As iron oxidizes, the result is rust. As faces oxidize, the result is chronic inflammation leading to the appearance of aging.
The Tin Man in Wizard of Oz seemed more concerned about his oxidizing joints and his lack of brain than his oxidizing face. But then he was not applying daily doses of “massively oxidizing“ chemicals to his face. Which may indicate he wasn’t that lacking in smarts! (cue theme song – “If I Only Had a Brain”)
Let’s talk about oxidation. Is rusting metal really an apt metaphor for aging skin? If we peer down to the cellular level, we see that the decay process in metal and the decay process in skin are not all that dissimilar. In both instances it starts with oxygen, (key to life, and to death) interacting with other elements. Combustion. Making heat from light, or fuel, or just getting irradiated by the sun. Too many electrons get produced. That’s a problem. A game of dodge the electrons. Free radicals, the culprit in cell and DNA damage. Nasty, inflammatory molecules create a firestorm within. Thankfully, we have good natural defenses against these evildoers. Not just “antioxidants” (although they are a first line of defense) but also a complex immune apparatus that kicks into play when damage has been done. But if that gets out of hand, then inflammation can result. So our defense themselves are a bit of a two-edged (rusty) sword. And of course the whole balance tips with increasing age. Dilemma!
Antioxidants been touted for years as a cure all for just about every malady that plagues humanity. Fortunes have been made selling juices, pills, nutritional supplements, and skin care products yet if you ask the average person what anti-oxidants are, what they do, and how they do it, you’re more likely to get a blank stare than an explanation. And what good are anti-oxidants slathered on the skin, anyway? For this post, let’s focus on the basics of oxidation, and the role of anti-oxidants. We can do a deep dive into inflammation next time around.
To tell the story we have to start at the beginning.
The Periodic Table and Electronegativity
The periodic table consists of 118 different elements. All of them below uranium (element #92) exist in nature; the others are manmade and have been created in laboratories and nuclear accelerators. Less than 1/3 of the naturally occurring exist in their pure elemental state because most have some level of reactivity that causes them to combine with other elements to form compound substances. They do this by donating or accepting electrons. The reactivity of elements varies with some so reactive they are never found in nature in the uncombined state.
The electronegativity of an element reflects it “willingness” or “power” to donate or accept electrons. The greater the electronegativity, the more attraction it has for electrons. When you take two elements with differing electronegativity and connect them with a conducting substance (e.g. metal wire or electrolyte solution), electrons will flow from the element with the lesser electronegativity to the one with the greater. This is how a battery is created. The principle of electron flow powers watches, flashlights, and electric cars. Below, you will see that it also powers life.
Although the halogen fluorine has the most electronegativity of any element, it is oxygen, the second place electron acceptor that plays the critical role in producing energy in biological systems. How is the energy “stored” in the first place? Hooray for photosynthesis!
The radiant power from the nuclear furnace of the sun is harnessed by green algae and plants and used to “push” electrons from oxygen against the electronegativity gradient down to carbon. This process creates the fuel of life, otherwise known as food. Plants and algae obtain carbon from carbon dioxide from the environment and use it to build tissues (stems, leaves, roots, fruit, etc.) Elemental oxygen is “exhaled” back into the environment.
This is the ultimate source of all food. Animals that eat plants become the food for animals that eat other animals. Whether in the form of carbohydrates, fats, or proteins, all food starts with a sunbeam. Natural gas, petroleum, and coal are also storage forms of sunlight but when oxidized, they rapidly produce huge amounts of energy (heat and light), amounts utterly incompatible with life. Biologic systems must extract energy in small incremental and sequential chemical reactions, shuttling electrons from higher to lower states of energy in manageable baby steps. The common oxidizer that unleashes the stored energy that propels an aircraft, cooks a meal, or throws a fastball is oxygen.
Oxygen is life sustaining. We all know about the need for our blood to carry oxygen to our tissues and that some organs, particularly the brain, are exquisitely sensitive to oxygen deprivation. The cellular machinery that enables our neurons to create and transmit the electrochemical signals that move muscles and maintain consciousness requires the constant production of biological energy. Neurons have very high metabolic rates and produce energy the same way other cells do, by oxidizing fuel (glucose) within small intracellular structures (organelles called mitochondira. Unlike skin or fat cells that can survive for hours without oxygen, however, neurons show their disdain by ceasing to function after only a few seconds (unconsciousness) and by undergoing irreversible damage within minutes (brain death.)
Apples “Rust” and So Do We
Oxygen can also cause damage. Oxygen is very indiscriminate in what it oxidizes, and the more oxygen available, the faster the process. Sustained exposure to high levels of oxygen leads to pulmonary and retinal damage, seizures and eventual death. Even steel wool burns ferociously in 100% oxygen.
Like a fire throwing off embers, the oxidization of glucose throws of embers, albeit of a different kind – reactive oxygen species, also called ROS or “free radicals”. These oxygen containing molecules have un-paired electrons which makes them highly unstable. They indiscriminately “attack” nearby molecules in order to grab the missing electron. This, in turn, creates another ROS that steals another electron. The process can continue for generations. External factors can also create ROS. The common causes are pollutants, tobacco, smoke, drugs, and solar radiation.
ROS can damage all cellular components from nuclear DNA to cell membranes and everything in between. The damage caused by ROS leads to a state of chronic inflammation which is a proved causative factor in the aging process.
Anti-oxidants to the Rescue (sort of)
Because ROS pose a constant threat to the function and survival of cells, Mother Nature has developed intrinsic systems whose sole purpose is to prevent the damage caused by ROS. They do this by supplying electrons that neutralize ROS.
(Note that antioxidants are intended to provide a protective function against ongoing damage. They do not undo damage that has already occurred.)
There are several naturally occurring enzymatically based antioxidant systems, each capable of neutralizing ROS. Oxidative stress occurs when the endogenous ability to cope with ROS is exceeded and is considered a causative factor in nearly all conditions and diseases associated with aging. This is particularly true of photoaging and cancer of the skin.
The major endogenous antioxidants are superoxide dismutase, catalase, and glutathione peroxidase. The levels and composition of endogenous antioxidant molecules differ from tissue to tissue and by cell type. It is possible to overwhelm the body’s antioxidant capability, especially if environmental factors (sun exposure, smoke, toxins, etc.) are substantial. Changes during aging also contribute to the decline in endogenous antioxidant defenses.
How Topical Antioxidants May Defend Against Free Radical Damage
Vitamins C and E are thought to protect the body against the destructive effects of free radicals by donating one of their own electrons, thus ending the electron-“stealing” reaction. The antioxidant nutrients themselves don’t become free radicals by donating an electron because they are stable in either form. Instead, they act as scavengers, helping to prevent cell and tissue damage that could lead to cellular damage and disease.
Vitamin E is the most abundant fat-soluble antioxidant in the body and one of the most efficient chain-breaking antioxidants available. It is the primary defender against oxidation. Primary defender against lipid peroxidation (creation of unstable molecules containing more oxygen than is usual).
Vitamin C is the most abundant water-soluble antioxidant in the body and acts primarily in cellular fluid. It is of particular value in combating free-radical formation caused by pollution and cigarette smoke.
Other antioxidants of potential value are selenium, zinc, silymarin, soy isoflavones, and tea polyphenols. Their topical use may favorably supplement sunscreen protection and provide additional anticarcinogenic protection.
Good News, Bad News
So there you have it. good news is topical anti-oxidants do have value in preventing damage from the effects of oxidative stress on the skin. The bad news is you should have asked this question many years ago so you could have prevented damage from ROS. It’s way too late to undo the damage now.
Lin JY, Selim MA, Shea CR, Grichnik JM, Omar MM, Monteiro-Riviere NA, Pinnell SR. UV photoprotection by combination topical antioxidants vitamin C and vitamin E. J Am Acad Dermatol. 2003 Jun;48(6):866-74.