L-Citrulline vs L-Arginine: How the Two Amino Acids Differ
L-citrulline and L-arginine both feed the nitric oxide pathway, but they travel through the body differently. Here is what that means for you.
Look at almost any nitric oxide formula and you will find L-arginine, L-citrulline or both. They are closely related amino acids, but they reach the nitric oxide pathway in different ways, which is why some formulas, Nitric Boost Ultra included, use both.
L-arginine: the direct building block
L-arginine is the amino acid that nitric oxide synthase enzymes convert into nitric oxide. On paper it is the obvious ingredient. The catch is the journey. When you swallow arginine, a large share is broken down in the gut and liver before it reaches general circulation. This is often called "first-pass" metabolism.
L-citrulline: the indirect route
L-citrulline is found naturally in watermelon. It is mostly not broken down on the way in. Instead it travels to the kidneys, where it is converted into L-arginine and released into the bloodstream. That makes citrulline an indirect but efficient way to supply arginine. It is the reason citrulline has become such a popular sports-nutrition ingredient.
Why use both?
- Arginine is available right away.
- Citrulline provides a steadier supply of arginine after conversion.
- Together they feed the same pathway from two angles.
What is "DL-malate"?
Nitric Boost Ultra lists L-citrulline DL-malate. This is citrulline bonded to malate (malic acid), a compound involved in the cell's energy cycle. Citrulline malate is a common form in training supplements.
The seller does not publish the amount of each amino acid per serving. Check the Supplement Facts panel on the jar if dosage matters to you.
Food sources
Arginine is found in protein foods such as meat, fish, dairy, nuts and seeds. Watermelon is the best-known source of citrulline. A balanced diet supplies both. Supplements simply provide a concentrated, consistent amount.
Safety notes
Amino acids from food are part of a normal diet, but concentrated supplements are different. People with heart or kidney conditions, or anyone taking blood pressure, nitrate or erectile dysfunction medication, should check with a doctor first.
See the full Nitric Boost Ultra ingredient list or read the workout performance guide.
This article is for general education and is not medical advice. Talk to a qualified healthcare professional about your own situation.
