Hyperventilation is an important part of our “fight-or-flight” response. In such conditions, large muscles need more blood for a better chance of survival. That means that more blood would be diverted to the large skeletal muscles, resulting in less blood for vital organs, including the organs of digestion. Indeed, British and Japanese scientists found decreased blood flow to the liver (Hughes et al, 1979 and Okazaki et al, 1980), while American medical doctors confirmed the same effect for the colon (Gilmour et al, 1980). Hence, the more heavily we breathe, the less blood goes to our digestive organs.

In addition, the suppressed Bohr effect reduces oxygenation of the digestive organs, as documented by various Western studies.

Almost a century ago, Yale Professor Yandell Henderson from Yale’s School of Medicine found that a low CO₂ in the arterial blood (due to hyperventilation) resulted in loss of tone of the intestines, producing extreme intestinal congestion. Saturation of the blood with CO₂ rapidly eliminated the congestion (Henderson, 1907). The results were published in the American Journal of Physiology.

Warning. In some people, mild voluntary hyperventilation can almost halt their digestion so that it can take up to 5-7 or more hours to empty the stomach. Note that such “experimentation” can be dangerous leading to the aggravation of existing gastrointestinal problems. Breathing less (or hypoventilation) can also make some digestive problems worse.

Hence, chronic hyperventilation can interfere with normal digestion. Poor blood and oxygen supply can lead to a lack of digestive enzymes, accumulation of metabolic waste products, slower digestion, putrefaction of some foods and nutrients and mal-absorption. Systematic research in this area is absent and there are more questions than answers.

From a practical viewpoint, the above suggests that smaller CPs correspond to slower digestion. For example, a person with about a 60 s CP may need about 1-1.5 hours to digest a regular meal (when almost no food is left in the stomach). The same meal for a sick individual (e.g., 10-15 s CP) would need 1-2 more hours of digestion. The person with normal breathing after this meal would still be reasonably fit and able to exercise (not very rigorously, of course) after eating the same meal. The sick person would definitely need a rest.

Be observant. When we are acutely sick with the flue, cold or other infection or disease, our CP probably decreases about 2 or more times from its usual level. What happens with your digestion? How would you feel if you were to eat your regular meal while sick? What would happen with your CP? Which meals and foods do you prefer when you are sick?

Questions. For primitive people, it was vital to defend themselves any time, day and night, including after meals. Could they be physically strong and mentally fit after meals if their usual CPs were about 20-25 s (as in a modern population)? What would you expect their usual CPs to be?

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