Grape Seed Extract and Testosterone: Enhance Nitric Oxide

By Ali Kuoppala | Last reviewed Tue 25 September 2018

Medical Review by Gerardo Sison, PharmD

Grapes are one of the most beneficial foods for men’s health. That’s because they’re rich in antioxidants and polyphenols, such as the testosterone boosting and estrogen blocking resveratrol. This post is about grape seed extract and testosterone.

Not to mention that the skin is filled with Calcium-D-Glucarate, a fiber that binds into estrogen molecules making the clearance process easier…

So grapes are great.

But aside from the actual grape, the seeds also pack in some testosterone boosting phytonutrients:

How Grape Seeds Can Boost Your Testosterone Levels

grape seed extractGrape seeds, or high potency grape seed extract, as said above, can be used to boost testosterone levels.

That’s because 2 molecules hidden in the seeds – proanthocyanidin and procyanidin – can both effectively block the conversion from testosterone to estrogen via inhibiting the aromatase enzyme.

Being structurally similar to pycnogenol (nitric oxide boosting compound in maritime pine bark) proanthocyanidin and procyanidin both also enhance circulation and nitric oxide production in the body.

So grape seeds should lower your estrogen levels, increase testosterone levels, and improve your blood flow.

Here’s some science to back up the claims above:

a) The researchers in this study found out that grape seed extract was able to inhibit aromatase enzyme in a dose-dependent manner via competitive and reversible inhibition.

b) Similar results were seen in this study where the researchers concluded that grape seed extract blocked estrogen synthesis by inhibiting the aromatase enzyme.

c) The estrogen-blocking mechanism was confirmed in-vivo when the researchers in this study saw that grape seed extract blocked aromatase expression in animal-model.

d) This study found out that in rats 100 mg/kg of grape seed extract was enough to increase nitric oxide (a molecule that widens blood vessels) by 125,6% in rest and 138,3% after exercise. The mechanism of action was confirmed in this study, the grape seed extract works by stimulating the enzyme system that releases nitric oxide.

e) Multiple human studies have reached similar conclusions; grape seed extract increases nitric oxide production and improves blood flow. This, in turn, lowers blood pressure, heart rate, leg swelling, and cardiovascular risk (study, study, study, study, study).

f) The researchers in this study saw that grape seed extract may protect testosterone molecules from toxin and alcohol-induced testicular damage.

According to the research, grape seed consumption would be pretty damn beneficial for us guys…

…However, by eating grapes alone, you can’t get enough proanthocyanidin and procyanidin into your system for them to have any noticeable effects. That’s because of the studies above used dosages equal to about 2 grams of the active ingredients, which equals a massive amount of grapes consumed.

To reap the full benefits from proanthocyanidin and procyanidin you can supplement with grape seed extract.

Piperine can also be used to supercharge the absorption, and grape seed extract can be stacked with L-citrulline to furthermore increase the nitric oxide release.

Grape seed extract should also be taken on an empty stomach, as this study saw that the proanthocyanidin/procyanidin content in the bloodstream was roughly 5 times greater in a fasted state than in a fed state.

Interesting Peripheral Benefits Of Grape Seed Extract

GSE isn’t just great for your hormonal health, but it also appears to benefit other areas of your health, like your gut, kidneys, pancreas, and colon. It even has some compelling research around its ability to tighten the skin, benefiting skin quality around the face and eyes, as well as hands.

Grape Seed Extract and Stomach Ulcers

One 2011 study analyzed GSE, Vitamin E, and Vitamin C in relation to their effect on stomach ulcers. GSE was more effective than Vitamin E (but less effective than the almighty Vitamin C) in stopping stomach ulcer formation induced by Aspirin.

This is good news for those of you who regularly take NSAIDs, as they are notorious for causing ulcers. Most people don’t know this, but Chris actually had 3 stomach ulcers from NSAID pain relievers in his late teens. GSE is a good preventative measure to take if you need to consume NSAIDs for whatever reason.

Grape Seed Extract and Kidneys

This study found that GSE at a dosage of 100mg/kg provides the most potent protective effect against all metabolic stressors on the kidneys. The researchers also noticed better structural health of the kidney, including tubules in the GSE supplemented group.

Grape Seed Extract and the Pancreas

It appears that in humans, supplementation of GSE can also protect the pancreatic secretion of insulin, which is obviously extremely important in preserving insulin sensitivity in men and women, playing into not just general hormonal health but also obesity, fat gain, and ability to utilize carbohydrate properly for ATP production in the cells.


Grape seeds have a good amount of research backing up their use as a nitric oxide booster and estrogen blocker. However, to get any noticeable benefits from the seeds, supplementation with strong extract is needed.

To enhance the bio-availability and nitric oxide boosting effects of the grape seed extract use piperine and L-citrulline in combination with it.

Ali Kuoppala

Ali Kuoppala is the founder of Anabolic Men. He has authored and co-authored multiple men's health books and focuses on uncovering the methods of optimizing hormonal health. To date, his articles on various websites have been read more than 15-million times. To read more about Ali, visit his Medium article.