Bottom Line: Grape seed has not been shown to treat or prevent cancer.
Grape Seed Extract is derived from the oil that comes from ground red wine grapes. The extract contains a substance called proanthocyanidin which has antioxidant activities, meaning it that it can protect cells from certain kinds of damage. Proanthocyanidins have also been shown to reduce cholesterol in patients with high cholesterol. Other substances within the grape seed may also help protect teeth from decay.
To lower high cholesterol One study showed a combination of Grape Seed Extract and chromium to be effective at lowering cholesterol levels. Further study is warranted.
As an antioxidant One small study showed Grape Seed Extract to increase antioxidant levels in the blood. Further study is warranted.
To treat atherosclerosis Although studies have shown that substances found within grape seeds may have an effect in reducing the thickening of arteries, further study is needed to determine whether Grape Seed Extract will reduce atherosclerosis in humans.
As a topical wound treatment Animal studies have shown a possible effect, but further study is required to determine its effect in humans.
As a laxative No scientific evidence supports this use.
As an antacid No scientific evidence supports this use.
To treat ulcers No scientific evidence supports this use.
High Cholesterol: Forty patients with high cholesterol took part in a study of chromium and Grape Seed Extract (GSE) for high cholesterol. For two months, patients received one of four treatments: placebo, chromium, Grape Seed Extract or chromium and Grape Seed Extract together. Only those taking the chromium and Grape Seed Extract had significantly reduced total cholesterol and LDL ("bad") cholesterol levels. While this study shows that Grape Seed Extract may play a role in reducing cholesterol levels when combined with chromium, larger studies need to be done to determine what effect the extract has by itself.
This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. The product may not contain the labeled amount. In addition, it may not have been tested for safety or effectiveness.
Obtained as a by-product of wine production, grape seeds are ground to produce grape seed oil. Anecdotally, grape seed oil and grape seed extract (GSE) have been used as a laxative, antacid, cholagogic agent, in treating burns, ulcers, and as a hand cleanser (1)(2). Studies of grape seed proanthocyanidin extract (GSPE) in mice have shown effectiveness in minimizing doxorubicin-induced cardiotoxicity as well as other drug-induced nephrotoxicity, pulmonary toxicity (3). In vitro studies have shown GSPE to have synergistic anti-cancer effects with doxorubicin (13). GSPE also inhibits atherosclerosis (4)(5). Small human trials have shown possible efficacy in decreasing LDL (6) and increasing total serum antioxidant activity (7). Additionally, topical application of GSPE has been shown to accelerate wound contraction and closure (8). But orally administered GSPE was not effective for breast induration following radiotherapy in patients with breast cancer (14). Few side effects have been reported for GSPE consumption, however, because of its interference with cytochrome P450, it may affect the metabolism of certain drugs.
Proanthocyanidins and minor phenolic compounds found in GSPE are also found naturally in many foods including fruits, vegetables, chocolate and tea. On average, people consume 460-1000 mg/day of these combined substances (9). Procyanidins, subunits of proanthocyanidins, from V. vinifera seeds have been shown to have antioxidant activity and to alter capillary permeability in animal models (2). GPSE has protective effects on doxorubin-induced cardiotoxicity (3). Cardioprotective effects theoretically come from its ability to modulate anti-apoptotic genes and modify molecular targets such as DNA damage and repair, lipid peroxidation and intracellular calcium homeostasis (5). Procyanidins also inhibit xanthine oxidase activity and non-competitively inhibit the proteolytic enzymes collagenase and elastase and the glycosidases hyaluronidase and beta-glucuronidase. Polyphenolic substances from grape seeds have been shown to inhibit the growth of Streptococcus mutans and glucan formation from sucrose, which may aid in the prevention of dental caries. Seed tannins may stimulate cell renewal by interfering with mucosal proteins (1).
GSPE is an inhibitor of cytochrome P450 (3). Gastrointestinal absorption of GSPE is rapid. 70% of the extract is eliminated within the first 24 hours, most through the urine and feces although some through the bile (2).
Cytochrome P450: Grape seed extract has been shown to inhibit cytochrome P450 isoenzymes (3), therefore may affect serum concentrations of certain medications metabolized by the same enzyme. Warfarin (Coumadin): due to its tocopherol content, GSE may theoretically enhance the activity of warfarin (11)(12).
Preuss HG, Wallerstedt D, Talpur N, Tutuncuoglu SO, Echard B, Myers A et al. Effects of niacin-bound chromium and grape seed proanthocyanidin extract on the lipid profile of hypercholesterolemic subjects: a pilot study. J Med 2000;31:227-46. A randomized controlled trial testing total cholesterol and LDL change in forty subjects with total cholesterol levels of 210-300 mg/dL. Subjects were randomized into one of four groups to receive either placebo, Chromium Polynicotinate (Cr) 200 micrograms twice daily, Grape Seed Extract (GSE) 100 mg twice daily or both Cr and GSE intervention. After two months, a significant decrease in total cholesterol and LDL was observed only for the Cr and GSE combination group. HDL and triglyceride levels did not change significantly for any group. The two groups receiving GSE also showed a decrease in circulating autoantibodies to oxidized LDL. Further study is needed to determine whether GSE has a role in treating hypercholesterolemia.
