scale: 21.2–67.6) scores by a magnitude (95% CI) of 1.0 (0.21–1.86), 5.7 (2.33–9.07), and 3.0 (20.37–6.37), respectively, over placebo. Conclusions β -glucan ameliorates PQi in PQD individuals. By using stringent evidence-based methodologies, our study demonstrated that Western medicine-derived remedies, such as β -glucan, can be employed to advance CM therapeutics. (ClinicalTrial.Gov registry: NCT03782974)