www.drvaibhavshah.net---
Skin whitening, skin lightening, and skin bleaching refer to the practice of using chemical substances in an attempt to lighten skin tone or provide an even skin complexion by reducing the melanin concentration in the skin. Several chemicals have been shown to be effective in skin whitening, while some have proven to be toxic or have questionable safety profiles, adding to the controversy surrounding their use and impacts on certain ethnic groups.
 |
| Dr Vaibhav Shah |
 |
| Dr Vaibhav Shah |
 |
| Dr Vaibhav Shah |
Skin whitening, skin lightening, and skin bleaching refer to the practice of using chemical substances in an attempt to lighten skin tone or provide an even skin complexion by reducing the melanin concentration in the skin. Several chemicals have been shown to be effective in skin whitening, while some have proven to be toxic or have questionable safety profiles, adding to the controversy surrounding their use and impacts on certain ethnic groups.
Uses
Specific zones of abnormally high
pigmentation such as moles and birthmarks may be depigmented to
match to the surrounding skin. Conversely, in cases of vitiligo, unaffected skin
may be lightened to achieve a more uniform appearance Long
term use of skin whiteners can lead to pigmentation increasing to the joints of
the fingers, toes, buttocks and ears. The skin of
the face can become thinned and the area around the eyes can have increased
pigmentation causing a 'bleach panda effect'.
2012 sales of skin lightening creams in India
alone totaled 258 tons and the global market for skin
lighteners is projected to reach US $19.8 billion by 2018 based on sales growth
primarily in Asia, Africa and the Middle East.
Combination
treatments
Most skin-lightening treatments, which can
reduce or block some amount of melanin production, are aimed at
inhibiting tyrosinase.
Many treatments use a combination of topical lotions or gels containing
melanin-inhibiting ingredients along with a sunscreen, and a prescription retinoid. Depending on how the skin
responds to these treatments, exfoliants— either in the
form of topical cosmetic or chemical peels — and lasers may be used. New development
using LED systems are also
showing good results.
There are various mechanisms described for
achieving this. Inhibiting tyrosinase activity reduces the synthesis of melanin
so that as existing skin cells are naturally exfoliated keratinocytes with less
melanin are eventually brought to the surface, giving the skin a lighter, more
even toned complexion.
Pre-melanin
synthesis
Tretinoin
Research has shown that the use of tretinoin (also known
as all-trans retinoic acid) can only be somewhat effective in treating skin
discolorations.[6][11][12][13] Users of tretinoin
have to avoid sunlight, as the skin can tan. Using tretinoin always makes the
skin more sensitive to UVA and UVB rays.
During
melanin synthesis
Hydroquinone
In medical literature, hydroquinone is
considered the primary topical ingredient for inhibiting melanin
production. Its components have potent antioxidant abilities.
Topical hydroquinone comes in 2%
(available in cosmetics) to 4% (or more) concentrations (available from a
physician or by prescription), alone or in combination with tretinoin0.05% to 0.1%. Research has
shown hydroquinone and tretinoin to prevent sun- or hormone-induced melasma.
Hydroquinone is a strong inhibitor of melanin
production, meaning that it prevents dark skin from making the substance
responsible for skin color. Hydroquinone does not bleach the skin but
lightens it, and can only disrupt the synthesis and production of melanin hyperpigmentation. It has
been banned in all European countries (e.g. France) because of fears of a
cancer risk.
Some concerns about hydroquinone's safety on
skin have been expressed, but the research when it comes to topical application
indicates negative reactions are minor or a result of using extremely high
concentrations or from other skin-lightening agents such as glucocorticoids or mercury iodine. Any perceived risk is
most likely applicable for African women. Hydroquinone has been shown to
cause leukemia in mice and other
animals. The European Union banned it from cosmetics in 2001, but it shows up
in bootleg creams in the developing world. It is sold in the United States as
an over-the-counter drug, but with a concentration of hydroquinone not
exceeding 2 percent. Because of hydroquinone's action on the skin, it can be an
irritant, particularly in higher concentrations of 4% or greater and
predictably when combined with tretinoin. Some medications have been created
that combine 4% hydroquinone with tretinoin and a form of cortisone. The cortisone is included
as an anti-inflammatory. The negative side effect
of repeated application of cortisone is countered by the positive effect of the
tretinoin so that it does not cause thinning of skin and damage to collagen.[
Safer alternatives are more expensive but are available.
Arbutin
Some of alternative lighteners are derived
from natural sources of hydroquinone. These include Mitracarpus scaber extract, Uva
ursi (bearberry) extract, Morus
bombycis(mulberry), Morus alba (white mulberry), and Broussonetia
papyrifera (paper mulberry). All of these
contain arbutin (technically
known as hydroquinone-β-D-glucoside), which can inhibit melanin production.
Pure forms of arbutin are considered more potent for affecting skin lightening.
Arbutin is derived from the leaves of bearberry, cranberry, mulberry or blueberry shrubs, and also is present in
most types of pears. It can have melanin-inhibiting properties.[23]Arbutin and other plant
extracts are considered safe alternatives to commonly used depigmenting
agents to make the skin fairer. Medical studies have shown the
efficiency of arbutin for skin lightening. There are patents controlling
its use for skin lightening. Arbutin actually exists in two isomers, alpha and
beta. The alpha isomer offers higher stability over the beta isomer and is the
preferred form for skin lightening indications.
Kojic
acid
Kojic acid is a by-product in
the fermentation process of malting rice for use in the manufacturing of sake, the Japanese rice wine. 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. Further, some
controversial research has suggested that kojic acid may have carcinogenic properties in large
doses. Other further studies show that kojic acid is not carcinogenic, but can
cause allergic contact dermatitis and skin irritation.
Azelaic
acid
Azelaic acid is a component of
grains, such as wheat, rye, and barley. It is applied topically
in a cream formulation at a 10-20% concentration. Azelaic acid is used to
treat acne, but there also is
research showing it to be effective for skin discolorations. Other
research also indicates azelaic acid may be an option for inhibiting melanin
production.
Vitamin
C
Vitamin C and its various forms
(ascorbic
acid,
magnesium ascorbyl phosphate, etc.) are considered an effective antioxidant for
the skin and help to lighten skin.One study found it raises glutathione levels in the body.
Another study found that brownish guinea pigs given vitamin C, vitamin E and L-cysteine, simultaneously, led to
lighter skin.[32]
Glutathione
Glutathione is a tripeptide
molecule found in mammalian bodies. It is an antioxidant that plays an
important role in preventing oxidative damage to the skin. In
addition to its many recognized biological functions, glutathione has also been
associated with skin lightening ability.
Glutathione is an ingredient in some
cosmetics preparations. Glutathione for skin whitening is available in cream,
soap, lotion, nasal spray and injectable form. Glutathione that is applied on
the skin in the form of lotion is not efficiently absorbed by the skin cells as
the thiol group undergoes
rapid formation of disulfide.] When taken orally,
glutathione is hydrolyzed by enzymes in the gastrointestinal tract resulting in
reduced bioavailability. The level of glutathione increased in smalls amounts
temporarily when large oral doses were administered. As a result, the
effectiveness of externally administered glutathione is slowed down by its
inability to cross cell membranes efficiently and its rapid degradation by
enzymes in the gastrointestinal tract. On the contrary, intravenous
glutathione delivers very high doses directly into the systemic circulation and
is the preferred mode of administering glutathione. However, this method of
administrating the antioxidant might flood the cells with glutathione that may
cause reductive stress. This might expose people to potential health risks
associated with long-term use of high dose of glutathione
Glutathione can be combined with many other
agents like vitamin C to increase its absorption, N-acetyl cysteine to boost its level,
and other antioxidants like vitamin E. Some oral intake of glutathione could
have dangerous effect when combined with other skin whitening agents such as
hydroquinone which is a carcinogenic element and monobenzonewhich causes irreversible
depigmentation.
Cinnamomum
subavenium
Cinnamomum subavenium, a Chinese herb, has been
suggested for use as a skin whitening agent. The plant contains substances
which inhibit production of tyrosinase, an enzyme which catalyzes the
production of melanin. The herb has not been established as either effective or
safe but is being researched by Hui-Min Wang and his colleagues at Kaohsiung
Medical University in Taiwan where experiments shown that it was effective at
causing Zebrafish to lose their stripes.
Post-melanin
synthesis
Alpha
hydroxy acids
Alpha
hydroxy acids (AHAs)
— primarily in the form of lactic acid and glycolic acid — are the most
researched forms of AHAs because they have a molecular size that allows
effective penetration into the top layers of skin. It is generally assumed that
in and of themselves AHAs in concentrations of 4% to 15% are not effective for
inhibiting melanin production and will not lighten skin discolorations in that
manner. It is believed that their benefit is in helping cell turnover rates and
removing unhealthy or abnormal layers of superficial skin cells (exfoliation)
where hyperpigmented cells can accumulate. However, other research has shown
that lactic and glycolic acids can indeed inhibit melanin production separate
from their actions as an exfoliant on skin. Alpha hydroxy acid peels (using 50%
concentrations or greater) may remove skin discolorations. Only a qualified
physician should perform these types of facial peels.
Niacinamide
Niacinamide is claimed to be a
much safer alternative when applied topically for skin or genitalia whitening.
According to research by Procter & Gamble, a cosmetics company,
niacinamide has no adverse side-effects. It also promotes acne reduction,
increases skin moisture, and reduces fine wrinkles.[44]
Other/ungrouped
Most
commonly, depigmentation of
the skin is linked to people born with vitiligo, which produces
differing areas of light and dark skin. These individuals, if they so decided
to use a lightening process to even out their skin tone, could apply a topical
cream containing the organic compound monobenzone to lessen
the remaining pigment. Monobenzone may cause destruction of melanocytes and
permanent depigmentation. An alternate method of lightening is to use the
chemical mequinol over an
extended period of time. Increasingly, people who are not afflicted with the
vitiligo experiment with lower concentrations of monobenzone creams in the hope
of lightening their skin tone evenly. However, monobenzone is not recommended
for skin conditions other than vitiligo.
Mercury
Many skin whiteners contain toxic mercury such as mercury(II)
chloride or ammoniated
mercury as
the active
ingredient.
However mercury has been banned in most countries for use in skin whitening
(1976 in Europe, 1990 in the USA) because it accumulates on skin and it can have
the opposite results in the long term. As late as January 2016, the FDA
published a warning not to use a particular brand of whitener sold in the
United States due to its mercury content.[45] Some studies suggest
that long-term use could cause systemic absorption that leads to tissue
accumulation of the substance.
Other
Other options with some amount of research
regarding their potential skin lightening abilities are licorice extract
(specifically glabridin).[citation
needed]
There is also a small amount of research
showing oral supplements of pomegranate extract, ellagic acid, vitamin E, and ferulic acid can
inhibit melanin production.
Laser
treatments
Both ablative and nonablative lasers can have
a profound effect on melasma[citation
needed]. However, the results are not always consistent,
and problems have been reported (such as hypo- or hyperpigmentation). Laser
treatments of this kind are more likely to result in problems for those with
darker skin tones.[48]
Cryosurgery
Another alternative to laser treatment
is cryosurgery using liquid
nitrogen. Controlled destruction of skin cells causes the skin to naturally
regenerate itself. Excess melanin comes to the surface and peels off in a few
days. This is particularly useful in sensitive areas like the genitals where
laser treatment could leave a scar. Efficacy of the treatment depends on the
depth of the pigment. Freckles in any part of the body can be treated the same
way.
Controversy
and negative health effects
There is evidence to suggest that some types
of skin-whitening products use active ingredients (such as mercurous chloride)
and hydroquinone which can be harmful.Hydroquinone had been
banned in Europe. However, it is now available again but only when prescribed
by a medical doctor. This is also the case in many other countries, where
hydroquinone can only be prescribed by a doctor for certain skin conditions.
A test of common skin lightening creams
available in Nigeria showed that they
caused mutations in bacteria and were
possibly carcinogenic.
DR. VAIBHAV SHAH
www.vaibhavshahblog.blogspot.com
No comments:
Post a Comment