Which is the Best Source of Nitric Oxide?

November 5, 2025 •

4 min read

According to a 2022 review, consuming a single dose of beetroot juice can elevate nitric oxide levels in the body by over 20% in as little as 45 minutes. When considering which is the best source of nitric oxide, the answer depends on your specific goals, lifestyle, and overall health.

Quick Summary

The most effective sources of nitric oxide include nitrate-rich foods, especially beetroot and leafy greens, and amino acid supplements like L-citrulline. Exercise also significantly boosts natural nitric oxide production. The ideal method depends on individual needs and goals, such as immediate performance enhancement or long-term health benefits.

Key Points

Dietary Nitrates: Foods like beetroot juice and leafy greens are powerful sources of nitrates, which the body converts into nitric oxide for rapid vascular effects.
L-Citrulline Supplementation: This amino acid is more effective than L-arginine for raising blood arginine levels and boosting nitric oxide, as it avoids extensive breakdown in the gut and liver.
Regular Exercise: Physical activity, especially cardiovascular and HIIT training, stimulates the natural release of nitric oxide from the blood vessel lining, improving blood flow and endurance.
L-Arginine Ineffectiveness: As a supplement, L-arginine has low bioavailability, meaning much of it is broken down before it can significantly increase nitric oxide levels, unlike L-citrulline.
Antioxidant Support: Antioxidant-rich foods such as citrus fruits, dark chocolate, and pomegranates help protect nitric oxide from breaking down, increasing its overall effect.
Holistic Approach: The safest and most effective long-term strategy involves combining a diet rich in whole foods, regular exercise, and potentially targeted supplementation with L-citrulline under medical supervision.

Understanding How Nitric Oxide is Produced

Nitric oxide (NO) is a crucial signaling molecule produced naturally in the body, vital for vasodilation, which relaxes and widens blood vessels to promote healthy blood flow. This process is essential for regulating blood pressure, delivering oxygen and nutrients to muscles, and supporting cardiovascular health. The body produces nitric oxide through two main pathways:

The L-arginine pathway: The enzyme nitric oxide synthase (NOS) converts the amino acid L-arginine into nitric oxide.
The nitrate-nitrite-NO pathway: Found in plant-based foods, dietary nitrate is first converted to nitrite by bacteria in the mouth and then further reduced to nitric oxide in the body, especially in conditions of low oxygen.

Natural Food Sources of Nitric Oxide

For most people, a well-rounded diet rich in specific whole foods is the safest and most sustainable way to increase nitric oxide levels naturally. Many vegetables, fruits, and other foods contain the nitrates, antioxidants, or amino acids necessary for the body's own production of this molecule.

Nitrate-Rich Vegetables

Leafy greens and root vegetables are the superstars of nitric oxide production, primarily relying on the nitrate-nitrite-NO pathway. Studies show that a nitrate-rich diet can significantly increase nitrate levels in both blood and tissues.

Beets and beetroot juice: Renowned for their high nitrate content, beets are a top choice. A 2017 review on beetroot juice supplementation highlighted its effectiveness, particularly in athletes, for improving cardiorespiratory endurance.
Arugula: Containing one of the highest levels of nitrates, arugula is a potent source for boosting NO.
Spinach: This leafy green is packed with nitrates and supports the conversion process effectively.
Garlic: Studies indicate that garlic can activate nitric oxide synthase, the enzyme responsible for converting L-arginine to NO.

Amino Acid-Rich Foods

These foods provide the building blocks, like L-arginine and L-citrulline, for the body to synthesize its own nitric oxide.

Watermelon: Watermelon is a key source of L-citrulline. This amino acid is efficiently converted to L-arginine in the kidneys, leading to a sustained rise in NO.
Nuts and Seeds: Almonds, walnuts, and sunflower seeds contain L-arginine and other nutrients that support nitric oxide levels.
Meat, Poultry, and Seafood: These are excellent sources of Coenzyme Q10 (CoQ10), which helps preserve nitric oxide in the body.

Antioxidant-Rich Foods

Antioxidants are crucial for protecting nitric oxide from breakdown by free radicals, ensuring its bioavailability in the body.

Dark Chocolate: Rich in flavanols, dark chocolate helps stabilize NO levels and promotes heart health.
Pomegranates: Loaded with antioxidants, pomegranate juice helps protect nitric oxide from oxidative damage.
Citrus Fruits: Vitamin C, abundant in citrus fruits like oranges and grapefruit, can enhance nitric oxide's bioavailability.

Exercise as a Natural Booster

Beyond diet, exercise is one of the most effective and natural ways to boost nitric oxide production. Physical activity triggers the endothelium, the inner lining of blood vessels, to release nitric oxide. This improves blood flow and enhances oxygen delivery to working muscles, improving exercise performance and speeding up recovery. Both cardiovascular and strength training activities are beneficial.

Supplements vs. Whole Foods: A Comparison

While a diet rich in whole foods is the safest long-term strategy, supplements offer a concentrated dose for specific needs, such as athletic performance.


Feature	Nitrate-Rich Foods (e.g., Beets)	Amino Acid Supplements (L-Citrulline)
Mechanism	Converts dietary nitrates via the nitrate-nitrite-NO pathway.	L-citrulline converts to L-arginine, which then produces NO.
Speed of Action	Can be fast-acting (e.g., beetroot juice showing effects in 45-90 minutes).	L-citrulline is highly bioavailable and raises blood arginine levels more effectively than L-arginine supplements.
Side Effects	Generally minimal to none. High consumption may stain urine and feces red.	Higher doses of L-arginine can cause gastrointestinal distress; L-citrulline is generally better tolerated.
Added Nutrients	Provides a host of complementary nutrients, fiber, and antioxidants.	Offers a concentrated dose of a single or specific blend of amino acids.
Cost	Typically more affordable and part of a normal grocery budget.	Can be more expensive than dietary sources, with costs varying by brand and quality.
Consistency	The nitrate content in foods can vary, requiring attention to sourcing.	Standardized dosing ensures consistent intake for specific performance goals.

Is L-Citrulline Better than L-Arginine?

Research indicates that L-citrulline may be a more effective supplement than L-arginine for consistently raising nitric oxide levels. When L-arginine is supplemented, it is heavily metabolized in the gut and liver, leading to poor bioavailability. L-citrulline, however, bypasses this initial breakdown and is efficiently converted into L-arginine in the kidneys, leading to higher and more sustained plasma L-arginine levels—and therefore more nitric oxide. This makes L-citrulline a superior choice for supplementation, particularly for endurance and performance benefits.

Conclusion

While a natural, holistic approach combining a nitrate-rich diet with regular exercise is the safest and best long-term method for most individuals, the single "best" source of nitric oxide is situational. For sustained health and daily wellness, prioritize a diet abundant in leafy greens and beets, supplemented with exercise. For targeted, potent boosts—such as for athletic performance—high-quality L-citrulline supplements offer a more direct and efficient route. Ultimately, the best strategy is a layered approach that includes a nutritious diet, an active lifestyle, and strategic supplementation when appropriate.

The Best Source of Nitric Oxide: Final Considerations

Choosing the optimal source of nitric oxide involves balancing natural methods with potent, targeted options. The efficacy of foods like beetroot juice is well-supported, while supplements like L-citrulline offer a consistent, high-impact alternative. A multi-pronged approach encompassing diet, exercise, and potentially supplementation is the most comprehensive strategy for maximizing nitric oxide levels and its associated health benefits.

Frequently Asked Questions

L-citrulline is generally considered more effective than L-arginine for boosting nitric oxide. This is because L-citrulline is more efficiently absorbed and converted into L-arginine in the kidneys, leading to higher and more sustained levels in the blood, while L-arginine is heavily metabolized in the digestive system.

Yes, beets and beetroot juice are highly effective at increasing nitric oxide. They are rich in dietary nitrates that your body converts to nitric oxide. Studies have shown that consuming beetroot juice can significantly increase nitric oxide levels and improve athletic performance and blood pressure.

Excessively high levels of nitric oxide from supplements can cause side effects like headaches, low blood pressure, and gastrointestinal issues such as diarrhea and nausea. In rare, extreme cases, it could lead to more serious conditions, emphasizing the need for proper dosage and medical supervision.

Yes, common side effects of nitric oxide supplements, particularly L-arginine, include bloating, diarrhea, stomach pain, headaches, and heartburn. L-citrulline is generally better tolerated, but individual tolerance varies, and higher doses can increase the risk of gastrointestinal issues.

The best natural way to boost nitric oxide is a combination of regular exercise and a diet rich in nitrate-heavy vegetables like beets, spinach, and arugula. Including antioxidant-rich foods like citrus fruits and pomegranates further supports the process by protecting NO from degradation.

The time frame can vary. For acute effects related to performance, some sources like beetroot juice or L-citrulline can show measurable increases in plasma nitrate levels within 45 to 90 minutes. Consistent, long-term use is required for more sustained health benefits.

For most people, getting nitric oxide precursors from a diverse diet is the safest and healthiest option, as it provides additional nutrients and reduces side effect risks. Supplements are most beneficial for targeted, short-term use, such as enhancing athletic performance, under a doctor's guidance.