Effect of a commercially-available algal phlorotannins extract on digestive enzymes and carbohydrate absorption in vivo

The ability of naturally occurring polyphenols and phlorotannins (PHTs) from some species of brown seaweeds to inhibit α-amylase and α-glucosidase enzymes in vitro has already been demonstrated. This study aimed at validating the efficacy of a new food ingredient extracted from Ascophyllum nodosum and Fucus vesiculosus PHTs at inhibiting digestive enzymes in vitro and slowing carbohydrate absorption in vivo. In vitro, the PHT extract completely inhibited in a dose-dependent fashion α-amylase and α-glucosidase with very low IC50 values compared to other plant polyphenols. In animals, the PHT extract was able to reduce the normal increase in postprandial blood glucose seen 30 min after a meal by 90% (p < 0.05), and consecutively reduce peak insulin secretion by 40%. These results demonstrate the potency of this specific PHT extract to beneficially modulate carbohydrate digestion and assimilation, in a way that would be suitable for use in foods and dietary supplement formulations.

► Validation of brown seaweed phlorotannins for inhibiting α-amylase and α-glucosidase.
► Dose-dependant inhibition in vitro with low IC50.
► Reduction of postprandial blood glucose by 90% and insulin by 40% in vivo.
► Phlorotannins are potential food ingredients for lowering glycemic response.