A randomized, double-blind, placebo-controlled study on immune improvement effects of ethanolic extract of Echinacea purpurea (L.) Moench in Korean adults.

Echinacea purpurea (L.) Moench (EP), a medicinal plant native to North America, is now cultivated in various regions including Europe. With increasing popularity of Echinacea in Korea recently, a human clinical trial was conducted to evaluate immune-enhancing efficacy and safety of EP 60% ethanolic extract (EPE) in Koreans. Eighty volunteers were recruited for this randomized, double-blind, placebo-controlled clinical trial. They were randomly divided into two groups and given either a daily dose of 200 mg of EPE or a placebo. All participants underwent testing for Natural Killer (NK) cell cytotoxic activity, serum cytokine levels (IL-2, IL-6, IL-10, IL-12, IFN-γ, TNF-α), Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21), and Multidimensional Fatigue Scale (MFS) during this study to assess changes in outcomes. After 8 weeks of EPE consumption, a significant increase in NK cell cytotoxic activity compared to the placebo was observed. Additionally, serum cytokine levels of IL-2, IFN-γ, and TNF-α also significantly increased following EPE consumption. However, no significant changes were observed in WURSS-21 and MFS before and after EPE consumption. Throughout the 8-week study period, no adverse reactions were reported in relation to EPE consumption, and there were no clinically significant changes in diagnostic laboratory tests or vital signs in the EPE group. These results indicate that consumption of EPE could lead to immune improvement without any adverse effects. This clinical trial was the first to demonstrate beneficial effects of EPE consumption on immunity in Korean adults.