Which Fruit is Rich in Citrulline? The Answer Is Watermelon

November 22, 2025 •

4 min read

According to numerous scientific studies, watermelon is by far the richest and most significant natural plant source of the amino acid L-citrulline. This nutrient, while produced naturally by the human body, is found in exceptionally high concentrations within watermelon, leading to its name derived from the fruit's Latin classification, Citrullus lanatus. Boosting your intake through diet can offer a range of benefits, particularly for cardiovascular health and athletic performance.

Quick Summary

Watermelon is the top dietary source of the amino acid L-citrulline, significantly surpassing other fruits. This non-protein amino acid plays a key role in producing nitric oxide, promoting blood flow, and improving athletic performance. Its concentration varies by watermelon variety and tissue type, including the rind. A daily intake through food or supplements can enhance overall health.

Key Points

Watermelon is the top source: Watermelon contains significantly more citrulline than any other fruit, with its name derived from the fruit's Latin classification.
Rind offers a boost: The white rind of a watermelon contains a high concentration of citrulline and should not be discarded if you aim to maximize your intake.
Supports athletic performance: L-citrulline helps improve blood flow and oxygen delivery to muscles, which can enhance endurance and reduce muscle soreness.
Promotes heart health: By increasing nitric oxide and widening blood vessels, citrulline from watermelon can help lower blood pressure and support cardiovascular function.
Yellow flesh can be higher: Some varieties, particularly yellow-fleshed watermelons, can have an even higher citrulline content compared to their more common red-fleshed counterparts.
Found in other cucurbits: Other members of the gourd family, such as cucumbers, cantaloupe, and pumpkin, also contain citrulline, though in much smaller amounts.

Why Watermelon Is Uniquely High in Citrulline

Watermelon's status as the king of citrulline-rich fruits is well-documented in scientific literature. While many fruits contain trace amounts of this amino acid, none come close to the concentration found in various watermelon parts. The name citrulline itself is a direct nod to its discovery in the watermelon (Citrullus lanatus), highlighting the fruit's historical and biological significance as the primary source. This makes it an especially potent and natural way to boost your body's L-citrulline levels.

The amino acid is not used to build proteins but is crucial for the body's urea cycle, which helps remove harmful substances like ammonia. More importantly, it's a precursor to L-arginine, which the body converts into nitric oxide (NO), a powerful vasodilator. This process relaxes blood vessels, improves circulation, and offers a host of related health benefits.

Factors Influencing Watermelon's Citrulline Content

Not all watermelons are created equal when it comes to their citrulline concentration. Several factors can influence the final amount of this valuable amino acid, including:

Flesh Color: Research suggests that the citrulline content can vary significantly based on the color of the flesh. Yellow-fleshed watermelons have been found to contain higher levels of citrulline compared to red varieties in some studies. For example, one study found yellow watermelon to have 3.5 mg/g of fresh weight, while red flesh had 1 mg/g.
Cultivar and Ripeness: The specific variety of watermelon, known as the cultivar, also plays a role. Certain types, such as 'Crimson Sweet,' have demonstrated particularly high levels. Additionally, citrulline levels tend to peak as the fruit reaches full ripeness.
Rind vs. Flesh: Counterintuitively, the white rind of a watermelon, which is often discarded, contains significant amounts of citrulline, and on a dry weight basis, can have a higher concentration than the red flesh. This makes eating the rind, or at least including some of it when juicing, a smart strategy for maximizing intake.
Growing Conditions: Environmental factors like drought and light intensity can also affect the citrulline content, as the compound is thought to play a role in plant stress tolerance.

Other Cucurbitaceae Fruits Rich in Citrulline

While watermelon is the clear winner, other members of the Cucurbitaceae family contain notable, albeit lower, amounts of citrulline. These include:

Cantaloupe: A popular melon known for its sweetness, cantaloupe contains a moderate amount of citrulline, though far less than watermelon.
Cucumbers: Closely related to melons, cucumbers also provide some citrulline, along with high water content, making them a hydrating option.
Squash: Various types of squash, such as pumpkin and zucchini, are part of the same plant family and contribute to citrulline intake.

How Watermelon's Citrulline Impacts the Body

The citrulline from watermelon is converted to L-arginine in the body, which then fuels the production of nitric oxide (NO). The increase in NO has several physiological effects:

Vasodilation and Blood Pressure: NO signals the smooth muscle cells surrounding blood vessels to relax, causing them to widen. This vasodilation improves blood flow and can help lower blood pressure, especially in individuals with hypertension.
Improved Athletic Performance: Enhanced blood flow means more oxygen and nutrients are delivered to working muscles during exercise. This has been linked to improved endurance, reduced muscle soreness, and better overall performance in strength training and aerobic activities.
Heart Health: By improving circulation and reducing blood pressure, citrulline supports overall cardiovascular health and reduces strain on the heart.

Comparing Citrulline Sources: Watermelon vs. Other Fruits


Feature	Watermelon	Cantaloupe	Cucumbers	Pumpkin/Squash
Citrulline Content (Fresh Weight)	Highest (varies by variety)	Lower	Lower	Varies (Generally low)
Best Part for Citrulline	Flesh and Rind	Flesh	Flesh	Flesh (Seeds have less)
Associated Nutrients	Lycopene, Vitamin C	Potassium, Vitamin C	High Water Content	Beta-carotene, Vitamin A
Versatility	Smoothies, salads, juice, fresh	Salads, fresh, desserts	Salads, pickled, fresh	Cooked dishes, smoothies
Impact on Nitric Oxide	Significant boost (via L-arginine)	Minor contribution	Minor contribution	Minor contribution

Conclusion

When searching for the fruit richest in citrulline, the answer is definitively watermelon. Its high concentration of this amino acid, combined with other beneficial nutrients like lycopene and vitamin C, makes it an excellent dietary choice for supporting cardiovascular health, improving athletic performance, and aiding the body's natural detoxification processes. While other fruits like cantaloupe and cucumbers also contain citrulline, their levels are significantly lower. To maximize your intake, don't just eat the red flesh; including some of the nutrient-rich white rind is a smart and easy strategy. By incorporating watermelon into your diet, you can naturally and effectively harness the power of citrulline for improved blood flow and overall well-being. For even greater benefits, consider consuming watermelon juice or powder, or talk to a healthcare provider about supplements, though a food-first approach is often recommended. Outbound link: For more nutritional information on amino acids, you can refer to authoritative sources like the National Center for Biotechnology Information (NCBI).

Frequently Asked Questions

Citrulline is a non-essential amino acid that plays a vital role in the urea cycle, helping the body eliminate harmful ammonia. More notably, it is a precursor to L-arginine, which the body uses to produce nitric oxide (NO) for improved blood flow and cardiovascular health.

While it can vary by cultivar and ripeness, some studies have shown that yellow and orange-fleshed watermelons, on a dry weight basis, can contain higher levels of citrulline than red-fleshed varieties.

Yes, watermelon rind contains a high amount of citrulline. On a dry weight basis, some studies suggest the rind has more citrulline than the flesh, making it a valuable source often overlooked.

Besides eating watermelon and its rind, you can also consume other cucurbit fruits like cucumbers, cantaloupe, and squash, though their citrulline content is much lower. Many people opt for L-citrulline supplements for more concentrated doses.

The bioavailability of citrulline is often higher when consumed from a food matrix like watermelon rather than as a pure compound. However, supplements offer a more concentrated and controlled dose, which can be important for targeted benefits like athletic performance.

Yes, studies have shown that citrulline from watermelon, particularly in concentrated forms like extract or powder, can help lower blood pressure in individuals with pre-hypertension and hypertension by promoting vasodilation.

According to research, the citrulline content in seedless watermelons is comparable to or slightly higher than seeded types on a dry weight basis, though it is slightly less on a fresh weight basis due to higher moisture content.