Oregano oil (Origanum vulgare)

Tier 3 — weak evidence · Antimicrobial · Gut · Antifungal

Kills bacteria and fungi effectively in lab settings, which has led to enthusiastic marketing. However, NCCIH notes human trial evidence for oral supplement use is essentially nonexistent. High concentrations can irritate the stomach lining and esophagus. Using oregano in cooking is safe and enjoyable, but taking concentrated oil supplements is not supported.

Dose: No evidence-based dose for internal supplement use; culinary use in food is safe