Does Watermelon Contain Citrulline? A Complete Nutritional Guide

October 3, 2025 •

4 min read

Watermelon is one of nature's richest dietary sources of the amino acid citrulline, a compound that plays a significant role in promoting cardiovascular health. Whether you are an athlete looking to boost performance or simply curious about the health benefits of this popular fruit, knowing the answer to 'Does watermelon contain citrulline?' is key to maximizing its nutritional value.

Quick Summary

Watermelon is a potent source of the amino acid L-citrulline, a precursor to nitric oxide, which supports blood vessel health and athletic performance. The concentration varies by part, with the rind often containing more. Consuming the fruit or its extracts can enhance circulation, reduce blood pressure, and alleviate muscle soreness.

Key Points

Rich Dietary Source: Watermelon is a primary, natural source of the amino acid L-citrulline, named after the fruit itself.
Rind is High in Citrulline: The white part of the watermelon, known as the rind, often contains a higher concentration of citrulline than the red flesh, especially when analyzed on a dry-weight basis.
Boosts Nitric Oxide: Once consumed, citrulline is converted into L-arginine, which increases the body's production of nitric oxide, a molecule crucial for relaxing and dilating blood vessels.
Supports Cardiovascular Health: Increased nitric oxide can lead to lower blood pressure and improved arterial stiffness, offering significant benefits for cardiovascular health.
Aids Athletic Performance: By improving blood flow and circulation, watermelon-derived citrulline can enhance exercise performance and help reduce muscle soreness post-workout.
Bioavailability Varies: Citrulline from whole watermelon can be more bioavailable than synthetic supplements due to the complex food matrix, though supplements offer more precise dosing.
Factors Influence Content: The amount of citrulline can be affected by the watermelon's variety (yellow vs. red flesh) and ripeness, with concentrations peaking at maturity.

The Clear Answer: Yes, Watermelon is Rich in Citrulline

Yes, watermelon is a natural and prominent source of the non-essential amino acid L-citrulline. In fact, the name citrulline is derived from the Latin word for watermelon, Citrullus vulgaris, from which it was first isolated. In the human body, citrulline is converted into another amino acid, L-arginine. This conversion is a vital step in the body's synthesis of nitric oxide (NO), a potent signaling molecule that helps regulate blood pressure by causing blood vessels to relax and dilate. This fundamental process is why watermelon consumption is linked to several cardiovascular and exercise-related benefits.

The Role of Citrulline in the Body

When you consume citrulline from watermelon, it bypasses metabolism in the liver and is efficiently converted to L-arginine in the kidneys. Because L-citrulline is not broken down as much as L-arginine when initially absorbed, it can be a more effective way to increase the body's L-arginine levels and, consequently, nitric oxide production. This biological pathway contributes to improved blood flow, which in turn benefits organ function, wound healing, and athletic performance.

The Surprising Location of Citrulline in Watermelon

While most people enjoy the sweet, red flesh, the highest concentration of citrulline in watermelon is actually found in the white rind. The distribution and exact concentration can vary based on several factors, including the melon's variety and ripeness, which can lead to some conflicting research findings. Some studies note that while the rind is higher in citrulline on a dry-weight basis, the flesh might contain a higher amount when measured by fresh weight due to its greater water content. For instance, a 2023 study found the highest citrulline concentration in the flesh on a fresh weight basis, but also noted that the rind and skin still offer valuable amounts.

Where to Find the Most Citrulline

Rind: The white part between the green skin and the red flesh contains significant levels of citrulline. Rather than discarding it, the rind can be pickled, juiced, or added to smoothies to boost citrulline intake.
Flesh: While potentially lower in concentration than the rind on a dry-weight basis, the flesh provides a substantial amount of citrulline and is the most commonly consumed part of the fruit.
Seeds: Watermelon seeds also contain some citrulline, but in much smaller quantities compared to the flesh and rind.

Factors Influencing Citrulline Content

The amount of citrulline can vary significantly based on the watermelon's characteristics. Different varieties and flesh colors, for example, have distinct concentrations of citrulline. Research has shown that yellow and orange-fleshed watermelons tend to contain more citrulline than the more common red-fleshed varieties. Environmental factors like drought stress can also influence the accumulation of citrulline in the plant. For human consumption, ripeness also plays a role, with citrulline levels peaking at physiological ripeness.

Health Benefits of Watermelon-Derived Citrulline

Beyond its role in nitric oxide synthesis, the citrulline from watermelon offers several health benefits:

Cardiovascular Health: Increasing nitric oxide levels helps improve blood flow and can lead to a reduction in blood pressure and arterial stiffness, especially in individuals with elevated blood pressure.
Athletic Performance and Muscle Recovery: Improved circulation means more oxygen and nutrients are delivered to muscles. This can lead to enhanced exercise performance and reduced muscle soreness after strenuous workouts.
Erectile Dysfunction: The enhanced circulation provided by nitric oxide production is also thought to help with erectile function.
Antioxidant Properties: Citrulline acts as a hydroxyl radical scavenger, which helps protect cells from oxidative damage.

How to Maximize Your Citrulline Intake

To get the most citrulline from your watermelon, consider consuming the rind in addition to the flesh. Here are some ideas:

Watermelon Rind Juice: Blend the white rind with the red flesh and a squeeze of lime for a refreshing and citrulline-rich drink. Some studies suggest that the complex food matrix of watermelon juice may even improve citrulline bioavailability compared to pure citrulline powder.
Smoothies: Toss chunks of watermelon rind into your next smoothie to boost its nutritional content without significantly altering the flavor.
Pickled Rind: Pickling the rind is a classic way to use this often-discarded part of the fruit and can add a tangy crunch to salads or sandwiches.

Watermelon vs. Citrulline Supplements


Feature	Watermelon Consumption	Citrulline Supplements
Source of Citrulline	Natural food source, comes with other nutrients like lycopene and antioxidants.	Concentrated, isolated form of L-citrulline.
Nutrient Synergy	Benefits from other bioactive compounds, which may enhance bioavailability.	Lack of other co-factors found in the whole fruit.
Dosage Control	More variable, depends on ripeness and variety. Higher volumes needed for significant doses.	Precise dosing is possible. Smaller volume for effective intake.
Practicality	Can be cumbersome to consume the high volume needed for a therapeutic dose.	More convenient for achieving targeted, higher dosages for specific health goals.

Conclusion

In summary, the answer to the question does watermelon contain citrulline? is a resounding yes. Watermelon is a rich and bioavailable dietary source of this beneficial amino acid, particularly when incorporating the often-overlooked white rind. By understanding the factors that influence its content and exploring creative ways to consume the entire fruit, you can unlock the full spectrum of its health benefits, including enhanced cardiovascular function and improved athletic performance. While supplements offer a convenient and concentrated dose, incorporating whole watermelon and its rind into your nutrition diet provides a holistic and flavorful approach to wellness.

For more information, consider exploring studies on the effects of watermelon ingestion on vascular health: https://pmc.ncbi.nlm.nih.gov/articles/PMC9318495/.

Frequently Asked Questions

Citrulline is a non-essential amino acid that is converted to L-arginine in the body, which is a precursor for nitric oxide production. Nitric oxide helps relax and widen blood vessels, promoting healthy blood flow.

The highest concentration of citrulline is typically found in the white rind of the watermelon. While the red flesh also contains a significant amount, incorporating the rind is an excellent way to maximize intake.

Yes, watermelon juice is a good source of citrulline, but its concentration can depend on how it is processed and whether the rind is included. Studies show that using technologies like microencapsulation can preserve citrulline content in juices.

Yes, several studies indicate that consuming watermelon products can help reduce blood pressure and arterial stiffness in individuals with hypertension, particularly when the intake provides a sufficient dose of L-citrulline.

While supplements offer precise dosing, some research suggests that the complex food matrix of whole watermelon may lead to better bioavailability and absorption of citrulline. Choosing between whole food and supplements depends on your specific health goals and dosage requirements.

While watermelon is the richest known dietary source, citrulline is also found in smaller amounts in other cucurbit family members, such as cucumbers and pumpkins. Fermented foods like soy sauce and cocoa pulp also contain some citrulline.