Cardio-Protective Power of Grapes
Grape Study Shows the Benefits of a Fruit and Vegetable-Rich Diet
Researchers at the University of Michigan Cardiovascular Center fed groups of rats diets enriched with grape powder made from a mixture of red, green and black table grapes, including skins and seeds. All the rats were from a research breed that develops high blood pressure when fed a salty diet.
Half the rats were given a high salt diet, the other half a low-salt diet. A third group of rats was the control group, which had no grape powder added to their food.
The researchers compared 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, hydrazine.
Cardio-Protective Results from Grape-Enriched Diets
After 18 weeks, the rats that received the grape-enriched diet had lower blood pressure, better heart function, reduced inflammation throughout their bodies, and fewer signs of heart muscle damage than the rats that ate the same salty diet but didn’t receive grapes.
The rats that received the blood-pressure medicine, along with a salty diet also had lower blood pressure, but their hearts were not protected from damage as they were in the grape-fed group.
While no human trials have yet been performed to repeat these results, Mitch Seymour, who led the research as part of his doctoral work in nutrition science, said they suggest 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.”
Seymour manages the U-M Cardioprotection Research Laboratory, headed by heart surgeon Steven Bolling, Dr Bolling said it was likely that the flavonoids in the grapes were providing the cardiovascular protection, “either by direct antioxidant effects, by indirect effects on cell function, or both.”
Flavonoids Reduce Harmful Molecular and Cellular Activity
Flavonoids, naturally occurring phytochemicals, have already been shown in other research to reduce potentially harmful molecular and cellular activity in the body.
Grapes are rich in flavonoids in the skin, pips and flesh. The study was the first to show flavonoids’ cardio-protective effects in reducing hypertension and heart failure.
Not Just Grapes: Eat Nine Serves of Fruit & Veg
Seymour said that while this particular line of research was focusing on grapes, the wider story was the importance of eating a total of nine servings of fruit and vegetables a day.
“The grapes were used as a model of a fruit and vegetable-rich diet, because they contain a wide variety of the compounds in fruits and veggies,” he said.
To get the cardio-protective benefits the rats experienced, people “would need to eat nine servings of fruits and veggies per day, which is the current recommendation for optimal health.
“So we're not making any ‘recommendations’ for grape intake per se, but for a fruit and vegetable enriched diet.”
It was not yet clear which phytochemicals were responsible for the rats’ cardiovascular protection, he said.
“Actually, we expect that they act together in the whole food, and that if taken separately, may not be as beneficial.”
The study, ‘Chronic Intake of a Phytochemical-Enriched Diet Reduces Cardiac Fibrosis and Diastolic Dysfunction Caused by Prolonged Salt-Sensitive Hypertension’, was published in the October 2008 issue of the Journal of Gerontology: Biological Sciences,
For more on protecting your heart, you might like to read Cardio-Protective Benefits of Weekly Fatty Fish
and Choose a Heart-Healthy Lifestyle.
See also: Ways to Eat More Fruit and Veg
Eating Grapes Can Protect your Heart
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