Citrulline vs Arginine: Which Is Better?

What is Nitric Oxide and Why Does It Matter?

Nitric oxide (NO) is a gas that dilates blood vessels. More NO = better blood flow to muscles.

NO effects on training:

• Better muscle pump
• More oxygen to muscles
• Better endurance
• Faster recovery

Arginine - The Original NO Booster

L-arginine is an amino acid from which the body directly produces nitric oxide.

Logic: More arginine → more NO → better pump

Problem: Arginine absorbs poorly and breaks down in the intestines.

Arginine Studies

Studies have been disappointing:

• Highly variable absorption (20-50%)
• Digestive issues at high doses
• Unclear results for athletic performance

Citrulline - The Better Alternative

Citrulline is an amino acid that's converted to arginine in the body, then to NO.

But why does citrulline work better than direct arginine?

The Citrulline Bypass

1. Arginine is broken down in intestines by enzymes
2. Citrulline bypasses this breakdown
3. Citrulline converts to arginine in kidneys
4. This arginine reaches bloodstream cleanly

Result: Citrulline raises blood arginine more than arginine itself (Schwedhelm et al., 2008)!

Scientific Comparison

Arginine

Citrulline

Citrulline Forms

L-Citrulline

• Pure citrulline
• Dose: 3-5g
• Best for: General NO support

Citrulline Malate (2:1)

• Citrulline + malic acid
• Dose: 6-8g (= ~4-5g citrulline)
• Best for: Training performance, endurance
• Bonus: Malate supports energy production

Citrulline Malate (1:1)

• Half citrulline, half malate
• Dose: 8-10g needed for same effect
• Lower quality products

Citrulline Studies

Strength Training (2010)

Study: 41 men, bench press to failure (Pérez-Guisado & Jakeman, 2010)

Result with 8g citrulline malate:

• +52% more reps compared to placebo
• Less muscle soreness 24-48h after

Endurance (2016)

Study: Cyclists, 4km time trial (Bailey et al., 2015)

Result with 6g citrulline:

• -1.5% time (significant in competitive sports)
• Better oxygen utilization

When to Take?

Citrulline

pre-workout supplements:

• 30-60 minutes before training
• 6-8g citrulline malate
• Empty stomach or with light meal

Daily use:

• Can take on rest days too
• 3-6g L-citrulline
• Helps maintain NO levels

Arginine

If you use at all:

• Smaller doses (3-5g)
• Split into multiple doses
• Don't expect big effect

Who Should Take Citrulline?

Greatest benefit:

• Strength trainers (better pump, more reps)
• Endurance athletes (better oxygen delivery)
• High-intensity trainers
• Those wanting better pump

Less benefit:

• Low-intensity trainers
• Beginners (baseline sufficient)

Combinations

Good Combination

Citrulline + beta-alanine + caffeine

• Classic pre-workout combination
• Each component supports different aspect

Citrulline + creatine supplements

• Pump + strength
• Complementary mechanisms

Avoid

Citrulline + arginine

• Same pathway, don't need both
• Citrulline alone is sufficient

Our Recommendation

Choose citrulline, not arginine!

1. Dose: 6-8g citrulline malate (2:1) before workout
2. Timing: 30-60 min before training
3. Frequency: On training days
4. Form: Powder (cheaper) or in pre-workout

Forget arginine - it's an outdated supplement that citrulline replaces in every aspect.

Summary

Citrulline is one of the few pre-workout supplements that actually works. Arginine is a historical relic.

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Browse our citrulline selection at MaxFit.ee →

References

1. Pérez-Guisado J, Jakeman PM. (2010). Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. Journal of Strength and Conditioning Research, 24(5), 1215-1222.
2. Bailey SJ, Blackwell JR, Lord T, et al. (2015). L-citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans. Journal of Applied Physiology, 119(4), 385-395.
3. Schwedhelm E, Maas R, Freese R, et al. (2008). Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine. British Journal of Clinical Pharmacology, 65(1), 51-59.
4. Gonzalez AM, Trexler ET. (2020). Effects of citrulline supplementation on exercise performance in humans: A review of the current literature. Journal of Strength and Conditioning Research, 34(5), 1480-1495.
5. Bescós R, Sureda A, Tur JA, Pons A. (2012). The effect of nitric-oxide-related supplements on human performance. Sports Medicine, 42(2), 99-117.

See also:

• Citrulline Malate: The Science of Muscle Pump and Performance Enhancement
• Best Pre-Workout Supplements 2026: Complete Ranking
• Beta-Alanine: Complete Guide for Athletes

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Read more: Pre-Workout Supplements: A Science-Based Guide