Why insulin hormone cannot be given orally but has to be given intravenously?
Insulin hormone is a protein. So if a protein is taken orally, it will be digested and broken down into simple units like a normal protein. The chemical nature of this hormone will be lost before it reaches the target organ to do its activity. Hence this hormone should not be taken orally. If insulin hormone is given intravenously, it travel along with blood circulation and reach the target organ without loosing its chemical structure to start its function.