Nitric Oxide and Mouth Breathing


Relatively recently discovered (1998) Nitric Oxide (NO) is produced in the nasal mucosa and to a greater degree, the paranasal sinuses – underlining the importance of nasal over mouth breathing. NO has several important functions within the body.

In 1998 Robert F. Furchgott, Louis J. Ignore and Ferid Murad were jointly awarded the Nobel Prize for their discoveries concerning nitric oxide as a signalling molecule in the cardiovascular system.

 Nitric Oxide (NO) producing enzymes are found in the nasal mucosa and to a greater degree, the paranasal sinuses underlining the importance of nasal over mouth breathing. NO has several functions within the body including

Regulator of oxygen bonding to haemoglobin – see, Nitric oxide effect on the hemoglobin-oxygen affinity.

Signalling molecule in multiple body systems – see, NO as a signalling molecule in the nervous system.

A vasodilator, it decreases BP and increases tissue perfusion – see, Role of Nitric Oxide in the Cardiovascular and Renal Systems.

As a free radical itself, it acts as an intra-arterial anti-oxidant and coagulant – see, Inflammation-induced endothelial dysfunction involves reduced nitric oxide bioavailability and increased oxidant stress.

Shown (likely through respiration) to increase neurological and cognitive function – see, Impaired cognitive function and mental performance in mild dehydration.

A regulator of smooth muscle (bladder), hormones, erectile function and digestive health. – see, The epidemiology and pathophysiology of erectile dysfunction and erectile dysfunction in obstructive sleep apnea.

Nasal breathing acts as a flow limiter, increasing air flow resistance by up to 200% assisting the uptake of oxygen. Mouth breathing disrupts orofacial muscular balance leading to normal developmental disturbance. It can lead to chronic hyperventilation, reduced perfusion, oxygen lowering and vasoconstriction.

Mouth breathing can also cause sleep difficulties, causing  people to wake in the night, if they aren’t getting enough oxygen.

 In children, lack of sleep may reduce their ability to pay attention and concentrate at school, which may be mistaken for attention deficit disorder.

 Mouth breathing can be related to sleep apnea, causing people to wake frequently at night and excessive daytime sleepiness.

Think of these things next time you watch a child playing or watching something at rest with their lips apart, mouth breathing. Nitric oxide formation – increase you antioxidant intake.

Nitric oxide is an unstable molecule that degrades quickly in the bloodstream, so it must be constantly replenished. See, Nitric oxide metabolism and breakdown.

One way to increase Nitric oxide stability and limit its breakdown is by consuming antioxidants.

Antioxidants are molecules that neutralize free radicals, which contribute to the short life of nitric oxide, see, Role of oxidative stress and nitric oxide in atherothrombosis.

These antioxidants are found in all foods but primarily those of plant origin, such as fruits, vegetables, nuts, seeds and grains. It is sometimes necessary to supplement such a diet with appropriate supplementation, hence my recommendations at the foot of this article.

A few important antioxidants include:

Vitamin C: This antioxidant helps your body form connective tissues, including skin, bones, tendons and cartilage. It also produces brain chemicals that help nerve cells communicate- see, Vitamin C in Health and Disease: Its Role in the Metabolism of Cells and Redox State in the Brain.

Vitamin E: This antioxidant protects cells from the damaging effects of free radicals, which are thought to contribute to aging and disease. It also plays an important role in keeping the immune system strong – see, Vitamin E: function and metabolism, and The Role of Vitamin E in Human Health and Some Diseases.

Polyphenols: This category of antioxidants is associated with several health benefits, including a reduced risk of cancer and cardiovascular disease – see, Polyphenols and Human Health: Prevention of Disease and Mechanisms of Action.

Glutathione: Coined “the mother of all antioxidants,” glutathione is the master antioxidant and detoxifier of every cell in your body. Also, see; “The master anti oxidant”.

Several studies have found that ingesting nitric oxide precursors, such as nitrate or citrulline, with antioxidants maintains greater levels of nitric oxide in your body by helping reduce its breakdown – see, Combined L-citrulline and glutathione supplementation increases the concentration of markers indicative of nitric oxide synthesis.

See also, Tetrahydrobiopterin, l-Arginine and Vitamin C Act Synergistically to Decrease Oxidative Stress, Increase Nitric Oxide and Improve Blood Flow after Induction of Hindlimb Ischemia in the Rat (9),

Also; Long-term vitamin C treatment increases vascular tetrahydrobiopterin levels and nitric oxide synthase activity.

Also; Effect of ascorbic acid supplementation on nitric oxide metabolites and systolic blood pressure in rats exposed to lead.

Vegetables that are high in nitrate are also inherently high in antioxidants, which is likely why vegetables are so effective at increasing and maintaining optimal levels of nitric oxide – see, Fruit and vegetable consumption and the incidence of hypertension in three prospective cohort studies.



Good sleep is crucial to good health and longevity.

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