Re: Asian Skin Types

[Guest guest]

In a message dated 5/25/04 11:00:46 AM !!!First Boot!!!,

alicehammermeister@... writes:

Hey everyone, I'm assisting a gal in the ines with the formulation of

skin care products, especially moisturizers, toners and masks. They have an

extremely humid climate and I've found the recent posts regarding glycerine and

it's differing behavior of interest. Can anyone lend any additional insight on

essential oils or additives that would be beneficial in high humid climate.

It is different than in dry or in mixed climates. Regardless, it's important

not to overly dry out the skin in an attempt to control oiliness. I'm sure

many will love the nice clays in the masks, but some would need something less

oil absorbant ... Meanwhile, honey would be an excellent additive to a mask.

It's very " drawing, " yet humectant and wonderfully emollient (leaving softness

and pliability behind). Aloe for or in a toner is very hydrating and

anti-inflammatory ... which translates to it helping the fight against pores

blocking

due to inflamation common in heat and humidity, but also a very hydrating

addition for drier skin. Consider the witch hazel hydrosol for normal-to-oily

and rosewater for dry skin ... even a soothing chamomile tea, as well

(especially nice after a mask).

Have fun! -

[Guest guest]

In a message dated 5/25/04 11:00:46 AM !!!First Boot!!!,

alicehammermeister@... writes:

Hey everyone, I'm assisting a gal in the ines with the formulation of

skin care products, especially moisturizers, toners and masks. They have an

extremely humid climate and I've found the recent posts regarding glycerine and

it's differing behavior of interest. Can anyone lend any additional insight on

essential oils or additives that would be beneficial in high humid climate.

It is different than in dry or in mixed climates. Regardless, it's important

not to overly dry out the skin in an attempt to control oiliness. I'm sure

many will love the nice clays in the masks, but some would need something less

oil absorbant ... Meanwhile, honey would be an excellent additive to a mask.

It's very " drawing, " yet humectant and wonderfully emollient (leaving softness

and pliability behind). Aloe for or in a toner is very hydrating and

anti-inflammatory ... which translates to it helping the fight against pores

blocking

due to inflamation common in heat and humidity, but also a very hydrating

addition for drier skin. Consider the witch hazel hydrosol for normal-to-oily

and rosewater for dry skin ... even a soothing chamomile tea, as well

(especially nice after a mask).

Have fun! -

[Guest guest]

, thanks so much. I have the ingredients you mentioned and am going to

go start formulating. I've got four different clays to play with and all the

hydrosols, so now....I'll let the fun begin! I'm still pretty novice at this

as is likely obvious, and my knowledge is slowly matching my passion, which

I'm sure sounds like most everyone else when they started, it can surely be

a humbling process. I''ll be thanking you again when I'm doing the usual

happy dance

Alice ~

Moose Creek Bath & Body

[Guest guest]

, thanks so much. I have the ingredients you mentioned and am going to

go start formulating. I've got four different clays to play with and all the

hydrosols, so now....I'll let the fun begin! I'm still pretty novice at this

as is likely obvious, and my knowledge is slowly matching my passion, which

I'm sure sounds like most everyone else when they started, it can surely be

a humbling process. I''ll be thanking you again when I'm doing the usual

happy dance

Alice ~

Moose Creek Bath & Body

[Guest guest]

>Hey everyone, I'm assisting a gal in the ines with the formulation of

skin care products, especially moisturizers, toners and masks.

Here's an article about asian skin that you may find interesting. It

appeared in the September 2002 issue of Cosmetics & Toiletries.

==========================================

Asian Skin: Its Architecture, Function and Differences from Caucasian

Skin

G. Yosipovitch and C.T.S. Theng

Asian skin belongs mainly to people of the Mongoloid group, which

includes the Chinese and Malays. People from India belong to the

Caucasoid group, although those who come from southern India have black

skin that bears more resemblance to the skin of the Negroid group.

In the increasingly important global cosmetic market, and with the

opening of markets in China and other parts of Asia, knowledge of the

similarities and differences of the various skin types will be of

increasing importance. There have been few and conflicting studies

comparing the differences between Caucasian and Asian skin. We will

examine the evidence and share our own experience on this issue.

Singapore has a unique population composed principally of ethnic

Chinese, with two big minority groups (Malays at 17% and Indians at

10%) and a smaller group of Caucasians and Euroasians. This racial

variety has enabled us to conduct several studies on skin physiology

and structure in the different ethnic groups in Asia.

Stratum Corneum

The stratum corneum is made up of cornified cells, with the

intercellular region composed of lipids and desmosomes. It plays a

crucial role in barrier function and impacts on occurrence of irritant

reactions and absorption. Because the stratum corneum acts as the

barrier to the outside environment, any racial differences in the

function of this layer may have a major impact on transcutaneous

penetration of chemicals.

One study1 of Asian, Black and Caucasian skin showed no significant

differences in corneocyte size. It also showed that desquamation of the

stratum corneum was the same between Asians and Caucasians, but greater

in Blacks.

Transepidermal water loss (TEWL) reflects the integrity of the barrier

function of the stratum corneum. Several small-scale studies comparing

TEWL between Asians and Caucasians did not demonstrate any significant

differences in basal TEWL between the different races. Most researchers

agree that basal measurements of TEWL do not correlate with the ability

of the stratum corneum to function under conditions of skin irritation

and adverse occupational environments. Therefore, several studies have

examined the TEWL of the skin after acute and cumulative skin

irritation with chemicals of varying reactivity, in Asians as well as

in Caucasian subjects.

Goh and Chia found no significant differences in TEWL in irritated and

non-irritated skin of the different Asian subgroups ƒ€ " Chinese, Malays

and Indians.2

The transdermal penetration of nitroglycerine in Black, Caucasian and

Asian patients was examined by et al.3 They found that the

mean plasma concentrations of nitroglycerin and its metabolite were

significantly lower in Blacks, compared to the levels in Asian and

Caucasian patients.

Kompaore et al.4 evaluated the stratum corneum function of Blacks,

Caucasians and Asians in vivo, using laser Doppler velocimetry to

evaluate the lag time before vasodilation induced by application of

methyl nicotinate, a local vasodilator drug. TEWL was also determined

before and after tape strippings of the stratum corneum. There were 7

Blacks, 8 Caucasians and 6 Asians in this study. The results showed

that skin permeability was higher in Asians and Caucasians than in

Blacks. After 8 to 12 strippings, the order of sensitivity was

Asian>Caucasian>Black.

In another study of TEWL after tape stripping in a small group of

Caucasian and Asian subjects, et al.5 found no difference in

barrier perturbation and recovery, although it was noted that subjects

of darker skin showed superior barrier function after tape stripping.

We performed a study on skin barrier function and integrity in

different subpopulations of healthy Asian skin (unpublished data).

Included in the study were 10 Chinese, 10 Malays, 10 Indians and 10

Caucasians. TEWL and laser Doppler perfusion imaging (LDPI)

measurements were measured at baseline, after tape stripping and during

recovery 3 hours after tape stripping. Barrier integrity was assessed

by counting the number of tape strippings required to cause average

TEWL of 20 g/m2/hr, which is considered a significant impairment of

stratum corneum. There was no statistically significant difference in

barrier function and integrity between the races or between different

skin types.

Epidermis

Function: The epidermis lies just beneath the stratum corneum and is

important for the generation of the stratum corneum. Other important

functions of the epidermis include metabolism of substrates, including

generation of lipids and proteins of the stratum corneum and synthesis

of melanin from melanocytes for photo protection.

Skin pigmentation: The melanocyte plays a major role in distinguishing

colored races. The difference in skin color is determined by the amount

of melanin and its distribution within the epidermis. Between the

different races, however, there is no difference in the number of

melanocytes.

The racial difference in color is due to the differences in the

aggregation, size and number of melanosomes found in the melanocytes

and keratinocytes. In Blacks, the melanosomes are dispersed

individually and only a few are found in aggregates. The melanosomes in

Blacks are also larger in size. In contrast, melanosomes in Caucasian

and Mongoloid skin are grouped in aggregates, and the aggregates tend

to be more compact in Mongoloids than in Caucasians. Even within the

Asian skin type, there are skin subtypes that differ in their

composition of melanosomes. The larger, non-aggregated melanosomes

offer greater protection from UV and skin malignancy.

Melanosomes in Blacks are distributed throughout the epidermis from the

stratum basale to the stratum corneum. A study on Thai subjects6 found

similar distribution thoughout the epidermis. This pattern of

distribution differs from that of Caucasian subjects, where the

melanosomes are found mainly in the stratum basale and are absent in

the outer layers of the epidermis.

Clinical application: Several pigmentation disorders are typically seen

in Asian skin. Melasma in females is one example. A recent study in

Korean skin7 found that each subject had more melanin in melasma

lesions than in the normal skin throughout the epidermis, including the

stratum corneum.

Mongolian spots are blue-black macules that appear frequently on the

back after birth and are seen in up to 90% of Asians and less

frequently in Blacks and Caucasians. Naevus of Ota, which is a

congenital pigmentary patch, and cafe au-lait spots are also more

frequently seen in Asians.

The Dermis

The dermis is comprised mainly of collagen fibers and elastic tissue

that provides the structural framework for this layer. The dermis

contains an extensive network of vessels essential for its role in

thermal regulation, skin nutrition and repair and immune response.

Within the dermis are the appendages of the skin: the hair follicles,

sebaceous, sweat and apocrine glands.

The nerve network of the skin is made up of somatic and sympathetic

autonomic fibers. This network is also found within the dermis and

penetrates to the epidermis.

There are no published studies comparing the dermis in Asians. However,

keloids, which are an exuberant form of scar formation, are more common

in Asians than in Caucasians. Fibroblast hyperactivity and a decrease

in collagenase enzyme activity are believed to be important factors in

the formation of keloids.

There are racial differences in keloid formation. Blacks and Asians are

known to be more susceptible to development of keloid scarring.8 In a

study among Chinese, Malays and Indians, keloid scarring was found to

be more common among the Chinese population.9 In our experience, keloid

scarring has also been found to occur more often in the Chinese

population than with the Malays and Indians.

Sebaceous glands: The sebaceous glands are attached to the hair

follicles and are responsible for sebum production. There have been

conflicting reports on the differences in sebum production in the

different races. In a study10 on 60 White, Black and Asian subjects,

there was no statistically significant difference in the rate of sebum

secretion among the different races.

However, we recently conducted a pilot study comparing sebum

measurements in age- and sex-matched Asians and Caucasians. Sebum

secretion was significantly higher in Asian skin than in Caucasian

skin. This has possibly resulted in a higher incidence of acne vulgaris

in Asians. It is our observation that Asians also often complain of

oily scalp.

Hair: Differences exist in hair among the races. Asian hair is more

circular and of a larger cross sectional area than the hair Caucasian

subjects.11

A recent study compared the hair of Koreans, Whites and Blacks.12

Koreans had significantly lower hair density than either Whites or

Blacks.

Nerves and skin perception: Perception of pain and skin irritation is

affected by many factors, including genetic, cultural and ethnic

issues. The effect of these factors on pain perception is not well

understood. It is often believed that different ethnic populations have

different levels of pain threshold tolerance, but this has never been

quantified.

A recent study (unpublished data) of 20 Chinese, 14 Malay and 15 Indian

subjects measured thermal pain thresholds with computerized

quantitative thermal sensory testing13 before and after barrier

perturbation with tape strippings. No differences in thermal pain

perception before and after barrier perturbation were found between the

different races and skin types. Future studies may investigate whether

pain tolerance, which is the maximum stimulus a subject will tolerate

over a specified period of time, differs in different subgroups of

Asians.

Conclusions

The skins of Asians, Caucasians and Blacks show racial differences.

There are also skin differences among the different Asian

subpopulations. Understanding the similarities and differences in the

architecture and function of Asian skin will enable us to develop and

prescribe new therapies in a more focused and rational way.

References

Address correspondence to Gil Yosipovitch, M.D., c/o Editor, Cosmetics

& Toiletries magazine, 362 South Schmale Road, Carol Stream, IL

60188-2787 USA.

1. P Corcuff, C Lotte, A Rougier and HI Maibach, Racial differences in

corneocytes. A comparison between black, white and oriental skin, Acta

Dermatovenereologica 71 146-148 (1991)

2. CL Goh CL and SE Chia, Skin irritability to sodium lauryl sulphate

as measured by skin water vapour loss- by sex and race, Clin Exp

Dermatol 13 16-19 (1988)

3. RL , KM Thakker, V , ET Lin, W Liang-Gee W and LZ Benet,

Nitroglycerin absorption from transdermal systems: Formulation effects

and metabolite concentrations, Pharm Res 8 744-749 (1991)

4. F Kompaore, JP Marty and C Dupont, In vivo evaluation of the stratum

corneum barrier function in Blacks, Caucasians and Asians with two

noninvasive methods, Skin Pharmacol 6 200-207 (1993)

5. JT , R Ghadially and PM Elias, Skin type, but neither race nor

gender, influence epidermal permeability barrier function, Arch

Dermatol 131 1134-1138 (1995)

6. R Kotrajaras and AM Kligman, The effect of topical tretinoin on

photodamaged facial skin: the Thai experience, Br J Dermatol 129

302-309 (1993)

7. WH Kang, KH Yoon, KS Lee, J Kin, KB Lee and H Yim, Melasma:

Histopathological characteristics in 56 Korean patients, Br J Dermatol

146 228-237 (2002)

8. SS Urioste, KA Arndt and JS Dover, Keloids and hypertrophic scars:

Review and treatment strategies, Seminars in Cutaneous Medicine and

Surgery 18 159-171 (1999)

9. SC , Skin of color; Biology, structure, function and

implications for dermatologic disease, J Am Dermatol 46 S41-62 (2002)

10. SK Abedeen, M , H Judodihardjo, S Gaskell and P Dykes,

Racial variation in sebum excretion rate. Program and abstracts of the

58th Annual Meeting of the American Academy of Dermatology, March

10-15, 2000, in San Francisco (Abstract #559)

11. DG Vernall, Study of the size and shape of hair from four races of

men, Am J Phys Anthropol 19 345 (1961)

12. HJ Lee, SJ Ha, JH Lee, JW Kim, HO Kim and DA Whiting, Hair counts

from scalp biopsy specimens in Asians, J Am Acad Dermatol 46 218-221

(2002)

13. G Yosipovitch and HI Maibach, Evaluating subjective irritation and

sensitive skin, Cosmet Toil 114(1) 41-42 (1999)

==========================================

Maurice

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Maurice O. Hevey

Convergent Cosmetics, Inc.

http://www.ConvergentCosmetics.com

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