Nitric Oxide Pathways:
Raw Materials vs. Repair

The difference between taking more Arginine and actually fixing the blood vessel lining.

Comparison Breakdown
L-Arginine
(Old School)
L-Citrulline
(Better Absorption)
Rhamnan Sulfate
(Vessel Repair)
How It Works Direct Ingredient Indirect Ingredient Repairs the Lining
Efficiency Poor. Up to 40% is destroyed by the liver before it ever reaches your blood. High. Bypasses the liver. Travels to the kidneys where it turns into Arginine naturally. Foundational. Fixes the "sensors" your arteries need to produce Nitric Oxide.
Limitation Stops working as you age because your body breaks it down too fast. You have to keep taking high doses to see results. Takes time (3-4 months) to fully repair the structure.

The Reality: Ingredients vs. Factory

Taking Arginine is like dumping raw steel into a factory with broken machines. It doesn't matter how much material you have if the machines can't process it.

Your Endothelial Glycocalyx is the machine. It senses your blood flow and tells your body to release Nitric Oxide. If this lining is damaged, your body literally cannot use the ingredients you are giving it.

The Problem with L-Arginine

For decades, L-Arginine was the standard. But we now know it has a major flaw: Your Liver Destroys It. When you swallow it, your liver breaks down a huge portion of it before it reaches your bloodstream. Plus, as you get older, your body produces an enzyme that specifically targets and destroys Arginine.

The Advantage of L-Citrulline

L-Citrulline is different. It slips past the liver undetected and travels to the kidneys. Once there, your kidneys efficiently convert it into Arginine. Studies show that taking Citrulline actually gives you higher blood levels of Arginine than taking Arginine itself.

If you just want to increase your Nitric Oxide levels, Citrulline is the clear winner.

The GRN Labs Verdict

You Need Both Raw Materials and Function

Vascular health requires two things: enough "ingredients" (Precursor) and a working vessel lining (Function).

The GRN Vascular Protocol does both:

Common Questions

Which is better for Nitric Oxide: Arginine or Citrulline?

L-Citrulline is better. Because it bypasses the liver, it converts to Arginine in the kidneys, resulting in higher and more sustained blood levels than if you just took Arginine.

Does Rhamnan Sulfate boost Nitric Oxide?

Indirectly. It repairs the endothelial glycocalyx (the vessel lining). Since the glycocalyx contains the sensors that tell your body to produce Nitric Oxide, repairing it restores your natural ability to produce it.

Why do Nitric Oxide supplements stop working?

This is often due to damage to the lining. Adding more ingredients (Arginine) won't help if the lining (Glycocalyx) is damaged. Without a healthy lining, your body simply can't process the ingredients.

Assess Your Vascular Function

Before supplementing, understand your baseline. Effective protocol design begins with accurate biomarker assessment.

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Medical Disclaimer

GRN Labs provides educational content and data-driven biomarker audits. We are not medical doctors, and nothing on this website constitutes medical advice, diagnosis, or treatment. This content is for informational purposes only and is not intended to replace the relationship between you and a qualified healthcare provider.

These statements have not been evaluated by the Food and Drug Administration (FDA). Any products or protocols discussed are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary. Always consult your physician before beginning any new supplement, diet, or health regimen.