Enhancing the oral bioavailability of natural astaxanthin using plant protein and lipids: In vitro and clinical human study results

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 crossover clinical study in human volunteers. Three different formulations were prepared, encapsulating AX oleoresin (AXO) with (1) PP only, (2) PP+lecithin (LEC), and (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 bioaccessibility was 33, 47, and 69%, respectively, versus 16% only for the raw AXO. In a randomized, double-blind, crossover 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) compared to the raw AXO formulation (P <0.001). In conclusion, a non-allergenic, vegan, PP-based delivery system made of “all-natural ingredients” offers great promise for increasing oral bioavailability of lipophilic bioactives such as AX, for the enrichment of food and for dietary supplements, or oral delivery of lipophilic drugs.