Encapsulated phenolic compounds: clinical efficacy of a novel delivery method

Abstract Encapsulation is a drug or food ingredient loaded-delivery system that entraps active components, protecting them from decomposition/degradation throughout the processing and storage stages and facilitates their delivery to the target tissue/organ, improving their bioactivities. The application of this technology is expanding gradually from pharmaceuticals to the food industry, since dietary bioactive ingredients, including polyphenols, are susceptible to environmental and/or gastrointestinal conditions. Polyphenols are the largest group of plants' secondary metabolites, with a wide range of biological effects. Literature data have indicated their potential in the prevention of several disorders and pathologies, ranging from simpler allergic conditions to more complex metabolic syndrome and cardiovascular and neurodegenerative diseases. Despite the promising health effects in preclinical studies, the clinical use of dietary polyphenols is still very limited due to their low bioaccessibility and/or bioavailability. Encapsulation can be successfully employed in the development of polyphenol-based functional foods, which may improve their bioaccessibility and/or bioavailability. Moreover, encapsulation can also aid in the targeted delivery of polyphenols and may prevent any possible adverse events. For the encapsulation of bioactive ingredients, several techniques are applied such as emulsion phase separation, emulsification/internal gelation, film formation, spray drying, spray-bed-drying, fluid-bed coating, spray-chilling, spray-cooling, and melt injection. The present review aims to throw light on the existing literature highlighting the possibility and clinical benefits of encapsulated polyphenols in health and disease. However, the clinical data is still very scarce and randomized clinical trials are needed before any conclusion is drawn. Graphical abstract