Citrulline: The Pump Ingredient Explained

Scroll through the ingredients list of any pre-workout and you'll see it: citrulline (or L-citrulline, or citrulline malate). It's THE pump ingredient of the moment. But what does it actually do, and does it work?

What is citrulline?

Citrulline is a non-essential amino acid. Your body makes it, and you get it from certain foods (watermelon is packed with it — the name comes from 'citrullus', Latin for watermelon).

In your body, citrulline converts to arginine, and arginine converts to nitric oxide (NO). That nitric oxide? It widens your blood vessels, allowing more blood to flow to your muscles.

More blood flow = better pump + better nutrient delivery + faster waste removal.

Why citrulline and not arginine?

Good question. If citrulline converts to arginine anyway, why not just take arginine directly?

Because arginine has poor absorption. Much of it gets broken down in your liver and intestines before reaching your muscles. Citrulline gets through and converts IN your body. Citrulline actually gives a higher arginine spike than direct arginine supplementation.

Citrulline vs Citrulline Malate

You'll see two forms:

L-Citrulline: Pure citrulline
Citrulline Malate: Citrulline bonded to malic acid

Citrulline malate is most researched, usually in a 2:1 ratio. The malate may help with energy production, but evidence is thin. Practical difference? Minimal. Both work.

How much citrulline do you need?

Most studies use:

L-Citrulline: 3-6g
Citrulline Malate (2:1): 6-8g

Under 3g you won't feel much. From 6g (pure) or 8g (malate) you're in the optimal zone.

Does it actually work?

Yes, with nuance:

✅ Improved blood flow and pump (consistent evidence)
✅ Slightly more reps on strength exercises (multiple studies)
✅ Reduced muscle soreness after training (mixed evidence)
❓ Better endurance (some studies yes, others no)

It's not a miracle. You won't suddenly get 20% stronger. But 1-2 extra reps across your whole workout? That adds up.

When to take?

30-45 minutes before training. Citrulline needs time to convert.

Side effects?

Almost none at normal doses. Some people report mild stomach issues at high doses (10g+).

Looking for a pre-workout with proper citrulline dosing? Compare options at whey-wijzer.fit.