Bioidentical hormones have the same chemical structure as hormones produced in the human body. There have been many studies demonstrating their safety. At this time, with the ready availability of bioidentical hormones, there is no reason to use non-human formulations. There is a track record of benefit and safety for women taking controlled doses of these hormones, in carefully selected formulations, under medical supervision. Horse hormones and progestins for hormone replacement should become obsolete. Patient demand will make this happen.
A Stanford University School of Medicine meta-analysis of clinical studies on the subject published in early 2007 showed that the application of GH on healthy elderly patients increased muscle by about 2 kg and decreased body fat by the same amount.  However, these were the only positive effects from taking GH. No other critical factors were affected, such as bone density, cholesterol levels, lipid measurements, maximal oxygen consumption, or any other factor that would indicate increased fitness.  Researchers also did not discover any gain in muscle strength, which led them to believe that GH merely let the body store more water in the muscles rather than increase muscle growth. This would explain the increase in lean body mass.