A systematic review of in vitro studies evaluating the inhibitory effects of polyphenol-rich fruit extracts on carbohydrate digestive enzymes activity: a focus on culinary fruits consumed in Europe

Abstract

Evidence shows that polyphenols can attenuate postprandial blood glucose responses to meals containing digestible carbohydrate. Polyphenol-rich plant extracts are emerging as potential ingredients in functional foods and/or beverages despite limited understanding of their physiological effects. Many studies have investigated the mechanisms of polyphenol-rich fruit extracts on inhibition of digestive enzymes. However, the evidence available has yet to be critically evaluated systematically. This report reviews the in vitro literature to quantify the effect of fruit polyphenol extracts on the activities of digestive carbohydrases. A systematic literature search was conducted using six science databases. Included studies, totaling 34 in number, were in vitro digestion models which quantified gut digestive enzyme(s) activity on starch digestion in the presence of fruit polyphenol extracts. Most studies assessed the effects of fruit extracts on either α-amylase (n = 30) or α-glucosidase (n = 30) activity. Studies were consistent overall in showing stronger inhibition of α-amylase compared to α-glucosidase by proanthocyanidin- and/or ellagitannin-rich fruit extracts. Recommendations are proposed for future reporting of this type of research to enable meaningful synthesis of the literature as a whole. Such knowledge could allow effective choices to be made for development of novel functional foods and beverages.

KEYWORDS:

• Amylase
• carbohydrases
• digestion
• fruit
• glucosidase
• polyphenols
• systematic review

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. EJP has a PhD studentship funded by DIANA Food Ltd. (Rennes, France).

Author contributions

EJP compiled and performed the search strategy, extracted data and wrote the manuscript; BB supervised the research and participated in interpretation of the data, editing and final revisions of the manuscript; WH designed and supervised the research, participated in interpretation of the data, editing and revision of the manuscript. PB, PE, CC participated in editing and revision of the manuscript. All authors read and approved the final draft. All of the authors declared they had no conflicts of interest.