Supplementing the diet with wild blueberries may reduce blood pressure, suggests a new study with hypertensive rats.
Animals fed a diet supplemented with 8 percent wild blueberries experienced less constriction in blood vessel, compared with animals fed a control die, 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 8 week dietary treatment with 8 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 NO pathway – nitric oxide is a potent vasodilator, or compound that promotes the dilation or relaxation of blood vessels, thereby easing blood pressure.
Blueberries, nature's only 'blue' food, are a rich source of polyphenols, potent antioxidants that include phenolics acids, tannins, flavonols and anthocyanins.
The berries are said to have a number of positive health effects, including cholesterol reduction, and prevention against some cancers and neurodegenerative diseases such as Alzheimer's.
The popularity of the berry has increased in recent years with the publication of more science supporting its health benefits, and an overall consumer move towards 'superfruits' and all things 'antioxidant'.
Led by Maine’s Dorothy Klimis-Zacas, the researchers fed spontaneously hypertensive rats a control or a wild blueberry diet for eight weeks. The blueberries were provided as a composite by the Wild Blueberry Association of North America (WBANA), and were freeze-dried and powdered by Illinois’ FutureCeuticals.
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,” they concluded.
Source: Journal of Agricultural and Food Chemistry
2010, Volume 58, Issue 22, Pages 11600-11605
“A Wild Blueberry-Enriched Diet (Vaccinium angustifolium) Improves Vascular Tone in the Adult Spontaneously Hypertensive Rat”
Authors: A.S. Kristo, A.Z. Kalea, D.A. Schuschke, D.J. Klimis-Zacas