Bioavailability and safety of phytonutrients

Phytonutrients are natural bioactive compounds obtained from plants that perform specific biological activities and modify different physiological functions to improve general human health. The utilization of phytonutrients has become widespread to treat deficiency syndromes and to reduce disease risk, dedicating special attention to numerous biologically active metabolites. Several classes of secondary compounds are derived from phytonutrients, among which terpenoids, flavonoids, and alkaloids are the most studied due to their widespread distribution, and their multiple chemical structures that allow them to disseminate different biological activities. However, the phytonutrients market is still not well organized, and appropriate regulations are still lacking, as quality, safety, long-term adverse effects, and toxicity are of concern. In this chapter, we discuss the bioavailability of the most relevant phytonutrients, the in vitro and in vivo methods used in their determination, and highlight their safety aspects and regulations, as well as the progress made so far to enhance their bioavailability.