Mast Chew chewing gum is made from an ancient Mediterranean gum called Pistacia Resin, and is free of synthetics, latex, sugars, colours, additives or artificial sweeteners. The mastic-like secretion from the Pistacia genus of trees has been used for thousands of years to maintain gut health and treat abdominal related issues including heartburn, gastric and intestinal ulcers. The chewing of gum has also been linked to reduced stress, improved memory function and decreased hunger levels by mimicking the rhythmic act of chewing food.