We come into this world with healthy cells, but every day the negative effects of free radicals add to the damage of the previous day. In fact, many of the processes we call "aging" are simply evidence of the minute, cumulative effects of free radical damage on cells and tissues in the skin, heart, blood vessels, brain, and so forth. What are free radicals and, more importantly, how can free radical damage be prevented? The answer lies with antioxidants, the molecules that fight free radicals.
What Are Free Radicals?
Free radicals are highly reactive, unstable molecules that cause damage to healthy cells, leading to internal aging as well as visible signs of external aging. Each day, our young, healthy skin is exposed to trillions of free radicals; they are created inside our bodies through normal, necessary chemical reactions and all around us through pollution, UV radiation, x-rays, stress, strenuous exercise, and smoking. Smoking in particular can be harmful: each cigarette releases ten quadrillion free radicals into the lungs. This is why smokers age so much faster than nonsmokers.
Overexposure to free radicals damages not only our cells' ability to function, but also the integrity of our cells' overall composition, resulting in a next generation of cells that is less healthy and less productive than the cells they came from. In the case of our skin, cells exposure to free radicals can mean that over time our fibroblasts—the cells responsible for collagen and elastin production—work less efficiently to produce the skin protein necessary for skin smoothness, firmness, and elasticity. Although this decrease in collagen and elastin production happens gradually beneath the outermost surface of our skin, it becomes visible sometime in our late 20s or early 30s when we look in the mirror and discover our first wrinkle.
Free radicals damage lipids, proteins, and DNA (DNA is present in the nucleus of almost every cell, stores all genetic information, and dictates cellular functions). This damage is the root cause of aging. Every day, the DNA in a single cell receives thousands of free radical assaults. While our cells have repair enzymes that fix most of this damage, unfortunately, as we get older, the delicate balance between damage and repair becomes uneven. When cells with damaged DNA replicate, they create cells with imperfect structure and a compromised ability to function.
In addition to the molecular DNA damage that free radicals create, they also cause damage to other basic cellular structures such as mitochondria, the structures inside the cell responsible for cellular energy production. Think of the cell as a small factory. In this factory, thousands of mitochondria act like tiny power generators that enable the cell to function properly.
When scientists talk about the effect of free radicals on cellular components, such as DNA or mitochondria, they say the structure has been "oxidized." When free radicals oxidatively damage cell structures, the health of the entire cell is weakened. For more information on how free radicals work, see Technical Appendix A at the end of this article.
Antioxidants Are Anti-Aging
Despite the seemingly overwhelming assault of free radicals on our healthy cells, there is a line of defense. Antioxidants are a category of nutrients that have the ability to defend our cells by fighting cell-damaging free radicals. Since free radicals are created both in the environment and in our bodies, a continuous supply of antioxidants is critical for internal and external health and longevity. By defending our cells against free radicals, antioxidants can help slow the internal and external aging processes.
Just as health and nutrition experts recommend a high intake of antioxidants from a variety of fruits and vegetables and nutritional supplements, skin care experts are now recognizing the anti-aging benefits of topically applied antioxidants. Some skin care products offer antioxidant benefits directly to the skin by including antioxidant-rich vitamins and extracts in their formulations.
There are hundreds of known antioxidants, many of which are plant derived. In order to protect their constantly exposed tissues from free radicals, plants have developed free radical fighting phytochemicals as a natural defense system. Every plant contains hundreds of phytochemicals, many of which provide antioxidant protection and fulfill many other essential functions.
Antioxidants work together to fight free radicals directly or to regenerate and support other antioxidants; in other words, antioxidants rely on a network for protection and support. In the antioxidant network, carotenoids are the first line of defense. By destroying free radicals, carotenoids protect and enable other antioxidants to perform their more specific and critical functions.
Carotenoids are a major class of phytonutrients responsible for many of the red, orange, and yellow hues of plant leaves, fruits, and flowers. Examples of carotenoids include beta-carotene, alpha-carotene, lutein, and lycopene. These are natural fat-soluble pigments found principally in plants and algae, where they play a critical role in protecting and aiding the photosynthetic process.
Carotenoids are sometimes referred to as the "first line of defense" because they provide critical antioxidant protection to cells and other antioxidants by absorbing or "blotting up" large amounts of attacking free radicals. This absorption allows other antioxidants to function in more specialized ways. While carotenoids have typically not been included in skin care products due to their intense color, a unique form of colorless carotenoids with enhanced UV protective properties has been discovered.
Just as plants produce lipid soluble carotenoids to protect cellular structures composed mostly of lipids, plants also produce phenolic compounds to guard their tissues against free radical damage. These compounds can be fat- or water-soluble. Examples of phenolic compounds include hydroxytyrosol in olive oil and polyphenols found in strawberries.
Flavonoids are a class of polyphenolic compounds. It is estimated that there are over 600 different flavonoids present in foods and beverages. Some common flavonoids are catechins (green tea), quercetin, proanthocyanidins (grape seed extract), and soy isoflavones. Flavonoids provide increased cell protection for the DNA as well as promote the repair of DNA damaged by free radical oxidation.
Vitamins and Other Key Antioxidants
The core of the antioxidant network includes powerful antioxidants such as CoQ10 and vitamins C and E. In addition to their free radical fighting properties, these antioxidants have other functions that allow them to make critical contributions to our health and longevity.
Vitamin E is one of the body's most important fat soluble antioxidant nutrients. Vitamin E protects healthy cell membranes (largely composed of fatty acids) from oxidative free radical damage. There are eight natural forms of vitamin E (four tocopherols and four tocotrienols).
Vitamin C (ascorbic acid) is water soluble, enabling it to scavenge free radicals in aqueous (watery) environments, such as the inside of our cells and extracellular body fluids. Vitamin C works synergistically with vitamin E to quench free radicals and also works to regenerate vitamin E, keeping it active.
Other key antioxidants include coenzyme Q10 and alpha lipoic acid. Alpha lipoic acid is a naturally occurring molecule in plants and animals that has the ability to neutralize free radicals. Another important function of alpha lipoic acid is its ability, when applied topically, to improve skin tone and texture. Coenzyme Q10, or CoQ10, is found naturally in our cells; however, CoQ10 levels in the body have been shown to decline after age 20. Highly concentrated within the cell's mitochondria, CoQ10, like vitamins C and E, quenches free radicals and helps regenerate other antioxidants. For more information on how antioxidants work, consult Technical Appendix B at the end of this article.
In summary, free radicals are highly unstable, reactive molecules that damage the DNA within cells. This damage is passed on to newly replicated cells. Over time, genetic damage builds up and interferes with healthy cell function. Fortunately, antioxidants, the natural compounds found in fruits and vegetables, neutralize the negative effects of free radicals. Some key antioxidants include vitamins E and C, carotenoids, flavonoids, alpha lipoic acid, and CoQ10. Antioxidants are a true defense in fighting the assault of free radical damage on healthy cells.
Technical Appendix A: How Free Radicals Function
Free radicals are unstable, highly reactive molecules because they have one or more unpaired electrons. In order to stabilize themselves, free radicals seek ways to pair their unpaired electrons. To do this, they may steal electrons from other stable molecules. This can cause the secondary molecule to become a reactive, unstable free radical. Having lost its electron, these secondary molecules become free radicals that in turn steal electrons from other molecules. This cascading effect sets off a free radical chain reaction of molecular destabilization. Free radical chain reactions can continue indefinitely, ultimately damaging millions of cells. Much of what is damaged by free radicals are DNA, lipids, and proteins that makeup the cellular structures in our bodies. Among other serious consequences, this damage leads to side effects associated with skin aging, such as poor cell renewal, and slowed collagen and elastin production.
Technical Appendix B: How Antioxidants Work
Antioxidants are stable molecules with electrons to spare; they also have the ability to receive extra electrons. Antioxidants are nature's defense against the damaging effects of free radicals. They guard cellular structures and DNA against electron-scavenging free radicals. Antioxidants can donate or receive electrons to neutralize free radicals, stopping the cascading effect of oxidation.