CHICAGO (Reuters) - Grapes helped lower blood pressure and improve heart function in lab rats fed an otherwise salty diet, U.S. researchers said on Wednesday.

A woman cuts a bunch of grapes during a harvest near the Georgian town of Sagarejo, some 50 km (31 miles) east of Tbilisi, October 3, 2008. REUTERS/David Mdzinarishvili

The findings, published in the Journal of Gerontology: Biological Sciences, may help people with high blood pressure, they said.

“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,” Mitchell Seymour of the Cardioprotection Research Laboratory at the University of Michigan said in a statement.

In a study sponsored in part by California grape producers, Seymour and colleagues examined the effects of ordinary grapes on rats that develop high blood pressure when fed a salty diet.

Some of the rats ate a diet containing a powder from red, green and purple table grapes and a high-salt diet. Others were fed the grape powder and a low-salt diet. The powder, which contained the same nutrients in fresh grapes, allowed the scientists to measure the rats’ intake carefully.

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.

“The inevitable downhill sequence to hypertension and heart failure was changed by the addition of grape powder to a high-salt diet,” Dr. Steven Bolling of the University of Michigan, who heads up the lab, said in a statement.

Bolling said he thinks flavonoids, beneficial chemicals found in grapes, green tea, cocoa and tomatoes, could be having an effect on blood pressure. Flavonoids have been shown in other studies to have heart-health benefits.

Food producers are keen to show the health benefits of their products. Studies sponsored by chocolate makers, almond and walnut producers have shown various heart benefits, including reducing inflammation in blood vessels and lowering the risk of heart attacks and stroke.

Grape powder comprised about three percent of the rats’ diet. For humans, that would be about nine servings of grapes a day. One serving is about 15 grapes.

The California Table Grape Commission provided financial support for the study and supplied the grape powder. Other sponsors included the National Heart, Lung and Blood Institute, part of the National Institutes of Health.

High blood pressure, also known as hypertension, can lead to heart attack, heart failure, stroke and kidney failure.