The new study, published in the October issue of the Journal of Gerontology: Biological Sciences, gives tantalizing clues to the potential of grapes in reducing cardiovascular risk. The effect is thought to be due to the high level of phytochemicals - naturally occurring antioxidants - that grapes contain.
The study was performed in laboratory rats. The researchers noted that while these study results are extremely encouraging, more research needs to be done.
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. They performed many comparisons between the rats consuming the test diet and the control rats receiving no grape powder - including some that received a mild dose of a common blood-pressure drug.
All the rats were from a research breed that develops high blood pressure when fed a salty diet.
In all, after 18 weeks, the rats that received the grape-enriched diet powder had lower blood pressure, better heart function, reduced inflammation throughout their bodies, and fewer signs of heart muscle damage than the rats that ate the same salty diet but didn't receive grapes. The rats that received the blood-pressure 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.
Says Mitchell Seymour, M.S., who led the research as part of his doctoral work in nutrition science at Michigan State University, "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."