Oxygen - the forgotten nutrient.

Area of Science:

• Physiology
• Nutritional Science
• Cellular Biology

Background:

• Oxygen (O2) is crucial for aerobic animal maintenance and growth.
• Unlike traditional nutrients, O2 is not typically classified as such due to its entry route (lungs/gills vs. gastrointestinal tract).
• O2 deficiency occurs in various conditions, including high altitudes, deep-sea diving, and lung diseases like emphysema.

Purpose of the Study:

• To highlight the essentiality of oxygen (O2) for life.
• To propose the inclusion of O2 within the scope of nutritional science.
• To discuss cellular and molecular adaptations to O2 deficiency.

Main Methods:

• Review of physiological and molecular responses to O2 deficiency.
• Analysis of O2's role in mitochondrial respiration and oxidative phosphorylation.
• Examination of gene expression changes driven by hypoxia-sensitive transcription factors, such as hypoxia-inducible factor-1.

Main Results:

• O2 is indispensable for mitochondrial respiration and oxidative phosphorylation.
• Cells adapt to O2 deficiency by shifting to anaerobic glycolysis.
• Hypoxia-inducible factor-1 plays a key role in regulating cellular responses to low O2 levels.

Conclusions:

• Oxygen (O2) functions as an essential nutrient for aerobic organisms.
• Nutritional science should encompass O2 alongside traditional macronutrients.
• Understanding O2's role is critical for addressing conditions of O2 deficiency.