Nitric oxide (NO) is a gaseous molecule produced naturally by our bodies that plays a key role in cardiovascular, metabolic, immune and sexual health. Although it is very small, its impact is enormous: it regulates circulation, blood pressure and communication between cells.
What is nitric oxide?
It is a biological signalling gas that allows blood vessels to relax, facilitating the passage of blood, oxygen and nutrients to tissues. Unlike other molecules, it is not stored: it is produced when the body needs it and acts quickly.
How and where is nitric oxide formed in the body?
There are two main production pathways, both of which are fundamental and complementary:
Endogenous pathway: L-arginine → Nitric oxide
This is the classic pathway and occurs within cells.
Where it is produced:
- Blood vessel endothelium
- Nervous system
- Immune system
How it occurs:
The enzyme nitric oxide synthase (NOS) transforms the amino acid L-arginine into nitric oxide and citrulline, in the presence of oxygen, iron, vitamins B6 and B12, folic acid and antioxidants.
This pathway is particularly active during physical exercise, sexual stimulation and situations of increased circulatory demand.
Enterosalivary pathway: nitrates → nitrites → nitric oxide
(The oral pathway, dependent on the tongue and microbiota)
Step 1: Nitrate intake
Nitrates come mainly from:
- Beetroot
- Spinach
- Rocket
- Swiss chard
- Celery
- Lettuce
Step 2: Conversion in saliva
Some of these nitrates pass into saliva.
Step 3: Conversion at the back of the tongue
The back of the tongue, especially at the junction between the teeth and gums, is home to beneficial bacteria that convert nitrates into nitrites.
Step 4: Conversion in the stomach and blood
When we swallow saliva:
- Nitrites are converted into nitric oxide in the acidic environment of the stomach.
- They can also be converted into NO in the blood and tissues, especially in low-oxygen situations (exercise, hypoxia).
Key fact:
Excessive use of antibacterial mouthwashes can reduce these oral bacteria and decrease nitric oxide production by up to 60%.
What is nitric oxide used for?
General functions
- Vasodilation → improves blood pressure
- Increased blood flow
- Improved immune function
- Optimisation of energy metabolism
- Regulation of mitochondrial function
Benefits in men
- Improved erectile function
- Increased athletic performance
- Better muscle oxygenation
- Cardiovascular protection
Benefits in women
- Improved uterine and ovarian blood flow
- Supports fertility
- Reduces fatigue
- Improves vascular health during menopause
Nitric oxide precursors and key foods
L-arginine
- Chicken, turkey, fish
- Eggs
- Legumes
- Nuts
L-citrulline (very powerful indirect precursor)
Watermelon (star food)
- Melon
- Cucumber
- Pumpkin
Natural nitrates
- Beetroot
- Spinach
- Arugula
- Swiss chard
- Celery
What conditions or problems can it help with? Always under the supervision of a healthcare professional (doctor or nutritionist)
✔ High blood pressure
✔ Erectile dysfunction
✔ Peripheral vascular disease
✔ Chronic fatigue
✔ Athletic performance
✔ Insulin resistance
✔ Muscle recovery
Contraindications and drug interactions
Caution if you have:
- Hypotension
- Uncontrolled heart disease
- Advanced renal failure
Interacts with:
- Nitrates (nitroglycerin, isosorbide)
- Sildenafil, tadalafil
- Potent antihypertensive drugs
- High-dose arginine supplements
How to boost your production naturally
· Eat vegetables rich in nitrates
· Eat watermelon regularly
· Stay physically active
· Do not overuse antibacterial mouthwashes
· Sleep well
· Avoid tobacco
Key foods:
Beetroot > Watermelon
Beetroot (nitrates) — rapid and vascular effect
✔ Activates the oral pathway nitrate → nitrite → NO (tongue + bacteria)
✔ Produces rapid vasodilation
✔ Improves blood pressure and acute athletic performance
✔ Ideal before exercise or for cardiovascular health
Watermelon (citrulline) — sustained and metabolic effect
✔ Increases plasma arginine
✔ Improves endogenous NO production in the medium term
✔ Benefits muscle recovery and chronic endothelial function
Practical conclusion
Beetroot is the most powerful food for immediately increasing NO.
Watermelon is better for sustaining NO levels in the long term.
If I had to choose just one for clinical vascular impact, it would be:
Beetroot.