Berry Polyphenols Inhibit Digestive Enzymes: a Source of Potential Health Benefits?

Abstract

This paper provides an overview of work that suggests that polyphenol components from berries can inhibit crucial enzymes involved in starch and lipid digestion and potentially influence blood glucose levels and fat digestion. Polyphenols from certain berries have been found to inhibit lipase activity in vitro at low levels. By screening berries with differing polyphenol composition for their inhibitory effectiveness, certain polyphenol classes were implicated as active components. The inhibition was caused at low levels, certainly achievable in the gut after intake of a small amount of berries and approached inhibition achieved by the pharmaceutical lipase inhibitor, orlistat. Polyphenols from berries also have the potential to modulate starch digestion as they inhibit both α-amylase activity and α-glucosidase activity in vitro at low levels. Different berries showed very different levels of effectiveness against the two enzymes and a comparison of their polyphenol composition indicated which components were the most effective inhibitors. For α-amylase, tannins (ellagitannins and proanthocyanidins) were found to be the most effective components but their effectiveness may be modulated by other polyphenols. The active components in the inhibition of α-glucosidase were less obvious and a range of different polyphenol classes may be effective. In both cases, the berry components could act additively with the pharmaceutically used inhibitor, acarbose, and there is potential for berry components to substitute for acarbose or reduce the dose required for effective glycaemic control.