International audience ; Belgian endive (Cichorium intybus var. foliosum) is an Asteraceae mainly produced in the north of France with 124,400 tons per year, but this production generates a lot of co-products like roots after forcing or endive peelings (Anon s. d.). Belgian endive is rich in inulin, and in specialized metabolites like polyphenols and lactone sesquiterpenes. The latter are responsible for bitterness and have been reported to exert different activities such as anti-inflammatory or anti-tumoral activities. Polyphenols are the main specialized metabolites produced by Belgian endive, particularly hydroxycinnamic acids such as chicoric, chlorogenic, caffeic, or caftaric acid which are also presents in co-product Their antioxidant capacity can be improved by bioconversion. In this context, the main goal of this study is to develop an antioxidant ingredient by bioconversion that exerts its activity after gastrointestinal digestion in the intestine and after crossing the intestinal barrier. To reach this objective, endive co-products were first fermented by selected acid bacteria. Then, the supernatants were concentrated and digested using the INFOGEST protocol, which mimics the three first steps of digestion (mouth, stomach, and intestine) (Brodkorb et al. 2019; Fouré et al. 2018). Digested samples were challenged with a cell co-culture (Caco-2/HT29-MTX) intestinal barrier model. The antioxydant capacity was followed in HepG2 hepatic cells at each step of the process (after bioconversion, digestion, and crossing the intestinal barrier). Results obtained evidenced that bioconversion enhanced the antioxidant activity of Belgian endive by-products which was maintained after digestion and after crossing the intestinal barrier. Therefore, this ingredient appears to be promising for nutrition, feed and pet-food, or even cosmetics applications.