e200921c_sity_of_Michigan_Health_System__Why
[Supplement] 2 Stars American Ginseng 400 mg per day of a freeze-dried extract [Why] 
In a double-blind study, supplementing with American ginseng significantly reduced the number of colds that people experienced over a four-month period. In a double-blind study, supplementation with American ginseng significantly reduced by 27% the number of colds that people experienced over a four-month period, compared with a placebo.24 The amount used in this study was 400 mg per day of a freeze-dried extract.
Common Cold/Sore Throat (Holistic) | University of Michigan Health System
Why