Enhancing the oral bioavailability of natural astaxanthin using plant-based micro- and nano-encapsulation materials: Results of an In vitro evaluation and a cross-over study in humans

Astaxanthin (AX) is a red xanthophyll carotenoid found mainly in algae (notably Haematococcus pluvialis microalga) and marine animals. AX is a stronger antioxidant than vitamin E and β–carotene, but has very low oral bioavailability. The purpose of this study was to develop a potato protein (PP)-based delivery system for increasing oral bioavailability of lipophilic bioactives (nutraceuticals and drugs), using AX as a model, and to evaluate the system in vitro and in vivo in a cross-over clinical study in human volunteers. Three different formulations were prepared, encapsulating AX oleoresin (AXO) with: (1) PP only, (2) PP+lecithin (LEC), (3) PP+olive oil (OO). The average particle diameters after preparation were 0.29, 0.29 and 1.76 µm, and after freeze-drying and reconstitution 0.17, 0.07 and 6.93 µm, respectively. In vitro bioaccessibilities were 33, 47 and 69%, respectively, vs. 16% only for the raw AXO. In a randomized, double-blind, cross-over study in human subjects, the PP-OO-AX formulation had a 4.8-fold higher median plasma AX area under the concentration-over time curve (AUC; P