NOW Supplements Zinc is essential to the normal function of many organs and systems within the body including the skeletal, immune, neurological, and endocrine systems.* Zinc is a necessary mineral co-factor for hundreds of enzymatic reactions related to protein and carbohydrate metabolism, RNA/DNA synthesis, and intercellular signaling.* It is also known to play a critical role in the body's defense against oxidative processes and is especially helpful for maintenance of healthy aging.*