What is the Difference Between Arginine and Citrulline?

Arginine and citrulline are two amino acids that are often discussed together due to their interconversion in the body and their roles in nitric oxide (NO) production. Here are the main differences between them:

1. Sources: Arginine is found in foods such as fish and nuts, while citrulline is found in fruits and vegetables, with the highest concentration in watermelon.
2. Conversion: In the body, arginine is broken down into nitric oxide by an enzyme called nitric oxide synthase (NOS). Citrulline then travels to the kidneys, where it is transformed into arginine and starts the same cycle.
3. Effectiveness: Recent research suggests that citrulline is more effective than arginine in boosting NO levels and expanding blood vessels. This is because the body uses arginine for various functions, and not all of the absorbed arginine is used to produce NO. Additionally, higher doses of arginine have been linked to gastrointestinal problems.
4. Bioavailability: When consumed orally, L-arginine undergoes significant breakdown by the enzyme arginase in the gastrointestinal pathway, resulting in low plasma L-arginine levels and lower bioavailability for nitric oxide production. In contrast, L-citrulline supplements are shown to increase arginine levels more than arginine supplements.
5. Uses: Both L-arginine and L-citrulline help the body, but they often get lumped together. L-arginine encourages blood flow and circulation by relaxing and widening blood vessels, which may help with erectile dysfunction and improving immune systems. L-citrulline can help with muscle recovery, blood flow, reducing blood lactate levels, increasing time to exhaustion, physical performance, and reducing blood pressure.

Although L-citrulline has more pronounced effects than L-arginine, research shows that the two compounds can have a more substantial impact by promoting one another when taken together.

Comparative Table: Arginine vs Citrulline

Arginine and citrulline are amino acids that play important roles in the body, including in the production of nitric oxide (NO) and the immune system. Here is a table comparing the differences between arginine and citrulline:

In summary, arginine and citrulline are amino acids with distinct functions and properties. Arginine is essential for protein production and is involved in the production of nitric oxide, while citrulline serves as a precursor to arginine and helps maintain adequate arginine levels in the body. Citrulline supplementation has been shown to be more efficient at increasing arginine availability than arginine supplementation itself.