Elucidating the Effect of Estragole: Unlocking the Fine Line between Dose, Risk and Efficiency - A Scientific Narrative Review

Background: Estragole is a constituent of herbs such as tarragon, basil, and fennel. It is known for its anti-inflammatory and antimicrobial activity. There is evidence of its carcinogenic potential in animal models. Estragole carcinogenicity may be linked to its metabolic conversion, forming 1′-sulfoxy metabolites. These metabolites can form covalent DNA adducts, inducing hepatic tumors at high-dose repeated exposure in rodents.  Aim: This narrative review aimed to evaluate the carcinogenic potential of estragole by systematically analysing published animal trials and assessing the neoplastic changes.  Materials and Method: A systematic review was conducted using Pubmed, Elsevier Science Direct, Wiley Online library, Scopus data bases. The keywords “Estragole” and “Neoplasm” were used as MeSH terms. From the initially identified articles 296, 286 were screened after duplicate removal based on inclusion criteria (English language, Full-text articles, animal trial studies on the carcinogenic effect of estragole). 4 studies were selected for final analysis.  Results: The included animal trials investigated estragoles effect on mice and rats at various doses. Estragole was shown to have high carcinogenic potential at high doses. With an increase in estragole dosage, there was an increase in hepatic tumors in both mice and rats.  Conclusion: In rat and mice animal models, high dosage of estragole induces tumor formation. The risk of estragole for humans is presently not determined, as it is consumed at low ppm levels. Estragole is a potential carcinogenic agent. Further metabolic, and human related studies are needed to determine carcinogenic risk of estragole to human.