Ginsenosides are not absorbed but metabolized by intestinal microflora (Bacteroides, Fusobacterium, Eubacterium and Provetella species) into forms that can be absorbed by the body. They exhibit pharmacological activity by absorption through the liver, but some of the ginseng is eliminated continuously via urine.
Following oral administration of ginseng powder by human subjects, Compound K (or C-K, the main intestinal bacterial metabolite of protopanaxadiol ginsenosides) was detected in the blood. In addition, the blood absorption of C-K began 4h after taking the ginseng powder in some subjects, and maximum absorption occurred 9–14h after taking the ginseng powder. The average time to reach the maximum blood concentration was 10.76 ± 2.07h.
The absorption of the final metabolites of ginseng is thought to be independent of the metabolite transforming activity of intestinal microflora. However, the Tmax, Cmax and AUC of the transformed metabolites are dependent on the activity of microbial flora of the individual (37).