Sam Stephens

January 2020

Better workouts, more muscle mass, less body fat, and an overall healthier life from one little amino acid. 

Today’s Supplement Spotlight is about one of my favorites – L-Citrulline. 

Citrulline is a non-essential amino acid that primarily aids in the production of nitric oxide while also supporting a ton of other great benefits. Some of those benefits include:

  • Decreased blood pressure (hypertension)
  • Increased protein synthesis
  • Increased blood flow (endothelial vasodilation) 
  • Increased fat burn (lipolysis/fat oxidation)
  • Decreased cellular inflammation
  • Increased nitric oxide production
  • Decreased insulin resistance
  • Reduced chance of heart disease (atherosclerosis)
  • Decreased muscle wasting (supported nitrogen levels)
  • Reduced cellular oxidative stress (antioxidant)

Although arginine is frequently taken/used as a pre-workout, it’s not able to be used well when ingested orally. The enzyme arginase in our digestive tract ends up breaking down and metabolizing arginine before it can be used. Citrulline, on the other hand, is not affected in the same way. Instead, citrulline is converted into arginine in our kidneys, which then is used to produce nitric oxide and aid in all of the other great benefits listed earlier. So, if you’re only taking arginine, you’re missing out. Take citrulline instead. 

While burning more fat, reducing inflammation, and keeping heart disease away are cool, let’s focus on the exercise side of things. How does citrulline help us in our workouts?

The simple answer is better blood flow. 

Citrulline allows our blood vessels to relax and expand (vasodilation), resulting in more blood to pass through our muscles. And an increase in blood volume means we can transport more energy and remove more waste from tissues during demanding sessions.

It’s also great for a sick pump, brah.

So, how much should you take? That will vary from person to person, but 3-10g/day is right for most people. I take 6g half an hour before I lift, and then 2g more in the evening. You can also get citrulline from watermelon, but you have to eat a ton of it. 

For more info, check out the paper below or shoot me a message.

Allerton, T. D., Proctor, D. N., Stephens, J. M., Dugas, T. R., Spielmann, G., & Irving, B. A. (2018). l-Citrulline Supplementation: Impact on Cardiometabolic Health. Nutrients, 10(7), 921.