Educational information, not medical advice — ask your doctor or midwife.
Mastic tree (Pistacia lentiscus) is a small evergreen shrub of the Mediterranean. When the bark is cut, it weeps a resin that dries into pale drops called tears. That resin is sold as mastic gum.
It is called aroeira in Portugal and lentisco in Spain. On the Greek island of Chios, a local variety has been farmed for the resin for centuries. The leaves and twigs were also used in folk practice.
People take it today as chewing gum, as powder in capsules, or as an oil. It also flavours sweets, bread and liqueur in Greece and Turkey.
Here is the honest evidence verdict. A few small, short human trials point to mild help with indigestion. Lab work shows action against stomach bacteria.
The results are mixed and far from settled. Long traditional use is not proof that it works. It is also not proof that it is safe.
The short answer is that nobody has pinned down how mastic acts in the body.
In test tubes, mastic resin slows Helicobacter pylori, a stomach bug linked to ulcers. Whether this happens in a living stomach, at the amounts people take, is not established.
In cell and animal studies, the triterpene acids in the resin appear to damp down markers of inflammation. A few small human studies have reported changes in gut symptoms and blood fats. That is far too little to call the effect proven.
Chewing the gum makes you produce more saliva and scrubs the teeth. In small dental studies, chewing mastic gum lowered counts of mouth bacteria. The gain over ordinary sugar-free gum is unclear.
The leaf and bark are rich in tannins, which bind proteins and taste astringent. That is the usual explanation given for their folk use on wounds and loose stools. It rests on chemistry, not on human trials.
Mastic is sold mainly as the raw resin and as products made from it.
Raw tears are hard, pale crystals of resin. People chew them like gum or crush them into powder.
Capsules and tablets hold the powdered resin. These are the forms used in most of the small human trials.
Mastic chewing gum is a sweetened, ready-made version. Dental studies have used this form.
Mastic oil is steam-distilled from the resin. It is strong and is used mostly in cosmetics, mouthwash and toothpaste.
Leaf and twig teas belong to the older folk practice. They are astringent and taste sharp. They are far less studied than the resin.
It also turns up in food. Greek sweets, tsoureki bread, Turkish ice cream and mastiha liqueur all use it.
Mastic has a long, well-documented record in the Mediterranean.
Greek and Roman writers described chewing the resin for the breath and the stomach. Dioscorides listed it in the first century for digestive complaints.
On Chios, mastic farming was organised and protected from the Byzantine period onward. The resin was traded across the Ottoman world as a chewing gum and a medicine.
In Iberian and North African folk use, the plant was called aroeira or lentisco. The leaves and bark were steeped and applied to sores, gums and skin rashes.
The wood and leaves were also used for tanning and dyeing. The oil was burned and used in varnish.
These records tell us what people did. They do not tell us whether it helped.
Stop and get urgent medical help if you have a rash with swollen lips or face, or any trouble breathing.
Get urgent care for black or tarry stools, vomit that looks like blood or coffee grounds, or severe stomach pain.
See your doctor soon if you have heartburn or stomach pain lasting more than a few weeks, trouble swallowing, or weight loss you cannot explain.
Stop taking it and ask a pharmacist if you get persistent nausea, headache or a skin rash.
In the European Union, Chios mastic is a protected food product and is also sold as a supplement. EU regulators list the resin as a traditional herbal medicine for mild digestive complaints, based on long use rather than trials.
In the United States it is sold as a dietary supplement. It is not approved there to treat any disease.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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