Grape seed extract (GSE) is a dietary supplement made by removing, drying and pulverizing the bitter-tasting seeds of grapes.
Grape seeds are rich in antioxidants, including phenolic acids, anthocyanins, flavonoids and oligomeric proanthocyanidin complexes (OPCs).
Here are 10 health benefits of grape seed extract, based on science.
1. Can Reduce Blood Pressure
They found that 100–2,000 mg of GSE per day significantly reduced systolic blood pressure (the top number) by an average of 6.08 mmHg and diastolic blood pressure (the bottom number) by 2.8 mmHg.
Those under the age of 50, who were obese or had metabolic disorders showed the greatest improvements.
The most promising results came from lower doses of 100–800 mg daily for 8–16 weeks rather than a single dose of 800 mg or greater.
Another study in 29 adults with high blood pressure found that 300 mg of GSE daily lowered systolic blood pressure by 5.6% and diastolic blood pressure by 4.7% after six weeks.
2. Can Improve Blood Flow
Some studies suggest that GSE may improve blood flow.
In an eight-week study in 17 healthy postmenopausal women, taking 400 mg of GSE had blood-thinning effects, potentially reducing the risk of blood clots.
An additional study in eight healthy young women assessed the effects of a single 400 mg dose of proanthocyanidin from GSE immediately followed by six hours of sitting. It was shown to reduce leg swelling and edema by 70%, compared to not taking GSE.
In the same study, eight more healthy young women, who took a daily dose of 133 mg proanthocyanidins from GSE for 14 days, experienced 40% less leg swelling after six hours of sitting.
3. Could Reduce Oxidative Damage
Elevated blood levels of “bad” LDL cholesterol are a known risk factor for heart disease.
Oxidation of LDL cholesterol significantly increases this risk and plays a central role in atherosclerosis, or the build-up of fatty plaque in your arteries.
GSE supplements have been found to reduce LDL oxidation triggered by high-fat diets in several animal studies.
Some research shows similar results in humans.
When eight healthy people ate a high-at meal, 300 mg of GSE inhibited the oxidation of fats in the blood, compared to a 150% increase seen in those who did not take GSE.
In another study, 61 healthy adults saw a 13.9% reduction in oxidized LDL after taking 400 mg of GSE. However, a similar study was unable to replicate these results.
Additionally, a study in 87 people undergoing heart surgery found that 400 mg of GSE given the day before surgery significantly reduced oxidative stress. Therefore, GSE likely protected against further heart damage.
4. May Improve Collagen and Bone Strength
Increasing flavonoid consumption is proven to improve collagen synthesis and bone formation.
As a rich source of flavonoids, GSE may thus help increase your bone density and strength.
In fact, animal studies have found that adding GSE to either a low-calcium, standard or high-calcium diet can increase bone density, mineral content and bone strength.
Rheumatoid arthritis is an autoimmune condition that results in severe inflammation and destruction of bone and joints.
Animal studies have shown that GSE may suppress bone destruction in inflammatory autoimmune.
GSE also significantly reduced pain, bony spurs and joint damage in osteoarthritic mice, improving collagen and reducing cartilage loss.
Despite promising results from animal research, human studies are lacking.
5. Supports Your Brain as It Ages
Flavonoids are thought to delay or reduce the onset of neurodegenerative diseases like Alzheimer’s disease through a combination of antioxidant and anti-inflammatory properties.
One of the components of GSE is gallic acid, which has been shown to inhibit the formation of fibrils by beta-amyloid peptides in animal and laboratory settings.
Clusters of beta-amyloid proteins in the brain are characteristic of Alzheimer’s disease.
Animal studies have found that GSE may improve brain antioxidant and cognitive status, prevent memory loss and reduce brain lesions and amyloid clusters.
One 12-week study in 111 healthy older adults found that 150 mg of GSE daily improved attention, language and both immediate and delayed memory.
However, human studies on the use of GSE in adults with pre-existing memory or cognitive deficits are lacking.
6. Can Improve Kidney Function
Your kidneys are particularly susceptible to oxidative damage, which is often irreversible.
Animal studies have shown that GSE may reduce kidney damage and improve function by reducing oxidative stress and inflammatory damage.
In one study, 23 people diagnosed with chronic renal failure were given 2 grams of GSE daily for six months and were assessed against a second non-intervention group. Urinary protein decreased by 3% and kidney filtration improved by 9%.
This means that their kidneys were much better able to filter urine than those of the control group.
7. Can Inhibit Infectious Growth
GSE displays promising antibacterial and antifungal properties.
Studies have shown that GSE inhibits the growth of common foodborne bacterial infections, including Campylobacter, E. coli and Shiga toxins — all of which are often responsible for severe food poisoning and abdominal upsets
In the lab, GSE has been found to inhibit 43 strains of antibiotic-resistant Staphylococcus aureus bacteria.
Candida is a common yeast-like fungus that can sometimes result in candida overgrowth, or thrush. GSE is widely used in traditional medicine as a remedy for candida.
Mice infected with vaginal candidiasis were given an intravaginal GSE solution every two days for eight days. The infection was effectively inhibited after five days and gone after eight.
Unfortunately, human studies on the effect of GSE on infectious growth are still lacking.
8. May Reduce Cancer Risk
The causes of cancer are complex, though DNA damage is a central characteristic.
High intake of antioxidants, such as flavonoids and proanthocyanidins, are associated with a reduced risk of various cancers.
The powerful antioxidant activity of GSE has shown potential in inhibiting human breast, lung, gastric, oral squamous cell, liver, prostate and pancreatic cell lines in laboratory settings.
In animal studies, GSE has been shown to enhance the effect of different types of chemotherapy.
GSE appears to protect against oxidative stress and liver toxicity while targeting chemotherapy action on the cancerous cells.
A review of 41 animal studies found that either GSE or proanthocyanidins reduced cancer-induced toxicity and damage in all but one of the studies.
Keep in mind that the anti-cancer and chemopreventive potential of GSE and its proanthocyanidins may not be directly transferable to people with cancer. More studies in humans are needed.
9. May Protect Your Liver
Your liver plays an important role in detoxifying harmful substances introduced to your body through drugs, viral infections, pollutants, alcohol and more.
GSE appears to have a protective effect on your liver.
In test-tube studies, GSE reduced inflammation, recycled antioxidants and protected against free radical damage during toxin exposure.
The liver enzyme alanine aminotransferase (ALT) is a key indicator of liver toxicity, meaning that levels elevate when the liver has sustained damage.
In one study, 15 people with non-alcoholic fatty liver disease and subsequent high ALT levels were given GSE for three months. Liver enzymes were monitored monthly, and results were compared to taking 2 grams of vitamin C per day.
After three months, the GSE group had a 46% reduction in ALT, while the vitamin C group showed little change.
10. Enhances Wound Healing and Appearance
Several animal studies have found GSE can aid wound healing.
Human studies show promise as well.
35 healthy adults who had undergone minor surgery were given either a 2% GSE cream or placebo. Those using the GSE cream had full wound healing after eight days, while the placebo group took 14 days to heal.
These results are most likely due to high proanthocyanidins in GSE triggering the release of growth factors in the skin.
In another 8-week study in 110 healthy young men, a 2% GSE cream improved skin appearance, elasticity and sebum content, which reduces acne and helps your skin look better with aging.
GSE is generally considered safe with few side effects.
Dosages of around 300–800 mg per day for 8–16 weeks have been found safe and well-tolerated in humans.
Those who are pregnant or breastfeeding should avoid it, as there is insufficient data on its effects in these populations.
GSE may lower blood pressure, thin your blood and increase blood flow, so caution is advised for those taking blood-thinning or blood pressure medications.
Furthermore, it may reduce iron absorption, as well as improve liver function and drug metabolism.