Microalgae-derived carotenoids: Digestive fate and interplay with gut microbiota

Background: Carotenoids have been extensively utilized as food supplements, nutraceuticals, and natural colorants for many years, owing to their significant potential in beneficial biological activities such as anti-oxidative and anti-inflammatory effects. Microalgae serve as abundant sources of diverse carotenoids including beta-carotene, astaxanthin, and fucoxanthin, thereby playing crucial roles in the natural carotenoids market. However, understanding of the bioaccessibility and bioavailability of microalgae-derived carotenoids in the gastrointestinal tract, their bio-conversion processes, and their interactions with gut microbiota remains largely unexplored. Scope and approach: This review focuses on the biochemical properties of microalgal carotenoids and their fate in the gastrointestinal tract, with particular emphasis on their intricate interplay with gut microbiota. It also discusses emerging technologies aimed at enhancing bioavailability and gaining deeper insights into their interactions with gut microbiota. Key findings and conclusions: Current studies suggest that the bioavailability of most microalgal carotenoids is quite low, with a portion undergoing conversion within the gastrointestinal tract. The unabsorbed carotenoids play a significant role in modulating gut microbiota, showing promising potentials in influencing host metabolism. Emerging technologies such as nanotechnology, foodomics, artificial intelligence and synthetic biology are expected to revolutionize the study of microalgal carotenoids, providing crucial insights to facilitate their incorporation into food products.