Here is a small section relevant to why I believe this herb was suggested....(Information from Isabell Shipards..How to use herbs in your daily life).
- Comfrey acts as an emollient and is very soothing, inhibiting further damage to tissues, stimulating the production of cartilage, tendons and muscles. It has been esteemed as a blood and flesh builder.
- The dark green colour of the leaves indicates the richness of chlorophyll with a molecular structure closely resembling our blood. Chlorophyll acts as a catalyst, to promote healing within the body of man and animals, and is a valuable blood purifier. Scientific research shows that chlorophyll helps to rejuvenate old celss and promote the growth of new cells . This action, together with comfrey's allantoin properties (a cell prolifierant) provides us with a very powerful herb.
- Allantoin is one of the elements that make comfrey unique. Allantoin is also produced in the allantois gland of the umbilical cord (the link between mother and developing baby, which feeds the embryo) for promoting rapid cell growth. Mothers milk is also rich in allantoin (which stimulates rapid growth of the new baby) and then the element fades out. This process also takes place in other mammals.
- Allantoin is a leucocytosis promoter (increases white blood cells) that helps to establish immunity from many infectious conditions.
More reading....(thanks Sarah)