Researchers have found that grapes increase the activity of certain genes that are associated with antioxidant defense in the heart tissue.

The study was conducted by researchers from University of Michigan Health System and is supported by a grant from National Institutes of Health (NIH). The team discovered a novel mechanism through which grapes benefit the heart.

A recent study had found that grapes can protect organs such as the liver and kidney from damage due to metabolic syndrome. Another study, published in the journal Diabetes Care, had earlier found that polyphenols in grapes could offset the damage done by a high-fructose diet.

In the present study, researchers found that grapes increase levels of glutathione, the most important of all antioxidants, known to be beneficial against cancers, heart disease and dementia.

The study was conducted on a group of rats that had hypertension and were fed a diet rich in grapes. Study results showed that after 18 weeks of this diet, rats had better heart health, with reduced levels of heart muscle enlargement and fibrosis, coupled with better diastolic function. Also, researchers found evidence of increased activity of gene associated with the production of glutathione.

"Our earlier studies showed that grapes could protect against the downward spiral of hypertensive heart failure, but just how that was accomplished - the mechanism - was not yet known. The insights gained from our NIH study, including the ability of grapes to influence several genetic pathways related to antioxidant defense, provide further evidence that grapes work on multiple levels to deliver their beneficial effects,"  said E. Mitchell Seymour, PhD and lead author of the study. According to a new report from CDC, about 67 percent Americans had hypertension.

In the next part of the study, researchers will be looking at other mechanisms that might be associated with the benefits of grapes. Also, they'll be finding out whether eating whole grapes has more benefits, or consuming just individual phytonutrients.

"Our hypothesis is that whole grapes will be superior to any individual grape component, in each of the areas being investigated," said Dr. Seymour in a news release. "The whole fruit contains hundreds of individual components, which we suspect likely work together to provide a synergistic beneficial effect."

The study is published in the Journal of Nutritional Biochemistry.