Study results have shown that daily consumption of Echinacea is indeed prophylactic, extends the life span of aging mice, significantly abates leukemia and extends the life span of leukemic mice.
Given that humans are 97% genetically common with mice and that virtually all our basic physiology is identical, it is not unjustified to extrapolate these observations to humans.
Contained within Echinacea root extract is a family of complex polysaccharides known as arabinogalactans. These sugars directly stimulate macrophages to produce three cytokines that, in turn, directly stimulate NK cells.
It has been known for some years that NK (and T) cells decline with age, and correspondingly, cancers of assorted types increase with age in both mice and humans.
Chronic (long-term) intake of Echinacea was not only not detrimental but also distinctly prophylactic. Mice in control cages eating untreated chow had a 79% survival by 10 months of age, while mice living under identical conditions, with the one variable being Echinacea in the daily chow, were still 100% alive by 10 months of age. By 13 months of age, control mice were 46% still alive, while those consuming Echinacea were 74% alive.