What are nitric oxide supplements, really?
Here’s the most important thing to understand straight away: nitric oxide supplements don’t actually contain nitric oxide. Instead, they contain precursors — compounds your body converts into NO through natural biological pathways.
This distinction matters because it shapes how you use them and what results you can reasonably expect. Your body is doing the heavy lifting, not the pill.
The two production pathways
Your body makes nitric oxide through two main routes:
1. The Dietary Nitrate Pathway is the most common. Nitrates from foods like beetroot, spinach, rocket, and kale travel to your mouth, where oral bacteria convert them into nitrite. This nitrite is swallowed, reaches your stomach, and converts into NO. This is a surprisingly elegant system — your oral microbiome is critical to the process working at all.
2. The Amino Acid Pathway works differently. L-citrulline (an amino acid found in foods and supplements) converts to L-arginine in your kidneys and tissues. L-arginine then triggers an enzyme called eNOS (endothelial nitric oxide synthase) to produce NO directly. This pathway is less dependent on your oral bacteria, making it a useful complement to the dietary nitrate route.