Tannins. Bioactivity and effect on gut microbiota

Abstract

Changes due to modern life behaviours have led to a progressive modification of dietary patterns. The consequent increasing interest of consumers for new healthy foods has given a big push to the development of innovative functional products. Tannins are appealing bioactive ingredients for designing dietary supplements as they have been described to help in prevent or delay the evolution of several diseases. However, these polyphenols are not yet really exploited in the food industry due to a lack of information on various aspects. Therefore, this doctoral thesis has been developed to determine the different interactions and effects that tannins can have on the human body depending on their chemical origin and the administered amount. The second step focused on the study of the incorporation of tannins in food. The search was directed for technological strategies to mask possible alterations in the flavour and to avoid possible detrimental changes in the structure of food products, while maintaining unaltered the bioactive effect exerted by tannins. Thanks to the results obtained from the in vitro studies it was possible to design a small nutritional intervention with healthy volunteers. This research highlighted the powerful bioactive effect of tannins after gastrointestinal digestion and fermentation, exerted as antioxidant activity and as a prebiotic effect that induces beneficial shifts in the microbiota, in terms of composition and functionality. Tannins, as promising tools for the promotion of a healthy gut environment could be applied as bioactive ingredients boosting the effects induced by food, or as dietary supplement, with potential long-term benefits for metabolism and immunity.