October 29, 2008
Study Suggests Grapes May Aid In Lowering Hypertension
Research released on Wednesday shows that grape intake lowered blood pressure and signs of heart muscle damage, and improved heart function in lab rats.
The report suggests that eating grapes may help fight high blood pressure related to a salty diet. Grapes could also calm other factors related to heart diseases such as heart failure.
"These findings support our theory that something within the grapes themselves has a direct impact on cardiovascular risk, beyond the simple blood pressure-lowering impact that we already know can come from a diet rich in fruits and vegetables," said Mitchell Seymour of the Cardioprotection Research Laboratory at the University of Michigan.
Seymour and colleagues examined the effects of regular table grapes (a blend of green, red, and black grapes) on rats that develop high blood pressure when fed a salty diet.
Comparisons were performed between the rats consuming the test diet and the control rats receiving no grape powder "” including some that received a mild dose of a common blood-pressure drug. All the rats were from a research breed that develops high blood pressure when fed a salty diet.
After 18 weeks, the rats that ate the grape-enriched diet had lower blood pressure, better heart function, reduced inflammation throughout their bodies, and fewer signs of heart muscle damage than rats that ate a salty diet but no grapes.
Dr. Steven Bolling of the University of Michigan, who heads up the lab, said the inevitable downhill sequence to hypertension and heart failure was changed by the addition of grape powder to a high-salt diet.
He noted that the animals in the study were in a similar situation to millions of Americans, who have high blood pressure related to diet, and who develop heart failure over time because of prolonged hypertension.
"The things that we think are having an effect against the hypertension may be the flavanoids "“ either by direct antioxidant effects, by indirect effects on cell function, or both, said Bolling. "These flavanoids are rich in all parts of the grape - skin, flesh and seed, all of which were in our powder."
Food producers are keen to show the health benefits of their products. Research on grapes and other fruits containing high levels of antioxidant phytochemicals continues to show promise. As does research on the impact of red wine on heart health, though that issue is also far from settled.
"Though it's true that your mom told you to eat all your fruits and your vegetables, and that we are learning a lot about what fruits, including grapes, can do in this particular model of hypertension and heart failure, we would not directly tell patients to throw all their pills away and just eat grapes," said Bolling.
High blood pressure, also known as hypertension, can lead to heart attack, heart failure, stroke and kidney failure.
Bolling suggests that people who want to lower their blood pressure, reduce the risk of heart failure, or help their weakened hearts retain as much pumping power as possible should follow tried-and-true advice: Cut down on the amount of salt you get through your food and drink.
The California Table Grape Commission supplied financial support and the grape powder used in the study. Other sponsors included the National Heart, Lung and Blood Institute, part of the National Institutes of Health.
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