Skin conditions within all phototypes, including aging, pigmentary disorders, overexposure, and health-challenged skin, manifest at variable degrees. The ability of skin care professionals to establish a logical pathway for skin treatment and correction relies on continuing education in skin physiology, biology, melanogenesis, the immune system, inflammatory responses, the aging process, cosmetic chemistry, and treatment choices. Additionally, professionals should be mindful of potential risks during any treatment for each color gradation, which are greatly influenced by the variations of genetic and environmental factors, skin cells and systems, and cultural variations.

Success in the treatment room begins with an assessment process that ultimately determines the suitability and outcome of the chosen path for skin management. Professionals should become aware of and explore the emerging field of skin diversity.

Cultural Diversity and Beauty
Numerous and diverse population groups circle the globe. In the United States, it is estimated that by the year 2050, over 50 percent of all inhabitants will be non-Caucasian.1 This information sends a beckoning message for further awareness during the client assessment. Given the demographic trends for an increased multicultural population, it is beneficial for skin care professionals to recognize the concepts surrounding color gradation in a changing population. Furthermore, it is also valuable to understand any health implications that may arise when people move away from their country or region of origin; it may affect skin behavior and immune response, especially when there has not been adequate time for the skin to adjust to a new environment.

This awareness also brings up the need to understand each culture's perception of beauty. Surveys conducted within numerous demographics regarding personal perception of beauty resulted in a general consensus that it is important to have even skin color and texture that is free of pigment abnormalities.2 Moreover, hair and physical features are also a measure of beauty. When races and cultures migrate away from their country of origin into a more racially blended society, it is not uncommon for their perceptions of beauty to shift. These nuances must be taken into consideration during the initial consultation. Additionally, alterations in their skin's appearance may occur due to dietary and environmental fluctuations. Becoming aware of the common traditions, beliefs, and practices of clients will contribute to a greater understanding of their skin and general health.2

Defining Diversity
There are diverse interpretations of the terms race and ethnicity; they are reported to be sociopolitical concepts that are poorly defined or understood.3 These terms are used to classify and group diverse populations into socially and politically defined categories. These terms are sometimes narrowly defined for population and surveillance reasons, especially within the United States Census Bureau, so defining classifications for each term may be arbitrary, subjective, and absent of a biological basis.3 However, genetic studies concur that genetic variation refers to geographic origin. Global groupings, or race, are based on phenotype characteristics – morphology, biochemical, or physiological properties – geographic origin, and psychological impressions.3 Race populations have been divided into five categories:3

Caucasoid – Europeans and people from the Middle East and India
Negroid – African Americans, Africans, and Caribbeans
Mongoloids – East Asians, Indonesians, Polynesians, Micronesians, American Indians, and Eskimos
Australoid – Aborigines, Melanesians, Papuans, tribal people of India, and other darker skin types
Capoid – Jung San tribe of Africa

Ethnicity identifies individuals and populations on the basis of shared social variables such as religion, language, diet, and customs.3 There can, however, be divisions or boundaries within each group, so not all members will adhere to all aspects of that one particular group.

Skin Color, Light, and Biological Requirements
The most discernible physical characteristics of each race are their skin color, hair, and anatomical features; the most prominent feature is skin color. What differentiates the gradation or degree of color in humans is based on several observations. Regardless of skin color, the purpose, function, and biological necessities of cells remain similar in all individuals regardless of their geographical location.3

Humans have an amazing ability to adapt to their surroundings. It may take a few hundred years, but this innate ability occurs for survival purposes. Studying the life of earlier humans elucidates scientific clues regarding the importance of dietary intake and its relevance for growth and staying healthy and free of disease. For example, fats are substantial dietary molecules necessary for energy stores and adenosine triphosphate, as well as for building structural and regulatory mechanisms in all cells, especially cell membranes. Fat requirements for each population group varied regionally and were reflected by the amount of energy levels necessary for survival.

Moreover, each group's digestive systems adapted to foods available in the local region and were able to synthesize nutrients from what they ate. For example, Inuits living in the far north consumed diets high in meats from fish, marine mammals, and local wildlife with very little vegetables and fiber.4 A prime example to exemplify the human capability for adaptation was remarkably displayed during days of polar winter darkness. Inuits received a large amount of stored sunlight from the chemical bonds they stowed within their bodies, which were obtained from their diet of fatty fish.5 Fatty fish are naturally saturated with vitamin D. Dietary fats supplied almost 60 percent of their calories and were very high in unsaturated omega 3 fatty acids.

The study of human requirements for optimum health reveals numerous observations that are common within the species. Optimal body health requires proper nutrients, such as vitamins, minerals, water, and oxygen; sleep; optimum immune response; healthy cell membranes; a healthy skin barrier; and balanced chemical exchanges between all cells in order to manufacture quality proteins that are the building blocks of body tissues, organs, and systems. Cells have receptors and sensors that are responsive to internal and external stimuli that collectively become part of a greater communication network inside the body. Ultimately, the synchronicity of all systems is based on genetic adaptations that lead to optimum human survival.

Color diversity has been influenced through innate natural adaptability traits that allow humans to live in a healthy state as they migrated further away from the equator. This natural selection process evolved over millions of years to enable humans to live in extreme climates from mountain areas to sea level and in latitudes from the equator to the north and south Polar areas.5

The closer in proximity to the equator one originates from, the darker their skin. Populations living in colder latitudes north and south of the equator are lighter in skin color.6 There are exceptions, however, that relay another point. The skin of Inuits residing in far northern regions shows a bronze appearance. Skin pigment is based on sun exposure and length of time spent living in an area. The reflection of ultraviolet radiation from surrounding water and snow requires a greater effect from melanocytes, creating a darker pigment.

The skin serves as a protective envelope for the body's organs. A variation of one of its most important features is the built-in ultraviolet radiation exposure-regulating cell, melanocytes.7 Melanocytes are responsible for producing melanin, a polymer that shields important cellular components within the dermal layers from overexposure to ultraviolet radiation.

Circadian Rhythms
All life requires a certain amount of light each day to regulate circadian rhythms, which help trigger biological activities for all living beings.8

Thousands of chemical reactions occur within the physical, mental, and behavioral body systems every moment of a 24-hour cycle. The health of the body and its innate biological functions are dependent upon several factors, including light and darkness. A person's internal biological clocks are controlled by circadian rhythms. Many biological and chemical reactions occur and are triggered by the presence of light and darkness. Light is a main cue that influences these circadian rhythms, turning on or off genes that control the body's internal clocks.8

Innate responses are controlled and synchronized by these internal clocks. They include sleep-wake cycles, hormone release, body temperature, production of melatonin, and other important bodily functions.8

Adaptability
Scientific studies concur that regardless of where people live, there are inherent physical characteristics and biological responses that must adapt to different areas, such as sea level, mountains, rain forests, or hot deserts. Body structures, height, and body fat are all adaptive mechanisms that reveal clues to a person's origin.

Long, linear bodies tend to be correlated with hot, dry climates, while short, stocky body builds with shorter fingers and toes are found in colder, wet climates. The contraction and dilation of blood vessels help support climate adaptations in cold and hot climates. Individuals whose ancestors originated at higher elevations, where there is a lower oxygen supply, tend to have larger lungs and chest cavities. Dark skin types tend to be thicker and have adapted to surviving in tropical environments where acquiring diseases through biting insects is prevalent.9, 10

Migration of population into regions away from their original equatorial zone evolved into a gradual loss of skin pigmentation. Systemic changes included both physiological and genetic traits with long-range genetic changes occurring as a result of natural selection that favored mutations.

The Importance of Ultraviolet Radiation
Overexposure to ultraviolet radiation, including changes in the Earth's atmospheric ozone layers, is a determining factor that leads to genetic mutations, cell damage, and the potential for skin cancer. At the same time, sunlight is essential for photosynthesis in plants and for life in general.

Photoreceptors in the eye convert light into signals required for stimulating biological processes in the body.

Ultraviolet radiation comes in three forms: UVA, UVB, and UVC, each of which filters through the Earth's atmosphere at varying degrees.

UVA (400 to 320 nanometers) accounts for about 95 percent of radiation reaching the earth's surface. It penetrates the skin more deeply than UVB and triggers a tanning effect and is a primary factor in aging. Continued exposure leads to erythema, oxidative stress, cell DNA damage, and breakdown of dermal structures.11

UVB (290 to 320 nanometers) is considered to be the most destructive form of ultraviolet radiation since overexposure to its energy causes photochemical damage to cellular DNA.11 However, it is required for the synthesis of vitamin D.

UVC (100 to 290 nanometers) is completely absorbed by the Earth's atmosphere, however, it is artificially manufactured for germicidal lamps. Accidental contact can cause burns on the skin or in the cornea of the eye.

Ultraviolet Radiation Influences on Vitamins B and D
A controlled amount of UVB must infiltrate the skin in order for the body to catalyze vitamin D. Vitamin D is a group of fat-soluble secosteroids. Approximately 90 percent of this vitamin is normally synthesized in the basal and spinosum layers of the skin, as well as in the kidneys from 7-dehydroxholesterol, a cholesterol-like precursor chemical.12 The remaining 10 percent of vitamin D comes from foods such as fatty fish and egg yolks. Vitamin D is converted into two sequential forms and its benefits are far reaching for one's health.

Vitamin D is important for the immune system because it promotes the production of cathelicidin, an effective defender against fungal, bacterial, and viral infections. It also affects neuromuscular function and inflammation and influences the action of many regulating genes for the regeneration, differentiation, and apoptosis of cells. Women who have had prolonged vitamin D deficiencies during their developing years have a higher risk of pelvic deformities that prevent normal delivery of babies.12

Vitamin D3 (choleccalciferol) is required for the intestines to absorb calcium and phosphorus from food for bone growth and repair.12 Calcium is required for proper heartbeat and bone growth and repair.12

In areas of the world that have high ultraviolet radiation, maintaining adequate levels of B12 (folate) becomes challenging due to a condition of ultraviolet-induced folate photolysis.6 Deficiencies in folic acid can lead to anemia and create a risk of miscarriage in pregnant women. Folic acid is required for DNA replication during cell mitosis. Research confirms that a person's ability to produce melanin was selected in their early ancestors to help preserve the body's folic acid supply and deter the risk for cancer. Lack of B12 may lead to macrocystic megaloblastic anemia due to its requirement of bone marrow and development of red blood cells.13

Inhabitants of northern latitudes with lighter skin tones have less skin-shielding pigmentation in order for the skin to receive adequate UVB radiation for the production of vitamin D. A darker skin type moving into a northern region may not be able to receive adequate UVB. There is a potential for the development of rickets in children and osteoporosis in adults. In contrast, lighter skin types moving to regions closer to the equator are highly susceptible to developing cell damage and skin cancer.

There is an exception to finding darker skin types in colder regions, in particular the polar regions. Inuit people actually have moderate to heavy skin pigmentation that deters vitamin D production. However, their diet of fish and sea mammal blubber adequately supplements their body with vitamin D.14

Skin color provides a protective regulating factor that is closely tied to human health, light absorption, and the ability to synthesize vitamin D, as well as other biochemical responses. During recent years, vitamin D deficiency has become a growing health concern. People spend less time outdoors and many have replaced quality nutrition with fast foods, sugar, artificial sweeteners, sodas, and other refined products.

It is essential to create an awareness of the underlying causes of a skin condition. A blending of the population brings with it the combined genetic traits of ancestors. It is also important that people have a healthy life balance of nutrients, outdoor activity, quiet time, and adequate rest. This realization indeed confirms that people must use critical thinking to ensure that they understand how to establish a clear pathway for corrective skin treatments based on the personal health and genetic history of each client.

References
1 Passel, J., & Cohn, D. (2008, February 11). U.S. Population Projections: 2005-2050.
2 Alam, M., Bhatia, A., Yoo, S., & Chan, H. (2009). Cosmetic dermatology for skin of color. New York: McGraw-Hill Medical.
3 Rawlings, A. V. (2006). Ethnic skin types: are there differences in skin structure and function? International Journal of Cosmetic Science, 28(2), 79-93.
4 Zani, A. (2014, March). The Essential in Fats: A Global Perspective For Healthy Skin Cells. Skin Inc., 54-60.
5 Erasmus, U. (1993). Fats that heal, fats that kill: The complete guide to fats, oils, cholesterol, and human health. Burnaby, BC: Alive Books.
6 Jablonski, N. (2006). Skin: A natural history. Berkeley: University of California Press.
7 Jablonski, N., & Chaplin, G. (2000). The evolution of human skin coloration. Journal of Human Evolution, 39(1), 57-106. doi:10.1006/jhev.2000.0403
8 Science Daily. (n.d). Circadian rhythm.
9 Encyclopedia Britannica, Inc. (2016). Welcome to Encyclopædia Britannica's Guide to Black History.
10 O'Neil, D. (n.d.). Human Biological Adaptability: Skin Color Adaptation.
11 Epstein, J., & Wang, S. (2013, May 24). UVA & UVB - SkinCancer.org. Retrieved from skincancer.org/understanding-uva-and-uvb.html
12 Holick, A. (1995). Environmental factors that influence the cutaneous production of vitamin D. The American Journal of Clinical Nutrition, 61(3), 638S-645S.
13 The Healthline Editorial Team. (2015, November 5). Megaloblastic Anemia. Retrieved from healthline.com/health/megaloblastic-anemia#Overview1
14 Erasmus, U. (1993). Fats that heal, fats that kill: The complete guide to fats, oils, cholesterol, and human health. Burnaby, BC: Alive Books.

Alexandra J. Zani is an international educator, researcher, and author with a background in cell biology and medical. Her passion for education resulted in receiving numerous advanced certifications, both in the United States and abroad. Zani earned an instructor license for aesthetics/cosmetology, is National Catholic Educational Society (NCEA) Nationally Certified, certified in Oncology Esthetics®, and the Pastiche Method® of Skin Analysis. She is a member of the International Association for Applied Corneotherapy (IAC). Zani presents education for advanced aesthetic technology, including microcurrents, LED, and non-ablative laser. She is a specialist in the anti-aging sciences, including the effects of nutrition, lifestyle, and the mind/body connection.