Effects ofCordyceps militarissupplementation on the immune response and upper respiratory infection in healthy adults: a randomized, double-blind, placebo-controlled study

Abstract

Purpose: Upper respiratory tract infections are major causes of the common cold throughout the world. Cordyceps militaris (C. militaris) is a well-known functional food for its anti-fatigue and immunomodulating activities. On the other hand, there are no reports on the protective effect against upper respiratory tract infections (URI). This study was a 12 week randomized, double-blind, and placebo-controlled trial in healthy volunteers. Methods: A total of 100 subjects 20~70 years of age with a history of at least two colds in the year were enrolled in the study. The participants were required to record any adverse events and rate any cold-related incidents in a diary during the investigation period. The efficacy end point was the symptoms and incidence of URI, and changes in cytokines, IgA and natural killer (NK) cell activity. Results: The Cordyceps militaris group over 12 weeks showed no significant impact on the incidence and symptomatology of URI compared to the placebo group. On the other hand, the experimental group showed significantly higher NK cell activity (p = 0.047) and IgA level (p = 0.035) compared to the placebo group. The NK-cell activity and IgA level were increased significantly by Cordyceps militaris over 12 weeks. Conclusion: The results suggest the possible beneficial immunomodulating effects, but the protective effects on URI could not be demonstrated under these conditions. Additional research will be needed to determine the efficacy and mechanisms of Cordyceps militaris function.

Effects of <em>Porphyra tenera</em> Supplementation on the Immune System: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

“…Kwak et al [28] reported that changes in NK-cell activity were related to the level of serum IFN-γ. The changes in NK-cell activity and cytokines identified in this study are consistent with the results reported in several earlier studies [26,31,32] and cases [19,28,30,38,39]. Healthy adults who received Cordyceps militaris [31] supplements for 8 weeks or a mycelium extract of Cordyceps [32] for 8 weeks showed an increase in NK-cell activity without a change in cytokine levels, consistent with our findings in the current study.…”

“…The changes in NK-cell activity and cytokines identified in this study are consistent with the results reported in several earlier studies [26,31,32] and cases [19,28,30,38,39]. Healthy adults who received Cordyceps militaris [31] supplements for 8 weeks or a mycelium extract of Cordyceps [32] for 8 weeks showed an increase in NK-cell activity without a change in cytokine levels, consistent with our findings in the current study. Cordyceps militaris increased IL-2 and IFN-γ levels in addition to NK-cell activity in healthy males (average age, 36.5±11.2 years) after 4 weeks of supplementation [38], but after 12 weeks of intake, only NK-cell activity was increased in healthy males and females (average age 48.9±6.7 years [31]), similar to our findings.…”

“…Healthy adults who received Cordyceps militaris [31] supplements for 8 weeks or a mycelium extract of Cordyceps [32] for 8 weeks showed an increase in NK-cell activity without a change in cytokine levels, consistent with our findings in the current study. Cordyceps militaris increased IL-2 and IFN-γ levels in addition to NK-cell activity in healthy males (average age, 36.5±11.2 years) after 4 weeks of supplementation [38], but after 12 weeks of intake, only NK-cell activity was increased in healthy males and females (average age 48.9±6.7 years [31]), similar to our findings. In other studies, intake of Chlorella [28] by healthy adults (WBC counts 4,000-8,000 cells/μL) for eight weeks increased cytokine levels (IFN-γ, interleukin-1β) in addition to increasing NK-cell activity.…”

“…Subjects without a URI in the PTE group showed an increase in NK-cell activity at an E:T ratio of 25.1:1 compared to the placebo group. Several previous studies [19,26,[28][29][30][31][32][33] reported enhanced NK-cell activity in healthy adults only at certain E:T ratios; in this study, enhanced NK-cell activity was consistently identified in the PTE group at all E:T ratios (E:T=12.5:1, E:T=25:1, and E:T=50:1).…”

“…The results of these studies differ from our current findings. In the studies mentioned above, both NK cell activity and cytokine levels changed upon supplementation in healthy adults under 40 years of age [19,28,29,33,38,39]; in our study, only NK-cell activity increased [26,31,32], although our subjects were generally older than 40 years. This suggests that age moderates the effects of PTE and related supplements on cytokine levels.…”