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Skin lightening & brightening – An overview
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Dr Rashmi Shetty
July 08 , 2013
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People have been conscious of their skin colour since the ancient times, and hence always used to find such measures that could lighten their skin. So skin lightening, skin whitening and skin brightening trends are not new in the market. People may lighten their skin because of leftover acne scars, sun spots or freckles.
The skin is the principal organ of beauty, touch, pleasure and sensuality. Protecting and preserving the skin is essential for good health.
Natural ingredients in the form of phytonutrients, microbial metabolites, dairy-derived actives, mineral nutrients, and animal protein components have long been believed to benefit healthy skin aging (mainly skin lightening, skin whitening and skin brightening). Many individuals of colour complain of dull, rough, or ashy skin and look for products to brighten their skin. This can be achieved with use of products containing moisturisers that prevent ash build-up and exfoliants that remove retained dead cells that may dull the skin appearance.
Skin lightening products form a major segment of cosmetic products worldwide and carry with them the promise of flawless skin free from age spots, blemishes and scars. Whatever the colour of the skin, it is susceptible to damage due to environmental agents, physiological changes and psychological factors. The demand for skin fairness products is rooted in the need to eliminate localised hyper-pigmentation as well as to lighten the general skin tone. The motives behind the use of skin lightening products vary considerably between cultures. In Western countries, people wish to eliminate or inhibit the development of irregular pigmentation, including melasma (chloasma or localised discolouration), age spots and freckles.
Skin pigmentation is influenced by several factors, including haemoglobin in the blood vessels, carotenoids in the dermis and, particularly, the dark pigment, melanin in the epidermis. Two forms of melanin are produced in the epidermis – pheomelanin, which is red brown to yellow in colour, and eumelanin which is dark brown to black. The relative proportions of these also influence the skin colour. In addition, individuals differ in the number and size of melanin particles. Melanin biosynthesis (melanogenesis) is influenced by genetics, environmental factors, diet and medication. The production of melanin by specialised cells called melanocytes (in the basal layer of the epidermis in light skinned people and in the basal as well as horny layer in dark skinned people) occurs through the action of the enzyme tyrosinase.
In Asian culture, having white skin is considered an important element in female beauty and a lighter skin colour is associated with beauty and aristocracy. Therefore, in Asian countries, skin lightening products are used with the intent to lighten and brighten the skin tone. They have long histories of utilising white skin as a key criterion of personal beauty. In India, white skin is considered as a mark of class and caste as well as an asset. Historically, women (especially married women) in South India bathed with turmeric. Apart from the health benefits involved, it also has skin lightening and anti-inflammatory properties. In China, “milk-white” skin is a symbol of beauty, and some Chinese women used to swallow powdered pearls in the hopes of becoming whiter. Skin lightening products are popular not only in Asian cultures, but also in other countries.
The beauty business in the Asia-Pacific region is estimated to be worth $80 billion, and the skin-lightening market alone is valued at over $13 billion. Since the 1970s, Asia has been the fastest growing sector in the global skin-lightening market. Asia is a lucrative market with high-growth potential because of a rising middle-class with increasing disposable income and centuries-old entrenched cultural impressions of beauty.
India’s domestic cosmetics industry is set to grow to $3.6 billion by 2014, according to the Associated Chambers of Commerce and Industry of India (ASSOCHAM). The skin-lightening cream market alone was worth $432 million in 2010 and growing at 18 per cent annually.
In China, where the skin care market is worth more than 35 billion yuan ($5.5 billion), whitening products comprise a whopping 71 per cent of the market. Elsewhere in Asia, a survey by the London-based market research firm Synovate found that four out of ten women in Hong Kong, Malaysia, the Philippines, South Korea and Taiwan use a skin whitening cream.
The mass media, particularly television and newspapers, promotes whiteness and brightness as symbols of attractive, adorable, desirable, pure, loveable and competent. A lighter skin tone is thus promoted as a standard for attractiveness and competence. Whiteness and brightness is more bearing on women than men, because of physical attractiveness is perceived as associated with social and intellectual competence, integrity, potency, dominance, and even good mental health. This explains why women constitute the overwhelming majority of those who practice skin lightening.
Natural skin lighteners and skin brighteners
Ascorbic acid derivatives such as ascorbyl acetate and ascorbyl palmitate have been used for over 25 years as depigmenting agents in concentrations of 2-3 per cent. These are now replaced by the more stable derivative magnesium ascorbyl phosphate in several formulations.
Tyrosinase inhibitors such as arbutin (from the leaves of the common bearberry, Arctophylos urva ursi and other plants), glabridin from licorice (Glycyrrhiza glabra roots), ascorbic acid and its derivatives, kojic acid (a bacterial carbohydrate metabolite) are better tolerated than hydroquinone. Aloesin from Aloe is reported to be a non-competitive inhibitor of tyrosinase, affecting the action of tyrosinase complex in the substratum and reducing the conversion of DOPA into melanin. Arbutin and kojic acid inhibit tyrosinase directly, while L-ascorbic acid and its derivatives are believed to act as reducing agents on intermediates in melanin biosynthesis at various points in the oxidation chain reaction from tyrosine/DOPA to melanin.
Arbutin is a glycosylated hydroquinone (beta-D-glucopyranoside) effective in the topical treatment of various skin hyper-pigmentations characterised by hyperactive melanocyte function. It is found that several plants, including Arctostaphylos Uva-Ursi (bearberry), leaves of pear trees and certain herbs. In in-vitro studies, it was determined that arbutin inhibited tyrosinase activity of cultured human melanocytes at noncytotoxic concentrations, unlike hydroquinone.
Tetrahydrocurcuminoids is a colourless composition derived from the yellow curcuminoids, useful in brightening and lightening skin tone, and in offering protection against the development of melanoma.
Tetrahydrocurcuminoids provide the bioprotectant antioxidant effects of turmeric without the yellow colour of curry. Derived from turmeric roots, this composition is a scientifically-proven topical antioxidant and anti-inflammatory agent, with ultraviolet B (UVB) protectant effects and superior antioxidant efficacy as compared to ascorbic acid and Vitamin E. A potent inhibitor of melanogenesis, its activity was found to be several fold greater than Kojic acid, glabridin and other natural extracts. The hydrogenated and colourless derivatives of curcuminoids, namely tetrahydrocurcuminoids, include tetrahydrocurcumin (THC), tetrahydrodemethoxycurcumin (THDMC) and tetrahydrobisdemethoxycurcumin (THBDMC). Studies indicate that tetrahydrocurcuminoids, particularly tetrahydrocurcumin, efficiently inhibit tyrosinase. Tetrahydrocurcumin efficiently inhibits tyrosinase and is more effective than Kojic acid, arbutin and Vitamin C, which are used as natural depigmenting agents. The powerful tyrosinase inhibitory activity of tetrahydrocurcumin could also slow down melanogenesis, thereby lightening the skin tone.
In a randomised, double-blind, placebo-controlled study in 50 human subjects, 0.25 per cent tetrahydrocurcumin cream was found to be a more effective and safer alternative to four per cent hydroquinone cream in depigmenting formulation.
Skin-lightening actives
Glabridin is a potential molecule which is known for its skin lightening properties. Licorice possesses potent and effective anti-inflammatory, antioxidant as well as melanogenesis-inhibiting properties. Glabridin helps to lighten the skin colour by inhibiting melanin formation, mainly by the inhibition of tyrosinase activity. Glabridin also has anti-inflammatory effects via inhibition of superoxide anion production and cyclooxygenase activity.
Pterostilbene is a natural skin-lightening ingredient obtained from Pterocarpus marsupium. It has significant antioxidant and anti-inflammatory effects. Its UV protection potential is comparable to that of Resveratrol. It is reported to be safe and non-irritant.
Artocarpus lakoocha extract is obtained from dried heart wood of Artocarpus lakoocha and standardised for Oxyresveratrol 95 per cent. Oxyresveratrol is 32 fold stronger than Kojic acid with regard to skin-lightening potential. Artocarpus lakoocha extract acts on some of the major targets that cause undesirable pigmentation, age spots, freckles and other related skin conditions.
The skin-lightening activity of Artocarpus lakoocha extract was evaluated by two methods – enzyme-based tyrosinase inhibitory assay and cell-based melanogenesis inhibitory assay.
Artocarpus lakoocha extract has a strong tyrosinase inhibitory activity when compared over Kojic acid for skin-lightening application.
Artocapus lakoocha extract also showed a strong inhibitory activity on melanogenesis with IC50 of 12µg/ml as compared to Kojic acid which showed IC50 of100µg/ml.
Hydroquinone is a strong inhibitor of melanin production, meaning that it prevents dark skin from making the substance responsible for skin colour. Hydroquinone does not bleach the skin, but lightens it, and can only disrupt the synthesis and production of melanin hyper-pigmentation. It has been banned in some countries (e.g. France) because of fears of a cancer risk.
Some research shows kojic acid to be effective for inhibiting melanin production. However, kojic acid is an unstable ingredient in cosmetic formulations. Upon exposure to air or sunlight it can turn brown and lose its efficacy. Many cosmetic companies use kojic dipalmitate as an alternative, because it is more stable in formulations. However, there is no research showing kojic dipalmitate to be as effective as kojic acid, although it is a good antioxidant.
Ellagic acid is a polyphenol antioxidant found in numerous fruit and vegetables, including raspberries, strawberries, cranberries, walnuts, pecans, pomegranates and other plant foods. Pomegranate extracts, within the five to 60mg/l range, are effective in protecting human skin fibroblasts from cell death following UV exposure. Pomegranate extracts have a protective effect against UVA- and UVB-induced cell damage and thus has potential use in skin-whitening formulations.
In 2011, whitening continued to be the key trend; however, it was no longer restricted to females. In addition, manufacturers started to focus on men’s skin care, which is the next major area with potential. Furthermore, the skin whitening attribute in skin care products started to become stronger, with products for a light skin tone.
(The author is a renowned cosmetologist.
She can be contected at rashmi@drrashmishetty.com)
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