In vitro and in vivo study of the enhancement of carotenoid bioavailability in vegetables using excipient nanoemulsions: Impact of lipid content

The impact of lipid content of excipient nanoemulsions on the bioavailability of carotenoids from spinach was assessed using a combination of in vitro and in vivo digestion models. Alterations in the particle size, charge, microstructure, and lipid digestion were monitored as the spinach-nanoemulsion mixtures passed through the digestive tract. There was an increase in both bioaccessibility (19.2% > 14.4% > 7.5% > 3.1%) and bioavailability (106.7 > 39.6 approximate to 35.3 > 15.0 ng/mL) of carotenoids with increasing lipid content (1.0, 0.6, 0.2, 0 g), which attributed to higher transfer efficiency of the carotenoids from spinach to fat droplets and mixed micelles in increasing lipid content. The polarity of carotenoids also had an important impact: the bioavailability of lutein was significantly higher than that of beta-carotene. Our findings show the importance of selecting an appropriate lipid content of reduced-fat emulsion-based foods to enhance the oral bioavailability of co-ingested hydrophobic nutraceuticals.