Enhancing the bioavailability of encapsulated hydrophobic nutraceuticals: Insights from in vitro, in vivo, and clinical studies

The realization of the health benefits of hydrophobic bioactives is often limited by low bioavailability. Numerous delivery systems have been developed to enhance the bioavailability, but too few in vivo studies, and even fewer clinical studies, have reported the evaluation of such systems. The aim of this paper was to review the recent literature on improving the bioavailability of hydrophobic nutraceuticals using delivery systems, with emphasis on in vivo studies. Smaller particle size, digestible amphiphilic protective wall material, digestible core, low crystallinity, and easily degradable surrounding food matrix improve the bioavailability and bioefficacy, but correlation between in vitro and in vivo results is often elusive, owing to the great complexity and variability of physiological systems. In vivo studies are crucial for determining the real effect on the bioavailability and safety of these systems. Human studies should be preferred over animal studies whenever possible.