The subjects. Consumption of a berry meal

The first step in carbohydrate digestion is their
breakdown into absorbable monosaccharides in the small intestine. Carbohydrates
are digested by enzymes such as ?-amylase
and ?-glycosidase, and after that by small
intestinal maltase, sucrase, and lactase 261. As discussed above, glucose absorption
in the small intestine is facilitated via carriers such as GLUT2 and SGLT1. The
pharmacological inhibition of the digestive enzymes and/or glucose transporters
will reduce glucose absorption, thereby lowering postprandial blood glucose levels
262, 263. Proanthocyanidins-rich extracts
from raspberry and rowanberry inhibited
?-amylase activity and acted synergistically
with the drug acarbose to inhibit ?-amylase activity in vitro 264. Also, anthocyanins-rich
berry extract from raspberry, blueberry, cranberry, strawberry, and other
berries reduced glucose absorption by inhibiting SGLT1 and GUT2 and their
expression in human intestinal Caco-2 cells 265. Moreover, in experimental studies,
the oral administration of a flavonoid-rich
extract of serviceberry in diet-induced obese and hyperglycemic mice delayed
carbohydrate absorption and subsequently ameliorated postprandial hyperglycemia at least partially through inhibiting intestinal
?-glucosidase activity 266. However, in clinical trials, the consumption of a variety of
berries had different outcomes on the glycemic response in healthy and T2D
subjects. Consumption of a berry meal (containing bilberries, blackcurrants, cranberries, and strawberries) sweetened with
sucrose, delayed glucose appearance in the blood of healthy subjects 267. Similarly,
in another study, sweetened blackcurrant juice fortified with crowberry powder
improved postprandial glycemic control in healthy subjects 268. On the contrary, the addition of raspberries and blueberries to
starch-based food did not reduce blood glucose in healthy subjects 269. The consumption of a sweetened
cranberry juice did not improve the glycemic responses in healthy subjects, but some improvement was noted with unsweetened cranberry juice 270. The latter finding was consistent with another study in which
a cranberry product led to improvement in the glycemic response in T2D subjects
when compared with cranberry products that contained more sugar 271.