Human Growth Hormone (HGH)
Produced in the pituitary gland, the hormone helps us grow up big and strong and then helps us maintain our healthy bodies. However, as we age, we produce less and less HGH. Because of this shortage, researchers have been experimenting with a synthetic form of this hormone that may increase muscle mass, protect cells and boost skin health. It also has a slew of negative results: HGH may cause high blood pressure, joint pain, irregular heart rhythms and a higher risk of diabetes and carpal tunnel syndrome [source: Kuczynski].