Evidence is mounting that grapes are a surprisingly healthy choice of foods, as are all fruits and vegetables, but the benefits of grapes, rich in health-protecting phytochemicals, seem to outnumber the rest.  A new study from the Cardiovascular Center at the University of Michigan reveals several ways a grape-rich diet improves the health of the heart.

Mitchell Seymour, MS, a doctoral student at Michigan State University, based his thesis on the theory that grapes play a significant role in maintaining cardiovascular health.  Seymour, director of the University of Michigan Cardioprotection Research Laboratory, used specially bred mice as study subjects.  The mice were selectively bred to develop hypertension (high blood pressure) when fed a diet high in salt, similar to the diets enjoyed by so many Americans today.

The mice were divided into diet-defined groups, with one group getting a low-salt diet, another getting an equal weight of highly salted foods.  A third group got a high-salt diet in which 3% by weight had been replaced with a powder made from a mixture of red, green, and black grapes.  Another group got the high-salt diet, without the grapes, but with a mild dose of hydrazine, a commonly used blood-pressure medication which was given to the mice in their water and in dosages high enough to effectively reduce their hypertension.  The study lasted 18 weeks.

The grape-fed mice were the healthiest at study’s end, with lower blood pressure, better function of the heart, less inflammation throughout their bodies, and less sign of heart muscle damage than the mice getting the high-salt diet.  The hydrazine-fed mice also enjoyed lower blood pressure but they did not exhibit the same degree of protection for their hearts as the grape-fed mice did.

Eventually, the mice getting grapes and hydrazine developed hypertension but their systolic readings remained lower than the mice who got the high-salt diet alone.

Damage to the heart muscle, a sign of heart failure, includes distorted size, excess weight of the heart, and impaired function.  The mice eating grapes experienced less change of these factors than those getting hydrazine.  Diastolic blood pressure, another signal of heart failure, proved healthiest in the grape-fed group.  The grape-fed mice also had improved cardiac output, enabling them to pump more blood, than the other mice.

Seymour’s team is quick to acknowledge the difference between mice and humans but its research does confirm the healthful benefits of eating grapes, an abundant source of antioxidants called phytochemicals that are common in many fresh fruits and vegetables.  Current dietary recommendations are for all adults to consume between five and nine servings of fruits and vegetables every day.
Seymour’s mice consumed enough powdered grapes each day to equal nine human-sized servings of fresh grapes.

It will take further research to determine if Seymour’s findings remain true for grape-eating human hypertension patients but most people can enjoy a handful of grapes with no worries.  The research team, however, suggests eliminating the salt in one’s diet is a more effective means of controlling hypertension than merely adding a handful of grapes to an otherwise too salty diet.

The Seymour study was funded in part by the California Table Grape Commission, which maintains it had no influence whatsoever in any phase of the study.  The National Heart, Lung and Blood Institute also supplied funding.  The October 10 issue of the Journal of Gerontology: Biological Sciences carries the full story.

Source: University of Michigan