Oxidation Reduced to Its Radical Essentials

Wellness Foods

Antioxidants have a great reputation for staving off the ravages of time from the human body, but they are not well understood, even by many food industry pros. Read this to get up to speed.

By John K. Ashby, Contributing Editor

Oxidation kills, yet also enables life. Perhaps more precisely, insufficiently controlled oxidation kills, and sufficiently controlled oxidation is how we get our energy to live. And despite the fundamental importance of oxidation to how foods do their work, the concept is often poorly misunderstood by food industry professionals.

The most simplistic definition of oxidation is the addition of oxygen to a given molecule, the combination of which liberates energy. Burning a piece of wood is a visible example of oxidation. When you burn a piece of wood you “oxidize” it. You are starting with the cellulose molecules of the wood that are mostly carbons and hydrogen (with some oxygen), and break these molecules apart by adding more oxygen molecules to them. The end result is water, carbon dioxide and a pile of ash—as well as heat and light generated along the way. The cellulose has been oxidized.

A more precise physical chemistry explanation of oxidation is that you have oxidized the cellulose because you took away electrons from the cellulose. When an otherwise stable molecule has an electron taken away from it, it is not as stable anymore. This weakened (oxidized) molecule can then break, or might stay together until it “breaks” another molecule.

Either way, oxidation causes molecules to change, and that induced change can be very bad. If the oxidizing damage is to DNA molecules in the cell, or to fat molecules holding cells together, or to proteins needed for structure or to fat cells lining the circulatory system, the result is damage.

Good Oxidation?

The controlled burning, or oxidation, of fuel that occurs in the mitochondria of our cells is the source of the energy we need to live. Our bodies (and every other living organism for that matter) continuously run a dangerous and precarious balancing act. The goal is to oxidize the right molecules in the right way at the right rate while minimizing the production of uncontrolled free radicals that can cause untended oxidation and physical damage.

Even if mitochondria are running very smoothly, the process is not 100% efficient. Some small amount of this energy will not be perfectly funneled into creating the energetic molecules our mitochondria are designed to produce. The energy then goes into creating free radicals instead. And the more unbalanced the system is, the more free radicals are produced.

If, in an extreme example, one of the enzymes used in the mitochondria energy production process is destroyed –- the reaction up to that point (leading up to that enzyme’s function) would continue. The energetic intermediate would continue to build up without the enzyme present to use it. This pool of energetic molecules is now available to diffuse away and oxidize any susceptible molecule it encounters. Not to mention that the end product that the mitochondria is attempting to make, that the cell needs, will not be made.

It is clear, therefore, that our bodies produce damaging oxidizing chemicals as a natural by-product. Less when the engine is running efficiently, more when the engine is running inefficiently.

Oxidants Defined

A free radical—or oxidant or oxidizer—is essentially a molecule with an unpaired electron. This unpaired electron is a dangerous thing because it wants to steal an electron from another molecule. When it does steal an electron from a target molecule, that target molecule is oxidized.

Table I lists the basic hierarchy of primary metabolic oxidants—reactive oxygen species, or ROS, that if uncontrolled can produce significant physiological damage. Normal, atmospheric oxygen also is called “triplet” oxygen. If energy is added to this regular oxygen, one of the electrons can be forced into the opposite spin state. This elevated-energy form of oxygen is “singlet” oxygen, a much more reactive and dangerous form.

Superoxide is formed when a regular oxygen molecule accepts an additional electron. Superoxide can either oxidize or reduce (donate an electron to) another molecule, and can create hydrogen peroxide. Hydrogen peroxide can be physiologically useful, but also can lead to extremely reactive hydroxyl radicals, which, in turn, can lead to peroxyl radicals. Peroxyl radicals can cause massive damage to DNA, proteins and to the lipids in cell walls—particularly the circulatory and nervous system.

There are more radicals that our bodies have to deal with (reactive nitrogen species, for instance) but this is the basic set of destructive radicals that our body produces and we have to deal with.

First Line of Defense

Anti-oxidants work by reacting with free radicals before they can damage important molecules (proteins, DNA, fatty acids, etc.). Anti-oxidants are the pawns sacrificed to protect Queen. There are three main mechanisms for this anti-oxidant activity: quenching, scavenging and supporting less inflammatory physiological changes.

Quenching is frequently used in reference to singlet oxygen. Singlet oxygen has an electron that is in an energetic and therefore dangerously oxidizing state. A quenching involves accepting the energy from that energized molecule and returning the original molecule to its resting state. The anti-oxidant molecule now is energized; however, this is of physiological value if the energized anti-oxidant molecule is less dangerous--less reactive--than the original molecule.