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Skin Diversity Explained

Contact Author Pascaline Criton and Olga Gracioso
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In 2013, only 1.13% of all personal care productsa launched around the world made ethnic claims. This is not surprising, as non-white people represent the majority of the world’s population. Asians in particular represent more than half of the total. However, the current knowledge of cutaneous physiology and pathologies is based on studies performed on Caucasian skin. There are differences in skin function and reactivity based on ethnicity, which is why more and more skin care brands offer dedicated product ranges formulated to target these specific needs. The following is an overview of the physiological differences that are less visible than color and important for understanding how to best address various skin care needs.

Asian Skin Specificities

Two-thirds of ethnic personal care productsa launched worldwide during 2011–2013 were intended for the Asian market. This large preeminence is due to the number of whitening products launched in the region, combined with the increased purchasing power of consumers in China. Beyond their well-known enthusiasm for whitening products, individuals with Asian skin face other specific concerns due inherent yellow pigmentation. Indeed, it appears that this skin type is less resistant to mechanical stress and therefore more sensitive to environmental aggressions and irritants (i.e., pollution). The reason for this is a thinner, less resilient stratum corneum, which is composed of fewer and less cohesive corneocytes than Caucasian and Black skin;1 while Asian skin has high levels of ceramides, they are not sufficient to offset the smaller number of corneocytes. Asian skin also is more sensitive to exogenous chemicals, probably due to a higher eccrine gland density, compared to other skin types.2 Regarding water content in the stratum corneum, it has been reported that Asian subjects have lower levels of Natural Moisturizing Factor (NMF), compared with Caucasians and African-Americans,1 which leads to reduced hydration.

Skin pigmentation also dictates many of the changes in skin associated with aging. Since Asian skin is one of the fairest-colored and thus less protected by melanin, one could expect it to present evident modifications after UV exposure. However, it seems that Asian skin is less affected by skin wrinkling from photo-aging than Caucasian and African-American skin.3 This finding suggests that Asian individuals, and more particularly East Asian, have mechanisms other than melanin photo-protection to reduce the negative effects of UV irradiation on skin.

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Differences in facial muscle positioning, content and their movements, as well as diet, may also contribute to UV protection. Indeed, consuming fish oil can deliver a sun protection factor of up to 5.4 Another explanation could come from the dermis of Asian skin having more collagen I than other groups. Nevertheless, regarding photo-aging, it is generally admitted that Asian skin is prematurely marked by irregular pigmentation and spots.5, 6 This observation has led to tremendous progress in understanding the signaling processes involved in hyperpigmentary responses of different racial groups, notably those involving the protease-activated receptor-2 (PAR-2).7 Today, some specialized active ingredients are available to efficiently address these specific skin care needs. Měiritage by Sederma, for example, is an anti-aging active designed to answer the problems associated with Asian skin: pigment spots, dehydration and sensitivity to external aggressions. This ingredient is based on three root extracts that were selected according to the principles of Traditional Chinese Medicine.

Black Skin Specificities

Findings regarding the stratum corneum of Black skin are the opposite of those for Asian skin. In general, Black skin exhibits the least TEWL and highest water content, with the lowest lipid levels.8 One study found no significant differences in corneocyte size between Black, White and Asian subjects;9 however, the same study demonstrated that the spontaneous desquamation rate was approximately 2.5 × greater in Black subjects vs. the two other groups. Due to this enhanced spontaneous desquamation, tape-stripping initially revealed a weaker barrier in Black skin when only a few strips were used. With further tape-stripping, though, Black skin apparently has a stronger barrier, presumably due to its increased cohesiveness.1, 10 This increased cell cohesion may also explain the reduced potential for irritation in Black skin from a variety of chemical stimuli.11

Many dark-skinned individuals are affected by ashy skin. This can be described as the physiological skin condition where light reflectance on extremely dry and flaky stratum corneum cells of dark skin results in a dull, ashy appearance. It is induced by environmental influences, in particular dry weather, and by reduced epidermal cathepsin L2 levels in subjects of colored skin.12 For these reasons, Black skin requires personal care products formulated with strong moisturizing ingredients such as Sederma’s Moist 24, which has been demonstrated to improve hydration levels by 58% after one hour, and still by 30% after 24 hours in volunteers having type IV skin (melanin index ~ 631).

Other main features of Black skin are its greater pore size, increased number of apocrine and apoeccrine glands, and higher sebum secretion,2, 3 compared with other ethnic groups. This probably accounts for the developed microbial flora present on dark skin.13 Therefore, this skin type would likely benefit highly from skin care products offering pore-size and sebum-secretion reduction, as well as control over bacterial proliferation.

Last but not least, darker-pigmented skin shows dermatological signs of aging later than lightly pigmented skin—usually not until the late fifth to early sixth decade of life. However, it was also reported that hyperpigmentation and uneven skin tone are amplified problems in African-American skin, compared with Caucasian.14 Bearing in mind that Black skin has the same amount of melanocytes as light skin, although much greater tyrosinase basal activity,14 dark-pigmented subjects would therefore benefit from cosmetic products to reduce tyrosinase activity, to avoid this hyperpigmentation phenomenon. Even more, skin whitening is a noticeable trend within this ethnic group—in Black Africa, more than one quarter of cosmetic products are whitening products—and some individuals do not hesitate to use harmful chemicals to lighten their skin.

White Skin Specificities

As stated previously, Caucasian skin has been the most widely studied, so this overview will cover only a few main points. Caucasian is the fairest skin, so it ages more quickly. It is prone to wrinkling and sagging due to tissue degradation and as such, the anti-aging market in Western Europe and North America is the largest in terms of revenue.b Another characteristic of Caucasian skin is its sensitivity to mechanical aggressions, pollution and other exogenous agents. According to Mintel’s Global New Products Database (GNPD), between January and April 2014, sensitive skin claims represented 25% of total skin care claims in the United States, compared to 15% in 2009. The personal care market for Caucasian skin is quite mature. Today’s product trends are mainly driven by ease of use and multifunctionality, sustainability and ethics, rather than needs specific to this skin type.

Conclusion

This review attempted to highlight the specificities of the three main ethnic skin types but take it for what it’s worth. There is little and often contradictory information on skin structure and function differences between ethnic types, apart from the inherent coloration. Indeed, factors such as climate, which can be different even within one country; seasonal changes; diet; lifestyles; and many others can affect skin composition, making ethnic skin types difficult to characterize. Globalization has dramatically accelerated within the last decade, making racial mixing the rule. So what are the frontiers between skin types?

In any case, more specific product formulations and claims are now possible, and consumers must learn what their individual skin type conforms to, independently of their birthplace, \skin color or cultural preference—and keeping in mind that skin adapts to external circumstances.

References

This article is inspired from A. V. Rawlings, “Ethnic skin types: are there differences in skin structure and function?” Int. J. Cosm. Sc. 28, 79-93 (2006).

  1. Hellemans, L., Muizzuddin, N., Declercq, L. and Maes, D. Characterization of stratum corneum properties in human subjects from a different genetic background. J. Invest. Dermatol. 124, 371 (2005).
  2. Quinton, P.M., Elder, H.Y., McEwan Jenkinson, D. and Bovell, D.L. Structure and function of human sweat glands. In: Antiperspirants & deodorants, Chapter 2 (Laden, K., ed.), pp. 17–58 (1999).
  3. Hillebrand, G.G., Levine, M.J. and Miyamoto, K. The age dependent changes in skin condition in African-Americans, Asian Indians, Caucasians, East Asians & Latino’s. IFSCC Mag. 4, 259–266 (2001).
  4. Rhodes, L.E., Durham, B.H., Fraser, W.D. and Friedmann, P.S. Dietary fish oil reduces basal and UVB generated PGE2 levels in skin and increases the threshold to provocation of PLE. J. Invest. Dermatol. 105, 532–535 (1995).
  5. Griffiths, C.E.M., Wang, T.S., Hamilton, T.A., Voorhees, J.J. and Ellis, C.N. A photonumeric scale for the assessment of cutaneous photodamage. Arch. Dermatol. 128, 347–351 (1992).
  6. Larnier, C., Ortonne, J.P., Venot, A. et al. Evaluation of cutaneous photodamage using a photographic scale. Br. J. Dermatol. 130,167–173 (1994).
  7. Babiarz-Magee, L., Chen, N., Seiberg, M. and Lin, C.B. The expression and activation of protease-activated receptor-2 correlate with skin color. Pigment Cell Res. 17, 241–251 (2004).
  8. Sugino, K., Imokawa, G. and Maibach, H.I. Ethnic difference of stratum corneum lipid in relation to stratum corneum function. J. Invest. Dermatol. 100, 587 (1993).
  9. Corcuff, P., Lotte, C., Rougier, A. and Maibach, H.I. Racial differences in corneocytes. Acta Derm. Venereol. (Stockh) 71, 146–148(1991).
  10. Reed, J.T., Ghadially, R. and Elias, P.M. Skin type but neither race nor gender influence epidermal permeability barrier function. Arch. Dermatol. 131, 1134–1138 (1995).
  11. Hicks, S.P., Swindells, K.J., Middelkamp-Hup, M.A., Sifakis, M.A., Gonzalez, E. and Gonzalez, S. Confocal histopathology of irritant contact dermatitis in vivo and the impact of skin color (black vs white). J. Am. Acad. Dermatol. 48, 727–734 (2003).
  12. Chen N., Seiberg M., Lin C.B. Cathepsin L2 Levels Inversely Correlate with Skin Color J. Invest. Dermatol. 126, 2345–2347(2006)
  13. Rebora, A. and Guarrera, M. Racial differences in experimental skin infection with Candida albicans. Acta Derm. Venereol. (Stockh) 68, 165–168 (1988).
  14. Grimes, P., Edison, B.L., Green, B.A. and Wildnauer, R.H. Evaluation of inherent differences between African American and White skin surface properties using subjective and objective measures. Cutis 73, 392–396 (2004).

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