Ingredient Focus: Citrulline Part 2 – What It Does

In Part 1, we used grapes and toothpicks to understand what citrulline is. In part 2, we discuss what it does.

Like a watermelon seed, the best part of citrulline is not what it is, but what it becomes: arginine. When citrulline is ingested, it is converted into the amino acid arginine.

Arginine is an amino acid the body uses to make proteins. Arginine has several important roles in the body, but one is to remove ammonia; another is to make nitric oxide.

Ammonia gets into the body through the breakdown of amino acids, through food sources, and through natural chemical reactions in the body. Because we are not birds nor fish, we can’t pee ammonia. We have to make it something more pH neutral: urea.

The Urea Cycle is a major part of how the body removes waste. Nitric oxide is important because it regulates blood pressure, blood flow, and muscle relaxation. Nitric oxide triggers the same chemical reactions as certain medication that are also designed to help with blood flow. Wink.

WTRMLN WTR label GreenEyedGuide Energy Drink of the Month June 2016
WTRMLN WTR lays out the people and situations this product is suited for…

Citrulline as a sports performance supplement

Aside from nitric oxide production and ammonia removal through the urea cycle, arginine is used in the first reaction of creatine synthesis. But don’t count on citrulline to dramatically improve your workout. In one study, weightlifters that got citrulline did more reps that the placebo group, but in another study the citrulline group got tired QUICKER than the placebo group during treadmill incline walking.


There is not enough evidence to support a connection between citrulline and…

  • Muscle soreness
  • Training volume
  • Creatine production
  • Aerobic exercise
  • Muscle protein synthesis


But here’s the good news:

If you are on a high-protein diet, metabolism of that protein makes a lot of ammonia, which means the body has to make a lot of urea. Arginine is in the starting line up for the urea cycle, but its second job is nitric oxide production. When arginine’s first job takes up so much of its resources, it’s not as available for the second job. In other words, when so much arginine is needed for metabolizing protein, less arginine is available for nitric oxide production. Nitric oxide regulates blood pressure, blood flow, and muscle relaxation, so all three can suffer on a high-protein diet.

Citrulline to the rescue!!! As we discussed in Part 1, citrulline is better absorbed than arginine, so the best way to get more arginine is to consume citrulline!


For how much citrulline or citrulline malate to take and for possible side-effects, see PART THREE. We’ll review the dosage, side effects or dangers, and timing.



References and Related Reading

Citrulline Part 1 (What It Is) and Part 3 (How Much)

WTRMLN WTR – Energy Drink of the Month – June 2016

Citrulline on (note – this site has HEAPS of information, but it may be a bit technical for some)



Explore the CAFFEINE INFORMER database

Visit the Energy Drink Guide Facebook page (Woo-hoo!!! 100 Likes!)
Follow the GreenEyedGuide on Twitter
Follow GreenEyedGuide-the-NPC-Figure-Athlete on Instagram and Tumblr

Get your copy of “Are You a Monster or a Rock Star: A Guide to Energy Drinks — How They Work, Why They Work, How to Use Them Safely”



5 thoughts on “Ingredient Focus: Citrulline Part 2 – What It Does

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.