Nitric oxide (NO) is a gas produced from the amino acid arginine, responsible for a number of important physiologic functions. Among them: NO helps to protect against bacterial infection, modulates inflammation, and sends signals in the nervous system. But it’s probably best known for its role in regulating smooth muscle, in both the lungs and the blood vessels.

Because of this, problems in the NO system are associated with heart disease, high blood pressure, and pulmonary hypertension.

Consuming adequate precursors for the production of NO (arginine, or else nitrates found in fruits and veggies) is only half the battle, though. It’s also important to engage those systems in the body that trigger the release of NO. One of them, interestingly enough, is breathing through your nose.

Mouth Breathing and Cardiovascular Risk

Have you ever wondered why it seems so much more difficult to feel like you’re getting enough oxygen when your nose is stuffed up? You’re breathing through your mouth, and that’s a bigger airway, so you’d think oxygenation wouldn’t be a problem.

But mouth breathing actually does lead to lower oxygen concentration in the bloodstream. This study demonstrates that oxygenation is about 10% higher in nasal breathing than in mouth breathing.

This effect is at least in part due to nitric oxide release from the sinuses.

It’s well established that sleep apnea is an independent risk factor for cardiovascular disease; decreased release of NO due to mouth breathing may be part of the reason behind this.

Other Risks of Mouth Breathing

If mouth breathing decreases oxygenation, as you might imagine, this could have wide reaching effects. Mouth breathing is associated with ADD and ADHD, for instance, probably due to decreased oxygen to the brain.

New memory formation is less efficient when breathing through the nose, too, presumably for the same reason.

The nose humidifies the air when breathing in, but the mouth does not. Thus, mouth breathing will dry up saliva, which is antimicrobial. This can set you up for bad breath, and periodontal disease (which is its own separate risk factor for CVD).

For children whose faces are still taking shape, mouth breathing can lead to dental and facial irregularities as well.

Causes of Mouth Breathing

Some of the most obvious causes of mouth breathing include congestion, either acute or chronic, from allergies, sinusitis, or an upper respiratory infection.

Enlarged tonsils, adenoids, turbinates, or often polyps are usually secondary to either chronic allergies (food or environmental), toxic mold exposure, MARCoNS (a bacterial colony in the nose), or a chronic fungal overgrowth.

A chronic, stressed state of “fight or flight” sympathetic overdrive might cause short, shallow mouth breathing. In this case, the treatment would involve deep breathing and other stress management practices.

Sometimes structural abnormalities, such as a deviated septum, might require surgical intervention.

The Upshot

Even if it seems like something you can live with, chronic congestion (or any other cause of mouth breathing) has potential long-term implications for cardiovascular health. I’d highly recommend finding and treating the root cause before complications arise down the line.

Does Mouth Breathing Increase Cardiovascular Risk?