Dr Natasha Verma outlines the differences between the composition of South Asian and Caucasian skin
An American study has shown that dermatologists, aesthetic doctors and other skin professionals lack knowledge or experience when treating patients with skin of colour.1 Alexis et al. discussed the requirement for further training and education when an Australian national survey determined that 75% of dermatologists were not confident performing cosmetic and aesthetic procedures on patients with skin of colour.1
This lack of knowledge impacts practitioners’ professional confidence, resulting in hesitance when treating patients with darker skin types, such as those from South Asian communities.1 In turn, this can affect the management of skin concerns in these skin types due to reduced awareness of the appropriate treatment solutions. This discussion is outside the remit of this article as I will focus on the differences in composition between these two ethnic skin types.
The skin is the largest organ in the human body, playing an essential role in maintaining overall health and wellbeing. The composition of the skin can vary significantly based on several factors, including ethnicity, age, sex and environmental factors.2 South Asians and Caucasians have distinct skin types, which can affect the way their skin responds to various products and treatments, such as laser, as well as abrasive products.2
By increasing awareness and education around these variations in skin types, practitioners can enhance access to specialised guidance for individuals within the South Asian community.
A hallmark biological feature in skin of colour is the amount and epidermal distribution of the cutaneous melanin.2 Alaluf et al. proposed that variation in dermatological pigmentation is associated with content and composition of epidermal melanin.3 The authors proposed that lighter skin types with Fitzpatrick skin types I-III (Caucasians) possess half the quantity of epidermal melanin compared to darker skin types with Fitzpatrick skin types IV-VI (Indians and Africans).3
However, it has also been argued that lighter-skinned individuals may not have less melanin in their skin, rather melanin components that are lightly pigmented.3 Melanin is composed of red and yellow pheomelanin, light brown eumelanin and dark brown/black eumelanin.3 The authors have suggested that a variation of proportions in these components are present within different ethnicities.3
Darker skin consists of darker melanin chromatophores compared to lighter skin types, whilst lighter skin consists of lightly coloured alkali-soluble melanin components, such as pheomelanin and DHICA-enriched euomelanin.3 In a study of 48 participants, Alaluf et al. discussed that variations of melanin content and composition may differ as a result of varying tyrosinase activity within different ethnicities.3
It was also considered that melanosome size may play a significant role in skin pigmentation (Figure 1). It was found that sizes differed within ethnicities in that the largest melanosomes were found within those of African origin, followed by South Asians, Mexicans and East Asians, whilst the smallest melanosomesIt was observed that the progressive and statistically significant increase in average melanosome size was noticed when moving from the lightly pigmented (European) to the darkly pigmented (African) skin types, thereby confirming the differences in melanosome size between different skin types.3
Compared to Caucasian skin, Asian skin is typified by greater dermal thickness, collagen and melanin content. These characteristics contribute to a stigma around ageing in Asians, manifested more by pigmentation changes than fine facial wrinkles.2,8 However, they also render Asian skin more susceptible to pigmentary dyschromia following treatment.2,8
Some have also proposed that melanosome distribution may be sensitive to particle size. Darker skin types, with a greater quantity of larger melanosomes, have melanin packaged within larger singly dispersed particles in the epidermis. However, lighter skin types form membrane aggregates with smaller melanosomes within the epidermis.3,4 Larger single melanosomes indicate a lower reflectance value, thus resulting in darker skin.3
It is also believed that the effect of skin colour and melanin variations is poorly understood; however, Aluluf et al. concluded that melanocyte numbers did not vary between ethnicities, and melanin content, composition, melanosome size and dispersion played a significant role in skin colour.3,4
Asians possess a heightened level of photoprotection due to this variation in dermatological melanin. However, this advantageous characteristic predisposes them to a higher likelihood of experiencing pigmentary disorders. Epidermal abnormalities, such as lentigines, ephelides and melasma are prevalent, as well as dermal pigmentary disorders like nevus of Ota and Hori’s nevus.5
Additionally, post-inflammatory hyperpigmentation is a distinct trait of this skin type, often occurring after cutaneous injury or following the utilisation of lasers and other light-based therapies.5
The skin barrier is composed of several molecules; however, the barrier function is dependent on the integrity and optimal composition of the stratum corneum lipid molecules.5 In a study of 25 participants of Asian origin, 18 of African origin and 28 of Danish origin, Jungersted et al., found that the ceramide/cholesterol ratios were statistically different between ethnic groups.5 Asians had the highest ratio, followed by Danish (light-skinned) and African skin.5
Ceramide levels were inversely correlated with transepidermal water loss and directly connected with the water content of the stratum corneum, indicating the strength and health of the skin barrier and resilience of Asian skin.6 Therefore, it was discovered that atopic eczema prevalence is higher in those with African skin than Western European, followed by Indian-subcontinent skin types.5
Within the winter season, a decrease in stratum corneum lipids has been noted, thereby having an impact on barrier integrity and an increase of atopic eczema, especially for darker-skinned individuals who have less cholesterol/ceramides ratios.5 Darker skinned patients (skin types V-VI) will require a skincare and treatment regime that provides more hydration and repair compared to lighter-skinned individuals.5
Jungersted et al. discovered that there was a statistical significance for the ceramides/ cholesterol ratio between 18 Africans and 25 Asians (p>0.001) and Africans and 28 light-skinned individuals (p>0.001), but no statistical significance was noted between Asians and light-skinned patients (p = 0.04).5 As a result, the difference in lipid composition of the skin barrier may only be significant for Fitzpatrick skin types V-VI. Similar to Alaluf et al., Jungersted et al. also acknowledged the scarcity of comparative studies on various ethnicities, and emphasised the need for additional research.3,5
The high occurrence rate of skin conditions, such as acne, in the South Asian population has led to an assumption that sebum composition or sebaceous gland activity may vary across ethnicities (Figure 2).7 However, Taylor et al., discussed a study of different racial groups (20 white, 20 black and 20 Asians) and found that there was no significant difference in the rate of sebum production among three different racial groups based on measurements taken using sebutape and a sebumeter.7
Nonetheless, there is a lack of comparative research on the differences in pilosebaceous follicle hyperkeratinisation, as well as investigations into sebum composition and sebaceous gland size, hindering the ability to arrive at a definite conclusion regarding pathogenesis.7 This paucity of information was highlighted by Taylor et al. in their study.7
While greater dermal thickness may lead to a lower propensity for fine facial wrinkles, it can also increase the occurrence of hypertrophic scars and pigmented dermatoses with age.8
Whilst research has shown that skin thickness is consistent across Caucasian and black skin, black skin has a higher density of corneocytes within the stratum corneum, implying a more tightly packed layer.9 This highlights structural differences within the stratum corneum across ethnicities, but does not adequately represent the South Asian community.
Naik et al., carried out a review study of 8,667 articles and indicated that there are no differences in corneocyte size or maturation within the stratum corneum of Caucasian, black and Asian skin.9 However, a small comparative study of 15 university student subjects of black, Asian and Caucasian skin revealed that Asian skin types had a lower absorption rate of topical substances than Caucasian ones.9
Unfortunately, well-controlled studies on individuals with skin of colour are limited, with most research comparing fair-skinned individuals of European descent to African or African American individuals.7
There are significant differences in the composition of South Asian and Caucasian skin types, which can affect their response to skincare products and clinical treatments. South Asians have higher levels of melanin which offers natural protection against the sun, but also makes them more susceptible to hyperpigmentation, skin cancer, dryness and sensitivity. In contrast, Caucasian skin has lower levels of melanin, making them more prone to sun damage, premature ageing and rosacea.
It is crucial for individuals with these skin types to take extra measures to protect their skin and use products tailored to their specific needs. Despite this, there is a lack of comparative studies on enzymatic activity, pilosebaceous follicle hyperkeratinisation, sebum composition and levels, as well as sebaceous gland size across different ethnicities.
Furthermore, there is a notable replace with breadth of research on South Asian skin specifically. These individuals are often classified under the umbrella terms of ‘skin of colour’ or ‘Asian groups’, which may also encompass East Asian populations.
Nonetheless, it is crucial for aesthetic professionals to consider the unique attributes of South Asian skin while addressing skin conditions and ailments in this demographic.
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