Amino AcidsModerate

L-Citrulline

Also known as Citrulline malate, Citrulline

L-Citrulline is a non-essential amino acid that the body converts to arginine far more efficiently than supplemental arginine itself — bypassing the gut and liver breakdown that limits oral arginine absorption. This makes it the preferred way to raise blood arginine and nitric oxide levels, giving better pumps, improved endurance, and reduced muscle soreness. Citrulline malate (paired with malic acid) is the most studied form for exercise performance.

Energy Recovery Heart health

Benefits

Raises nitric oxide more effectively than arginine

Strong

Citrulline survives gut and liver metabolism intact, reaching the kidneys where it is converted to arginine. Blood arginine levels rise higher with citrulline than with the same dose of arginine.

Improves exercise endurance and reduces fatigue

Moderate

Citrulline malate at 6–8 g pre-workout increases reps to failure, delays fatigue, and reduces perceived exertion in both resistance and endurance training.

Reduces post-exercise muscle soreness

Moderate

Multiple trials show significantly lower DOMS scores 24–48 hours after training with citrulline malate supplementation.

Supports blood pressure and vascular health

Moderate

By raising nitric oxide, citrulline dilates blood vessels and has shown modest reductions in blood pressure in several trials.

Pros & cons

Pros

Better absorbed and more effective than arginine for raising NO
Well tolerated with minimal side effects
Strong pre-workout evidence at 6–8 g citrulline malate
No herpes-flare risk unlike arginine

Cons

Needs a fairly large dose (6–8 g) for performance benefit
Citrulline malate vs pure citrulline dosing can be confusing (malate form is ~57% citrulline by weight)

Side effects

GI discomfort at high doses

Generally very well tolerated; occasional bloating at doses above 10 g.

Mild

Blood pressure drop

May lower blood pressure meaningfully; caution alongside antihypertensives.

Moderate

How to take it

Typical dose

6–8 g citrulline malate (2:1) or 3–4 g pure L-Citrulline, 30–60 min pre-workout

Timing

30–60 minutes before exercise

Common forms

Citrulline malate 2:1 (most studied)Pure L-Citrulline powderCapsules

Tip: Citrulline malate 2:1 means 2 parts citrulline to 1 part malic acid. 8 g of citrulline malate ≈ 5.6 g pure citrulline.

What the research says

Citrulline malate and resistance exercise

Moderate

8 g citrulline malate before training significantly increases repetitions to failure and reduces muscle soreness 24–48 h post-exercise.

RCTs · 2017View research

Citrulline vs arginine for blood arginine levels

Strong

Oral citrulline raises plasma arginine levels more effectively than equimolar arginine due to better intestinal absorption and reduced splanchnic extraction.

Pharmacokinetic studies · 2015View research