Grapes reach far back into history. Fossilized leaves and seeds from the Miocene and Tertiary periods have been unearthed in Europe, Iceland, and North America; in Switzerland from the period of the Bronze Age; and in Egyptian tombs and hieroglyphics. Grapes are noted in the Bible. Homer drank wine made from grapes, circa 700 B.C.

All parts of the plant have been used for medicinal purposes. Sap was used in Europe for eye and skin ailments. Leaves had astringent and hemostatic actions. Grapes that were not yet ripe were used for sore or infected throats. Raisins had therapeutic applications, too—for instance, in the treatment of consumption, constipation, and thirst. Ripe grapes, however, had a plethora of applications, including cancer, cholera, smallpox, nausea, ophthalmia, and skin, kidney, and liver diseases. Similar and additional applications were prevalent in the Middle East, India, and China. Grapes have also been listed in many pharmacopeias.

Today, however, grapes are rarely, if ever, used for any of these purposes. Apart from being source materials in the manufacture of food and beverages, grapes are harvested because they are a source of oligomeric proanthocyanidins (OPCs), therapeutically active antioxidants. Compared to most botanical products used for their own individual therapeutic properties, grape seed is used for the OPCs it contains. These polyphenolic constituents are also found in green tea and maritime pine bark. Extracts made from each of these plants contain similar OPC values and may be used interchangeably for specific indications, including chronic venous insufficiency and some ophthalmologic conditions. Effects have not been evaluated by Germany's Commission E, and in the United States, the use of pine bark (pycnogenol) for OPCs is much more prevalent than grape seed OPCs.

Grapes are the fruit of Vitis vinifera, native to Asia but naturalized to most other continents in temperate regions. The perennial consists of a woody, climbing vine. The stem produces a peeling bark, and the large, circular to circular-ovate leaves are dentate or jagged at the margins, pale green on the top, and grayer underneath. Fruits are oval, and may be green, red, or purple. OPCs occur on the outside of the grape seeds as well as on the inner grape skin.

• Seeds
• Fruit skin

OPCs, also called procyanidins, consist of a variable number of flavan units, and are dimeric, trimeric, tetrameric, and oligomeric, depending on the length of the bonds that link them. A patented process, developed by French biochemist Jaques Mesquelier in 1970, assures that each of these chains is present in a grape seed product.

Extracts are standardized to 95% OPC content.

Grape plants were originally used for purposes described in the overview. Because OPCs were not isolated from grape seed until 1970, there was no traditional folk use of OPCs.

Clinical applications: Results from controlled trials support the use of grape seed OPCs for impaired visual function due to macular degeneration and chronic venous insufficiency. In addition, lymphedema, acrocyanosis, varicose veins, telangiectases, capillary fragility and permeability secondary to diabetes, cancer, premenstrual syndrome, and dental caries are some of the many indications for which grape seed OPCs might prove useful.

Pharmacologic activities of OPCs are numerous. In vitro, OPCs' antioxidant activity is 50 times greater than vitamin E's and 20 times greater than vitamin C's, in both lipid and aqueous phases. OPCs significantly and dose-dependently prevent vitamin E loss, and lower blood cholesterol levels through possible reversal of cholesterol transport, and by increasing both intestinal cholesterol absorption and bile acid excretion. OPCs also inhibit angiotensin I converting enzyme, ascorbic acid oxidase, histidine decarboxylase, and prevents histamine release and arterial damage. OPCs are thought to prevent atherosclerosis by inhibiting platelet aggregation and vascular constriction. They stabilize capillary walls and prevent xylene-induced capillary permeability. OPCs also demonstrate antimutagenic activity, and inhibit carrageenan-induced rat paw edema.

In a double-blind, placebo controlled trial, grape seed extract was an effective prophylactic against postoperative facial swelling. In an open trial, venolymphatic symptoms of premenstrual syndrome in 165 study subjects were relieved with grape seed OPC therapy. Capillary resistance in 28 diabetic and hypertensive patients rose significantly in an open trial that provided patients with 150 mg OPCs daily. It is also effective in relieving upper extremity lymphedema secondary to radical mastectomy.

• As a preventive for atherosclerosis, ophthalmologic disorders, or other conditions: 50 mg standardized extract/day.
• For therapeutic purposes: 150 to 300 mg/day.

None known

None known

No clinically significant interactions between grape seed extract and conventional medications are known to have been reported in the literature to date.

In the United States, grape seed OPC is a dietary supplement. It was not reviewed by Germany's Commission E.

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