Why Mouth Breathing is Bad — the Carbon Dioxide Connection

Most people think that oxygen is the most important gas since that’s what we breathe in and that’s what keeps us alive. Very few people even think about carbon dioxide. They just know that it’s a waste gas that we exhale. Hopefully, this article will make you change your mind. The action of Carbon Dioxide (CO2) is explained by the Bohr Effect.

“(from Google) The Bohr effect is a physiological phenomenon first described in 1904 by the Danish physiologist Christian Bohr, stating that hemoglobin’s oxygen binding affinity (see Oxygen–haemoglobin dissociation curve) is inversely related both to acidity and to the concentration of carbon dioxide.[1] Id est, an increase in blood CO2 concentration which leads to a decrease in blood pH will result in hemoglobin proteins releasing their load of oxygen. Conversely, a decrease in carbon dioxide provokes an increase in pH, which results in hemoglobin picking up more oxygen. Since carbon dioxide reacts with water to form carbonic acid, an increase in CO2 results in a decrease in blood pH.”

The main idea is that CO2 is “manufactured” mostly from exercise and a bit from digestion. There is very little of it in the atmosphere. Oxygen, on the other hand, is everywhere (20% of atmospheric gas). Our bodies need 6% oxygen and 6.8% carbon dioxide. So we never have to worry that we’d run out of oxygen since there’s more than enough in the environment. But we need to think about how much carbon dioxide needs to be retained in our bodies since there is barely any in the atmosphere (less that 0.1%) and we actually have to manufacture it. When we breathe through the nose, we don’t exhale as much carbon dioxide as when we breathe through the mouth. (just because of sheer volume).

When blood pH is higher, this is when oxygen binds to the hemoglobin. That’s great because we need the hemoglobin to pick up oxygen from the lungs and carry the O2 to our tissues (like the brain, for example). But when the hemoglobin has to dump out the oxygen, this is when the Bohr effect comes in. When CO2 reaches 40 mm Hg pressure, it lowers the blood pH allowing the hemoglobin to release the O2 into the tissues. Ever notice that, after a workout, your muscles are all sore but you also feel invigorated? That’s because the CO2 reached its peak pressure point triggering the release of all the oxygen bound to the hemoglobin.

The problem with mouth breathing is that so much CO2 is released to the point that it couldn’t reach 40mm Hg pressure. But rather than let you die, your body decides to lower the bar and allow the hemoglobin to release some of the O2 at a lower trigger point. Obviously, this isn’t ideal and doesn’t work very well. This accounts for fatigue, sleepiness, tiredness and overall lack of energy. Over long term, that’s when you start seeing the body break down — weakened immune system, chronic fatigue, high blood pressure, mood swings, obesity etc… See the connection?


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