Is bST a hormone?
Yes. However, there are two types of hormones: steroids and proteins. bST is a protein hormone. Protein hormones have no activity when taken by mouth, while steroid hormones do have activity. For example, insulin is a protein hormone. Insulin has no activity if taken orally. Therefore, a diabetic has to have injections of insulin. Like insulin, the protein hormone bST has no activity when taken by mouth. In contrast, hormones used in birth control pills are steroids and therefore are effective when taken by mouth. Again, bST has no effect when taken by mouth. Furthermore, studies were conducted in the 1950’s to determine if children suffering from dwarfism could be given direct injections of high levels of bST to stimulate growth. The conclusion of the study was that somatotropin from cows is not active in humans even if injected. Why? The structure of human somatotropin is so different from bovine somatotropin, that injections of high levels of bovine somatotropin into children have n