Gray hair has a higher susceptibility to damage when exposed to UVA and UVB radiation.
Those with a significant amount of gray hair are keenly aware that it behaves differently than the rest of their tresses. By definition, gray hair is lacking color, leading to less luster and shine. It often doesn't have the same curl pattern or texture as the rest of the hair, which can make it appear unruly. Gray hair may also seem drier and more prone to frizz. However, really well-kept gray hair can be quite attractive. It is very delicate, though, and is especially prone to photo degradation and yellowing when exposed to excessive amounts of sunlight. This tendency is of particular concern as spring approaches, and many plan to spend more time outdoors gardening, swimming, or just basking in the sunshine. Fortunately, being armed with knowledge of the unique risks of sun exposure to gray hair can make it possible to prevent damage and maintain a healthy head of hair. So what does science tell us about gray hair and ultraviolet rays?
Testing and Data
Researchers have done comparative studies on various physical and chemical properties of blonde, brown, and gray hair, both before and after UV irradiation. One notable study examined a wide array of properties, including tensile modulus, tensile strength, wet combing forces, degree of swelling in basic solution, cuticle abrasion, and dynamic contact angle. They also assessed changes in hair color with exposure to UV radiation. All of these properties provided them with indirect information about the biopolymeric structure of the hair strands and how they were affected by the experimental conditions.
What they found was that the gray hair had a much higher susceptibility to damage than did the brown hair when exposed to both UVA and UVB radiation. The samples had a higher loss of mechanical strength, greater color change (yellowing), increased cuticle damage, and exhibited a marked transition from being hydrophobic to hydrophilic at the surface of the hair strands. This meant the gray hair was more likely to exhibit signs of yellowing after exposure, to become more easily tangled, to lose moisture easily, and to break. It was evident to this group that gray hair requires protection if it is going to be in the sun for prolonged periods.
For this reason, these researchers also performed their study using two different UV absorbers that have been used successfully in skin care products. One was octyl methoxy cinnamate (OMC), a commonly utilized sunscreen additive, frequently found in hair care products marketed as being effective for color retention and sun protection. The other ingredient was cinnamidopropyltrimonium chloride (CATC), a quaternized (cationic) UV absorber. Each UV absorber was applied to the hair via a soak/rinse cycle in a simple shampoo-like solution of SLS/sunscreen. The samples were irradiated for specified periods of time and then run through all of the same testing as the ones previously discussed.
Protect your gray or graying hair from sun damage.
The results showed that each UV absorber offered some protection to the hair, as the deterioration in properties was lessened measurably. However, the traditionally used OMC offered substantially less benefit than CATC and really only demonstrated marginal improvement over no treatment at all. It was found that the cationic UV absorber (cinnamidopropyltrimonium chloride) was more substantive to the surface of the hair after rinsing and was much more effective at maintaining the integrity of the hair for every single test. The molecule also had the property of being a mild conditioning agent, and added greater benefit to a formulation than the conventional OMC. CATC worked very well in oil-based leave-on sprays as well as shampoos, and the scientists concluded that it had real potential for helping prevent damage to gray hair (or any hair, for that matter) from the sun.
One important caveat is that it is not really possible to quantify the efficacy of sunscreens used in hair care products in the same manner as for sunscreens intended for skin protection. No standardized methods or tests exist for evaluation of sun protection for hair, and even if there were, consumer variability in application would render much of that type of data useless. Many cosmetic chemists completely dismiss any value to including UV absorbers in a hair product, despite the heavy marketing campaigns insisting otherwise. While I often share their skepticism regarding unlikely claims by manufacturers, this particular study showed that there does seem to be some benefit to formulating with cinnamidopropyltrimonium chloride (at least for the conditions in this particular study).
Scientists have long been interested in how the physical properties of gray hair differ from those of pigmented hair. Unfortunately, for those of us with gray or graying hair, research has shown that it is more susceptible than pigmented hair to various types of damage from UV radiation. Happily though, there does seem to be at least one UV absorber (and certainly others not covered in this study) that can help protect gray hair from damage in the sun. There are several products on the market that contain this ingredient, including Paul Mitchell's Color Protect Daily Conditioner, Soma Hair Technology's Colour Protect Shampoo and their Leave In spray, Kenra Platinum Smoothing Cream, and Aveda's Color Conserve Shampoo, to name a few. Not all of these products are necessarily compatible with the shampoo free method, but some are. Just make sure to check the ingredients list to be certain the product is right for you and your personal preferences. Products like this work best at minimizing incidental daily damage, in my humble opinion, so grab a cute straw hat or a pretty scarf to cover your hair when you plan to be in the sun for an extended time.