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Grape seed extract is an industrial derivative of grape seeds. It is rich in antioxidants and oligomeric proanthocyanidin complexes and has been linked to a wide range of possible health benefits.
Many of these health claims are still not completely backed by high-quality studies, but some evidence supports its use.
Grape seed extract is available as a dietary supplement in a liquid form, tablets, or capsules. Supplements commonly contain between 50 and 100 milligrams (mg) of the extract.
This article provides details on the benefits of grape seed extract as well as side effects and precautions associated with its use.
Fast facts on grape seed extract
Here are some key points about grape seed extract. More detail and supporting information is in the main article.
- Some evidence shows that grape seed extract might aid wound healing.
- Grape seed extract should be avoided during pregnancy.
- Some researchers believe that the proanthocyanidins it contains hold a range of benefits.
Studies on animal models have revealed that grape seed extract can be effective in treating heart disease.
Some experts think that grape seed extract could even have anticancer and cancer chemopreventive potential.
Over recent years, there has been a great deal of research pointing to possible therapeutic properties of grape seed extract. Listed below are some of the key findings.
Grape seed extract has the potential to increase the speed that wounds heal. A study, published in the journal Free Radical Biology and Medicine, applied proanthocyanidin extract onto wounds on the backs of mice. They found that the mice treated with this solution had quicker healing times.
According to the researchers they “provided firm evidence to support that topical application of GSPE [Grape seed proanthocyanidin extract] represents a feasible and productive approach to support dermal wound healing.”
Although it is not clear how this protection occurs, GSPE was found to increase production of vascular endothelial growth factor, a compound important in the wound healing process.
Improving bone strength
This is according to a study published in the Journal of Musculoskeletal & Neuronal Interactions that investigated the effects of calcium and proanthocyanidins on the bone structure of mice which had been fed a low-calcium diet.
A study conducted in Italy examined grape seed extract’s ability to attack Candida, a yeast-like parasitic fungus that can, sometimes, cause thrush. Grape seed oil contains flavan-3-ols. The researchers concluded:
“The results pointed out a significant inhibition of Candida albicans load 5 days after challenge. These findings indicate that grape seed extracts with high content of polymeric flavan-3-ols can be used in mucosal infection such as vaginal candidiasis.”
Preventing skin cancer
Grape seeds contain proanthocyanidins which might prevent the development of cancer. A study, published in the journal Molecular Nutrition & Food Research, found that grape seeds have properties that can reduce the severity of skin cancer.
Using hairless mice, the research team tested the ability of grape seed proanthocyanidins to slow the formation of skin tumor development.
The researchers concluded that grape seed extracts “could be useful in the attenuation of the adverse UV-induced health effects in human skin.”
It is thought that the protective nature of proanthocyanidins comes via a number of routes including a reduction in oxidative stress and immunosuppression by altering cytokine activity. Further research is needed to firm up the findings.
According to one study, published in the journal Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, “grape seed proanthocyanidin extract (GSPE) provides superior antioxidant efficacy as compared to Vitamins C, E, and β-carotene.”
The National Center for Complementary and Integrative Health (NCCIH) note that it may help reduce systolic blood pressure and heart rate, but they point out that it will not help decrease lipid levels, for example, cholesterol, in the blood.
Preventing cognitive decline
Grape seed extract is very high in proanthocyanidins which some believe could prevent cognitive decline.
One study identified “a critical role for grape seed proanthocyanidin extract (GSPE) as a neuroprotectant in the hippocampus and in preventing cognitive loss with aging.”
The NCCIH is supporting studies on the effect of grape seed extract on Alzheimer’s disease.
Other possible benefits
Other possible benefits associated with grape seed extract include:
- treating tooth decay
- protecting against pathogens
- improving night vision
- Alzheimer’s disease
- treating diabetic retinopathy and improving blood sugar control
- relieving symptoms of chronic venous insufficiency
- anti-aging properties (protecting collagen and elastin)
- reducing edema
- relieving symptoms of chronic venous insufficiency
- reducing iron levels in people with hemochromatosis
- reducing inflammation
However, a study in 2014 showed that four daily doses of grape seed extract “did not significantly decrease estrogen or increase androgen precursors.”
Preventing hair loss by consuming grape seed extract has been theorized. Some nutritionists believe that proanthocyanidins inhibit dihydrotestosterone (DHT), one of the hormones thought to be involved in hair loss but, evidence for its effectiveness is scant.
Common side effects include:
It is important to talk to your doctor before taking grape seed extract as it can affect the way that certain medications are broken down in the liver.
Grape seed extract might also act as an anticoagulant, or blood-thinner. It could increase the risk of bleeding if taken with other blood-thinners such as warfarin (Coumadin), clopidogrel (Plavix), or aspirin.
The NCCIH describes grape seed extract as “generally well tolerated when taken in moderate amounts.”
It is available for purchase online, but you should check with a doctor first to make sure it is safe for you to use.
Is is really useful?
The effect of grape seed extract has been investigated for the following:
- reducing body weight
- lowering lipid levels in the blood
- improving insulin sensitivity
- drop in diastolic blood pressure
However, the results have shown that it either made no difference or the effect was not significant enough to support its use for these purposes.
Some note that while the procyadins can be powerful in lab experiments, grape seed extract appears to have poor bioavailability, which means the body may not absorb it efficiently enough to make it worth using.
In addition, pregnant women should completely avoid taking grape seed extract supplements.
It may be that grape seed extract can offer multiple health benefits, but more research is needed to confirm this.