What Fruit Has the Most L-Citrulline?

November 2, 2025 •

4 min read

Multiple studies confirm that watermelon is the most significant natural plant source of the amino acid L-citrulline, surpassing all other fruits and vegetables tested. While L-citrulline is present in other cucurbits like cucumbers and melons, its concentration is highest in this popular summer fruit, particularly within the rind.

Quick Summary

Watermelon contains the highest concentration of L-citrulline among all fruits, with especially high levels found in the rind. The body converts L-citrulline into L-arginine, boosting nitric oxide production for improved blood flow, cardiovascular health, and exercise performance.

Key Points

Watermelon is the richest fruit source: L-citrulline was first identified in watermelon and this fruit contains the highest concentration among all natural plant sources.
The rind is the most potent part: While the flesh contains significant amounts, the white rind of a watermelon has been found to have a higher concentration of L-citrulline.
L-citrulline boosts nitric oxide: In the body, L-citrulline is converted to L-arginine, which increases nitric oxide levels and promotes vasodilation, or the widening of blood vessels.
Improves athletic performance: The increased blood flow from L-citrulline can reduce fatigue, improve oxygen delivery to muscles, and support enhanced endurance.
Supports cardiovascular health: The vasodilating effect helps regulate blood pressure, making L-citrulline beneficial for heart health.
Other fruits contain less: Although other cucurbits like casaba melon, cucumbers, and squash contain some L-citrulline, their levels are significantly lower than in watermelon.
Absorption is key: The bioavailability of L-citrulline from natural sources like watermelon may be superior to synthetic supplements due to the presence of other compounds in the fruit.

Watermelon: The Champion of L-Citrulline

Watermelon's status as the top source of L-citrulline is so prominent that the amino acid's name is derived from the fruit's scientific name, Citrullus lanatus. This non-protein amino acid is vital for the production of nitric oxide, a molecule that helps relax and widen blood vessels, promoting better circulation throughout the body. This effect can lead to a number of health benefits, from improved cardiovascular function to enhanced athletic performance. While the juicy red flesh is delicious, research shows that the white rind contains an even higher concentration of L-citrulline, making it a valuable, though often discarded, part of the fruit.

The Role of L-Citrulline in the Body

The benefits of consuming L-citrulline are linked to its conversion into L-arginine within the kidneys. L-arginine is the primary substrate for nitric oxide synthesis, and studies show that taking L-citrulline can be more effective at increasing plasma L-arginine levels than taking L-arginine itself. This is because L-citrulline bypasses the liver's metabolism, allowing more of it to reach the kidneys for efficient conversion. This process is critical for several bodily functions:

Enhancing Blood Flow: Increased nitric oxide levels lead to vasodilation, which improves blood flow to tissues and organs. This can have widespread effects on overall health.
Boosting Exercise Performance: Better blood flow delivers more oxygen and nutrients to muscles, which can reduce fatigue and improve endurance. Some studies suggest that L-citrulline also helps the body clear ammonia, a compound that builds up during intense exercise.
Supporting Heart Health: The vasodilating effects of L-citrulline can help lower blood pressure in individuals with pre-hypertension or hypertension. This effect helps reduce the strain on the cardiovascular system.
Aiding Erectile Function: The improved blood flow caused by increased nitric oxide production can also benefit erectile function.

Comparison of L-Citrulline Content in Fruits

While watermelon is the clear winner, other fruits in the Cucurbitaceae family contain lower but still notable amounts of L-citrulline. The table below illustrates the approximate difference in fresh weight concentration, although levels can vary based on factors like cultivar and ripeness.


Fruit/Part	Approximate L-Citrulline Content (g/kg fresh weight)	Key Takeaway
Watermelon (Flesh)	~1.5 mg/g, ranging widely	A significant source, readily consumed.
Watermelon (Rind)	Often higher than the flesh; up to 1.2 mg/g dry weight in one study.	More concentrated in the white part, often discarded but can be juiced or pickled.
Casaba Melon	0.86 g/kg	A decent source among other melons.
Mouse Melon	0.64 g/kg	A small but interesting contributor to L-citrulline intake.
Horned Melon (Rind)	0.45 g/kg	The rind is the most concentrated part.
Cantaloupe	~0.16 g/kg - 0.86 g/kg	A lower but still present amount compared to watermelon.
Cucumber	Considerably less than watermelon	Provides a small amount of L-citrulline.

Maximizing Your L-Citrulline Intake

To get the most L-citrulline from food, focus on consuming watermelon, particularly the rind. The rind can be processed into a juice, which is more concentrated, or pickled for consumption. Using concentrated watermelon powder or supplements is also an option for those aiming for a specific dose, as eating enough fresh watermelon to reach high supplement-level dosages can be challenging.

For general health and a moderate boost, a daily serving of fresh watermelon is an excellent choice. Studies have found that factors like the specific cultivar, ripeness, and even growing conditions can influence L-citrulline content, so levels will naturally vary. For example, yellow-fleshed watermelons might have higher concentrations than red ones on a dry weight basis. For a significant boost to support athletic performance, supplements may be more practical.

Conclusion

When it comes to fruit, watermelon is the unequivocal winner for L-citrulline content, far surpassing its closest competitors in the gourd family. Its high concentration of this beneficial amino acid, particularly in the white rind, makes it a potent natural source for supporting cardiovascular health, improving blood flow, and enhancing athletic endurance. While other fruits like casaba and mouse melons offer smaller amounts, integrating watermelon, and potentially its rind, into your diet is the most effective way to naturally increase your L-citrulline intake.

Natural Citrulline Absorption

One of the unique benefits of getting L-citrulline from watermelon is its bioavailability. The matrix of the fruit may aid in better absorption than synthetic supplements. Research suggests that L-citrulline from unpasteurized watermelon juice has better intestinal absorption than a pure L-citrulline standard. This indicates that the other compounds present in the fruit likely enhance the absorption and beneficial effects of L-citrulline. For those seeking to boost their intake, consuming whole or juiced watermelon is a natural and effective strategy. https://www.mdpi.com/2076-3417/13/8/4882

Frequently Asked Questions

Studies show that the white rind of the watermelon often contains a higher concentration of L-citrulline than the pink or red flesh.

While watermelon provides a good dose, achieving the high levels used in sports supplement studies (up to 15g) by eating fresh fruit alone is challenging and often requires consuming very large quantities.

Other foods in the Cucurbitaceae family contain L-citrulline, including cucumbers, squash, pumpkins, and other melons like cantaloupe and casaba. However, their concentration is much lower than in watermelon.

Supplements can deliver higher, more concentrated doses of L-citrulline, which is often more practical for achieving specific performance or health goals. However, consuming L-citrulline from watermelon offers the benefit of the fruit's natural matrix, which may enhance bioavailability and provides other beneficial nutrients.

Research indicates that L-citrulline content can vary by flesh color. Some studies suggest that yellow or orange-fleshed watermelons may contain more L-citrulline than red-fleshed varieties on a dry weight basis.

The body converts L-citrulline into L-arginine, which then helps produce nitric oxide (NO). NO signals blood vessels to relax and widen, leading to improved circulation.

L-citrulline is generally recognized as safe, especially from food sources. Side effects from supplements are rare, but high doses can cause some gastrointestinal discomfort. It's always best to consult a doctor, especially if you have pre-existing health conditions or take blood pressure medications.