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The mouth breathing problem part III: Loss of nose functions

In the 1970s, Dr Maurice Cottle, who founded the American Rhinologic Society and was a preeminent ear, nose, and throat surgeon, postulated that the nose has thirty functions (his list was never formalised). Given that he did not include the production of nitric oxide in his list (which was discovered in exhaled air in 1991), we can at least say there are many functions of the nose that we can only access by breathing through it.

It would be boring to simply write a list of the thirty remaining functions. Instead, I will highlight some key ones here. The important thing to note is that if you breathe through the mouth, you miss out on all these benefits.

One of the primary functions of the nose is to warm and moisturise the air that we inhale. As we inhale, the air attracts moisture from the nasal cavity, and heat is drawn from the blood capillaries. This warm, moist air keeps the tissues of the lungs moist and prevents the lung tissues from becoming inflamed. Mouth breathing, in contrast, draws in cool, dry air that can irritate the delicate tissue of the lungs (a problem common in elite athletes competing in snow sports).

Our sense of smell and taste are both dependent on nasal breathing. We have more than 400 types of olfactory receptors in our nose with a total of five to six million receptors (in comparison, a dog has an estimated one hundred to three hundred million receptors). These receptors enable us to smell a large number of different odours and also affect our ability to taste. Interestingly, research is now showing that a decline in our sense of smell can be an early indicator of degenerative diseases such as Alzheimer's and Parkinson’s.

Our sense of smell may even have an impact on the partner we choose. The influence of body odour on attraction was tested as early as 1975. Experiments confirmed that women preferred the odour of a man who was genetically dissimilar to themselves. However, there is no clear evidence that this will determine your future partner, as there are many factors that impact partner choice, but smell might be that thing that you can’t put your finger on that makes your partner that extra bit special.

From a biomechanical perspective, breathing through the nose recruits the diaphragm more than mouth breathing does. This improves its functionality by increasing its strength and endurance. The diaphragm is our primary breathing muscle, responsible for drawing in around 75% of the air we breathe, with the remaining 25% being supported by intercostal muscles (the muscles between the ribs). Mouth breathing leads to less recruitment of the diaphragm and an increase in shallow breathing into the upper chest that can trigger a stress response.

The second function of the diaphragm is to stabilise the core. Research has shown that, during exercise in athletes with a weak diaphragm, blood is diverted from the legs to the diaphragm to increase oxygenation of that muscle and prioritise breathing. Mouth breathers are more likely to have a weak diaphragm and, therefore, fatigue more quickly because of this effect. Tired legs might not just mean you’re unfit; it may also reflect suboptimal breathing mechanics, particularly if diaphragm function is impaired

Breathing through the nose is known to improve cognitive function. Test subjects with nasal congestion had slower reaction times, had more cognitive dysfunction, and fatigued more quickly than subjects without congestion. Nasal breathing can reduce the likelihood of congestion, and a combination of breathholds and nasal breathing can help clear congestion, improving cognition and increasing energy levels.

With so many benefits linked to nasal breathing (don’t forget to add improved sleep, antiviral/antimicrobial defence, and parasympathetic nervous system activation to the list), it is something that you should prioritise to support all aspects of your wellbeing.

Disclaimer

This blog is for informational purposes only. It is not medical advice. Always consult a healthcare professional for personalized guidance and treatment.