From a TCM perspective, it nourishes the spleen, which builds blood. From a scientific perspective it:
Zhang reported that Radix Codonopsis polysaccharides could elevate the hemoglobin content of the hemolysis-induced blood deficiency mice and increase the formation of endogenous spleen colony, but have less effect on DNA synthesis in the bone marrow of blood-deficiency mice caused by 60Co-γ ray. In conclusion, RC polysaccharides could improve the compensatory hematopoiesis of spleen [66].