Grape Seed Extract

Grape Seed

Grape seed extract is the primary commercial source of a group of powerful antioxidants known as oligomeric proanthocyanidins (OPCs), also generically called pycnogenol, a class of flavonoids. Laboratory studies have indicated OPCs are much more effective than vitamin C and vitamin E in neutralizing free oxygen radicals, which contribute to organ degeneration and aging in humans.

The primary sources of OPCs are pine bark extract and grape seed extract. However, the grape seed extract is more widely recommended for its lower cost and because it contains an antioxidant not found in pine bark.

General use

Grape seed extract is a mixture of complex compounds. It has a wide range of therapeutic uses, from preventing cancer and cardiovascular disease to alleviating symptoms of allergies, ulcers, and cataracts. Its antioxidant properties are believed to help slow the aging process.

Procyanidins, a group of compounds found in the extract, are thought to increase the effectiveness of other antioxidants, especially vitamin C and vitamin E, by helping them regenerate after neutralizing free radicals in the blood and tissue. OPCs in the extract are water-soluble, making them easily absorbed by the body.

They also are able to cross the stubborn blood-brain barrier, providing antioxidant protection to the brain and nervous system. Most of the research on grape seed extract has been done in Europe, so many of its reported benefits have not been reviewed or approved by the U.S. Food and Drug Administration. It is available as an over-the-counter supplement.

According to Varro E. Tyler, dean emeritus of the Purdue University School of Pharmacy and Pharmacal Sciences, the procyanidin compounds found in grape seed extract are useful in treating vascular disorders They also are antioxidants, or freeradical scavengers, that help prevent some age-related cancers and atherosclerosis.

Grape seed extract is a relatively new supplement in the United States, although it has been used in Europe for several decades. Its antioxidant properties were realized in the 1980s with the socalled French paradox, in which researchers discovered that the French had low rates of heart disease even though their diet was high in cholesterol.

This was credited to their widespread consumption of red wine. Further research led to the OPCs concentrated in grape seeds. More recent research suggests that grape seed extract may work at the genetic level, activating a gene that stops oxidation of bad cholesterol. A 2003 study found that grape seed extract worked well in replacing estrogen and blunting hypertension in postmenopausal women.

Cardiovascular disease

European studies have shown procyanidins to be useful in treating blood vessel disorders, such as fragile capillaries and poor circulation in the veins. Components bind to the walls of the capillaries, making them less likely to break down with the effects of aging. In one European study, researchers found that treatment with grape seed extract quickly relieved a chronic condition of poor circulation in the veins.

Grape seed extract also has been beneficial in treating edema, an excessive accumulation of fluid in tissue. Another use of grape seed extract is reducing blood pressure in people with hypertension. A study published in 1998 by cardiovascular researchers at the University of California, Davis, found that flavonoids in the extract helped increase flow in blood vessels, contributing to better regulation of blood pressure.


A study published in 1998 by a team of researchers at Creighton University, Georgetown University Medical Center, and the University of Nebraska at Omaha, reported that grape seed extract significantly inhibited and sometimes killed human cancer cells, while promoting the growth of normal healthy cells.

The extract was effective in killing 34–48% of breast, lung, and stomach cancer cells. It was not effective in destroying leukemia cells. Other studies have shown grape seed extract, combined with other antioxidants, can reduce the overall risk of developing cancer.

Respiratory conditions

Grape seed extract has been found to be beneficial in treating several respiratory conditions, including asthma, emphysema, allergies, and sinusitis. Pycnogenol helps inhibit the production of histamines, which decreases sensitivity to pollens and food allergens, thereby reducing allergic reactions.

Other conditions

OPCs in grape seed extract have shown effectiveness in treating a variety of other conditions. As an antiinflammatory, it helps prevent swelling of joints, heals damaged tissue, and eases pain in people with arthritis. Studies have shown OPCs can stop cataract progression, treat and prevent glaucoma, and aid in treating several types of retinal disease.

One of the extract’s most popular uses is in treating the effects of aging, including preventing wrinkles by protecting the skin against ultraviolet radiation damage from sunburn, improving skin elasticity and tone, and helping reduce the appearance of scars and stretch marks. A wide range of anecdotal reports tell of grape seed extract helping treat or reduce the effects of headaches, hemorrhoids, diabetes, prostate enlargement, and cellulite, although no clinical research supports these claims.


Grape seed extract generally is available in 50 mg (milligram) and 100 mg capsules. The acceptable adult daily dosage has been estimated at up to 150-200 mg, or 50 mg per 50 lb (22.7 kg) of body weight. In Europe, OPCs usually are prescribed at 300 mg a day to treat medical conditions such as varicose veins, edema, allergies, inflammation, and skin aging.

The extract contains varying amounts of proanthocyanics, although the label should indicate about 75–80% proanthocyanidins to be effective. Research in the United States and Europe has shown it is most effective when used in combination with other antioxidants, especially vitamin C and vitamin E. Grape seed extract is fully absorbed by the body within one hour after consumption. One-half the original dose is still functional within the body after seven hours.

In 2003, a liquid grape seed extract was made available in the United States. This version can be used in a number of beverages, including bottled water, without changing their taste. A 2003 trial at Ohio State University found that lotions made with grape seed extract helped cuts heal more quickly than they would on their own. The lotion helped improve blood flow to the wound site.


There are no known precautions associated with grape seed extract. However, persons with serious conditions such as cancer, diabetes, and cardiovascular disease should not substitute grape seed extract for their existing treatments without first consulting with their doctor. There is no clinical evidence that grape seed extract can cure any of these conditions.

Since grape seed extract is water-soluble, any excess intake that is not used by the body is eliminated in the urine. Studies have shown it is not carcinogenic, does not cause birth defects, and does not cause cells to mutate. Pregnant women and those with autoimmune conditions should probably avoid grape seed extracts. It is best to check with a clinician to ensure the safest dosage is being taken, as reports may vary on the latest research.

Side effects

Nausea and upset stomach have been reported on occasion. More rarely, allergic reactions in the form of temporary skin rashes have occurred in persons sensitive to grape products. There are no reported serious side effects associated with taking grape seed extract. It is non-toxic, even at high dosages.


There are no reported negative interactions associated with grape seed extract. However, several studies done in the United States and Europe show the extract has a positive reaction with vitamin C and vitamin E. Studies have shown that OPCs in grape seed extract are as much as 50 times more potent than those in vitamin E and up to 20 times more potent than OPCs in vitamin C.