Propolis is gathered when bees pollinate flowers. This natural supplement comes from untouched pristine environment. Propolis has high bioflavonoid levels that can be helpful in maintaining a healthy immune system.     Echinacea. Echinacea is a very popular herb, and people commonly take it to help combat flu and colds. It is a genus of herbaceous flowering plants in the daisy family - Asteraceae. It is also known as the American coneflower.