Bohr effect

The Bohr effect describes the physical equilibria of oxygen and CO2 in people who have adapted to living at different altitudes, where carbon dioxide (or acidity) displaces oxygen from hemoglobin 2. This phenomenon is a result of the reduced air pressure at high altitudes, which causes hemoglobin to retain a higher level of carbon dioxide 3. The Bohr effect is closely related to the Haldane effect, which describes the fact that increased oxygen pressure decreases the amount of carbon dioxide retained by hemoglobin, and decreased oxygen pressure increases the amount of CO2 retained 2.

The Bohr effect plays a crucial role in the adaptation to high altitude, where a steady increase of retained CO2 occurs in those who adapt, while people who fail to adapt experience a loss of CO2, with an increase of lactate 2. This is because the Bohr effect allows the body to maintain a balance of CO2 and oxygen in the tissues, which is essential for optimal thyroid function and mitochondrial production of carbon dioxide 3. In fact, Ray Peat has observed that correcting thyroid function can prevent the progression of myopia, which is often associated with prolonged hypothyroidism and high altitude exposure 3.

The neglect of the Bohr effect in medical physiology has led to a "high altitude lactate paradox," where maximal exertion at high altitude does not increase lactic acid production in the normal way 5. This is because the presence of carbon dioxide in the blood is essential for suppressing the formation of lactic acid, and its absence results in the syndromes of altitude sickness and ventilator-induced lung damage 5. In fact, breathing pure oxygen lowers the oxygen content of tissues, while breathing rarefied air or air with carbon dioxide oxygenates and energizes the tissues 6.

Despite its importance, the Bohr effect is often overlooked in medical education, with many doctors being unaware of its significance or even considering it an "exotic idiosyncrasy" 7. However, the Bohr effect is a fundamental aspect of respiratory physiology, and its understanding is essential for understanding many pathological changes and organ functions 6.