Abstract
Background: Orange peels (OP) are rich in flavonoids, pectin, essential oils, and carotenoids that can be upcycled into functional ingredients. These bioactive compounds (BCs) have been increasingly associated with beneficial effects on gastrointestinal (GI) and cardiometabolic health. This scoping review aimed to systematically map available evidence and synthesize reported GI and cardiometabolic health outcomes of upcycled OP ingredients. Methods: Conducted in accordance with PRISMA-ScR guidelines, the literature search was performed in the Scopus database and ClinicalTrials.gov for studies published between 2014-2025 using a predefined Boolean search query. After screening, 84 studies and 14 completed clinical trials met the inclusion criteria. Results: The mapped evidence spans mechanistic (in vitro), preclinical, and clinical studies. Preclinical studies report that flavonoids, pectin, and essential oils modulate gut microbiota composition, enhance intestinal barrier integrity, and improve glycemic, lipid, and inflammatory parameters through mechanisms involving short-chain fatty acid production, antioxidant activity, and modulation of key inflammatory pathways. Clinical studies, predominantly investigating hesperidin-rich and fiber-rich extracts, report improvements in postprandial glycemic response, lipid profiles, blood pressure, and selected microbiota-related markers. Conclusions: Upcycled OP ingredients show promising biological activities relevant to cardiometabolic health and gut modulation, particularly in mechanistic and preclinical models. However, the evidence base remains largely dominated by in vitro and animal studies, with limited and heterogeneous clinical data. Key gaps include the underrepresentation of pectin and carotenoids in human trials and the absence of standardized, long-term intervention studies. Future research should prioritize well-designed clinical trials and investigate potential synergistic interactions among OP-derived bioactive fractions to support their translational application.