"... a resin obtained from the mastic tree (Pistacia lentiscus). In pharmacies and Nature shops it is called "arabic gum" (not to be confused with gum arabic) and "Yemen gum". In Greece it is known as the "tears of Chios," being traditionally produced on that Greek island, and, like other natural resins is produced in "tears" or droplets. Originally liquid, it is sun-dried into drops of hard brittle translucent resin. When chewed, the resin softens and becomes a bright white and opaque gum. The flavor is bitter at first, but after chewing releases a refreshing, slightly piney or cedar flavor.
The word mastic derives from the Greek verb μαστιχειν "to gnash the teeth", which is the source of the English word masticate. The word mastic is a synonym for gumin many languages. ... Mastic contains antioxidants, and also has antibacterial and antifungal properties."
gum for chewing
powder for capsules
"Anti-inflammatory activity of Chios mastic gum is associated with inhibition of TNF-alpha induced oxidative stress" in Nutritional Journal (2012)
"Clinical studies have emphasized anti-inflammatory activity of Chios mastic gum [5,6]. This biological activity can be attributed to a variety of compounds. It contains triterpenes of the oleanane, euphane and lupine type [7,8]; alpha-tocopherol and polyphenols; the latter have been associated with a hypotensive effect of mastic . Chios mastic possesses anti-bacterial activity [10,11], for which verbenone, alpha-terpineol, and linalool seem to be responsible.
Chios mastic gum has been extensively used for centuries in Mediterranean and Middle Eastern countries, both as a nutritional supplement and herbal remedy. Medical trials show that gum mastic may have cytoprotective or anti-acid effects on the gastrointestinal system  . Recent studies seem to suggest that gum mastic may exhibit antibacterial properties  and inhibit the proliferation of androgen-dependent prostate cancer . This work makes an important addition to this list demonstrating potential role of antioxidant properties in the anti-inflammatory activity of the Chios mastic gum based on inhibition of PKC-dependent [Protein kinase C] NADPH [nicotinamide adenine dinucleotide phosphate-oxidase] oxidases."
"Pistacia lentiscus Resin Regulates Intestinal Damage and Inflammation in Trinitrobenzene Sulfonic Acid–Induced Colitis" in Journal of Medicinal Foods (2011)
"Mastic (Pistacia lentiscus) of the Anacardiaceae family has exhibited anti-inflammatory and antioxidant properties in patients with Crohn's disease. ... Histological amelioration of colitis (P≤.001) and significant differences in colonic indices occurred after 3 days of treatment. Daily administration of 100 mg of P. lentiscus powder/kg of body weight decreased all inflammatory cytokines (P≤.05), whereas 50 mg of P. lentiscus powder/kg of body weight and cortisone treatment reduced only ICAM-1 (P≤.05 and P≤.01, respectively). Malonaldehyde was significantly suppressed in all treated groups (P≤.01). IL-10 remained unchanged. Cytokines and malonaldehyde remained unaltered after 6 days of treatment. Thus P. lentiscus powder could possibly have a therapeutic role in Crohn's disease, regulating oxidant/antioxidant balance and modulating inflammation."
"Is Chios mastic gum effective in the treatment of functional dyspepsia? A prospective randomised double-blind placebo controlled trial" in Journal of Ethnopharmacology (2010)
"Chios mastic gum significantly improves symptoms in patients with functional dyspepsia compared to placebo."
"The effect of mastic gum on Helicobacter pylori: A randomized pilot study" in Phytomedicine (2009)
"Mastic gum has bactericidal activity on H. pylori in vivo."
"Chios mastic treatment of patients with active Crohn's disease" in World J Gastroenterol. (2007)
"The results suggest that mastic significantly decreased the activity index and the plasma levels of IL-6 and CRP in patients with mildly to moderately active CD."