A University of Michigan Cardiovascular Centre study suggests grapes may prevent heart risks beyond the simple BP-lowering impact that can come from a diet rich in fruits and vegetables.
The benefits may be the result of the phytochemicals - naturally occurring antioxidants - turning on a protective process in the genes that reduces damage to the heart muscle.
The researchers studied the effect of regular table grapes (a blend of green, red and black grapes) that were mixed into the rat diet in a powdered form, as part of either a high or low-salt diet.
Comparisons were made between rats consuming the grape powder and rats that received a mild dose of a common BP drug. All the rats were from a research breed that develops high BP when fed a salty diet.
After 18 weeks, the rats that received the grape-enriched diet powder had lower BP, better heart function, and fewer signs of heart muscle damage than the rats that ate the same salty diet but didn't receive grapes.
Rats that received BP medicine, hydrazine, 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.
"There are the small changes that diet can bring, but the effect of grape intake on genes can have a greater impact on disease down the road," said E. Mitchell Seymour, who led the research as part of his doctoral work in nutrition science at Michigan State University, said its release.
The study, performed in laboratory rats, was presented at the 2009 Experimental Biology convention in New Orleans.