Thousands of active components in the various herbs influence the human immune system. Regular consumption of a major immune-modulating herb, or a collection of herbs with modulating capacity, gradually builds up a person's resistance. I have seen hundreds of people who were immune deficient and thus prone to chronic colds and other infections. After taking the tonics for several months, their immune systems showed tremendous improvement. After taking the herbs for a year or so, they became highly resistant to common colds and flus.
People find it amazing.
It's this kind of response to the herbs that makes me think that the tonics are really foods that the body requires. It seems that without the herbs, the immune system is underfed. With the herbs in the diet, the immune system flourishes. The combination of factors found in the tonic herbs makes them an indispensable nutritional requirement. They replenish Primal Essence, they provide the energy to adapt to the stresses in our environment, and they protect us.