Tokyo Lab Study Finds Mint, Eucalyptus and Chili Compounds Work Better Together in Immune Cells

Compounds from familiar plants may work better together than alone, according to a laboratory study published January 23, 2026 in Nutrients by researchers at Tokyo University of Science. The team tested menthol (mint), 1,8-cineole (eucalyptus), β-eudesmol (hops and ginger) and capsaicin (chili peppers), alone and in combination, in mouse immune cells stimulated to mimic inflammation.

Capsaicin had the strongest effect alone, and pairing it with menthol or 1,8-cineole increased the anti-inflammatory effect several hundred-fold compared with each compound by itself, the researchers reported. Menthol and cineole acted through TRP channels and calcium signaling, while capsaicin appeared to act through a separate pathway, which the authors suggest may explain the synergy.

This was a cell study, not a human trial, so it does not show that eating these plants reduces inflammation in people. The authors say further research in animals and humans is needed.