Is L-Citrulline Good for Muscle Growth? An In-Depth Look

November 16, 2025 •

3 min read

While many fitness enthusiasts turn to traditional supplements like whey protein and creatine, a significant number of pre-workout formulas (around 70% in one analysis) also contain L-citrulline. But is L-citrulline good for muscle growth? The amino acid supports muscle building by enhancing exercise performance and promoting protein synthesis under certain conditions.

Quick Summary

This article explores the mechanisms behind L-citrulline's support for muscle growth, including its role in nitric oxide production, improved blood flow, and enhanced protein synthesis. Key benefits for athletes and strength trainers are examined, along with dosage recommendations and a comparison to L-arginine.

Key Points

Supports Nitric Oxide Production: L-citrulline boosts nitric oxide levels more effectively than L-arginine, enhancing blood flow and delivering more nutrients to muscles.
Enhances Exercise Performance: Increased blood flow from L-citrulline helps increase workout endurance and power output, enabling higher training volume.
Reduces Muscle Fatigue: By aiding in the clearance of metabolic waste products like ammonia and lactic acid, L-citrulline helps delay fatigue.
Stimulates Protein Synthesis: Studies indicate that L-citrulline can directly stimulate muscle protein synthesis, particularly in states of protein/energy deficiency.
Improves Post-Workout Recovery: L-citrulline may reduce delayed-onset muscle soreness (DOMS) and speed up recovery due to improved nutrient delivery and waste removal.
Superior to L-Arginine: Due to better absorption and bioavailability, L-citrulline is more effective at increasing long-term systemic arginine levels than L-arginine supplements.
Standard Dosage: For muscle growth benefits, 6-8 grams of citrulline malate or 3-6 grams of L-citrulline is a common daily dosage, often taken before workouts.

How L-Citrulline Aids Muscle Growth

L-citrulline is a non-essential amino acid that plays several vital roles within the body, many of which can indirectly support muscle growth. Unlike other amino acids, it is not directly incorporated into proteins but is a key player in metabolic pathways that optimize the muscle-building process.

Boosting Nitric Oxide for Enhanced Blood Flow

One of the most well-known functions of supplemental L-citrulline is its conversion into L-arginine within the kidneys. L-arginine then acts as a precursor to nitric oxide (NO). Nitric oxide is a vasodilator, meaning it helps to relax and widen blood vessels. This vasodilation leads to increased blood flow, which offers multiple benefits for muscle growth:

Improved Nutrient Delivery: Enhanced circulation delivers more oxygen, amino acids, and other anabolic nutrients to working muscles during and after intense training.
Increased Muscle Pumps: For resistance trainers, the increased blood flow translates to fuller, tighter muscle pumps, which is both aesthetically motivating and indicative of improved nutrient delivery.
Waste Removal: Better blood flow also helps clear metabolic waste products like lactic acid and ammonia from the muscles, which can delay the onset of fatigue and enable more productive workouts.

Promoting Muscle Protein Synthesis (MPS)

Beyond its effects on blood flow, L-citrulline has been shown to directly stimulate muscle protein synthesis (MPS). In studies involving subjects on low-protein diets, citrulline ingestion enhanced mixed muscle protein synthesis, indicating an anabolic effect. This mechanism appears to be independent of insulin, suggesting a unique pathway through which citrulline can support muscle repair and growth.

Increasing Performance and Reducing Fatigue

The ergogenic benefits of L-citrulline are not limited to its anabolic properties. By improving blood flow and aiding in the removal of fatigue-causing metabolites, it can increase an athlete's exercise capacity. Studies have shown that L-citrulline supplementation can increase the number of repetitions performed in resistance exercises and reduce perceived exertion. Some research also indicates that it can reduce delayed-onset muscle soreness (DOMS) up to 48 hours post-exercise, which can aid recovery and consistency.

L-Citrulline vs. L-Arginine: Why Citrulline is Often Preferred

Many people wonder whether they should take L-arginine, the direct precursor to nitric oxide, instead of L-citrulline. However, evidence suggests that L-citrulline is actually more effective at raising plasma arginine levels due to its superior bioavailability.


Feature	L-Citrulline	L-Arginine
Absorption	Highly efficient absorption.	Poor absorption due to extensive first-pass metabolism.
Systemic Arginine Levels	Leads to a more sustained and reliable increase in systemic arginine.	Provides only a temporary spike in plasma arginine levels.
Bioavailability	Superior bioavailability, as it bypasses the liver.	Low bioavailability due to metabolism in the gut and liver.
Side Effects	Generally well-tolerated, with minimal gastrointestinal issues.	Higher doses can cause significant gastrointestinal distress.

Practical Application: Dosage and Timing

For muscle growth, L-citrulline is most effective when taken consistently. While acute dosing can boost performance, sustained intake supports long-term benefits like improved nutrient delivery and protein synthesis.

Recommended Dosage: Research-backed dosages for performance range from 6 to 8 grams of citrulline malate or 3 to 6 grams of pure L-citrulline per day. Citrulline malate (a blend of L-citrulline and malic acid) is a common form in supplements.
Timing: For optimal performance benefits, it is best to take L-citrulline 30 to 60 minutes before your workout. On rest days, you can take it at any time to support recovery and circulation.

Considerations and Safety

L-citrulline is considered safe for most healthy adults, with some experiencing mild gastrointestinal discomfort at higher doses. However, individuals with pre-existing conditions or taking certain medications should consult a healthcare provider before supplementing. Since L-citrulline can lower blood pressure, caution is advised for those on blood pressure medication or erectile dysfunction drugs.

Conclusion

Based on current research, the answer to the question, "Is L-citrulline good for muscle growth?" is a definitive yes, though its effects are largely indirect. It enhances exercise performance by boosting nitric oxide and improving blood flow, which in turn leads to greater nutrient and oxygen delivery to the muscles. This supports increased training volume, reduced fatigue, and faster recovery. Furthermore, studies have shown that it can directly stimulate muscle protein synthesis, especially under stressed conditions. By choosing L-citrulline over L-arginine for its superior bioavailability and fewer side effects, athletes can maximize their muscle-building potential. Integrating L-citrulline into a training and nutrition plan can provide a valuable edge for those seeking to optimize their physique and performance.

Visit Examine.com for more detailed information on citrulline's benefits.

Frequently Asked Questions

While performance benefits like increased endurance and reduced fatigue can be felt shortly after taking a pre-workout dose, the long-term effects on muscle growth will be gradual. Sustained supplementation over several weeks, combined with consistent training and proper nutrition, is needed to see notable changes in muscle mass.

For consistent benefits such as improved circulation and recovery, daily supplementation is recommended. While a pre-workout dose is key for performance, taking a dose on non-training days can support overall recovery and nutrient delivery.

Yes. L-citrulline is the amino acid itself, while citrulline malate is L-citrulline bonded to malic acid. Citrulline malate is often the preferred form in supplements as the malic acid is believed to offer additional benefits for energy production and athletic performance.

For optimal performance during your workout, take your L-citrulline dose 30-60 minutes before training. On rest days, you can take it at any time to support recovery and maintain elevated nitric oxide levels.

L-citrulline is generally well-tolerated. Some individuals may experience mild gastrointestinal discomfort, such as stomach upset or heartburn, especially with higher doses. Because it can lower blood pressure, it may interact with medications for high blood pressure or erectile dysfunction.

Yes, L-citrulline is often stacked with other common supplements. Combining it with creatine can enhance high-power workouts, while pairing it with protein powder can further support muscle synthesis and recovery.

The effectiveness of L-citrulline can depend on an individual's training status and overall fitness level. While many studies show benefits for untrained or moderately trained individuals, the effects may be less pronounced in highly trained athletes who already have optimized physiological functions.