Evidence for the Health Benefits of Grape Seed Extract

Red grape seeds offer numerous health benefits, with little risk of adverse side effects. Red grape seeds are typically obtained as a by-product of the manufacturing of wine. The active components of red grape seeds are called oligomeric proanthocyanidins or OPCs. In order to concentrate the OPCs, the red grapes are made into a natural supplement called grape seed extract.

Research indicates that grape seed extract may be effective for two medical conditions in particular: Chronic venous insufficiency and eye stress from glaring screens and lights. Other medical conditions that grape seed may help with, though definitive evidence is lacking, include cardiovascular disease, high blood pressure, and night vision. Additionally, many individuals take grape seed extract for allergic rhinitis or hayfever. However, research seems to suggest that grapeseed extract is ineffective when used for allergic rhinitis.

Grape seed extract for chronic venous insufficiency:

Several studies have been done on individuals with chronic venous insufficiency using OCPs concentrated in the form of grapeseed extract. In these studies, taking grape seed extract reduced the symptoms of chronic venous insufficiency reported by the study participants and improved venous tone.

Another clinical trial used OCPs concentrated from grape leaf extract, known as red vine leaf extract. The supplement was given to patients with stage I and stage II chronic venous insufficiency. These individuals experienced a significant decrease in leg edema after 6 weeks of treatment compared to placebo.

In addition, these patients reported a significant decrease in subjective symptoms. The symptoms that improved included tired legs, heavy legs, tension in the lower extremities, and tingling and pain in the legs and feet. This improvement in symptoms was documented after 12 weeks of treatment with the oligomeric proanthocyanidins.

Grape seed extract for eye stress:

Individuals who experienced frequent eye strain and stress may benefit from taking grape seed extract. In particular, several studies found a decrease in eye stress caused by glare when the study participants used grape seed extract.

Grape seed extract for cardiovascular disease:

Grape seed extract may or may not be of benefit in reducing the risk of cardiovascular disease. Preliminary evidence suggests that grape extracts may improve endothelium-dependent vasodilation, prevent LDL oxidation, and suppress platelet-mediated thrombosis. This means that, at least theoretically, grape extract may reduce the risk of heart disease.

Grape seed extract for hypertension:

Grapeseed extract is often promoted for high blood pressure. However, the research has yet to clarify this issue. In fact, in the largest study done, grape seed polyphenols given at a dose of 1000 mg/day did not have a significant effect on blood pressure in hypertensive patients.

Grape seed extract for night vision:

OCPs concentrated from red grapes may be beneficial for improving night vision. However, more evidence is needed to rate grape seed extract for improving night vision in individuals.

Grape seed extract is generally very well tolerated. Headache, abdominal pain, sore throat, nausea, and cough have been reported with the use of red grape seed. However, these adverse effects occur at rates similar to placebo, meaning they may or may not have been related to the grape seed extract.

Grape seed extract and OCPs are available as over-the-counter supplements. While grape seed extract has few side effects, it can have significant interactions with other herbs and prescription medications. Speak with your healthcare provider before starting new herbal medicines.

Sources:

Anon. OPCs (Oligomeric Proanthocyanidins). The Natural Pharmacist 2000. http://www.tnp.com/substance.asp?ID=181.

Bombardelli E, Morazzoni P. Vitis vinifera L. Fitoterapia 1995;LXVI:291-317.

Freedman JE, Parker C, Li L, et al. Select flavonoids and whole juice from purple grapes inhibit platelet function and enhance nitric oxide release.

Kiesewetter H, Koscielny J, Kalus U, et al. Efficacy of orally administered extract of red vine leaf AS 195 (folia vitis viniferae) in chronic venous insufficiency (stages I-II). A randomized, double-blind, placebo-controlled trial. Arzneimittelforschung 2000;50:109-17.

Stein JH, Keevil JG, Wiebe DA, et al. Purple grape juice improves endothelial function and reduces the susceptibility of LDL cholesterol to oxidation in patients with coronary artery disease.

Ward NC, Hodgson JM, Croft KD, et al. The combination of vitamin C and grape-seed polyphenols increases blood pressure: a randomized, double-blind, placebo-controlled trial. J Hypertens 2005;23:427-34.