★★☆Single study — solid evidence, such as one good trial or a large observational dataset, but not replicated at the top tier.
What's in a bottle of oil of oregano varies by plant and by brand
Its main compounds make up as much as about 70% of the oil in some strains and far less in others. Combination softgels are labelled from about 300 mg to a claimed 6,000 mg equivalent a serving.
What the study found
Oregano oil's carvacrol content depends on the plant and the brand
Carvacrol, thymol or both make up as much as about 70% of the oil in some southern Mediterranean strains, and far less in others. Softgels with black seed oil are labelled from about 300 mg to a claimed 6,000 mg equivalent a serving. Two bottles can differ widely in what they hold.
The caveat · Makers' own labels, not lab-tested
The labelled amounts are the makers' own and none states a standard carvacrol content. Only combination products with black seed oil were checked, so plain oregano softgels were not compared.