Human Growth Hormone (HGH) is a hormone produced by the anterior pituitary gland in the brain. HGH promotes tissue repair, cell regeneration in the bones, muscles and vital organs, and supports the immune system in combating infection and disease. As the body's cells die off, HGH acts as a "trigger" to ensure that replacement cells are healthy and readily available.
As we age, our HGH levels decline, causing our cell replacement levels to reduce to a fraction of the levels of our youth. The exact reason why the pituitary gland's production of HGH falls so rapidly remains a mystery. By the age of forty, nearly everyone is deficient in HGH, and by eighty years of age, the body's production has usually diminished by 90-95%.