Our Cells,
Ourselves

The Fires that Burn Within

In The `60s the term “free radical” would typically have described a 14-wing university activist. Today the term carries a much more scientific nuance. Chemically speaking, a free radical is a molecule or molecular fragment that has an unpaired electron. It is highly unstable and extremely short-lived; in its brief, turbulent existence, it can inflict substantial carnage to other molecules and to the cells that contain them. The Following is a primer an what free radicals are all about and why they have become so prominent in the science of the cell. Learning about free radicals and the process of biological oxidation is paramount to understanding the critical role that antioxidants play in cellular nutrition.

Free radicals are chemical intermediates with a lifespan measured in trillionths of a second or less. Their presence in biological systems was first reported by scientists in the early 1960s[]. Using a special apparatus, they observed exceedingly short-lived events in enzyme-controlled oxidation-reduction reactions, such as take place inside our cells. Because of an unpaired electron, these chemical intermediates are extremely volatile, reacting aggressively with other molecules at the instant of their creation. Oxidation-reduction, chemical intermediates, unpaired electrons -- sounds like pretty boring stuff. It's not: in fact, it's absolutely essential to life itself. So hang in there and I'll explain.

The Miracle of the Cell

Human beings -- the paragon of animals -- biological machines so evolved that our complexity invokes awe in even the most brilliant of scientific minds. Our cells are the building blocks of life, miraculous biochemical factories far more intricate than we can ever hope to envision. It is here that the dance of life bursts fords on a scale of complexity unimaginable. When I ponder life at this most fundamental level, I often envision God as a most supreme biochemist.

Every living second, the magic of life is played out at the molecular level in the thousands of chemical reactions that take place in each or our body's trillions of cells. Life is a constant flow of energy, and in our cells it moves through a transfer of electrons from one molecule to the next. When a molecule gives up electrons it is oxidized. When it accepts electrons it is reduced. Oxidation and reduction, the chemical “yin and yang”, drive the machinery of the cell and let flow the river of life.

Scientists call this process respiration. It begins with a molecule of glucose, the energy source of the cell. Through a long and intricate series of steps, the molecule is broken down into its component parts. Along the way, energy is captured and stored for future use. Electrons are passed along in a complex series of oxidation-reduction reactions to the terminal step, where they combine with oxygen and hydrogen to form water.

So, in simple terms, respiration is really nothing more than controlled oxidation or combustion, much like the burning of wood or the rusting of iron. In our cells, however, each step is controlled by biological catalysts called enzymes. Enzymes allow the “oxidative fires” of the cell to burn at a much lower temperature, but the end result of this biologically-controlled combustion is essentially the same. Hydrogen combines with oxygen to form water and carbon dioxide is released. Paradoxically, oxygen -- the giver of life -- is also our enemy. Wile essential for cellular respiration, oxygen also forms a type of free radical known as singlet of oxygen, a species that is extremely volatile and damaging to the cell.

Oxidative Stress

Oxygen is not the only molecule to form free radicals. During the process of respiration -- the “handing-off” of electron from one molecular species to the next – many other highly reactive free radicals are formed. Scientists now know that excessive free radical formation in cells can be induced through exposure to such things as environmental pollutants, industrial chemicals, agricultural pesticides, cigarette smoke and radiation.

Once created, these highly unstable particles can inflict considerable damage during fleeting existence. Like sparks from a spitting fire chat burn pinholes in your living room carpet, these supercharged particles bounce around the cell, damaging its internal machinery. Punching tiny pinholes in membranes, altering the cell's molecular blueprint (DNA), and tearing apart proteins and lipids (fat), free radicals leave a virtual killing field of destruction in their wake -- nasty stuff with nasty consequences for the cell.

Nature's Fire Wardens

According to Dr. Edward West[]: “It is essential that in biological oxidation-reduction the transfer of [energy] takes place in a manner that controls the potentially destructive effects of free radical formation and conserve biological function…” These fundamental control mechanisms, of which West speaks, lay in the function of the enzymes and cofactor needed for the reactions to proceed, as well as in the cells’ natural defense mechanism – antioxidants.

Antioxidants are nature's fire wardens, complex molecules that police the chemical processes of the cell and ‘snuff out’ the molecular firestorm of free radicals that burst forth like sparks from a burning log. As long as we have sufficient antioxidant stores in our cells, the damage is kept intact. But, if we lack sufficient antioxidant reinforcements, the accumulated carnage of these free radical ‘sparks’ -- like those on your living room carpet -- will damage the delicate fabric of life. Such oxidative damage is now believed to be the dark force behind the onset of degenerative disease. In fact, over 50 degenerative disease processes have. been linked to oxidative stress[]. Dr. Ray Strand, in his recent book, Bionutrition (1998), adroitly calls the battle against oxidative stress “the war within”.

The Antioxidant Revolution

Dr. Denham Harman, in 1954, was the first scientist to theorize that the aging process was caused by free radicals. Until then, free radicals were thought to exist only outside the body. In 1968, his groundbreaking research on the free radical theory of aging showed that a small amount of vitamin E, added to the diet, increased life spans in mice by about five percent[]. At the time, not much was known about the biological relevance of vitamin E; science did not understand what an antioxidant powerhouse this vitamin really is. Research on radiation-induced free radicals and dietary supplementation with vitamin E, conducted in the early `70s, showed that ionizing radiation (gamma rays) damaged cell membranes, causing them to become leaky[]. The work also shed some light on the ability of vitamin E to quench the peroxidation of membrane lipids (a process whereby the oxidization of a fat molecule creates a chain reaction of further oxidation)[].

In 1971, Dr. Richard Passwater became the first scientist to publicly describe the nutritional role of antioxidants. Since that time, research on these important nutrients has grown prodigiously. Today vitamin A, vitamin C, vitamin E, beta-carotene, coenzyme Q10, selenium, zinc, glutathione, alpha-lipoic acid, n-acetyl-cysteinie, proanthocyanidins, bioflavonoids, and many ocher tongue-twisting names, have stepped into the limelight -- free radical fighters against the 10000 or more free radical ‘hits’ that each cell of your body sustains every day. Over a 70-year lifespan, that adds up to some 17 tons of free radicals[].

Symphony and Synergy

As mentioned earlier, antioxidants quench the highly reactive molecular fragments, called free radicals, stopping them dead in their cracks before they can cause structural damage to the cell. They do this by scavenging the unpaired electron from the free radical, rendering it harmless. In the process, the antioxidant itself is chemically altered. Some antioxidants can be regenerated, while other antioxidants are converted to different compounds or excreted from the body. Your body produces some antioxidants, but others must be obtained through the diet.

The endogenous antioxidants (those manufactured by the cell) generally include the enzymes, coenzymes and sulfur-containing molecules such as glutathione. The dietary antioxidants include vitamin A and the related carotenoids (including beta-carotene), vitamin E, vitamin C and the myriad of bioflavonoids and sulfur-containing compounds derived from fruits and vegetables. There are also a number of minerals that, while not themselves antioxidants, form vital parts of the different antioxidant systems in the body. These include selenium, iron, manganese, copper and zinc[].

When people debate which antioxidant is the best or which one is the ‘magic bullet’, they are missing the point. Just like firefighters on the front line, who replenish and reinforce one another, free radical fighting antioxidants work best when they work together. This is known as synergy, an idiom coined by Passwater, which denotes the fact that antioxidants work as a team, where the effect of the whole is greater than the sum of its parts.

They also work in different areas of the cell. Vitamin E is the premier antioxidant of the cellular membrane, quenching free radical-induced lipid peroxidation within the membrane itself. Vitamin C is king in the extracellular fluids and works alongside glutathione in the cytoplasm (fluid) of the cell. Both vitamin C and vitamin E, along with selenium, enhance the effect of beta-carotene. Coenzyme Q10 works deep within the mitochondrion (the powerhouse of the cell), assisting in the energy transfer reactions and rejuvenating vitamin E. Together with vitamin E, coenzyme Q10 protects the mitochondrial membranes from the ‘fires that burn within’.

Alpha-lipoic acid, along with a Family of powerful antioxidants called proanthocyanidins
found in grape seed and pine bark extracts), regenerates vitamin C, which in turn rejuvenates vitamin E. Working together, these free radical fighters toil in their daily battle, protecting the cell in a symphony of synergy.

It's a masterpiece written by Mother Nature.