Effects of physicochemical properties of carotenoids on their bioaccessibility, intestinal cell uptake, and blood and tissue concentrations

Scope: Carotenoid bioavailability is affected by numerous factors. Our aim was to assess the involvement of known carotenoid physicochemical properties (e.g., hydrophobicity, van der Waals volume,...) on the transport of the main dietary carotenoids (β-carotene, lycopene, lutein, and astaxanthin, from their food matrix to their main storage tissues. Methods and results: We used four complementary models: synthetic mixed micelles, an in vitro digestion procedure, Caco-2 cell monolayers, and a gavage experiment in rats. The efficiency with which pure carotenoids were incorporated into synthetic mixed micelles was related to their melting points (r = 0.99, p = 0.015). The efficiency with which pure carotenoids were transferred from dietary triglycerides into mixed micelles was related to carotenoid hydrophobicity (r = -1, p = 0.005). There was no relationship between the carotenoid physicochemical properties studied and their uptake efficiency by Caco-2. The postprandial plasma carotenoid response to carotenoid gavage was related to carotenoid hydrophobicity (r = -0.99, p = 0.006). Carotenoid adipose tissue response was not related to the carotenoid physicochemical properties studied. Conclusion: Thus, carotenoid hydrophobicity is important for bioaccessibility and postprandial blood response of carotenoids. In contrast, the carotenoid physicochemical properties studied are apparently not strong determinants of carotenoid uptake by enterocytes and adipose tissue.