Is Cucumber High in L-Citrulline?

November 3, 2025 •

3 min read

Watermelon is known as a top source of L-citrulline. Research confirms cucumbers also contain this amino acid. However, the key question is if the amount of L-citrulline in cucumber is enough to offer notable health benefits.

Quick Summary

Cucumber contains L-citrulline, but in lower concentrations than watermelon. This amino acid enhances blood flow and athletic performance. For higher intake, consider different sources or supplements.

Key Points

Moderate Content: Cucumber contains L-citrulline, but in much lower concentrations compared to watermelon.
Health Benefits: L-citrulline supports blood flow by producing nitric oxide, potentially benefiting cardiovascular health and athletic performance.
Watermelon is Superior: As the most potent natural source, watermelon provides a far higher dose of L-citrulline than cucumber.
Bioavailability: L-citrulline from food is highly bioavailable, as it bypasses liver metabolism for more efficient conversion to L-arginine.
Dietary Strategy: To increase L-citrulline, focus on watermelon and combine various cucurbits, rather than relying solely on cucumber.

Understanding L-Citrulline

L-citrulline is a non-essential amino acid, meaning the body produces it naturally. It's crucial in the urea cycle, which removes harmful ammonia. L-citrulline is a precursor to L-arginine. This conversion is vital because L-arginine produces nitric oxide (NO), a vasodilator that relaxes and widens blood vessels. Increased nitric oxide can lead to better blood flow, potentially benefiting cardiovascular health and athletic performance.

The Cucurbitaceae Connection

Cucumbers are in the Cucurbitaceae family, or gourd family. This includes watermelon, squash, and pumpkin. L-citrulline is common throughout this family, which is why cucumber and watermelon share this component.

Comparing Cucumber and Watermelon Citrulline Content

Cucumber contains L-citrulline, but not as much as watermelon. Several studies highlight this difference:

Watermelon: Regarded as the main dietary source of L-citrulline. Some varieties have higher amounts. Some red-fleshed watermelons contained over 2.85 g/kg of citrulline. The name "citrulline" comes from the Latin word for watermelon, Citrullus, highlighting its reputation as the top source.
Cucumber: Contains L-citrulline, but at much lower levels. Research found cucumbers had approximately 10 times less citrulline than watermelon. One study detected levels in fresh pickling cucumbers at around 110.3 mg/kg. Citrulline content can vary based on the vegetable and growing conditions, with cucumbers containing a range of 0.65 to 19.41 mg/100g, while watermelon ranged from 3.16 to 3.79 mg/100g.

Bioavailability of L-Citrulline from Food Sources

L-citrulline from food is often more bioavailable than L-arginine as a supplement. This is because L-citrulline bypasses breakdown in the liver before being converted to L-arginine in the kidneys. Consuming large quantities of a food with lower concentrations, like cucumber, is necessary to achieve a significant effect compared to a highly concentrated source like watermelon.

Health Benefits of Dietary L-Citrulline

Boosting L-citrulline intake has several health benefits, mainly from enhancing nitric oxide production:

Improved Blood Flow: L-citrulline increases nitric oxide, which helps relax and widen blood vessels, promoting better circulation.
Cardiovascular Health: Enhanced blood flow can support cardiovascular function and may help manage blood pressure.
Athletic Performance and Recovery: Higher nitric oxide levels can deliver more oxygen and nutrients to muscles during exercise, reducing fatigue and improving endurance. It may also aid in post-exercise recovery.
Erectile Dysfunction: Due to its impact on circulation and blood flow, L-citrulline may help ease symptoms of mild-to-moderate erectile dysfunction.

Comparison of L-Citrulline Food Sources


Food Source	L-Citrulline Concentration	Primary Takeaway
Watermelon (Red Flesh)	High (e.g., 2.85 g/kg fresh weight)	The most significant dietary source of L-citrulline.
Cucumber	Low (e.g., 110.3 mg/kg fresh weight)	Contains L-citrulline but in much lower concentrations than watermelon.
Pumpkin	Low	Similar to cucumber, contains trace amounts of L-citrulline.
Squash & Gourds	Variable, generally low	Part of the same family and contains L-citrulline in varying, but typically modest, amounts.
Nuts & Chickpeas	Contain L-citrulline	Offer L-citrulline along with a broader nutritional profile, though content varies.

Maximizing L-Citrulline Intake Naturally

Cucumbers have lower L-citrulline content. To maximize natural L-citrulline intake, include a variety of sources in your diet:

Consume the Best Source: Watermelon is the best source for L-citrulline. Eating the fruit or drinking its juice is effective.
Diversify Your Diet: Incorporate cucurbits like muskmelon and pumpkin, as well as other foods like nuts and dark chocolate, which also contain L-citrulline.
Don't Discard the Rind: In watermelon, the highest concentration of L-citrulline is often found in the rind. It can be juiced or pickled.
Combine Foods for Synergy: Eating L-citrulline-rich foods with L-arginine sources may improve absorption and effect.

Conclusion

Cucumber contains L-citrulline, but it is not a high source compared to watermelon. As part of the Cucurbitaceae family, it naturally contains the compound. For individuals seeking to significantly increase their L-citrulline intake, watermelon is superior. However, cucumber can be a beneficial part of a healthy diet, providing hydration and other essential vitamins and minerals. Dietary sources alone, including cucumber, may not be sufficient for therapeutic levels of L-citrulline, and supplementation might be necessary under a healthcare provider's guidance.

Authoritative outbound link: Read more about the health benefits of L-citrulline on WebMD

Frequently Asked Questions

No, L-citrulline is also found in other members of the gourd family (Cucurbitaceae) like pumpkin and squash, as well as in smaller amounts in nuts, chickpeas, and bitter melon.

The primary benefit of consuming L-citrulline is its ability to be converted into L-arginine in the body, which then increases nitric oxide production. Nitric oxide helps relax and widen blood vessels, improving blood flow.

For a noticeable effect, a very large amount of cucumber would be needed due to its low concentration of L-citrulline. It is far more efficient to consume watermelon or consider a balanced diet including multiple sources.

Research indicates that some nutrients, including certain phytochemicals, may be more concentrated in the peel of cucurbits. While L-citrulline is present throughout, eating the peel will maximize your nutritional intake.

For many, dietary sources of L-citrulline are sufficient. However, for those seeking a specific therapeutic effect or significant performance boost, the concentration from food, including cucumber, may not be high enough, and supplementation might be more appropriate.

By increasing nitric oxide production, L-citrulline can help widen blood vessels, which may lead to a reduction in blood pressure. Some studies suggest it can lower both systolic and diastolic blood pressure.

Yes, studies have shown that L-citrulline is present in both fresh and fermented cucumber. However, the fermentation process can alter the free amino acid profile, and concentrations may differ from fresh cucumber.