Abstract: The evidence for the effect of polyphenol components of berries on
digestive enzymes is reviewed. Anthocyanins inhibit α-glucosidase
activity and can reduce blood glucose levels after starch-rich meals, a proven
clinical therapy for controlling type II diabetes. Ellagitannins inhibit
α-amylase activity and there is potential for synergistic effects on
starch degradation after ingestion of berries such as raspberries and
strawberries, which contain substantial amounts of ellagitannins and
anthocyanins. A range of berry polyphenols (e.g. flavonols, anthocyanidins,
ellagitannins and proanthocyanidins) can inhibit protease activities at levels
which could affect protein digestion in the gastrointestinal tract. In
contrast, potential for the inhibition of gastrointestinal lipase activity, a
proven therapeutic target for the control of obesity through reduced fat
digestion, may be limited to proanthocyanidins. Taking into account the manifold possible synergies for inhibition
of starch, protein and/or lipid digestion by the spectrum of polyphenol
components present within berry species, the inhibition of digestive enzymes by
dietary polyphenols may represent an under-reported mechanism for delivering
some of the health benefits attributed to a diet rich in fruit and
vegetables.
