Zinc is important in building and maintaining muscle tissue and in building a healthy immune system. It helps in wound healing and injury recovery. It is necessary for growth, energy production and repair of body cells. Many runners are more susceptible to viral and bacterial infections after competitive events such as the marathon. (9) Athletes who sweat heavily have greater zinc losses and should make sure they're getting the RDA (15mg). (10) The best sources of zinc are beef, poultry, pork, lamb, and seafood.