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Grape Skin
You know those people who gleefully tout the health benefits of red wine? They’re onto something. Red wine is an excellent a source of antioxidants. Or more precisely, the grapes and their skin are a rich source of antioxidants.
Various studies have shown that grape skin provides excellent protection against oxidative stress by decreasing oxidants and increasing antioxidant levels in plasma.
This understanding of grape skin’s effects is being used to study its benefits relating to LDL cholesterol, skin health, diabetes, breast cancer, prostate cancer, respiratory health, and chronic venous insufficiency. Supplementation with grape skin has been shown to improve skin elasticity and sebum production, may have the potential to prevent diabetic complications, may inhibit prostate cancer cell growth, and may prevent inflammation in the lungs and oxidative damage after exposure to cigarette smoke.
Active constituents
Flavonoïdes: anthocyanines (3-O-monoglucosides ou 3,5-O-diglucosides de malvidine, de cyanidine, de péonidine, de delphinidine, de pelargonidine et de pétunidine 1-12, ainsi que leurs esters d’acétyle, de p-coumaroyle et/ou d’acide caféique), flavonols (3-O-glycosides de quercétine 16, kaempférol 17, myricétine 18, laricitrine, isorhamnétine 19 et syringétine), flavanols [(+) - catéchine 13, (-) - épicatéchine 14, (-) - épicatéchine-3 -O-gallate], dihydroflavonols (astilbin et engeletin) et proanthocyanidines
AVAILABLE RESEARCH
Antioxidant
In this study, researchers procured food samples from countries worldwide and assayed the samples for their total antioxidant content using a modified version of the FRAP assay. The results found that from this sample, “antioxidant-rich beverages include red wine” (which is made with grape skin).
In this study, researchers administered grape seed extract to healthy subjects with LDL cholesterol (LDL-C) levels of 100 to 180 mg/dL. The results concluded that “tablets containing grape seed extract exerted reducing effects on oxidized LDL, and might be useful in preventing lifestyle-related diseases such as arteriosclerosis.
The present study was designed to investigate the effect of supplementing a meal with grape seed proanthocyanidins (the main phenolic antioxidant of red wine) on healthy patients with plasma postprandial oxidative stress. The research concludes that “supplementation of a meal with grape seed extract minimizes the postprandial oxidative stress by decreasing the oxidants and increasing the antioxidant levels in plasma, and, as a consequence, enhancing the resistance to oxidative modification of LDL.”
This study assessed the concentration- or dose-dependent free radical scavenging ability of a novel IH636 grape seed proanthocyanidin extract (GSPE) both in vitro and in vivo models, and compared the free radical scavenging ability of GSPE with vitamins C, E and beta-carotene. The results demonstrate that “GSPE provides excellent protection against oxidative stress and free radical-mediated tissue injury.”
This study on mice looked at the comparative protective abilities of a grape seed proanthocyanidin extract (GSPE), vitamin C, vitamin E succinate, and beta-carotene on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced lipid peroxidation and DNA fragmentation in the hepatic and brain tissues. It also studied the production of reactive oxygen species by peritoneal macrophages. The results found that “GSPE and other antioxidants provided significant protection against TPA-induced oxidative damage, with GSPE providing better protection than did other antioxidants at the doses that were employed.”
ADDITIONAL RESEARCH
There is ongoing research on the effects of grape skin as it relates to the following health concerns:
Skin Health
This study suggests that supplementation with a blend of antioxidants including grape skin improved the following skin health markers: a) skin elasticity; b) sebum production; c) dermal ultrasonic markers.
This study suggests that grapes may protect against ionizing radiation and free radical damage; the seed had even greater activity than the skin of the grape.
Diabetes
According to this study, grape skin extract has a potentially potent antioxidant effect and antiglycation properties. It has been demonstrated to reduce advanced glycation end products in diabetic patients, and therefore may have the potential to prevent diabetic complications.
In an animal study supporting the use of grape skin extract in diabetic, obese mice, there was the possibility of improved glycemic control and reduced inflammation with grape skin extract supplementation.
This animal study showed the potential for reduced toxicity on the renal system (fat induced lipotoxicity) in obese rats with grape skin supplementation.
Prostate Cancer
This study suggests that grape skin extract may inhibit prostate cancer cell growth (in vitro).
This completed phase 1 clinical trial in men with recurrent prostate cancer determined that grape skin extract is safe. Grape skin extract contains ellagic acid, quercetin, and resveratrol and demonstrates preclinical activity against prostate cancer cells in vitro.
Breast Cancer
In this study, researchers compared red and white wines and their effect on breast cancer. The results found that because red wine is made with the skin of grapes, “red wine or red wine extract may be a chemopreventive diet supplement for postmenopausal women who have a high risk of breast cancer.” In comparison, white wine, which is free of grape skin “has proven to have no such benefit.”
Respiratory health
Animal studies support the hypothesis that grape skin extract may prevent inflammation in the lung and oxidative damage after exposure to cigarette smoke. The potential benefits of grape seed extract are nitric oxide dependent.
Chronic Venous Insufficiency
The aim of the present study was to examine the mechanisms involved in grape seed extracts (GSE), which contain polyphenolic compounds, in causing an endothelium-dependent relaxation of blood vessels on rabbits. These findings conclude that “grape seed relaxes the arteries.”
In this study, the administration of grape seed extract was tested on healthy people with high blood pressure. The study found that “there was a statistically significant improvement of blood pressure and heart rate, especially in the higher dosage group.”