Watermelon: The Best Natural Source of L-Citrulline

November 22, 2025 •

3 min read

According to scientific research, the amino acid L-citrulline derives its name from the Latin word for watermelon, Citrullus, a testament to this fruit being its most abundant natural source. This article explores why watermelon stands out, delves into other dietary sources, and explains the benefits of this powerful compound for the body.

Quick Summary

Watermelon is the richest natural source of L-citrulline, an amino acid with significant health benefits. The body converts L-citrulline into L-arginine and nitric oxide, which helps relax blood vessels to improve circulation and support heart health and athletic performance. Lesser amounts are found in other cucurbit family plants.

Key Points

Watermelon is King: Watermelon is confirmed by research to be the richest natural source of L-citrulline, particularly in the rind.
Enhanced Bioavailability: L-citrulline from whole-food sources like watermelon may be more bioavailable and have better absorption than synthetic L-arginine supplements.
Nitric Oxide Precursor: L-citrulline converts to L-arginine and then to nitric oxide, a compound that helps relax blood vessels and improve circulation.
Support for Performance and Health: Increased L-citrulline intake can support better athletic performance, cardiovascular health, and even help with mild erectile dysfunction.
Other Sources Exist: While less potent, other cucurbits such as cucumbers, pumpkin, and various melons also contain L-citrulline.
Don't Discard the Rind: For maximum intake, consuming the watermelon rind, which has higher concentrations, is a key strategy.

Watermelon: The Unequaled Champion of L-Citrulline

Watermelon is widely recognized as the single best natural food source of L-citrulline. Belonging to the Cucurbitaceae family, alongside cucumbers and squash, watermelon's concentration of L-citrulline significantly surpasses its relatives. Studies show red-fleshed watermelons contain 40-160 mg of L-citrulline per 100g, while the rind can reach 60-500 mg per 100g. The body absorbs L-citrulline from watermelon more effectively for L-arginine conversion than direct L-arginine supplements, making it a potent way to boost nitric oxide synthesis.

The Role of L-Citrulline in the Body

L-citrulline, a non-essential amino acid produced by the body, can be significantly boosted by dietary intake. It's crucial for the urea cycle, removing ammonia, and is a key precursor to nitric oxide (NO). NO is a vasodilator, relaxing blood vessels and improving blood flow, which offers several health benefits:

Enhanced Exercise Performance: Improves blood flow and oxygen delivery to muscles, potentially reducing fatigue and improving endurance.
Cardiovascular Health: Helps lower blood pressure by relaxing blood vessels.
Improved Recovery: Aids muscle recovery after exercise by buffering ammonia and increasing blood flow.
Sexual Health: Can be beneficial for men with mild erectile dysfunction due to enhanced blood flow.

Comparison of L-Citrulline Sources


Source	L-Citrulline Content (approx.)	Typical Serving Size	Pros	Cons
Watermelon Flesh	40-160 mg per 100g	1 cup (154g)	Readily available, high water content, good taste	Lower concentration than rind, requires large volume for high doses
Watermelon Rind	60-500 mg per 100g	Small amounts blended or pickled	Higher concentration, often discarded	Less palatable, not easily consumed in large quantities
Cucumber	Lower levels than watermelon	1 cup (104g)	Easily incorporated into salads and meals	Requires significant intake for meaningful citrulline boost
Pumpkin	Moderate levels, variable by variety	1 cup, cooked	Versatile ingredient	Requires larger servings for effect compared to watermelon
Citrulline Supplement	Standardized dose, e.g., 6-8g	Varies by product	Concentrated and convenient	Less bioavailable than whole-food sources, risk of low-quality products

Maximizing Your Natural L-Citrulline Intake

Beyond watermelon, incorporating other Cucurbitaceae can boost intake. Strategies include:

Eating the rind: The rind has higher L-citrulline and can be pickled, juiced, or blended.
Blending juice: Watermelon juice, including rind, offers a concentrated dose.
Other melons and gourds: Cucumbers, cantaloupe, and squash contribute to overall intake.
Consider combinations: Some research suggests combining L-citrulline with glutathione may enhance vasodilation. Consult a healthcare provider before adding supplements.

Conclusion: The Clear Winner is Watermelon

Watermelon is definitively the best natural source of L-citrulline. Its high concentration, particularly in the rind, makes it an excellent food for boosting nitric oxide. While other cucurbit family members contribute, their levels are lower. For those seeking to improve blood flow for performance or cardiovascular health, increasing watermelon intake is a highly effective dietary strategy.

: https://examine.com/supplements/citrulline/research/

Harnessing the Power of a Natural Amino Acid

Studies highlight the therapeutic potential of L-citrulline, especially from whole foods like watermelon, which may enhance bioavailability. Benefits extend to cardiometabolic health, suggesting broad applications for regular intake. Prioritizing natural food sources allows for safe and effective L-citrulline increase, potentially improving blood vessel function and well-being.

Frequently Asked Questions

The best food for L-citrulline is watermelon. Its flesh, and especially its rind, contain the highest concentrations of this amino acid compared to any other natural source.

Yes, watermelon rind contains a high concentration of L-citrulline, often in amounts higher than the red flesh itself. This makes it a valuable, though often discarded, source of the amino acid.

Increasing your L-citrulline intake can improve blood flow, support heart health by lowering blood pressure, reduce muscle soreness, and enhance athletic performance, particularly for endurance and recovery.

L-citrulline is converted into L-arginine in the kidneys, which then produces nitric oxide (NO). NO is a vasodilator, a compound that relaxes and widens blood vessels, thereby improving circulation throughout the body.

Yes, other members of the Cucurbitaceae family, including cucumbers, squash, and pumpkins, contain L-citrulline, but in much lower concentrations than watermelon.

While supplements offer a concentrated dose, studies suggest that L-citrulline from natural sources like watermelon may be more bioavailable and effectively utilized by the body.

Watermelon juice is an excellent source of L-citrulline. The juice from the flesh and rind can be blended for a concentrated, easy-to-consume dose.