Antioxidants: How They Protect Our Cells 10/03

Juvenon Health Journal volume 2 number 10 October 2003

By Benjamin V. Treadwell, Ph.D.

It’s likely that anyone who pays even passing attention to his or her health is aware that antioxidants are generally good for us. But what are they, really? How do antioxidants work? Are some better than others?


Before we get to the “anti” part of the story, let’s begin with the oxidants that the “antis” fight. The sun is a source of oxidants familiar to all. Its effects on manufactured products are well known. Colors fade in clothing, plastics, and on painted surfaces. The rubber tires on your car harden and then crack. The sun essentially takes the life out of the products exposed to its rays.

This happens because sun’s ultraviolet rays disrupt the chemical bonds that hold together materials such as rubber and plastics. Electrons in pairs characterize these bonds. The sun’s energy agitates the electrons and splits off some of them, leaving disrupted or broken bonds with, figuratively speaking, jagged ends characterized by a single unpaired electron. The unglued or broken bond with its single unpaired electron is an oxidant. And it doesn’t like the single life. It aggressively pursues a mate, another electron to pair-up with. The result is an attack on a chemical bond in the vicinity of the ruptured bond. The single electron ends up with a mate, but only by breaking up an existing pair, and thereby propagating another oxidant, or free radical. This series of events unfolds in chain-reaction fashion until the attacked material is completely oxidized (bleached and weakened fabric, or cracked rubber tire).

In the case of paint, rubber and fabrics, chemists have figured out ways to prevent, or at least inhibit oxidation by adding specific antioxidant compounds to the materials during their manufacture. These compounds safeguard the material through their greater susceptibility to oxidation than that of the materials they are protecting. When they are oxidized, their chemical structure stabilizes the unpaired electron. Thus they prevent and/or terminate the oxidant-induced chain of reactions and protect the material in which they are imbedded.

What About Human Cells?

Living tissue requires protection from environmental oxidants (the sun, smoke, pesticides, drugs etc.), as well as oxidants produced as by-products of normal metabolism. However, oxidants, including free radicals, are necessary for numerous reactions involved in cellular energy production and survival. Since the oxidation reactions necessary for normal cell health are tightly confined to specific cellular machinery known as enzymes, the antioxidants normally present in the cell cannot breach their domain. For this reason it is difficult (but not impossible) to overdose on most essential antioxidants.

Approximately 1-2% of the oxygen taken in through the lungs and used by the body to produce energy is released from the enzyme confines as nasty free radicals. This amounts to a whopping 20 billion molecules of free radicals produced by each cell per day. These molecules are the targets for the antioxidants that our bodies need to maintain cellular health.

Free radicals – toxic oxidants that are produced by our cells and that escape the antioxidant defense – are the basis for the free radical theory of aging. This theory, first proposed by Denham Harman in the 1950’s, states that free radicals are generated during normal metabolism, predominantly in the mitochondria, where virtually all the cell’s energy is produced. A certain percentage of these reactive radicals combine with and oxidize important cellular structures, thereby impairing their activity.

The effect of this process is cumulative and is exhibited by an age-associated decrease in the overall health and dynamic state of the organism and eventually culminating in death. The theory has evolved into the mitochondrial theory of aging. It has four key elements:

  • The mitochondria use the most oxygen in the production of energy and therefore are believed to be the major source of free radical production.
  • The mitochondria are more susceptible to damage by free radicals because of proximity to the components involved in their production.
  • The genetic code of the mitochondria is unique in that, unlike nuclear DNA, it lacks substances (histones) to protect it from free radical attack.
  • The machinery specialized for repair of the mitochondrial DNA damaged after free radical assault is much less efficient than its nuclear counterpart.

Fighting the Oxidants

To disarm the oxidants, our bodies use antioxidants that are either produced by our tissues or absorbed from the foods we eat. They divert the attack of free radicals from vital cellular components to the more oxidant-prone antioxidant. They, too, form free radicals when oxidized, but the odd reactive electron is dispersed over the specialized structure of the antioxidant, thus stabilizing it.

Scientists previously thought the organism excreted usurped (oxidized) antioxidants. Researchers have shown, however, that biological antioxidants are recyclable, unlike those added to synthetic materials such as paints and plastics. Work performed in the laboratories of Dr. Lester Packer (a member of Juvenon’s Scientific Advisory Board) and others has demonstrated the existence of a rechargeable antioxidant system utilized by our cells.

Which Antioxidants Are Best?

Two general types of antioxidants work together to protect the cells and tissues of our bodies. One type protects the aqueous (watery) portion of the tissues and the other the hydrophobic, or lipid (fatty) component. The aqueous environment is protected by vitamin C, and at least two additional antioxidants produced by tissues, glutathione and thioredoxin. Cell membranes are protected by the lipid-soluble antioxidants, including vitamin E, and CoQ10. Another antioxidant, alpha lipoic acid, is unique in that it can enter and protect both lipid and water environments.

When vitamins C and E react with and neutralize a free radical, the oxidized or spent vitamins are converted back to the reduced or recharged, active form. Vitamin C can donate electrons to oxidized vitamin E and convert the E back to its active state, leaving vitamin C oxidized. Vitamin C, in turn, can be recharged after reacting with glutathione or the more potent antioxidant, alpha lipoic acid.

The most versatile antioxidant in the cell is alpha lipoic acid. It is one of the more potent antioxidants, owing to its property of being the most easily oxidized. Alpha lipoic acid is the foundation of an antioxidant network involved in the conversion of the spent or oxidized forms of four different cellular antioxidants back to their active protective forms. The obvious questions, then, are how lipoic acid is regenerated and whether this process ever ends.

The answer lies in the unique property of lipoic acid, its solubility in both water and lipid. Lipoic acid can be converted from its oxidized state to its reduced state with the aid of a mitochondrial enzyme (the organelle within the cell where energy is produced). Unlike vitamins C and E, the cell has machinery specifically designed for the regeneration of reduced lipoic acid. Therefore, lipoic acid can itself react with and neutralize free radicals in addition to recycling vitamins C and E (as well as CoQ10, glutathione and thioredoxin). This is critical, since each antioxidant has a unique function. The conclusion, then, is that all of these antioxidants are required for optimal cellular health.

Scientists used to think that once an antioxidant disarmed (the technical word is “reduced”) a toxic oxidant, it was spent, and therefore excreted from the cell and eventually from the body. Over the past decade, however, a growing understanding has emerged of a complex cellular recycling system that “rearms” major antioxidant molecules, such as vitamins C and E. Alpha lipoic acid plays a central role in this recycling system.

Study of cellular behavior under oxidative stress, induced by exercise, has been central to learning the details of oxidant and antioxidant behavior within the cell. The seminal article describing the complex biochemical processes that make up the antioxidant defense network was written by Juvenon Scientific Advisory Board member Dr. Lester Packer and his colleague Chandan K. Sen. It’s not light reading, but it has shed a lot of light on our understanding of cellular health.

This Research Update column highlights articles related to recent scientific inquiry into the process of human aging. It is not intended to promote any specific ingredient, regimen, or use and should not be construed as evidence of the safety, effectiveness, or intended uses of the Juvenon product. The Juvenon label should be consulted for intended uses and appropriate directions for use of the product.

Dr. Treadwell answers your questions about Juvenon™ Cellular Health Supplement

QUESTION: I take two Juvenon pills a day. Since the alpha lipoic acid in the combination recycles antioxidants like vitamins C and E, should I reduce my intake of C and E?
G. R., via email

ANSWER: The alpha lipoic acid does recycle several antioxidants, including vitamins C and E, as well as glutathione and some others. However, I don’t think it is necessary to cut back on your vitamin C or E. Both are quite non-toxic as long as you are taking less than 1,000 IU of vitamin E per day. Most of the excess vitamins, especially those that are water soluble, are eliminated by the kidney.

Benjamin V. Treadwell, Ph.D., is a former Harvard Medical School associate professor and member of Juvenon’s Scientific Advisory Board.