Grapes and wine have long been shown to boost heart health. Now scientists think they know just how and why.
A new study published in the Journal of Nutritional Biochemistry shows grapes reduce heart failure tied to chronic high blood pressure by increasing the activity of several genes responsible for antioxidant defense in the heart tissue.
This study, funded by the National Institutes of Health and conducted at the University of Michigan Health System, found the antioxidants and other polyphenols in grapes activate genes and metabolic pathways that improve the levels of glutathione, a key antioxidant in the heart.
"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," said lead investigator E. Mitchell Seymour. "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."
Seymour said the next phase of the NIH study will allow his team to assess the impact of whole grape intake compared to individual grape phytonutrients on hypertension-associated heart failure.
"Our hypothesis is that whole grapes will be superior to any individual grape component, in each of the areas being investigated," said Seymour. "The whole fruit contains hundreds of individual components, which we suspect likely work together to provide a synergistic beneficial effect."
About one billion people worldwide have hypertension, which increases the risk of heart failure. Oxidative stress is strongly linked to heart failure, as is deficiency of glutathione. Antioxidant-rich diets, containing lots of fruits and vegetables, have consistently been shown to reduce hypertension.
For the new study, hypertensive rats were fed a grape-enriched diet for 18 weeks. The results showed grape consumption improved the function of the heart and "turned on" antioxidant defense pathways, increasing the activity of related genes that boost production of glutathione.
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