Grapes have been used for centuries for a variety of health purposes, and the recent interest in grape-seed extract has spurred scientific research into a range of possible medical uses for this product. Some of the most promising investigations have been focused on the idea that grape-seed extract may be able to reduce cholesterol and high blood pressure. So what does the latest science have to say about grape-seed extracts? 
As the name suggests, grape-seed extract is derived from the seeds of grapes that have been used in the production of wine. It has a high concentration of polyphenols, flavonoids and vitamin E. All of these are powerful antioxidants that reduce the amount of free radicals that cause damage to the body’s cells. Researchers are particularly interested in whether grape-seed extract may affect cardiovascular disease as well as its effect on oxidized “bad” low-density lipoprotein (LDL) cholesterol.
Oxidized LDL cholesterol is a form of cholesterol that is even more damaging than “regular” LDL cholesterol. When free radicals come into contact with LDL particles they create an oxidation reaction. This causes the newly oxidized LDL to become more reactive with the tissues surrounding it. The oxidized LDL then attaches itself to the epithelial cells lining the arteries, encouraging inflammatory cells to accumulate on the artery walls. Cholesterol is sent to the affected area in an attempt to reduce the inflammation. This eventually leads to a buildup of plaque in the arteries and increases the risk of a heart attack or stroke. Some studies have shown grape-seed extract to reduce oxidized LDL cholesterol.
A number of scientific studies have also demonstrated that grape-seed extract helps to reduce high blood pressure. In 2006, researchers at the University of California Davis studied the effect of grape-seed extract on 24 patients with metabolic syndrome. The patients were divided into three groups of eight. One group was given 150 mg of grape-seed extract, another was given 300 mg of the extract, and the third group was given a placebo. The patients’ blood pressure was then taken automatically for 12 hours following the ingestion of the extract. Both groups who received the grape seed extract experienced an equal drop of 12 mm systolic and 8 mm diastolic blood pressure. The 300 mg group also showed a reduction in oxidized LDL cholesterol.
While other trials have also confirmed the positive effect of grape seed extract on blood pressure, meta-studies of the extract’s effect on cholesterol are not as convincing. A 2011 meta-study, published in the Journal of the American Dietetic Association, found that grape-seed extract appeared to have no effect on lipid levels (cholesterol). However, that study’s authors also point out that “Larger randomized, double-blinded trials evaluating different dosages of grape-seed extract and for longer follow-up durations are needed.” Since other investigations have found an association with lower oxidized cholesterol levels when the grape-seed extract is combined with chromium, it’s fair to say that the jury is still out and more research is needed.
So what’s the bottom line? For the time being, research appears to support the idea that grape-seed extract can lower blood pressure, but its effect on reducing oxidized LDL cholesterol is still unconfirmed.
