Sustainably derived turmeric nanoparticles enhance gastrointestinal bioavailability of curcumin

Turmeric-derived curcumin offers various health benefits but has poor bioavailability due to low water solubility and rapid gastrointestinal degradation. A recently proposed raw-to-nano strategy enables the direct formulation of turmeric nanoparticles from raw turmeric, using inherent biopolymers to encapsulate and protect curcumin. However, it remains unclear how these nanoparticles enhance gastrointestinal bioavailability and how food matrices influence this process. This study investigated the gastrointestinal digestion of turmeric nanoparticles and assessed the influence of a nanoemulsion food matrix on curcumin's stability and bioavailability. Turmeric nanoparticles (∼0.11 μm) were formulated using the raw-to-nano strategy and incorporated into nanoemulsions as a food model. Their gastrointestinal fate was examined using a standardized in vitro digestion model, with curcumin crystals serving as the reference. Results showed that curcumin molecules were spontaneously encapsulated within the lipid phase of nanoemulsions. Turmeric nanoparticles exhibited significant size increases in different digestion phases, particularly in the gastric phase (pH 3), whereas their size remained stable when incorporated into nanoemulsions. Compared to curcumin crystals, turmeric nanoparticles significantly enhanced curcumin's gastrointestinal stability, particularly within nanoemulsions, where stability reached ∼92.2 %. Additionally, the bioaccessibility of curcumin in turmeric nanoparticles (∼66.8 %) was markedly higher than curcumin crystals (∼9.0 %) due to nano-encapsulation in mixed micelles, while curcumin from crystals largely remained in sediments, limiting absorption. Incorporation into nanoemulsions further improved curcumin bioaccessibility (∼82.5 %). This study demonstrates that turmeric nanoparticles formulated via a sustainable raw-to-nano strategy significantly enhance the gastrointestinal bioavailability of curcumin, offering a promising strategy for improving delivery of curcumin in functional foods.