L-citrulline vs. citrulline malate – which form is best and why?

You’ve seen it on labels everywhere: L-citrulline, citrulline malate, citrulline 2:1. But what is the actual difference? Which form provides the most pump, the best endurance, and the best value for money? And why does the dosage matter more than the form?

This guide breaks down everything you need to know about citrulline – the science, the forms, the dosage, and how to choose the right one.

What is citrulline and why is it important?

Citrulline is a non-essential amino acid that plays a central role in the urea cycle – the body's process for eliminating ammonia. But for athletes, another mechanism makes citrulline interesting:

Citrulline → Arginine → Nitric Oxide (NO)

Citrulline is converted into L-arginine in the kidneys, which increases the production of nitric oxide. Nitric oxide dilates blood vessels (vasodilation), which increases blood flow to working muscles. The result:

• Increased muscle pump
• Improved oxygen and nutrient delivery
• Reduced lactic acid accumulation
• Improved endurance during repeated exertion
• Reduced post-workout muscle soreness

Interestingly, citrulline is more effective than direct L-arginine supplementation for increasing plasma arginine – because L-arginine is broken down in the gut and liver before it reaches the blood, whereas citrulline passes directly to the kidneys.

The three forms of citrulline

1. L-citrulline (pure form)

L-citrulline is the pure amino acid without additives. It is the form used in most clinical studies and provides the most predictable effect per gram. Clinical dose: 6–8 g per serving, 30–60 minutes before training.

2. Citrulline malate (citrulline + malic acid)

Citrulline malate is a compound of L-citrulline and malic acid (malate) in a ratio, usually 2:1. Malate is an intermediate in the citric acid cycle and has its own potential effects on energy production and fatigue reduction.

Important to understand: In a 2:1 ratio, 8 g of citrulline malate contains only ~5.3 g of actual citrulline. Many products underdose citrulline malate and market it as "8 g citrulline" – which is misleading. Clinical dose: 8–10 g citrulline malate (2:1) = 5.3–6.7 g actual citrulline.

3. Citrulline 3:1 and other ratios

Some products use 3:1 ratios or other variants. The higher the citrulline proportion, the more actual amino acid per gram – but the effect of the malate decreases proportionally.

L-citrulline vs. citrulline malate – what does the research say?

Most studies showing positive effects of citrulline have used either 6–8 g of L-citrulline or 8 g of citrulline malate (2:1). Direct comparisons between the forms are limited, but there is no strong evidence that citrulline malate is superior to L-citrulline when the citrulline dose is matched.

Conclusion from research: It is the citrulline dose that determines the effect – not the form. Always ensure you are getting at least 6 g of actual citrulline per dose.

What does citrulline provide in practice?

Pump and blood flow

Citrulline is the most proven ingredient for muscle pump. Increased NO production dilates blood vessels and increases blood flow to working muscles – which provides the characteristic pump feeling during training, but also real performance benefits in the form of better oxygen delivery.

Endurance and volume

Studies show that citrulline can increase the number of repetitions to failure by 10–20% in strength training, reduce perceived exertion (RPE) at a given load, and improve performance during repeated intense bouts.

Reduced muscle soreness

A well-cited study showed that 8 g of citrulline malate 60 minutes before training reduced muscle soreness 24 and 48 hours post-workout by up to 40% compared to a placebo.

Common mistakes with citrulline

• Dose too low: Many pre-workout products contain 2–4 g of citrulline – far below the clinical dose of 6–8 g.
• Confusing citrulline malate dose with citrulline dose: 8 g citrulline malate (2:1) ≠ 8 g citrulline. It is 5.3 g citrulline + 2.7 g malate.
• Taking it too late: Citrulline needs time for conversion. Take it 30–60 minutes before training.
• Expecting immediate effect: Citrulline is not a stimulant – the effect is physiological and is noticed as better pump and endurance.

Citrulline in Skytrition's product line

Skytrition uses clinically dosed citrulline in its pump products – with full transparency regarding the actual citrulline dose.

BlowitUP – Non Stim

Skytrition's dedicated pump product without stimulants. BlowitUP contains citrulline in a clinical dose combined with PerforMelon® (patented watermelon extract rich in natural citrulline), S7® (plant-based NO complex), and GlycerSize™ (glycerol for extra pump and hydration). Perfect for evening training, caffeine-sensitive individuals, and caffeine cycling periods.

MessitUP – Stim, Nootropic & Pump

The ultimate all-in-one pre-workout with citrulline as one of the pump components – combined with stimulants and nootropics for a complete pre-workout protocol.

How to optimally combine citrulline?

• Citrulline + Glycerol (GlycerSize™): Double pump effect – NO-mediated vasodilation + osmotic pump from glycerol
• Citrulline + S7®: Complementary NO mechanisms for maximal nitric oxide production
• Citrulline + Beta-alanine: Optimal for HIIT and intervals – citrulline manages blood flow, beta-alanine buffers lactic acid
• Citrulline + Creatine: Powerful combination for strength and volume

Read more: Pre-workout guide: what should you take, when, and why?

Practical protocol

Dose: 6–8 g L-citrulline or 8–10 g citrulline malate (2:1)
Timing: 30–60 minutes before training
With what: Take with water and HydraUP – Electrolytes for optimal hydration and absorption

Read more in our series on ingredients and performance

• Pre-workout guide: what should you take, when, and why?
• Creatine for athletes: everything you need to know about dosage and timing
• Recovery is training – why rest is your secret superpower
• Skytrition's patented ingredients – complete guide

Summary

L-citrulline and citrulline malate are both effective – the crucial thing is that you get at least 6 g of actual citrulline per dose. The form matters less than the dosage. Skytrition’s BlowitUP combines clinically dosed citrulline with PerforMelon®, S7®, and GlycerSize™ for a complete, synergistic pump complex – with full transparency regarding every ingredient dose.

Pump is not just aesthetics. It is physiology.

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