What many people don’t realize is that steroids actually take many forms, only some of which are useful in building muscles. In fact, many steroids are used to break down muscles, not build them. These steroids, called corticosteroids, are also used in other processes, like stress response, immune response, carbohydrate metabolism, and electrolyte levels. There are literally hundreds of varieties of naturally occurring steroids, and they’re made by everything from fungi to virtually every vertebrate life form on the planet. The human body not only produces Testosterone naturally, but also produces other steroids like Cholesterol and Cortisol, for example.
Some of the approved drugs are synthetic versions of the natural hormones, such as trenbolone acetate and zeranol. Just like the natural hormone implants, before FDA approved these drugs, FDA required information and/or toxicological testing in laboratory animals to determine safe levels in the animal products that we eat (edible tissues). Furthermore, FDA required that the manufacturers demonstrate that the amount of hormone left in each edible tissue after treatment is below the appropriate safe level. As described above, a safe level is a level which would be expected to have no harmful effect in humans.