A recent study found that grapes helped laboratory rats, which were fed with salty diet, lower their blood pressure reduced and improve heart function. The study was sponsored in part by the California Table Grape Commission who provided financial support and supplied the grape powder; the National Heart, Lung and Blood Institute, and part of the National Institutes of Health.
The researchers from the Cardioprotection Research Laboratory at the University of Michigan, who carried out the study reported on October 29, 2008 in the Journal of Gerontology: Biological Sciences that their findings may help people with high blood pressure.
Meanwhile, they were also pleased to note that their findings support their theory that something within the grapes has a direct impact on cardiovascular risk. This is well beyond the already known fact that a diet rich in fruit and vegetables could lower blood pressure.
In the study, the effects of ordinary grapes were examined on rats that develop high blood pressure when fed a salty diet.
A powder from red, green and purple table grapes and a high-salt diet were given to some rats while others were fed the grape powder and a low-salt diet. Using grape powder, which contained the same nutrients in fresh grapes, would allow the scientists to measure the rats’ intake carefully.
18 week later, lower blood pressure, better heart function, reduced inflammation throughout their bodies, and fewer signs of heart muscle damage were observed among rats that ate the grape-enriched diet when comparing to rats that ate a salty diet with no grapes.
The grape powder used in the study comprised about 3 percent of the rats' diet. For humans, this should be about 9 servings of grapes a day. By the way, one serving is about 15 grapes, so it means people have to consume about 135 grapes per day.
It is believed that flavonoids, which are beneficial chemicals found in grapes, green tea, cocoa and tomatoes, could be responsible for the lowering of blood pressure.
Furthermore, flavonoids have already been shown in other studies to have heart-health benefits. In fact, various studies sponsored by chocolate makers, almond and walnut producers have shown some sorts of heart benefits, including reducing inflammation in blood vessels and lowering the risk of heart attacks and stroke.