The 2,500 year reputation of Chios mastiha rests on the raw resin, not the flavored, calcium fortified gum sold for jawline goals. The gap between what was tested and what is being sold is the real story.
The mastic tree (Pistacia lentiscus) has been chewed, brewed, and prescribed on the Greek island of Chios for roughly 2,500 years, long enough for Hippocrates to recommend the resin for gastrointestinal distress, according to a Science News explainer on the modern gum trend. What people are buying at the register today is a different product, and the difference is the point.
Most of the modern research on mastic does not actually test the gum. It tests concentrated oil or powdered extracts, often at doses and in forms that bear little resemblance to a stick of flavored chewing gum. The leap from "mastic contains bioactive triterpenoids" to "chewing mastic gum will do X" is the part that needs scrutiny, and it is the part most marketing copy skips.
Social media creators have promoted mastic chewing gum for gut health, oral health, and a more chiseled jawline, Science News reports. The first two categories at least have a mechanistic toehold. The third does not. A 2024 randomized controlled trial from researchers at Yonsei University College of Dentistry — 58 participants, six months, chewing gum three times a day — found no statistically significant change in masseter muscle thickness or mandibular shape (Journal of Oral Rehabilitation). There is no clinical evidence that chewing any gum remodels the bones or muscles of the jaw. The mechanical load of sustained chewing, in fact, can stress the temporomandibular joint and wear dental enamel, and orofacial medicine specialist Anette Vistoso of the University of Southern California has told Science News she has seen gum-chewing patients develop jaw pain or grind through a night guard.
Where the chewing form does have legitimate support is in the mouth itself. A 2023 review in the Journal of Natural Medicines summarized signals that mastic chewing gum reduced plaque and supported cavity and gum-disease prevention, and a 2025 double-blind randomized controlled trial — 32 adolescent orthodontic patients using mastic toothpaste three times daily for two weeks — found a statistically significant drop in hydrogen sulfide breath levels, from 158 parts per billion to 26 ppb (p=0.001), along with reductions in plaque and gingival indices (Journal of Breath Research). Both findings are reported and contextualized in the Science News piece.
Pharmacologist Roja Rahimi of Tehran University of Medical Sciences, who studies herbal remedies, has been quoted in coverage of mastic research warning that the human clinical evidence base for the modern gum is thin: small studies, limited replication, and a long distance between an extract in a lab and a chew in a person's mouth. "In gastrointestinal and metabolic conditions, chewing mastic gum does not have considerable efficacy," she told Science News. Plant compounds isolated from mastic resin do show antibacterial and anti-inflammatory activity in laboratory work, but those results do not automatically transfer to a five-minute chew of flavored gum.
That gap is the heuristic worth keeping. When a wellness product leans on a centuries-old reputation, the useful question is not "has this plant been used for a long time" but "what form was actually used, and what form was actually tested." For Chios mastiha, the traditional record is real, and partly vindicated by the compound research. The flavored, calcium-fortified gum next to the register is a 21st-century delivery system riding on a 2,500-year reputation, and the science has not caught up to the marketing.
The jawline claim, meanwhile, is not a soft "maybe." The evidence is absent, and the load on the joint is a real cost. Chewing mastic for fresher breath and possibly cleaner teeth is defensible. Chewing it for a sharper jaw is a story the research has not told.