Researchers at the University of California at Davis tracked 24 patients with metabolic syndrome, a cluster of problems that increase the risk of heart disease. One-third of the group were given a placebo while the other thirds were given either 150 milligrams or 300 milligrams of grape seed oil.

The groups getting grape-seed extract experienced an equal drop in blood pressure, which was measured for 12 hours after ingestion. The patients getting the larger amount of extract also had a drop in LDL cholesterol.

U.C. Davis is planning another study to determine if people with pre-hypertension benefit from grape-seed extract.