Grape seed extracts are industrial derivatives from whole grape seeds that have a great concentration of vitamin E, flavonoids, linoleic acid, and OPCs. Typically, the commercial opportunity of extracting grape seed constituents has been for chemicals known as polyphenols, including oligomeric proanthocyanidins recognized as antioxidants.
Potential anti-disease effects
Human case reports and results from laboratory and animal studies show that grape seed extract may be useful to treat heart diseases such as high blood pressure and high cholesterol. By limiting lipid oxidation, phenolics in grape seeds may reduce risk of heart disease, such as by inhibiting platelet aggregation and reducing inflammation.While such studies are promising, more research including long-term studies in humans is needed to confirm initial findings.
A polyphenol contained in grape seeds is resveratrol which may interfere with cancer cell growth and proliferation, as well as induce apoptosis, among a variety of potential chemopreventive effects.
Grape seed components may also be active against HIV by inhibiting virus expression and replication.
Preliminary research shows that grape seed extract may have other possible anti-disease properties, such as in laboratory models of
- wound healing—grape seed proanthocyanidins induced vascular endothelial growth factor and accelerated healing of injured skin in mice.
- tooth decay --seed phenolics may inhibit oral sugar metabolism and retard growth of certain bacteria causing dental caries.
- osteoporosis -- grape seed extracts enhanced bone density and strength in experimental animals.
- skin cancer -- grape seed proanthocyanidins decreased tumor numbers and reduced the malignancy of papillomas.
- ultraviolet damage to skin—dietary proanthocyanidins may protect against carcinogenesis and provide supplementation for sunscreen protection.
There is good evidence that grape seed extract can help treat chronic venous insufficiency and edema.
Currently, there are four clinical trials underway to assess the effect of grape seed extracts on human breast cancer, blood estrogen levels in postmenopausal women, and coronary artery disease.
Dosage, precautions and interactions
Oral grape seed extract is typically used as capsules or tablets usually containing 50 mg or 100 mg, or as a liquid to add drops to water and/or other drinks. Insufficient scientific information is known, however, about how long-term use of grape seed extract might affect health or any disease.
In a 12-month study, the safety of dietary intake of grape seed proanthocyanidins in a dose of 100 mg per kg per day was demonstrated in rodents
The US National Center for Complementary and Alternative Medicine (NCCAM) reports that oral administration of grape seed extract was well tolerated in people over 8 weeks of a clinical trial.In one completed clinical trial, grape seed extract did not alleviate the hardening of breast tissue in female patients undergoing radiation therapy to treat breast cancer.
Other NCCAM advisories
- side effects most often include headache, a dry, itchy scalp, dizziness or nausea
- interactions between grape seed extract and medicines or other supplements have not been carefully studied
Due to the action of proanthocyanidins on limiting platelet adhesion,grape seed extract may increase the clotting time of blood.