Phenolic diterpenes, particularly carnosic acid and carnosol found in rosemary (Rosmarinus officinalis) and sage (Salvia officinalis), have gained scientific interest for their antioxidant and anti-inflammatory properties, which are relevant to gastritis. Several in vitro and animal studies have demonstrated that these compounds can reduce gastric mucosal damage induced by oxidative stress and inflammation, both key factors in the pathogenesis of gastritis. For example, studies in rodents have shown that rosemary extracts rich in phenolic diterpenes can protect against ethanol- or NSAID-induced gastric lesions, likely by enhancing antioxidant defenses (such as increasing glutathione levels) and reducing pro-inflammatory cytokines.

However, there is a lack of robust clinical trials in humans directly investigating the efficacy of isolated phenolic diterpenes for treating or preventing gastritis. The available evidence is thus mostly preclinical, and while it supports a plausible mechanism of action, it does not yet provide high-level clinical validation. Some herbal traditions do use rosemary and sage for digestive complaints, but the rationale for their use in gastritis is primarily based on laboratory evidence rather than longstanding historical practice. Therefore, the evidence rating remains low to moderate (2/5), reflecting promising but preliminary data with a need for well-designed human studies.