Antioxidants in Hair Care Products

Most of us have been recipients of much indoctrination regarding the benefits of antioxidants, both for our health and our appearance. Eat your multi-colored vegetables, drink your freshly-obtained green juice, take your vitamins, and slather on expensive skin creams loaded with these nebulous molecules, and you will be fit, appear young, beautiful, active and healthy, right? With claims like these, it seemed inevitable that hair care products showcasing these materials would make their debut on the shelves of hair salons, health food stores, and drug stores, and of course, this is the case, especially in the natural market sector.

But are these ingredients truly beneficial when used in topically applied hair care products, or are they simply a clever marketing strategy with minimal effects? A consumer armed with knowledge of what oxidative damage is, how it occurs, and what can be used to protect against it has the advantage when evaluating product claims and making purchases.

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What is oxidative damage?

Oxidation is the process whereby a molecule loses an electron and is cleaved into its substituent atoms or groups. Some of these species are left having an unpaired electron in their outer shell, which leaves them in a highly unstable and reactive state, as they are driven to complete their outer shells via pairing all electrons. These are called free radicals or reactive oxygen species (ROS).

In order to complete its outer shell of electrons, the free radical will attack adjacent molecules and abstract an electron from them, generating a new radical which is also unstable and seeks to “steal” an electron from its neighbors. This initiates a chain reaction, which is the basis of many polymerization reactions, but which can also be very destructive to living cells and systems. These free radicals can attack cell lipid layers, DNA, proteins, and many other essential structures, disrupting key biological processes and resulting in aging, decreased function, and pathological processes such as cancer.
Hair is not comprised of living cells, but its keratin-based structures are still susceptible to oxidative damage from a wide variety of sources. This damage leads to split ends, broken hairs, rough cuticles, frizz, tangling, lack of luster, diminished curl retention, and loss of color (natural or artificial). Identification of the many sources of free radical exposure can help a curly to reduce their overall risk of accumulating this type of structural degradation.

Exposure to ultraviolet radiation is one frequent route for oxidative damage, where the sun’s rays penetrate the hair shaft and deplete the natural melanin resident in the cortex and also alter the protein structures of both the cuticle and cortex. Chemical processes, particularly bleaching and permanent dyeing are culprits in the depletion of natural melanin and creating substantial oxidative damage. Additionally, relaxers, perms, keratin treatments, and heat styling contribute to formation of free radicals, which attack both the lipids and the proteins in the cuticle structures. Exposure to ozone, pollutants, tobacco smoke, substances in our water, as well as radiation all add to the continual exposure to free radicals and their damaging processes. Damage is pervasive and cumulative, and damaged hair becomes more porous and even more vulnerable to oxidative damage. For this reason, prevention and minimization are critical to preserve the health and beauty of hair.

Common Antioxidants
Vitamin E (α-Tocopherol)
Beta Carotene
Vitamin C
Vitamin A
Phytochemicals
Plant extracts (green tea, grape seed extract, lemongrass, oolong, kiwi)
Selenium
Trace minerals

How Do Antioxidants Work?

We know from advertisements and reports in the media, as well as from more academic sources, that antioxidants are the key to dealing with this constant attack from free radicals, but what exactly is their role in the process? Antioxidants mitigate and prevent damage to cells and structures from free radical and reactive oxygen species by putting the brakes on the chain reaction that destroys everything around it. The mechanism by which they achieve this varies, depending upon the antioxidant, but generally it is accomplished via an electron or hydrogen donor process. These molecules are called free radical scavengers.

One common antioxidant is Vitamin E (α-Tocopherol), which donates an electron to an unstable free radical, rendering it stable, but becoming oxidized itself. However, rather than becoming a participant in the free radical chain reaction, the oxidized version of α-tocopherol is then either excreted or regenerated via reduction (hydrogen donation) by Vitamin C (ascorbic acid).

Effects for Hair?

While it is well-established that antioxidants are highly efficacious both when taken internally and applied to the skin via cosmetic preparations, it is natural to speculate whether or not they have equal value when applied topically to the hair, which is not a living cellular structure. Fortunately, the evidence indicates that there is plenty of benefit to be derived from the inclusion of antioxidants as components in formulations for rinse-off products, leave-in conditioners, and styling agents.
Vitamins and vitamin precursors such as Vitamin E, Vitamin C, and beta carotene have been found to have protective effects against environmental free radical assaults on hair. In a manner similar to sunscreens, these materials form a sort of interactive molecular shield against the elements, at least temporarily. By preventing the destruction of melanin and synthetic dye molecules in residence in the cortex of the hair strand, free radical scavengers can be quite useful in improving color retention and maintaining the health and integrity of hair. Experiments have also generated data that demonstrates the efficacy of topically applied antioxidants in mitigation of damage from both coloring and heat processes.

Oil soluble vitamins such as α-tocopherols and beta-carotene and vitamin A and lipophilic plant extracts are the more common antioxidants found in hair care preparations. The reason for this is that due to exposure to air many reactive oxygen species are generated in the aqueous phase in the bottle of product, where water soluble vitamins such as ascorbic acid (Vitamin C) would be present. The ascorbic acid is then rapidly depleted via oxidation reactions with the free radicals, and is thus comparatively short-lived in its availability to perform its preferred function on the hair.
One method chemists have used to circumvent this problem has been esterification of the ascorbic acid, which converts it to a lipophilic substance and increases its duration of efficacy. However, this additive is more expensive and diminishes its potential to scavenge radicals in the aqueous phase when hair is wet, which is when it is needed.

Furthermore, it is the assertion of research chemists at Mibelle Biochemistry in Switzerland that the inclusion of both water soluble and oil soluble antioxidants provides the best range of protection. For this reason they have been developing methods to include more stable water soluble antioxidants and blends (such as grape seed extracts + α-tocopherols) that provide highly effective protection of the cuticle and cortex, even in rinse-off products. Another research team has taken the approach of encapsulating ascorbic acid in micelles comprised of a nonionic surfactant (Polysorbate 80) and mixed tocopherols. This nanoemulsion is supplied as a gel-like aqueous solution that is easily mixed into a formula. The Vitamin C remains protected and active for a greater duration due to being in the interior of the micelle.

Conclusion

Our hair is being constantly bombarded by reactive species of molecules that slowly tear apart the very complicated biopolymeric structure of each strand. Without adequate protection, especially for longer hair, the damage grows continually worse until it becomes very evident. Color fades quickly. The surface becomes rough and porous. Tangles, breakage, and frizz become the norm. Curly hair, which has a rougher surface than straight hair is even more susceptible to this type of degradation. Fortunately, it has been found that some botanical oils, vitamin E, vitamin C, and beta carotene do indeed provide some protection against these environmental sources of free radicals. They also provide emollient properties and other benefits to the hair, and thus seem to be good additions to products for curly hair. They are not substitutes for wearing a hat and treating your hair kindly though, so protect those tresses!

References-
[1] F. Zülli, E. Belser, M. Neuenschwander & R. Muggli, Antioxidants from Grape Seeds Protect Hair Against Reactive Oxygen Species, Mibelle AG, Switzerland, http://www.mibellebiochemistry.com/publications/gsp-tantioxidants.php
[1] Behnam, Dariush (Rossdorf, DE), Aqueous solution of ascorbic acid and method for producing same, United States Patent 6774247, 2004, AquaNova German Solubilisate Technology (AGT) GmbH (Darmstadt, DE) http://www.freepatentsonline.com/6774247.html