Lee Swanson Research Update
Blueberries Linked to Improved Blood Vessel Health
Supplementing the diet with wild blueberries may reduce blood pressure, suggests a new study with hypertensive rats.
Animals fed a diet supplemented with eight percent wild blueberries
experienced less constriction in the blood vessels, compared with
animals fed a control diet, according to findings published in the Journal of Agricultural and Food Chemistry.
"The unique goal and approach of our study was to examine the dietary
effect of wild blueberries, and not isolated bioactive compounds, on
vascular tone of the adult spontaneously hypertensive rat (SHR)," wrote
researchers from the University of Maine, Northwestern University and
the University of Louisville.
"Our data provide clear evidence that the eight-week dietary
treatment with eight percent wild blueberry in the adult SHR with
established endothelial dysfunction results in a significant moderation
of the increased aortic vascular tone," they added.
The berries were proposed to act via the nitric oxide (NO) pathway.
Nitric oxide is a potent vasodilator—a compound that promotes the
dilation (relaxation) of blood vessels, thereby easing blood pressure.
Blueberries, nature’s only "blue" food, are a rich source of
polyphenols, potent antioxidants that include tannins, flavonols,
anthocyanins and more. The berries are said to have a number of positive
health effects, including cholesterol reduction and protection against
some neurodegenerative diseases such as Alzheimer’s.
Led by Maine’s Dorothy Klimis-Zacas, the researchers fed
spontaneously hypertensive rats a control or a wild blueberry diet for
eight weeks. After the eight weeks of intervention, the rats were
exposed to the compound l-phenylephrine (a vasoconstrictor), with or
without l-NG-monomethyl arginine, a compound known to inhibit the enzyme
NO synthase (NOS).
Results showed that the "vasoconstriction elicited by l-phenylephrine
was reduced in the wild blueberry group, attributed to the NO pathway,
favoring a lower vascular tone under basal conditions."
"These findings document the potential of wild blueberries to modify
major pathways of vasomotor control and improve the vascular tone in the
adult spontaneously hypertensive rats with endothelial dysfunction,"
Journal of Agricultural and Food Chemistry 58(22):11600-11605, 2010