Plus Mastic Gum, Aloe Vera & Slippery Elm Supports Gastric Health NOW Gastro Comfort is formulated to support a healthy stomach lining. Gastro Comfort features the clinically tested ingredient PepZin GI, which is a proprietary form of zinc complexed with carnosine that has been shown to support the integrity of the stomach lining by promoting its own natural healing processes. Gastro Comfort also includes mastic gum, a resin from the mastic tree, which has traditionally been used to maintain gastric health. In addition, this product has slippery elm and aloe vera to support a healthy digestive system.