Steroids are molecules that mimic the effect of natural hormones in the body. There are a number of different varieties, from steroids that help build muscle to steroids that help to reduce inflammation. The function of steroids largely depends on the type of steroid being used, as well as the symptoms being treated by using a particular substance.
A healthy person has a vast number of varying steroids moving around the body at all times. All natural steroids are fatty molecules. Some are signaling molecules, which tell one part of the body to do something at particular times, such as the female sex hormone steroids that control menstruation and female fertility.
The immune system also uses steroids, which in this case are called adrenocorticosteroids, to regulate inflammation in response to injury and infection. Some adrenocorticosteroids are regulators of metabolism, and help move glucose and other nutrients around the body. Testosterone, a male steroid hormone, promotes the development of male genitalia and body hair.
Although steroids are naturally occurring molecules, the term steroid is most commonly used in medicine and in bodybuilding to describe artificial forms of steroids. The function of steroids in bodybuilding is to increase the rate at which a person can develop muscle mass. These steroids are forms of testosterone that mimic the natural testosterone in the body.
Medical steroids are commonly used to treat inflammation. Autoimmune diseases like psoriasis or asthma are relatively common, and result from an overreaction of the body to a stimulus. Natural immune system steroids act as regulators of the inflammatory response. Modern medicine uses synthetic forms of these regulatory molecules to help control autoimmune inflammation and reduce inflammation from other causes when it could be dangerous to health.
Normally, a healthy body has complex systems in place which respond to problems and allow the body to function smoothly. Different natural steroids are part of these processes, and when a person introduces artificial levels of the steroids into the body, then the body responds to the synthetic steroids. When the body's own processes become disrupted through disease, then artificial steroids help restore balance.
Sometimes low levels of natural steroid can also cause problems like Addison's Disease, where the adrenal gland cannot produce enough steroids. In other cases, the body attacks itself in autoimmune diseases, and added steroid helps to dampen down the immune system. Steroids that are associated with bodybuilding can also be useful in medicine, if a person suffers from low levels of testosterone, and needs additional steroids to help develop normally.