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18 Grape Seed Extract Benefits + Side Effects & Dosage

Written by Aleksa Ristic, MS (Pharmacy) | Reviewed by Ana Aleksic, MSc (Pharmacy) | Last updated:
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Aleksa Ristic, MS (Pharmacy) | Reviewed by Ana Aleksic, MSc (Pharmacy) | Last updated:

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Grapes

After reading this article, you’ll stop throwing away the seeds when eating grapes! Grape seed extract contains antioxidants that may prevent heart disease, brain damage, skin aging, and more. That said, solid clinical evidence has backed up only a fraction of these effects. Learn more about the potential benefits and side effects of grape seed extract.

What Is Grape Seed Extract?

Grape seed extract is a concentrated source of antioxidant polyphenols from grape seeds [1, 2, 3].

Grapes and other berries abound with specific polyphenols, proanthocyanidins. They are responsible for the dry mouth sensation you get from drinking red wine or berry juice, but they also act as potent antioxidants [4].

Supplement manufacturers usually source grape seeds from winemakers, and they extract proanthocyanidins and other healthy components.

For other grape seed products and their uses, check out the FAQ section below.

Snapshot

Proponents:

  • Helps lower blood pressure
  • Protects the brain, heart and blood vessels
  • May help prevent cancer
  • May protect the liver and kidneys
  • Supports wound healing

Skeptics:

  • Most benefits lack clinical evidence
  • May not be safe for children and pregnant women
  • May interact with blood thinners and other medications

Grape Seed Extract Benefits

Preliminary research on grape seed extract promises a lot, but the available clinical evidence in people with health conditions is limited. The following studies should encourage further investigation before we make any definite conclusions and recommendations. Remember to speak with a doctor before taking grape seed extract supplements. They can not replace medical treatment for any health condition.

How It Works

Oxidative stress lurks as an underlying cause of many health conditions. Grape seeds are among the best sources of powerful antioxidants, proanthocyanidins, which build oligomeric proanthocyanidin complexes (OPCs) with unique antioxidant properties [4, 5, 6, 7].

Phenolic acids and flavonoids from grape seeds also combat oxidative damage [8].

Truth be told, this doesn’t mean grape seed extract can help with all conditions in which oxidative stress plays a role.

Apart from free-radical protection, this unique mixture of grape seed components may [9, 10, 11]:

  • Relieve inflammation and allergies
  • Kills microbes and cancer cells
  • Protect healthy cells against toxins and radiation

Likely Effective:

1) May Lower Blood Pressure

Two meta-analyses of 25 clinical trials (1,200 patients in total) concluded that grape seed extract can lower blood pressure. The effect was stronger in younger participants, obese patients, and those with metabolic disorders. That said, the impact on diastolic blood pressure (lower value) was less conclusive and requires further investigation [12, 13].

In 36 patients at risk of high blood pressure, the extract (300 mg daily for 6 weeks) reduced blood pressure and lowered their risk [14].

Possibly Effective:

The benefits in this section stem from low-quality clinical trials, animal, and cell-based studies. They are not researched well enough to recommend grape seed extract for any of the below conditions.

2) May Support the Heart and Blood Vessels

In 36 subjects, one-month supplementation with grape seed extract (2 g daily) protected blood vessels against free-radical damage by boosting nitric oxide [15].

In a series of smaller clinical trials (130 people in total), grape seed extract lowered the risk of heart disease by lowering oxidative stress and inflammation. It prevented the oxidation of LDL (“bad cholesterol”) in the blood vessels. Oxidized LDL can trigger plaque buildup or atherosclerosis [16, 17, 18, 19, 20].

Keep in mind that some of the above results were observed in diabetics and heavy smokers only, and they might not translate to the general population.

Animal trials confirmed the ability of this extract to protect the heart and blood vessels against [18, 21, 22, 23, 24]:

  • LDL oxidation
  • Clogging and hardening
  • Drug-induced damage
  • Damage due to heart attack
  • Lead poisoning

3) May Help Prevent Cancer

The findings discussed below stem from preliminary clinical research and animal studies. The National Cancer Institute “is supporting preliminary studies on grape seed extract for preventing prostate, lung, and colon cancer.” They should guide further investigation but shouldn’t be interpreted as supportive of the anticancer effects until more research is done. Grape seed extract supplements aren’t approved for cancer prevention or treatment [3].

In a large observational study of over 35,000 people, those who used grape seed extract had 41% lower rates of prostate cancer [25].

An even larger sample (over 65,000 subjects) from the same trial revealed that extract users also had 43% lower rates of leukemia (blood cancers) [26].

In many studies on rats and mice, grape seed extract prevented UV-induced skin cancer by blocking oxidative damage and inflammation [27, 28, 29, 30, 31].

Plus, this extract inhibited the growth of many other cancer types in lab animals, such as:

  • Colon cancer (by 44-88%) [32, 33]
  • Lung cancer [34, 35]
  • Prostate cancer (by 50%) [36]
  • Breast cancer [37]
  • Liver cancer [38]

Test tubes have confirmed its ability to kill different types of cancer cells while supporting the healthy ones [39, 40, 41, 42, 43].

Combinations with Standard Treatment

Chemotherapy and radiation as standard cancer treatments are facing challenges such as inadequate efficacy and significant adverse effects [44].

Grape seed extract boosted chemotherapy efficiency in animal and cell studies [45, 46, 47].

At the same time, it relieved side effects caused by chemo and radiation, including [46, 48, 49, 50, 45, 18, 47]:

  • Gut inflammation
  • Testicular damage
  • Kidney damage
  • Impaired immunity
  • Heart failure

In rats exposed to radiation, grape seed extract maintained the levels of crucial antioxidants (GSH, retinol, B-carotene) and prevented lipid peroxidation better than vitamin E [51].

According to preliminary research, grape seed extract may combat different types of cancer and improve standard cancer treatment. Well-designed clinical trials still haven’t confirmed these findings.

4) May Boost Mental Health

In over 100 older patients, supplementation with grape seed extract enhanced cognition and reduced the symptoms of stress and depression [52].

In animal and cell studies, these extracts protected brain cells against oxidative damage and death triggered by different toxins [53, 54, 55].

Alzheimer’s Disease

The National Center for Complementary and Integrative Health supports preliminary research on grape seed extract for Alzheimer’s disease [3].

The culprit of Alzheimer’s disease is age-related cognitive decline caused by protein mutations and free-radical damage in the brain [56].

Polyphenols from grapes and blueberries (600 mg daily for 6 months) relieved cognitive decline and memory loss in 215 older patients. This potent antioxidant mixture showed the same results in mice [57, 58].

Still, the above findings might not translate to pure grape seed extract.

In animal models, grape seed extract lowered the risk of Alzheimer’s disease by [59, 60, 61, 62]:

  • Reducing free-radical damage in the hippocampus (the brain’s memory hub)
  • Raising the levels of antioxidants
  • Preventing protein mutations
  • Boosting the animals’ cognition and memory

5) May Support Wound Healing

In 40 patients recovering from a surgery, grape seed extract 2% cream enhanced wound healing by stimulating VEGF production, blocking oxidative damage, and fighting microbes [63].

It showed the same effect in two animal studies [64, 65].

Grape seed extract ointment (5%) significantly improved wound healing after C-section in a trial of 129 women [66].

Insufficient Evidence:

No valid clinical evidence supports the use of grape seed extract for any of the conditions in this section. Below is a summary of up-to-date animal studies, cell-based research, or low-quality clinical trials which should spark further investigation. However, you shouldn’t interpret them as supportive of any health benefit.

6) Blood Flow and Swelling

In deep vein thrombosis, a blood clot from the legs can get stuck in the lungs and cause a life-threatening condition known as pulmonary embolism [67].

Grape seed extract (400 mg daily for eight weeks) had blood-thinning effects in a study of 17 older women. This effect could potentially lower the risk of blood clots and vein thrombosis, which are much more common in older (postmenopausal) women [68, 69].

In 16 younger women, both acute and two-week supplementation with grape seed extract reduced leg swelling after prolonged sitting [70].

Obviously, both studies had extremely small samples, so they don’t provide decent clinical evidence.

In rats with deep vein thrombosis, the extract prevented the formation of blood clots. It also inhibited blood clotting in many cell-based studies [71, 72, 73, 74, 75].

7) Liver Protection

In 15 patients with fatty liver, grape seed extract dropped liver enzymes and reversed fat buildup. It showed better results than vitamin C. But such a small sample prevents us from drawing firm conclusions from this study [76].

Thanks to its strong antioxidant action, grape seed extract shielded the liver of lab animals from damage caused by:

  • Bile duct obstruction [77, 78]
  • Heavy metals [79, 80]
  • Acetaminophen (Tylenol) [9]
  • Cut blood supply [81]
  • Chemicals [82]

In mice, it outperformed vitamin C, vitamin E, and beta-carotene in protecting the brain and liver against oxidative stress [55].

Aflatoxins are dangerous mold toxins that can wreak havoc on the liver and even cause liver cancer. In studies on chicken, grape seed extract prevented aflatoxin-induced damage [83, 84, 85].

8) Kidney Protection

In a clinical trial of 33 patients with kidney disease, grape seed extract enhanced kidney function by providing antioxidant and anti-inflammatory support. This study had a small sample size and uneven randomization, making the results questionable [86].

In animals, grape seed extract protected the kidneys from toxic drugs and high cholesterol. It worked by [87, 88, 50]:

  • Lowering markers of inflammation (IL-1B, TNF-a, MCP-1)
  • Raising protective molecules (HDL, NO, cGMP)
  • Boosting kidney function (reducing creatinine, urea, and uric acid)
  • Preventing LDL oxidation and its buildup

9) Hair Loss

Grape seeds contain procyanidins – powerful antioxidants that support hair growth. An extract of procyanidins (from Annurca apple) boosted hair growth in a trial on 250 men. Still, this doesn’t mean that grape seed procyanidins would achieve the same [89].

Grape seed extract and isolated procyanidins stimulated the hair follicles and enhanced hair growth in different animal and cell-based studies [90, 91, 92, 93].

10) Weight Loss

Many supplements are promoted to stimulate weight loss, but none of them has yet been supported by strong clinical evidence and approved by the health authorities. A healthy, calorie-controlled diet and increased physical activity remain the only proven strategies for weight control [94].

In 51 overweight patients, grape seed extract slightly reduced food intake but didn’t impact appetite. This study lasted only three days and had a small sample size [95].

In animals on high-fat and high-sugar diets, grape seed extract [96, 97, 98, 99]:

  • Blocked fat buildup and production in the liver
  • Enhanced fat burning
  • Lowered the levels of cholesterol and blood lipids

But one study revealed puzzling results. Low doses of grape seed extract lowered inflammation but increased body fat in pregnant rats and their offspring, when combined with a high-fat diet [100].

Well-designed clinical trials should clear up the conflicting effects of grape seed extract on weight loss and fat burning.

11) Reproductive Health and Testosterone Levels

In male rats, grape seed extract recovered testosterone levels and prevented testicular damage caused by [101, 102, 103, 49, 104]:

  • Chemotherapy and other drugs
  • Injury
  • Toxic chemicals

According to some animal studies, grape seed extract can inhibit an enzyme called aromatase, which converts male sex hormones (androgens) to female sex hormones (estrogens). This effect could, in theory, raise the levels of testosterone and protect against breast cancer [105, 106].

12) Diabetes

In diabetic rats, grape seed extract lowered blood glucose, cholesterol, and lipids while boosting insulin secretion and antioxidant support [107].

The extract had the same effects on animals with insulin resistance caused by a high-sugar diet. It prevented blood glucose spikes and restored antioxidant enzymes such as catalase and SOD [108, 109].

Plus, grape seed extract protected diabetic rats and mice against an array of complications, such as:

  • Heart disease [110, 111, 112]
  • Bladder dysfunction [113]
  • Brain damage [114]
  • Neuropathy (nerve damage) [115]
  • Lung impairment [116]
  • Nephropathy (kidney damage) [117]

13) Joint and Bone Health

In rats and mice with rheumatoid arthritis, grape seed extract improved symptoms and reduced autoimmune joint destruction. It lowered the levels of inflammatory molecules (TNF-a, IL-17, IL-21, ICAM-1) and silenced Th1 and Th17 autoimmune responses [118, 119, 120, 121, 122].

In another study, it protected rats against a different joint disease, osteoarthritis. The extract reduced joint pain and cartilage degradation [123].

Additionally, grape seed extract strengthened the bones and boosted their growth in several rat studies [124, 125, 126, 127].

14) Inflammatory Bowel Disease (IBD)

Widespread autoimmune inflammation and oxidative stress cause severe gut damage in Crohn’s disease and ulcerative colitis, the two main forms of IBD. Dietary antioxidants are being researched as a complementary approach to IBD [128].

In rats and mice with IBD, grape seed extract [129, 130, 131, 132]:

15) Asthma and Allergies

Grape seed extract relieved airway inflammation (IL-4, IL-5, IL-13, iNOS), IgE immune response, and mucus production in asthmatic rats [133, 134, 135].

In test tubes, it inhibited the release of histamine and other inflammatory components from mast cells, which play a central role in allergic response [136].

16) Bacterial Infections

Lipopolysaccharides (LPS) from the cell wall of gram-negative bacteria (Escherichia, Salmonella, Pseudomonas, etc.) can trigger inflammation and cause different symptoms of bacterial infections [137].

Grape seed extract controlled the inflammatory response (NOx, IL-6, iNOS) and boosted glutathione in rats infected with LPS [138].

In LPS-infected blood cells, the extract inhibited inflammatory molecules (such as NF-kB, PGE2, and MMP) [139, 140, 141].

In test tubes, grape seed extract suppressed the growth of [142]:

  • Bacillus cereus (causes diarrhea and foodborne illnesses)
  • Staphylococcus aureus (infects the skin, lungs, and soft tissues)
  • Escherichia coli (triggers UTIs and gut infection)
  • Pseudomonas aeruginosa (causes dangerous infections in hospitals)

It even killed drug-resistant superbugs known as MRSA in one cell experiment [143].

That said, the results of cell-based research don’t reveal much about the actual antibacterial effects in the human body.

Benefits for the Skin

17) UV Protection

Moderate sunbathing is essential for your vitamin D production and overall health and wellbeing. On the other hand, excess UV exposure may cause sunburns and skin damage [144].

The skin of 10 volunteers treated with grape seed extract before UV exposure had fewer mutated and damaged cells and more healthy ones. However, the lack of placebo control and a tiny sample minimize the relevance of this clinical study [145].

The extract also prevented UV-induced skin cancer by blocking oxidative damage and inflammation in many animal trials [27, 28, 29, 30, 31].

18) Anti-Aging

In 12 women, supplementation with grape seed extract (200 mg daily for 6 months) lightened the skin and reduced face spots [146].

Its combination with other antioxidants improved skin complexion in 35 women. They were able to get rid of dark circles, face spots, and other skin imperfections. The majority of women (82%) were satisfied with the results [147].

Likely Ineffective:

Blood Lipids

In a meta-analysis of nine clinical trials with 390 participants, grape seed extract had no effect on blood lipid levels and C-reactive protein (CRP), which indicates inflammation [13].

Grape Seed Extract Side Effects & Safety

Grape seed extract was safe and didn’t cause any notable side effects in clinical trials [12, 52, 86].

Animal safety studies confirmed that it is safe for long-term consumption. It may irritate the skin in rare cases [148, 149, 150].

Grape seeds and other foods rich in polyphenols may hinder iron absorption. To avoid iron deficiency, don’t take grape seed extract supplements with iron-rich foods (meat, legumes, greens). If you do, you can combine it with vitamin C to improve iron absorption [151, 152].

Children and pregnant women may want to avoid grape seed extract because we still lack evidence of its safety in these sensitive groups.

Drug Interactions

Supplement-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let him know about all drugs and supplements you are using or considering.

Although quite safe on its own, grape seed extract may inhibit some liver enzymes (CYP3A4 and CYP1A2) and thus impact the metabolism of certain drugs, such as [153, 154]:

  • Anti-seizure drugs
  • Antidepressants (SSRIs)
  • Antibiotics
  • Antifungal drugs (azoles)

Grape seed extract prevents blood clotting and may thus interfere with blood thinners such as warfarin (Coumadin) [3].

Grape Seed Extract For Dogs

Supplementation with polyphenols from grapes may prevent blood clotting and age-related cognitive decline in dogs [155, 156].

In test tubes, grape seed extract protected the dogs’ eye cells against oxidative stress. It may thus prevent visual impairment in aged dogs [157, 158].

CAUTION: While grape seed extract is safe for dogs, whole grapes and raisins may trigger life-threatening kidney failure [159, 160].

Grape Seed Extract Dosage

The below doses used in clinical trials may not apply to you personally. If your doctor suggests using a grape seed extract supplement, work with them to find the optimal dosage according to your health condition and other factors.

The following doses showed potential benefits in clinical trials:

  • Antioxidant support: 600 mg daily for 5 days [8]
  • Blood pressure and heart disease prevention: 300-2000 mg for 4+ weeks [12, 13, 19]
  • Mental health and cognition: 250 mg daily for 12 weeks [52]
  • Kidney disease: 2000 mg daily for 6 months [86]
  • Skin appearance: 200 mg daily for 6 months [146]

Skin application:

  • Anti-age: 2% GSE cream, 2x daily for 2 months [161]
  • Wound healing: 2% GSE cream, 2x daily for 3 weeks [63]

Grape Seed Extract Supplements

Despite the promising clinical and preclinical research, grape seed extract supplements have not been approved by the FDA for medical use. In general, regulatory bodies aren’t assuring the quality, safety, and efficacy of supplements. Speak with your doctor before supplementing.

Grape seed extract supplements usually contain pills with 120-400 mg of the extract. Bulk powders and liquid grape seed extracts are also available. Some products are standardized to 95% proanthocyanidins.

Cosmetics such as face and eye creams can contain grape seed extract, though grape seed oil is a more common ingredient in skincare.

User Reviews

The opinions expressed in this section are solely from the users who may or may not have medical background. Their reviews do not represent the opinions of SelfHacked. SelfHacked does not endorse any specific product, service, or treatment.

Do not consider user experiences as medical advice. Never delay or disregard seeking professional medical advice from your doctor or another qualified healthcare provider because of something you have read on SelfHacked.

Grape seed extract supplements are very popular; people take them for high blood pressure, varicose veins, swelling, etc. Most user reviews of grape seed extract are positive, though some of them experienced only mild benefits.

Older men report positive results for prostate health and libido while women often use it in skincare. Side effects are not common, and they include mild headache, nausea, and skin irritation.

Here’s what Joe, biohacker and SelfHacked CEO, has to say about grape seed extract:

“I like grape seed extract! It does initially have an immune-stimulating effect, which isn’t great for my overactive Th1-dominant immune system, but it’s good for Th2-dominant people.

So I don’t take it daily, but I think taking a supplement with proanthocyanidins is important, especially for people who don’t get enough antioxidants through their diet.”

Grape Seed Extract FAQ

Does It Contain Resveratrol?

Resveratrol is another antioxidant from grapes with a broad spectrum of potential health benefits. However, grape seed extract is not a good source of resveratrol since most of resveratrol comes from grape skin [162].

Extract vs. Oil vs. Flour

Grape seed extract is a concentrated source of antioxidant proanthocyanidins and has the most potent health effects.

Grape seed oil contains healthy fats, fat-soluble vitamins, and a fraction of antioxidants from the seeds. It shares some health benefits with the extract, but its main uses are in cooking (nutrition) and skincare.

Grape seed flour is a byproduct of oil extraction from the seeds. It contains antioxidants, minerals, fiber, and other nutrients, which makes it a healthy addition to baked goods.

Take-Away

Grape seed extract is an excellent source of antioxidant proanthocyanidins. According to limited clinical evidence, it may lower blood pressure, support the heart and blood vessels, and prevent cognitive decline.

Supplements and creams with grape seed extract may help rejuvenate your skin, remove face spots, and enhance wound healing. The evidence is insufficient when it comes to hair growth, weight loss, liver support, reproductive health, and more.

Overall, it’s a relatively safe supplement for antioxidant protection and general wellbeing. Children and pregnant women should avoid, while others should consult their doctor before supplementing.

Where to Buy

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About the Author

Aleksa Ristic

MS (Pharmacy)
Aleksa received his MS in Pharmacy from the University of Belgrade, his master thesis focusing on protein sources in plant-based diets. 
Aleksa is passionate about herbal pharmacy, nutrition, and functional medicine. He found a way to merge his two biggest passions—writing and health—and use them for noble purposes. His mission is to bridge the gap between science and everyday life, helping readers improve their health and feel better.

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