Dr. Maria Luz Fernandez and Jacqueline Barona, a doctoral student in Fernandez' lab at the Department of Nutritional Sciences of the University of Connecticut, recruited men ages 30-70 with metabolic syndrome for the study.
Metabolic syndrome is a cluster of conditions that occur together -- increased blood pressure, high blood-sugar level, excess body fat around the waist, low high-density lipoprotein (the "good," cholesterol) and increased blood triglycerides -- which increases the risk for heart disease, stroke and diabetes.
Following a three-week "washout" period during which neither grapes nor placebo were consumed, the study participants were randomly assigned to consume grapes, in the form of a freeze-dried, whole-grape powder, or a placebo powder for four weeks.
The study, published in the Journal of Nutrition, found for each of the study's subjects, grape consumption resulted in significant decreases in blood pressure, improved blood flow and decreases in a compound associated with inflammation.
"These results suggest that consuming grapes can improve important risk factors associated with heart disease, in a population that is already at higher risk," Fernandez, the study's principal investigator, said in a statement. "This further supports the accumulating evidence that grapes can positively influence heart health, and extends it to men with metabolic syndrome."