Echinacea purpurea and mucosal immunity.

This investigation examined the effects of Echinacea purpurea on mucosal immunity and the incidence and duration of upper respiratory tract infection (URTI). 32 subjects completed an exercise protocol known to affect mucosal immunity. Saliva was collected prior to and five minutes after completion of exercise testing. Subjects then took either a placebo (C) or Echinacea supplement (E) for 4 weeks and the testing procedure was repeated. Each time, s-IgA concentrations and saliva flow rate were measured and the secretion rate of s-IgA was calculated. In addition, standard logs indicating symptoms of URTI were completed throughout the study. Both groups demonstrated significant exercise induced reductions in s-IgA (C - 69 %; E - 43 %) and the secretion rate of s-IgA (C - 79 %; E - 53 %) at the beginning of the study (p < 0.05). Following the 4-week intervention, only the control group experienced the post intervention decrease in s-IgA (C - 45 %; E + 7 %) and the secretion rate of s-IgA (C - 45 %; E - 7 %). Further, while there was no significant difference in the number of URTI between groups, the reported duration was significantly different (C 8.6 days vs. E 3.4 days). The results suggest that Echinacea may attenuate the mucosal immune suppression known to occur with intense exercise and reduce the duration of URTI that subjects incur.