6. Oxygen Never Sleeps

You are probably familiar with the saying, "Rust never sleeps." Rust is the oxidation of iron through free radical exchanges with oxygen. The biologist would describe it more accurately: "Oxygen never sleeps." Oxygen always invites interaction with electrons of other molecules, either taking an electron (becoming a "superoxide" [O₂^O-] radical) or donating one of its loosely held electrons to another molecule (becoming singlet [O₂^O+] oxygen). We depend on this "reactive" quality of oxygen to produce the biological energy of life itself. But the energy we gain from oxygen comes with a price.

Oxygen's tendency to stimulate electron transfer creates a lot of compounds that are either missing an electron (giving them positive charge) or that have an extra electron (negative charge). The most energized of these are the free radicals (or oxyradicals, or oxidants). Each radical can generate a chain reaction of electron transfers that can alter hundreds of normal body molecules per second.

The external and internal membranes of the cells are especially vulnerable to radicals. Unchecked, radicals can rapidly alter the structures of membrane lipids and proteins, ruining membrane integrity as well as vital transport operations. These reactions can in turn stimulate chain reactions that spread damage deep within the cell, leading to cell mutation or death.²³

Superoxide Radical
Acquired Electron	Missing Electron
Superoxide Radical
Missing Electron
Missing Electron	Missing Electron
Hydroxyl Radical
Missing Electron	Missing Electron
Missing Electron

Other molecules (such as hydrogen peroxide and singlet oxygen) encourage radical-forming reactions. They are called proradicals because they spontaneously create superoxide, the radical that initiates oxidative chain reactions. Oxygen itself, which makes up 1/5 of the air your horse breathes and lives in, is by far the most abundant of the proradicals.

Oxygen is the "fire" that burns most of our energy, the universal activator required for thousands of essential biomolecular reactions. Oxygen has tremendous chemical power–to feed life, but also to damage and destroy it, when the "fire" rages out of control, and oxidizing radical exchanges overwhelm the body's antioxidant supplies.