Medical summary
Dr. Nathan Bryan is a molecular medicine researcher and leading authority on nitric oxide (NO) biochemistry, with a focus on its roles in vascular health, immune function, mitochondrial efficiency, and metabolic resilience. His work highlights the crucial regulatory role of NO as a gaseous signaling molecule, particularly in endothelial function, oxygen delivery, and mitochondrial ATP production.
Nitric oxide production often declines with age, poor diet, oral microbiome disruption, or chronic illness—factors also seen in post-COVID-19 and long COVID-19, where microvascular dysfunction, fatigue, and poor oxygen utilization are common. Bryan’s research shows that lifestyle, diet, and oral hygiene can profoundly affect endogenous NO levels, offering a low-risk, evidence-based avenue for improving energy, circulation, and immune response.
“If you don’t make nitric oxide, you die. It’s that essential.”
Key takeaways
- Nitric oxide (NO) is a key molecule for healthy blood vessels, brain function, and energy production.
- Low NO levels are linked to fatigue, poor circulation, high blood pressure, and brain fog—symptoms often seen in long COVID-19.
- You can increase NO naturally through specific foods (like beets, leafy greens), nasal breathing, and sunlight exposure.
- Avoiding antibacterial mouthwash is critical—your mouth bacteria are essential for activating nitrate from food into nitric oxide.
- Simple changes in diet and daily habits can rapidly boost your NO levels, sometimes within minutes.
“You don’t need a drug to fix nitric oxide deficiency. You need to stop doing what’s breaking it—and start feeding your body what it needs.”
Theory and practice
Dr. Bryan’s theory is simple but profound: nitric oxide is essential to human life and easily disrupted by modern lifestyle habits. He promotes a return to NO-friendly practices to restore energy, circulation, and immunity—especially for those recovering from infections like COVID-19.
1. What nitric oxide does
- Relaxes blood vessels, improving circulation and oxygen delivery
- Supports mitochondrial energy production
- Acts as a signaling molecule in the brain and immune system
- Protects against platelet aggregation, oxidative stress, and inflammation
2. How it’s made
Two main pathways:
- Endothelial NO Synthase (eNOS): converts L-arginine to NO (requires healthy blood vessels, oxygen, and enzymes)
- Nitrate–Nitrite–NO pathway: dietary nitrate (from food) is converted by oral bacteria into nitrite, then NO
Both pathways can be disrupted by:
- Aging
- Sedentary lifestyle
- Processed food diets
- Mouthwash use
- Antibiotic overuse
3. Why it matters for post-COVID-19
- NO improves oxygenation and vascular repair
- May reduce microclots and endothelial damage
- Supports brain perfusion, helping with mental clarity
- Enhances immune defense without overactivation
“Most long COVID symptoms reflect processes that nitric oxide regulates—yet almost no one is checking or restoring it.”
How to apply it yourself
Eat nitrate-rich foods
- Beets and beet juice
- Leafy greens: spinach, arugula (rocket), celery, kale
- Citrus fruits: for vitamin C, which supports NO production
- Pomegranate: enhances blood flow and NO signaling
- Nuts and seeds: especially those rich in L-arginine
- Watermelon: contains L-citrulline, which converts to arginine → NO
- Dark chocolate (≥80%): high in flavanols that stimulate NO
Change your habits
- Nasal breathing: increases NO from your sinuses
- Exercise regularly: especially cardio and resistance training
- Expose your skin to sunlight: UV light stimulates NO release
- Avoid antibacterial mouthwash: it kills good oral bacteria needed for NO conversion
- Tongue scraping: removes excess biofilm while preserving good microbes
Optional lifestyle additions
- Cold exposure (e.g., cold showers) may stimulate NO via sympathetic activation
- Intermittent fasting may improve endothelial NO synthesis
- Reduce oxidative stress through antioxidant-rich foods
“Fix your nitric oxide, and your body becomes more efficient at everything—from thinking to healing.”