Strawberry and Apple Compounds May Regulate Glucose Transport
According To New Study
Healthful Antioxidants, Carotenoids, Phytonutrients,
Phenolic Compounds Derived From Fruit and
Vegetable Sources Are Beneficial For Cardiovascular
Health, Diabetes And Are The Subject of Ongoing Research
Polyphenols and phenolic acids from strawberry and apple
may decrease glucose uptake by blocking transport through
human intestinal cells, according to a new study.
The research, published in Molecular Nutrition & Food
Research, suggests that some polyphenols, phenolic acids
and tannins extracted from apples and strawberries may
block the transport of glucose across intestinal tissues,
potentially reducing glucose spikes after meals.
"Our results indicate that unsweetened beverages rich in
these dietary phenolic compounds might provide a dietary
mechanism to dampen, blunt or regulate intestinal sugar
absorption, a potentially important factor in the management
of diabetes and the metabolic syndrome," said researchers
from the School of Food Science and Nutrition at the
University of Leeds in the U.K.
They added that their study is the first to show an inhibition
of glucose transport across intestinal tissue by phenolic fruit
extracts, and further characterize the contribution of individual
phenolic components for their role in the inhibition of glucose
transport.
Glucose Regulation
Repeated after meal (post-prandial) blood plasma glucose
'spikes' are associated with an increased risk of developing
cardiovascular diseases, metabolic syndrome and type II
diabetes. Reduction of post-prandial glucose concentration
in blood is potentially beneficial.
"There is recent evidence that some bioactive compounds
including polyphenols, phenolic acids and tannins (PPTs),
can affect the shape of the blood glucose curve. Some
studies have shown that these compounds may result in
an altered pattern of intestinal glucose uptake, possibly due
to interactions between compounds and sugar transporters,"
said the authors.
They said that PPTs have the potential to "readily affect
glucose absorption in the small intestine," noting that many
polyphenols, phenolic acids and tannins can interact with
certain sugar transporters - for example, inhibition of sodium-
dependent glucose transporter 1 (SGLT1 - an active transport mechanism in which glucose is co-transported with sodium
ion) or by inhibition of GLUT2.
Apples and strawberries, which are also used for producing
fruit juices, are high in flavonoids and phenolic acids, the
researchers noting that compounds in strawberries include
anthocyanins, flavonols, flavanols and ellagic acids. Apples
are known to contain flavanols, hydroxycinnamic acids, dihydrochalcones, phloridzin (phloretin glucoside), and phloretin xyloglucoside.
"Data indicate that the polyphenols, phenolic acids and
tannins from strawberry and apple are potent inhibitors of
GLUT2 and SGLT1 at concentrations predicted after dietary
ingestion. Therefore, the consumption of strawberry and
apple juices could affect glucose absorption via the inhibition
of glucose transport," said the researchers.
The researchers also investigated the effects of individual
PPT extracts from apples and strawberries. They observed
that Quercetin-3-O-rhamnoside, phloridzin, and
5-caffeoylquinic acid contributed 26, 52 and 12 percent
of inhibitory activity of the apple extract respectively,
whereas only pelargonidin-3-O-glucoside was found to
contribute to the total inhibitory activity in the strawberry
extract.
"The results obtained demonstrate that polyphenols,
phenolic acids and tannin-rich extracts from strawberry
and apple were able to influence glucose uptake into the
cells and transport by inhibiting activities of the glucose
transporters," explained the authors.
They added that these important new findings will assist
in the design of future studies.
Source: Molecular Nutrition & Food Research
Volume 54, Issue 12, pages 1773-1780,
"Polyphenols and phenolic acids from strawberry
and apple decrease glucose uptake and transport
by human intestinal Caco-2 cells"
Disclaimer: This article is not intended to provide medical advice,
diagnosis or treatment.
