Grapes are one of the most popular fruits in the U.S., but many people neglect to eat what is perhaps their healthiest feature — the seeds. Grape seeds are rich in powerful antioxidants and natural plant compounds called oligomeric proanthocyanidin complexes (OPCs).
OPCs are most well known for their antioxidant activity, which means, at the very least, grape seed may help to destroy free radicals in your body, which in turn may help you avoid premature aging and certain chronic diseases.
However, OPCs also demonstrate a host of other beneficial activities in the body, which may explain why grape seed extract appears to help so many different health conditions while exerting its effects body-wide.
According to the National Institutes of Health (NIH) National Center for Complementary and Integrative Health (NCCIH):
"Today, grape seed extract is used as a folk or traditional remedy for conditions related to the heart and blood vessels, such as atherosclerosis (hardening of the arteries), high blood pressure, high cholesterol, and poor circulation …
… [C]omplications related to diabetes, such as nerve and eye damage; vision problems, such as macular degeneration (which can cause blindness); swelling after an injury or surgery; cancer prevention; and wound healing.
The grape seeds used to produce grape seed extract are generally obtained from wine manufacturers."
OPCs Help make grape seed extract a health superstar
One of grape seed extract's claims to fame is OPCs, which are related to the much more well-known compound resveratrol (found in grape skins). According to the journal Alternative Medicine Review, OPCs not only have antioxidant activity but are also:
- Vasodilatory actions
In addition, the journal reported OPCs "have been found to inhibit lipid peroxidation, platelet aggregation, capillary permeability and fragility, and to affect enzyme systems … Based on these reported findings, OPCs may be a useful component in the treatment of a number of conditions."
OPCs may even play a role in cancer prevention. Research published in the journal Prostate found OPCs helped stop the spread of prostate cancer cells and also caused apoptosis (cell death) among prostate cancer cells. Further, according to the University of Maryland Medical Center:
"Studies have found that grape seed extracts may prevent the growth of breast, stomach, colon, prostate, and lung cancer cells in test tubes. However, there is no clear evidence whether it works in humans.
Antioxidants, such as those found in grape seed extract, may help reduce the risk of developing cancer. Grape seed extract may also help prevent damage to human liver cells caused by chemotherapy medications."
Grape seed extract also contains high levels of compounds (procyanidin dimers) that act as aromatase inhibitors. This is likely another way grape seeds may help prevent and treat cancer, specifically hormone-dependent breast cancer.
Aromatase, an enzyme, converts androgen to estrogen and is expressed at higher levels in breast cancer tissues than normal tissues.
Many types of breast cancer are fueled by estrogen, which is why some chemotherapy drugs work by inhibiting the activity of aromatase. Grape seed extract may exert similar effects naturally.
Grape seed for your heart health, skin and brain
The more research that emerges on grape seeds, the more it becomes clear they have wide-reaching health benefits. Grape seeds have been shown to improve flexibility in joints, arteries and body tissues such as your heart, for instance.
Grape seed also helps improve blood circulation by strengthening capillaries, arteries and veins. Additional health benefits include those that follow.
High blood pressure
The antioxidants, including flavonoids, linoleic acid, and phenolic procyanidins, in grape seed extract help protect your blood vessels from damage, which may help prevent high blood pressure.
Grape seed extract has previously been shown to help dilate blood vessels and was shown to lower blood pressure in people with metabolic syndrome (most of whom also had prehypertension).
Another study found that a grape seed extract beverage improved blood pressure in people with pre-hypertension, while a single dose of grape seed extract improved blood pressure in hypertensive rats.
Chronic venous insufficiency
The OPCs in grape seed extract may benefit this condition. About 80 percent of those who consumed OPCs had an improvement in symptoms after the first 10 days of treatment. Feelings of heaviness, itching, and pain were reduced significantly.
Grape seed extract has been shown to improve bone formation and bone strength in animal studies.
Grape seed extract has been found to inhibit leg swelling that can occur during prolonged sitting. In addition, according to the University of Maryland Medical Center:
"Edema is common after breast cancer surgery, and one double-blind, placebo-controlled study found that breast cancer patients who took 600 mg of grape seed extract daily after surgery for six months had less edema and pain than those who took placebo.
Another study found that people who took grape seed extract after experiencing a sports injury had less swelling than those who took placebo."
Animal studies suggest grape seed extract may reverse hippocampal dysfunction in the brain by reducing oxidative stress and preserving mitochondrial function. Grape seed extract may even be useful as a preventative or therapeutic agent in Alzheimer's disease.
Grape seed extract solution led to less demineralization and more remineralization of cavities in one lab study. Since remineralization is an effective treatment that may stop or reverse early tooth decay, grape seed extract could play a beneficial role in oral health.
Grape seed extract administered along with exercise training improved lipid profile, weight loss, blood pressure and other diabetic complications better than either intervention administered alone.
According to researchers, "This [grape seed extract and exercise training] may constitute a convenient and inexpensive therapeutic approach to diabetic complications."
Slight evidence suggests grape seed extract may also be beneficial for:
- Improving night vision
- Protecting collagen and elastin in your skin (for anti-aging effects)
- Treating hemorrhoids
- Protecting against oxidative rancidity and bacterial pathogens
Can you get the benefits of grape seeds from eating grapes?
If you enjoy snacking on grapes, there's no reason to spit out the seeds (and may be some benefit from eating them). However, to reach therapeutic quantities of grape seeds you'd need to eat a lot of grapes — and this is not recommended since grapes are one of the highest-fructose fruits.
Most grape-seed extract comes from ground-up seeds from grapes used to make red wine. In fact, grape seeds and their extract are considered a byproduct of the wine and grape juice industries.
While you can purchase whole grape seeds to consume for health purposes, they're very bitter. This is actually a good thing, as polyphenols, flavonoids, and other beneficial plant compounds almost always taste bitter — it's a sign they're good for you.
Unfortunately, since most people find them to be unpalatable, "the food industry routinely removes these compounds from plant foods through selective breeding and a variety of debittering processes."If you're willing to get past the bitter taste, then whole grape seeds are an option.
If not, grape seed and grape seed extract is available in supplement form. There is no daily recommended amount at this time, but some studies used doses of between 100 to 300 milligrams/day. The University of Maryland Medical Center recommends looking for products that are standardized to 40 percent to 80 percent proanthocyanidins, or an OPC content of not less than 95 percent.