Sun and Skin

Paper presented by Dr. Balasaraswathy P at the Photodermatology Workshop on January 22, 2004 during the National Conference of Indian Association of Dermatology, Venereology and Leprosy at Mumbai


Abstract

Sunlight has been used therapeutically for various dermatological disorders from time immemorial. Knowledge of flux of ultraviolet (UV) radiation is essential for phototherapy and to advise on protection against harmful effects of UV radiation.

In our country (8º-33ºN), sunlight is a rich source of UV light and it shines brightly for at least 8 months in a year and hence it could be utilized with advantage for treatment of vitiligo, psoriasis and other dermatological disorders. Data on UVA irradiance are limited. Knowledge of UVB irradiance is useful to optimize the conditions for phototherapy of skin diseases and to minimize the harmful effects of the Sun.

UVA and UVB irradiance varies with the time of the day, season of the year, place and atmospheric conditions. The first three factors determine the solar zenith angle and hence the path-length of the radiation through the atmospheric ozone and other absorbers. Therefore, the UV irradiance is highest in the tropics, in the summer at noon. However, for a given location, the most important factors that affect the UV irradiance are ozone, clouds and aerosols. The effect of ozone depletion is negligible at lower (between 30ºN and 30ºS) latitudes, including India. Clouds have a variable effect on UV irradiance; depending upon the height and amount of clouds, the reduction in irradiance can vary from 7% to as much as 87% compared to a clear sky. Aerosols can also affect UV irradiance with reductions exceeding 50% in the presence of dust and smoke plumes and sulfates and other industrial pollutants absorb UV only weakly and reduce the surface irradiance by 10%- 20%.

UVA irradiance is more than 50% of the peak irradiance between 9.15 a.m. and 3.30 p.m. and the peak irradiance occurs between 12.30 p.m. and 12.45 p.m. and maximum UVA irradiance is 7.14 mw/cm2. UVB irradiance is more than 50% between 10.15 a.m. and 2.45 p.m. with peak irradiance occurring between 12.30 p.m. and 12.45 p.m. and the maximum UVB irradiance recorded is 40.2 µw/cm2. The peak UVB irradiance is lower up to 27%, 46%, 24% and 17% in the months of November, December, January and February respectively compared to the months of March to October. The peak UVA irradiance is lower up to 15%, 30%, 21% and 13% in the months of November, December, January and February respectively compared to the months of March to October. The seasonal variation is significant in Northern India with the irradiance being 4-6 times higher in the months of April to September compared to that in November, December and January. In Southern India, UV irradiance is lower by 43% in the month of December.

Globally, a parameter of UV Index is used to provide comprehensive information on the amount of erythemally effective UV irradiance. UV Index provides a convenient measure of expressing changes in UV irradiance by a single number (scalar 1-20). It provides an idea of variation of erythemally effective UV irradiance at different locations in India at different months. UVI of greater than 10 prevails in Southern India between February and October and in Northern India between April and September.

Based on these data it can be concluded that sunlight is an inexpensive source of UV radiation in India.


Solar Radiation:

Every process necessary for life on earth is powered by the tiny fraction of solar energy that reaches earth’s surface, known as electromagnetic radiation. The electromagnetic spectrum ranges from very short wavelength gamma radiation through x-rays, ultra violet (UV), visible, infrared to radio waves.

Solar radiation outside the earth’s atmosphere is made of the entire spectrum. Our atmosphere (stratosphere) is very effective in absorbing and scattering much of this radiation. Essentially no radiation of wavelength shorter than 290nm reaches the earth’s surface. The atmosphere, especially the ozone layer, also absorbs a considerable quantity of the sun’s UVB energy so that the final make-up of UV radiation on earth is 94% UVA and 6% UVB with majority of total radiation comprising of visible and infrared radiation. Visible radiation and near-infrared radiation are implicated in raising the temperature of the skin. The UV radiation (UVR) is of special interest for the dermatologists.

UV Radiation and Photobiological Response:

Ultraviolet radiation spans the wavelength region from 400 to 100nm. It is divided into UVC (100-280), UVB (280-320) and UVA (320-400). Wavelength between 200 and 280 of UVC is absorbed by the DNA, RNA and cell proteins as well as the stratum corneum and can be lethal to the viable cells of the epidermis. Because of its germicidal action, it is often called germicidal radiation. UVB causes sunburn and is often referred to as sunburn spectrum. UVA is referred to as black light because it is not visible to the eye and causes certain substances to emit visible fluorescence.

The biological effects of UV radiation vary enormously with the wavelength. Photobiological response in the skin includes sunburn, pigmentation, aging and cancer.

Table 1: Response of human skin to UV Radiation
Spectral Band (nm) Sunburn Response (Erythmogenisity) Pigmentation (Melanogenesis) Aging Carcinogenic Property
UVA, 320-400 Weak Moderately high Definite but moderate Weak
UVB, 280-320 Strong Very strong Strong Strong
UVC, 200-280 Moderate Weak Uninvolved Moderate to high

Variation of UV Radiation:

Outside the earth’s atmosphere solar UV radiation is remarkably constant, varying less than 1%. Surface irradiance is affected, however, by many factors: solar zenith angle (varying with the latitude, time of the year and time of day), ozone, clouds and aerosols, altitude, ground reflection and scattering by air molecules (Rayleigh scattering).

Solar Zenith Angle (Solar elevation):

The variation in UV irradiance with the time of the day, seasons and the latitude is due to changes in the elevation of the sun above the horizon. Solar Zenith Angle (SZA) is often used in the place of solar elevation. It is the angle between the sun and the local vertical. SZA determines the path-length the radiation has to travel through the atmospheric absorbers (ozone) and scatterers before reaching the earth.

szaHigher the elevation (SZA=zero, at noon, in summer, near the equator), shorter the path-length, lesser the attenuation and therefore higher the irradiance. With increase in the solar zenith angle (at dawn and dusk, during winter and higher latitudes), the path-length increases, resulting in greater attenuation and lesser irradiance (Fig. 1). Shorter the wavelength, greater the attenuation and therefore, variation in SZA affects UVB more than UVA.

Fig. 1: Solar Zenith Angle–Influence on the path-length

The SZA also determines the dose per unit area; increasing angle spreads the same amount of energy over a larger area and thereby reduces the dose per unit area.

Ozone:

Ozone is by far the most important absorber of UVR. It is produced naturally in the stratosphere by reaction between oxygen and UVR of lesser than 240nm. It is mainly produced over the tropics due to higher levels of solar radiation and large scale weather transports it to higher latitudes during winter.

All of UVC and most of UVB radiation is absorbed by stratospheric ozone. With ozone depletion, UV irradiance, particularly UVB, increases at the earth’s surface. Ozone depletion is greater at higher latitudes towards the north and south poles and negligible at the lower latitudes between 35ºS and 35ºN. With a decrease of 1% in the ozone value, the irradiance increases by approximately 1.2%.

Clouds:

Effect of clouds on UVR is as variable as clouds themselves. Normally clouds attenuate UVA and UVB to the same extent. In certain conditions and for short times a small amount of cloud may even enhance UV irradiance compared to the fully clear skies.

The effect of clouds depends upon the height, thickness, amount of clouds and in-cloud absorbers (aerosols). For overcast skies, with cloud ceiling above 7kms (high level clouds), the attenuation is estimated to be only about 10%; between 3-7kms (mid-level clouds), attenuation is up to 50% and for lower level clouds (stratus clouds), attenuation is up to 80%. If the irradiance for clear skies is known, the irradiance in the presence of clouds can be calculated or estimated by multiplying the irradiance with the cloud modification factor (CMF) which ranges from 0.2 to 1 depending upon the height and the amount of the cloud.

The CMF for different levels and amount of clouds is as follows:

High level, Cirrus clouds: 1.0-0.9
Mid level, Alto clouds: 1.0-0.5
Low level, Stratus clouds: 1.0-0.2
Heaped, Cumulus clouds: 0.9-0.2
Cumulonimbus clouds: 0.2

Aerosols:

Aerosols are tiny particles suspended in the air that can scatter or absorb UVR. The effect of aerosols is independent of wavelength. Dust and smoke plumes can attenuate more than 50% of UVR. Sulfates and other industrial pollutants reduce UVR by 10-20% and this factor is important near industrial areas.

Aerosols also have an indirect effect on the climate by changing the properties of the clouds. Clouds with high aerosol content have small water droplets and scatter more UVR leading to greater attenuation. On the other hand, clouds with low aerosol content have large water droplets and therefore scatter less and allow much of the sunlight to pass through and reach the surface.

Altitude:

UV irradiance increases with altitude because the amount of absorbers and scatterers in the overlying atmosphere decreases. An increase in altitude by 1000m increases UV irradiance by 6-8%. Therefore places at higher altitude receive more UVR.

Surface reflection:

Reflection of sunlight from the terrain is of little importance, except from snow. Fresh snow may reflect 80% or more and may expose parts that are normally shaded; this is important at higher latitudes and altitudes. Sand reflects about 25%, so that sitting on the beach can lead to sunburn. Water reflects only 5%, but transmits up to 40%; so swimming in sea or pool does not prevent UVR.

Scattering by air molecules (Rayleigh Scattering):

This depends strongly on the wavelength and light of shorter wavelength is scattered more. UVR, particularly UVB, is scattered so much that at the surface of the earth the UVB is roughly composed of 1:1 mixture of direct and diffuse radiation (Sky radiation).

Sunlight in India:

Adequate amount of UV radiation is present in India (8º4′-37º6’N) for at least 10 months a year. Treatment of various dermatologic disorders using sunlight requires a thorough knowledge of the UVA and UVB irradiance in a given area and given time to optimize the dosage and minimize adverse effects.

uvabDiurnal variation: Measurement of UVR for one year at Coimbatore has shown that both UVB and UVA irradiance increase progressively from 8 a.m. until its peak value by mid-day (between 12 noon and 12.45 p.m.) and then declines (Fig. 2).

Fig. 2: Diurnal variation of UVA and UVB

More than 50% of the peak irradiance of UVA is present between 9.15a.m.-3.30p.m. and that of UVB between 10a.m.-2.45p.m. UVA irradiance is one fourth to one fifth of the peak irradiance at 8a.m. and 5p.m., where as UVB is less than one tenth of the peak in the early hours of morning and late afternoon. The mean peak UVA irradiance ranges from 4.7mw/cm2 to 6.59mw/cm2 and UVB irradiance ranges from 19.5µw/cm2 to 33.84µw/cm2 in different months, both being lowest in the month of December (Fig. 3).

Seasonal variation:

The UVB irradiance increases in March-April, without a corresponding rise in UVA irradiance. In the month of December, the UVB irradiance decreases by 46%, while the UVA irradiance decreases by 30%. Thus UVB irradiance shows a significant seasonal variation compared to UVA irradiance (Fig. 3).

season uvind
Fig. 3: Seasonal variation of UVA and UVB Fig. 4: Variation of UV irradiance at different latitudes in India

Seasonal variations are more pronounced at higher latitudes; in Northern India, the irradiance in winter is one third to one fourth of that in the months of April to September (Fig. 4).

UVB is lower by 55% at 48ºN (Paris) and by 15% at 28ºN (Delhi) compared to that at 11ºN (Coimbatore). On the other hand, UVA is lower by just 19% at 48ºN. Thus the UV irradiance, particularly UVB, decreases as one moves northwards from the equator.

Ozone, clouds and aerosols:
For a given location and time, the important factors that affect UVR are ozone, clouds and aerosols. Ozone depletion is negligible over India.

The attenuation of UV irradiance due to clouds varies from a minimum of 7% to maximum of 87% and can last from as short as 15 minutes to as long as whole day depending on the height, thickness and amount of cloud (Fig. 5).

cloudeff mumbacbe
Fig. 5: Effect of clouds on UVA and UVB Fig 6: UVA Irradiance in Mumbai and Coimbatore

UVA irradiance recorded in an industrial locality of Mumbai is 24-50% lesser compared to that recorded in Coimbatore (Fig.6), attributable to pollution.

The variations in UV irradiance influence the duration of exposure to sunlight for UVA and UVB phototherapy. For UVB phototherapy, the ideal time is 11a.m.-2 p.m. PUVASOL during this time leads to unwanted exposure to UVB; therefore the ideal time for PUVASOL is 9.30a.m.-11a.m. and 2p.m.-3.30p.m.

Table 2: Duration of exposure for UVB phototherapy
Time UVB Dose
10mJoules 45mJoules 60mJoules 90mJoules
11.00 a.m. 6m23s 28m43s 38m17s 57m25s
11.30 a.m. 5m39s 25m25s 33m54s 50m51s
12 noon 5m16s 23m40s 31m34s 47m20s
12.30 p.m 5m8s 23m8s 30m50s 46m16s
1 p.m. 5m18s 23m51s 31m48s 47m42s
1.30 p.m. 5m44s 25m50s 34m26s 51m40s
2.00 p.m. 6m5s 27m22s 36m29s 54m44s
Table 3: Duration of exposure for PUVASOL
Time UVA Dose
1 Joule 2 Joules 3 Joules 4 Joules
9.00 a.m. 5m50s 11m40s 17m29s 23m19s
9.30 a.m. 4m35s 9m11s 12m46s 18m22s
10 a.m. 3m52s 7m44s 11m37s 15m29s
10.30 a.m. 3m25s 6m49s 10m14s 13m38s
11 a.m. 3m7s 6m14s 9m22s 12m29s
2 p.m. 3m13s 6m25s 9m38s 12m50s
2.30 p.m. 3m29s 6m59s 10m28s 13m58s
3 p.m. 4m7s 8m13s 12m20s 16m26s
3.30 p.m. 4m32s 9m5s 13m37s 18m10s

The UVA and UVB irradiance being lower in the months of November-January, the duration of exposure will be correspondingly longer. Phototherapy is possible even in the presence of clouds.

UV Index:

UV Index is a parameter used to provide comprehensive information on the amount of erythemally effective UV irradiance. It is the integral of the UV irradiance weighted by the CIE Erythemal Action Spectrum. It provides a convenient way of expressing changes in the UV irradiance by a single number (scalar, from 1-20) and UVI of 1 unit = 2.5µw/cm2(25mW/m2). It is usually given for local solar noon when the sun is highest in the sky and for clear sky conditions.

UV Index is obtained by using the formula

formula

where El is solar spectral irradiance expressed in w/m2 at wavelength l ; dl is the wavelength interval used in the summation, Ser (l )is the erythema reference action spectrum andker is a constant equal to 40m2/w.

Table 4: UV Index for India (Source: GOME data)
Month South India Central India North India
January 10-11 6-9 4-5
February 11-12 8-10 5-7
March 13-14 10-13 8-9
April 14 13-14 10-12
May 12-14 13 12
June 12 13 12
July 12-13 12-13 13
August 13-14 12-13 11-12
September 11-13 11-13 9-10
October 11-12 9-10 6-8
November 9-11 6-8 4-5
December 8-10 6-7 3-4

uvidurUVI can be used to estimate the duration of exposure for UVB phototherapy and for advice on photoprotection.

The graph (Fig. 7) shows the duration of exposure for Type IV, Type V and Type VI skin with MED of 45millijoules, 60millijoules and 90millijoules respectively.

Figure 7: UV Index and duration of exposure for UVB

Conclusions

UV irradiance varies with the time of the day, season of the year and latitude and these variations affect UVB irradiance more than UVA irradiance. Seasonal variation is significant in Northern India compared to Southern India. Adequate UV irradiance is present for almost 10 months in a year in most parts of India. Effect of clouds is significant only with the overcast skies with low level clouds.

Ideal time for UVB phototherapy is between 11a.m.-2 p.m. and for PUVASOL between 9.30 a.m.-11a.m. and 2 p.m.-3.30 p.m. when the incidental UVB exposure and heat due to infrared are minimal.

Information on UV Index for different locations is available in weather forecasts and can be helpful as a guide on UV irradiance.

Bibliography:

  1. Beleo VA, Maso MJ. Photosensitivity. In Fletcher J, Moschella SL, Hurley HJ (ED). Textbook of dermatology. 3rd Edition. W.B. Saunders Company 1992
  2. Kochevar IE, Pathak MA, Parish JA. Photophysics, photochemistry and photobiology. In Freedberg IM et al (eds) Fitzpatrick’s Dermatology in Medicine. 5th Edition. Mc Graw Hill. 1999
  3. Pathak MA. Tropical and systemic approaches for the prevention of acute and chronic sunscreen induced skin reactions. Dermatology clinics. 1986;4(2):321-334
  4. Fitzpatrick TB, Pathak MA, Harber LC. Sunlight and Man. University of Tokyo Press. Tokyo. 1977;p35-40
  5. Tarasick DW, Fioletov VE, Wardle DI et al. Climatology and trends of surface UV radiation. Atmosphere Ocean. 2003;41(2):121-138
  6. Talawalkar PG, Gadgil RB. Diurnal and seasonal variations in long wave ultraviolet content of sunlight over the city of Bombay. IJDVL. 1980;46:346-349.
  7. Jeanmougin M, Civatte J. Dosimetry of solar ultraviolet radiation: Daily and monthly changes in Paris. Annals of Derm Venerol 1987;114(5):671-676
  8. Balasaraswathy P, Udaya Kumar, Srinivas CR, Shashidharan Nair. UVA and UVB in sunlight: Optimal utilization of UV rays in sunlight for phototherapy. IJDVL. 2002;68:198-201 [Full Text Online]
  9. UV- Index for the Public: A guide for publication and interpretation of solar UV Index forecasts for the public prepared by the Working Group 4 of the COST-713 Action “UVB Forecasting”. Available at http://www.lamma.rete.toscana.it/uvweb/uvbooklet/index.htm
  10. Clear-sky UV index from GOME. Available at http://www.temis.nl/uvradiation/UVindex/uvimonthly.php
  11. Intellicast: Weather for active lives. Available at http://www.intellicast.com

Skin and Diet

Skin does show several things that indicate what is right and what is wrong in our body. All disease processes that affect the internal organs also affect the skin and vice versa.

So, we, dermatologists, can identify such problems at a very early stage, and can guide the patient in the right direction, so as to prevent the progression of such diseases.

All diseases are result of interplay of inflammation, oxidative stress and proliferation resulting from imbalance of apoptotic and antiapoptotic factors.

Persistent acne, severe and chronic seborroeic dermatitis (dandruff), multiple benign growths like dermatosis papulosa nigra (DPN) and acrochordon, early onset female pattern hair loss and male pattern hair loss (female and male baldness), acanthosis nigricans (velvety thickening of the skin), chronic candidiasis, recurrent furuncles (boils), etc., can be regarded as cutaneous manifestations of metabolic syndrome (a constellation of hypertension, dyslipidemia, obesity).

Common skin diseases such as prosiasis, lichen planus, vitiligo, atopic dermatitis, alopecia areata etc., are also reported to be aggravated by oxidative stress, in turn linked to our diet and life styles.

Several studies in recent years have found close correlation between dietary factors and development of many skin diseases, especially acne, psoriasis,lichen planus, vitiligo, and metabolic syndrome. Given below are some important updates.

Milk Consumption Worsens Acne and Promotes Chronic Diseases:

Consumption of cow’s milk and cow’s milk protein result in changes of the hormonal axis of insulin, growth hormone and insulin-like growth factor-1(IGF-1) in humans. Raised levels of serum IGF-1 can explain the epidemic incidence of adolescent acne in Western milk-consuming societies. Acne can be regarded as a model for chronic Western diseases with pathologically increased IGF-1-stimulation.

See:

  • Melnik B. Milk consumption: aggravating factor of acne and promoter of chronic diseases of Western societies. Journal der Deutschen Dermatologischen Gesellschaft. April 2009;7(4):364–370. DOI: 10.1111/j.1610-0387.2009.07019.x. Free Full text
  • Solomons NW. Nature’s Perfect Food Revisited: Recent Insights on Milk Consumption and Chronic Disease Risk. DOI: 10.1301/002966402320243278. Nutrition Reviews. June 2002;60(6):180–182. Abstract
  • Danby FW. Acne: Diet and acnegenesis. Indian Dermatol Online J [serial online] 2011 [cited 2011 Aug 21];2:2-5. Available from: http://www.idoj.in/text.asp?2011/2/1/2/79851

Role of diet in acne:

A large body of evidence now exists showing how diet may directly or indirectly influence the development acne.

See:

Hyperinsulinemic diseases of civilization: more than just syndrome X [See]

More evidence to link psoriasis with metabolic syndrome:

Several reports in the recent years have suggested associations between psoriasis and metabolic syndrome sidorders. Results of a new study at Reykjavik’s Landspitali, the National University hospital of Iceland suggest that patients — especially women — with psoriasis may be at increased risk for metabolic syndrome. The study involving more than 6,500 people found the prevalence of metabolic syndrome to be higher among patients with psoriasis (40 percent) than among those without (23 percent) [See Love TJ et al. Prevalence of the Metabolic Syndrome in Psoriasis. Arch Dermatol. Published online December 20, 2010. doi:10.1001/archdermatol.2010.370. Abstract | Report

See Other Studies:

  • Cohen AD. Psoriasis and the Metabolic Syndrome. Acta Derm Venereol 2007;87:506–509. Full Text
  • Gottlieb AB et al. Psoriasis and the Metabolic Syndrome. Journal of Drugs in Dermatology. June, 2008. Full Text
  • Sommer DM et al. Increased prevalence of the metabolic syndrome in patients with moderate to severe psoriasis Arch Derm Res. 2006;298(7):321-328. Abstract
  • Gisondi P et al. Prevalence of metabolic syndrome in patients with psoriasis: a hospital-based case–control study
    British Journal of Dermatology. July 2007;157(1):68–73. Full text
  • Kimball AB et al. National Psoriasis Foundation clinical consensus on psoriasis co-morbidities and recommendations for screening. J Am Acad Dermatol. 2008 Jun;58(6):1031-42. Epub 2008 Mar 4. Available at http://www.uphs.upenn.edu/dermatol/faculty/pdf/gelfand/NPFcomorbidities.pdf
  • Rahat S. Azfar RS, Gelfand JM. Psoriasis and Metabolic Disease: Epidemiology and Pathophysiology. Curr Opin Rheumatol. 2008;20(4):416-422. http://www.uphs.upenn.edu/dermatol/faculty/pdf/gelfand/BOR309.pdf
  • More Evidence of Psoriasis Link to Metabolic Diseases Report 
  • Wolters M. Diet and psoriasis: experimental data and clinical evidence. Br J Dermatol. 2005 Oct;153(4):706-14. Full Text

Diet has been suggested to play a role in the aetiology and pathogenesis of psoriasis. Fasting periods, low-energy diets and vegetarian diets improved psoriasis symptoms in some studies, and diets rich in n-3 polyunsaturated fatty acids from fish oil also showed beneficial effects.

See:

  • Wolters M. Diet and psoriasis: experimental data and clinical evidence. Br J Dermatol. 2005 Oct;153(4):706-14. Full Text

Vitiligo and Diet:

Given the pivotal role of oxidative stress in the pathogenesis of vitiligo, food contaminants/additives/preservatives and cosmetic products could aggravate vitiligo because they produce oxidative stress in the skin. Increased consumption of omega-6 or a vegetable source of oils and decreased omega-3 intake may increase, in vivo , the production of free radicals and pro-inflammatory cytokines. Omega-3 fatty acids and eicosapentaenoic acid, in particular, are well-documented inhibitors of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and appear to exert protection against autoimmunity by enhancing antioxidant enzymes and transforming growth factor-β mRNA levels.

See:

  • Namazi MR, Chee Leok G. Vitiligo and diet: A theoretical molecular approach with practical implications. Indian J Dermatol Venereol Leprol [serial online] 2009 [cited 2011 Mar 14];75:116-8. Full text

Male pattern baldness and hyperinsulinemic disorders

See:

  • Herreraa CR, Lynch C. Is baldness a risk factor for coronary artery disease? A review of the literature. Journal of Clinical Epidemiology. 1990;43(11):1255-1260. doi:10.1016/0895-4356(90)90026-L. Abstract
  • Cordain L et al. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr February 2005;81(2):341-354. Full Text athttp://www.ajcn.org/content/81/2/341.full.pdf+html
  • Starka L, Duskova M, Cermakova I, Vrbiková J, Hill M. Premature androgenic alopecia and insulin resistance. Male equivalent of polycystic ovary syndrome? Endocr Regul.2005 Dec;39(4):127-31. Abstract at http://www.ncbi.nlm.nih.gov/pubmed/16552990
  • Signorello LB et al. Hormones and hair patterning in men: A role for insulin-like growth factor 1? Journal of the American Academy of Dermatology. February 1999;40(2):200-203. Abstract at http://www.eblue.org/article/S0190-9622(99)70188-X/abstract
  • Matilainen V, Koskela P, Keinänen-Kiukaanniemi S. Early androgenetic alopecia as a marker of insulin resistance. The Lancet. September 2000;356(9236):1165-1166 doi:10.1016/S0140-6736(00)02763-X. Available at http://download.thelancet.com/pdfs/journals/lancet/PIIS014067360002763X.pdf

Fructose (Fruit Sugar) is a more important cause for metabolic disorders like diabetes, hypertension, fatty liver disease, obesity

See:

Skin, Hair, Nail Care

Care of the skin is very important, not only for its appearance, but also to prevent certain problems.

Cleansing: Hygiene is one of the most important interventions for maintaining one’s health and well being. Cleansing is one of the routines followed to maintain hygiene. Cleansing is meant to remove the dirt, sebum, dead cells, bacteria etc. However, the act of cleansing is being promoted recently as a means of relaxation and a way to improve the skin health and appearance. These days, a wide variety of cleansing agents are available, made of different colours, scents and a variety of ingredients supposed to provide benefits to the skin.

Relatively young people with normal skin can use the cleansing agents of their choice. However, people with atopic predisposition, elderly, those suffering from acne, eczema (dermatitis) and those with sensitive skin should choose the cleansing agents that are compatible with the condition of the skin. A dermatologist may help in choosing cleansers.

Cleansing agents are of three major categories.

  • Soaps
  • Synthetic detergents (Syndet bars)
  • Lipid free cleansing agents

Soaps are alkali salts of fatty acids obtained from saponification of fatty acids derived from coconut or tallow (sodium cocoate, sodium talloate). They have an alkaline pH (>7). The irritancy potential of the soap depends upon the fatty acids used. Coconut derived fatty acids are believed to be more irritant to the skin. By adding certain additives, a variety of subsets of soaps are made:

  • Transparent soaps contain humectant glycerin that counters the drying effect of soap
  • Superfatted soaps contain excess of fatty materials like triglycerides, lanolin, paraffin, stearic acid or mineral oil. These are suitable for dry skin. These can cause pimples when used on the face, particularly in adolescence.
  • Deodorant soaps or antibacterial soaps contain antibacterial agents like triclosan, triclocarbon or carbanilade. Use of these soaps should be restricted to certain areas of the body like the arm pits, toe web spaces where the growth of bacteria can result in bad odour.
  • Anti acne soaps contain chemicals like sulfur, resorcinol or salicylic acid which have keratolytic properties. These should be used judiciously

Synthetic detergents: In contrast to the soaps, synthetic detergents’ structure often is tailored to impart specific properties to the molecules. Synthetic detergents are made up of surfactants which fall into four categories based on the charges.

  • Cationic (positively charged) surfactants
  • Anionic (negatively charged) surfactants
  • Amphoteric (both positively and negatively charged) surfactants
  • Non-ionic (uncharged) surfactants

Anionic surfactants are most commonly used in the cleansing agents. Among this group, sodium lauryl sulfate is the most commonly used surfactant and has the greatest irritancy potential. On the other hand, salts of isethionate such as cocoyl isethionate have excellent skin compatibility and are good detergents. Cationic surfactants such as acrylate polymers or non ionic surfactants like propylene glycol are combined with anionic surfactants to reduce the irritancy. Other surfactants that have got good skin compatibility are alkyl ether sulfate, alkyl glyceryl ether sulfonates (anionic) and betaines (amphoterics). Betaines, such as cocamido propyl betaine, are used in combination with anionic surfactants to reduce the irritancy of the anionics. However, cocamido propyl betaine can cause contact allergy in some individuals. Knowing the type of surfactant used in the cleansing agent is important, as it will help to know the offending agent in case of any adverse reactions.

Lipid free cleansing agents: These lotions contain fatty alcohols and they are designed for people with sensitive or dry skin. They also contain emollients and humectants (propylene glycol) to counter the irritancy or drying potential of the surfactant used.

Individuals with atopic dermatitis, eczemas, aged skin, sensitive skin etc., should follow the following precautions while cleansing:

  • Use luke warm water for bathing; avoid long bath
  • Use as minimal cleansing agent as possible
  • Use a mild cleanser

The mildness of a cleansing agent depends upon:

The pH of the soap: Though it is widely debated, it is believed that maintaining the pH between 4 and 6.5 prevents the overgrowth of certain micro-organisms on the skin.

Surfactant used: Combination of anionic surfactants with acrylate polymers and/or propylene glycol reduces the irritancy potential of anionic surfactants.

Skin cleanser residue: The agents that remain on the skin for longer length of time have greater irritancy potential. Lipid free cleansing lotions are associated with less residue.

Moisturizing: Skin care products like moisturizers can be used regularly on the body immediately after bath and it is a must after the age of 30 years and in those individuals with dry skin. [See moisturizers]

Clothing: Clothing should be comfortable and soothing to the skin. Woolen and rough clothing can precipitate itching and dermatitis in persons with dry skin. Tight clothing can precipitate boils/acne over the upper back, upper arms and buttocks.

Facial skin should be handled carefully after puberty. Those with a tendency for pimples should not use oily cosmetics. They should cleanse the face with proper cleansers. Facials should be avoided as it can precipitate burst of new pimples. Compacts and foundations that contain waxes should be avoided, on the other hand loose powders should be used. Use of turmeric and sandal can cause extreme dryness of the skin that can change the look and feel of the skin.

Hand Care:

  • Do not use soaps that are too harsh
  • Do not wash the hands frequently with soap
  • Wipe your hands dry immediately after hand wash and in between the work
  • Moisturize your hand skin as frequently as possible
  • Do not use plain rubber gloves; use cotton-lined gloves instead

Nail Care:

  • Do not use your finger nails to open the lids or scrape the dirt. Once you create a space between the nail and nail-bed, you will be inviting infection that can make your nails and nail folds look ugly.
  • Do not cut the nails too short, see that the nail bed is covered
  • Do not destroy the cuticle during manicure and pedicure
  • Regular use of nail polishes and removers can remove the moisture content of nails and can make them brittle.

Hair Care:

Hair cleansing should be done 2-3 times a week

Shampoo should be used in place of bath soap. Shampoo should be selected based on the type of hair

Excessive oiling of the scalp can precipitate acne after puberty and worsen dandruff. Oiling of scalp should be done 1-2 hours before hair wash. If oil has to be kept for longer duration, it should be applied only to the hair and not to the scalp. Oiling only conditions the hair and will not in anyway increase the number of hairs. Scented and medicated oils do not have any extra benefits over the ordinary oils.

  • Massage of the scalp improves the blood circulation and may increase the rate of growth. But if done vigorously, it can cause boils.
  • Minimize trauma while shampooing, drying, combing, brushing and styling
  • Hair should not be combed when wet; the hair shafts are prone to fracture due to increased elasticity when wet. Detangle with fingers and wide toothed comb.
  • Hair drying should be natural. If a dryer is used, it should be held at least 6” away and the lowest heat setting should be used
  • Minimize chemical treatment of hair

Normal Skin, Hairs and Nails

Skin is the largest organ of the body and is the mirror of one’s personality. It is the barrier against the environmental insults and prevents loss of water from the body. Skin has important role in regulation of body temperature, perception, synthesis of vitamin D and social communication. We have to understand our skin to not only understand the problems of the skin, but also to adjust to the surrounding environment and to communicate with our fellow humans.

The epidermis is made up of keratinocytes and melanocytes. The keratinocytes are arranged in layers and the top-most layer is called the stratum corneum. This layer is made up of dead cells which are continuously shed.  Lower most layer of the epidermis is called stratum germinatum. Cells in this layer divide constantly and give rise to daughter cells that replace the old cells in the stratum corneum. The process of daughter cells maturing and moving to the top layer is called keratinization (cell cycle). This process occurs constantly and continuously and the duration of this cell cycle is 26-42 days. The end product of this process is the stratum corneum. Stratum corneum maintains the water content in the skin. It is an effective barrier to trans-epidermal water loss and to penetration of exogenous substances. When the process of keratinization is disturbed either by disease (genetic or acquired), environmental factors or ageing, the barrier becomes defective. A defective stratum corneum leads to flaking of the skin due to increased trans-epidermal water loss, increased incidence of irritant/allergic dermatitis due to easy entry of obnoxious agents, increased incidence of UV radiation induced changes such as light eruption, pigmentation and growths.

Melanocytes are pigment (melanin) producing cells present in the lower most layer of the epidermis. They produce melanin and disperse it to the neighbouring keratinocytes. Melanin pigment gives colour to the skin and the hair and protects the skin from the sunlight. Each melanocyte is in connection with 32 neighbouring keratinocytes (epidermal melanin unit). Any defect in the process of synthesis and dispersion of the pigment leads to hyper (dark) or hypo (light) pigmentation.

Beneath the epidermis is the layer called dermis. It is made up of ground substance like hyaluronic acid and dermatan sulfate as well as fibres like elastin and collagen that are responsible for the elasticity of the skin. When the collagen and elastin in the dermis get damaged with age, the skin shows wrinkles.

The dermis has three types of glands: the apocrine, eccrine and sebaceous glands. The apocrine glands are found in association with hair follicles, abundantly in the arm pits. They are responsible for the body odour. The eccrine glands are distributed widely over the body; they produce sweat and help in regulation of the body temperature. Normally the sweat is odourless, but colonisation of certain bacteria may impart it a bad odour. The sebaceous glands are  present throughout the skin except the palms and soles and are numerous on the scalp and the face. These glands secrete an oily substance called sebum, which lubricates the skin and forms a coating on the hair, keeping it soft and shiny. When the sebum secretion is inadequate, the skin becomes dry and wrinkled and when the secretion is increased, the skin becomes oily and shiny.

In addition to this, the dermis contains a network of blood vessels, lymphatics, nerves and cells of the immune system.

Subcutaneous tissue comprises of fat globules and largely supports the overlying dermis and epidermis.

Hair is essentially a vestigial structure that man has lost during evolution. However, any change in the pattern, quality, quantity or colour of the hair causes a tremendous concern, out of proportion to its physiologic function.

Each hair undergoes a cyclic growth in three phases:

  • The growth phase – 3-4 years
  • Followed by catagen – 10 days
  • Followed by telogen (resting) – 2-3 months

During the resting phase the hair becomes detached from its root and falls out as a new growing hair replaces it in the follicle.

On an average, the scalp contains 100,000 hair. At any given time 10-15% of the scalp hair are in inactive phase, ready to fall out, while the remaining are in various stages of growth. A loss of up to 100 hairs per day is normal and is something one should not worry about as most of the lost hair would be replaced. With age, however, the rate of replacement slows down; so as you grow older, there is a natural tendency for some amount of sparseness of your scalp hair.

The rate of hair growth varies considerably, but on an average it is one cm per month and is more in summer than winter. Growth rate is maximum between 15-30 years. Cutting or shaving does not make the hair grow faster. Neither does trimming affect the growth rate in any way, though it does make you look good by eliminating straggling ends.

Good quality long hair runs in families and so does the male type baldness. A good balanced diet is a must for good growth and texture of hair.

Nails protect the tips of the fingers. The nail unit is composed of nail plate, nail matrix, nail bed and nail folds. The nail plate is surrounded on three sides by the nail fold, the invaginations of the epidermis that provide a guiding groove for nail growth. Cuticle is that part of the nail unit which is between the nail fold and the nail. It helps to seal the matrix and the soft nail from the outside. Nail matrix is a specialised epidermis that produces the nail. As the nail matrix cells differentiate, they keratinise (become hard) and produce the nail plate. The rate of growth of the nail plate is approximately 0.1mm per day.

ನಿಮ್ಮ ತ್ವಚೆಯ ಆರೈಕೆ

ಮುಖ ತೊಳೆಯಲು ಸಲಹೆಗಳು

1. ಮುಖವನ್ನು ಪದೇ ಪದೇ ತೊಳೆಯಬೇಡಿ: ಮುಖವನ್ನು ದಿನಕ್ಕೆ 2-3 ಸಲ ತೊಳೆದರೆ ಸಾಕಾಗುತ್ತದೆ. ಪದೇ ಪದೇ ತೊಳೆಯುವುದರಿಂದ ಚರ್ಮವು ಒಣಗಿ ಬಿರುಸಾಗುವ ಮತ್ತು ಮೊಡವೆಗಳಾಗುವ ಸಾಧ್ಯತೆಯು ಹೆಚ್ಚುತ್ತದೆ. ಅಷ್ಟೇ ಅಲ್ಲ, ಚರ್ಮದ ಗ್ರಂಥಿಗಳು ಇನ್ನಷ್ಟು ಎಣ್ಣೆಯಂಶವನ್ನು ಸ್ರವಿಸುವುದರಿಂದಾಗಿ, ಮೊಡವೆಗಳಾಗುವ ಸಾಧ್ಯತೆಯು ಹೆಚ್ಚುತ್ತದೆ.

2. ಬಲಶಾಲಿಯಾದ ಸಾಬೂನುಗಳು (ಬ್ಯಾಕ್ಟೀರಿಯಾನಾಶಕ) ಮತ್ತು ಕ್ಲೆನ್ಸರ್ ಗಳನ್ನು ಬಳಸಬೇಡಿ: ಬಾರ್‍ಸೋಪುಗಳು ಮತ್ತು ಬಾರ್ ಕ್ಲೆನ್ಸರ್‍ಗಳು ನಿಮ್ಮ ಚರ್ಮಕ್ಕೆ ಹಾನಿಯುಂಟುಮಾಡುತ್ತವೆ ಮತ್ತು ಚರ್ಮದ ರಂಧ್ರಗಳನ್ನು ಮುಚ್ಚುತ್ತವೆ. ಮೃದುವಾದ, ಮೊಡವೆಗಳನ್ನುಂಟುಮಾಡದ, ಅಲರ್ಜಿಯನ್ನುಂಟುಮಾಡದ ಕ್ಲೆನ್ಸರ್ ಗಳನ್ನೇ ಆಯ್ದುಕೊಳ್ಳಿರಿ.

3. ಕ್ಲೆನ್ಸರ್ ಗಳನ್ನು ಅತಿಯಾಗಿ ಬಳಸಬೇಡಿ: ತೊಳೆಯುವಾಗ ಕ್ಲೆನ್ಸರ್ ಅನ್ನು ಸಾಕಷ್ಟು ನೀರಿನೊಂದಿಗೆ ಬೆರೆಸಿರಿ. ಮೃದುವಾದ ಕ್ಲೆನ್ಸರ್ ಅನ್ನು ಬಳಸುವುದಿದ್ದರೂ ಅದನ್ನು ನೀರಿನೊಂದಿಗೆ ಬೆರೆಸುವುದು ಒಳ್ಳೆಯದು (ಅಂಗೈಯಲ್ಲಿ ಹಿಡಿಯುವಷ್ಟು ಕ್ಲೆನ್ಸರ್ ಸಾಕು). ಕ್ಲೆನ್ಸರ್ ಸಾಂದ್ರತೆಯು ಕಡಿಮೆಯಿದ್ದಷ್ಟೂ ನಿಮ್ಮ ಮುಖಕ್ಕೆ ಒಳ್ಳೆಯದು.

4. ಆಲ್ಕೋಹಾಲ್ (ಸ್ಪಿರಿಟ್) ಇರುವ ಕ್ಲೆನ್ಸರ್ ಅನ್ನು ಬಳಸಬೇಡಿ: ಟೋನರ್‍ಗಳು ಹಾಗೂ ಅಸ್ಟ್ರಿಂಜೆಂಟ್‍ಗಳನ್ನು ಬಳಸುವಾಗ ಹಿತಕರವಾದ ಅನುಭವವಾದರೂ, ಅವುಗಳ ಅತಿಯಾದ ಬಳಕೆಯಿಂದ ತ್ವಚೆಗೆ ಹಾನಿಯಾಗಬಹುದು! ಆಲ್ಕೋಹಾಲ್ ನಿಮ್ಮ ಮುಖದ ಸಹಜವಾದ ತೈಲಾಂಶವನ್ನು ಏರುಪೇರು ಮಾಡುವುದರಿಂದ, ತ್ವಚೆಗೆ ಹಾನಿಯಾಗುತ್ತದೆ.

5. ಯಾವುದೇ ಉತ್ಪನ್ನವನ್ನು ಹಾಗೇನೇ ಬಳಸಬೇಡಿ: ನಿಮ್ಮ ಚರ್ಮದ ಮೇಲೆ ಏನನ್ನೇ ಬಳಸುವ ಮೊದಲು ನಿಮ್ಮ ಚರ್ಮದ ವಿಧ ಹಾಗೂ ಅಂತಹ ಉತ್ಪನ್ನಗಳ ಬಗ್ಗೆ ಅರಿತುಕೊಳ್ಳಿ. ಒಣ ಚರ್ಮವಿದ್ದರೆ ಗ್ಲಿಸರಿನ್‍ಯುಕ್ತವಾದ ಮೃದುವಾದ ಸೋಪುಗಳನ್ನು ಬಳಸಿರಿ. ಮೊಡವೆಗಳಿಗೆಂದು ಮಾರುವ ಸೋಪುಗಳಲ್ಲಿ ಬೆಂಜೈಲ್ ಪೆರಾಕ್ಸೈಡ್ ಅಥವಾ ಸಾಲಿಸಿಲಿಕ್ ಆಮ್ಲಗಳಿರುವುದರಿಂದ, ಅವುಗಳ ಅತಿ ಬಳಕೆಯಿಂದ ತ್ವಚೆಯು ಅತಿಯಾಗಿ ಒಣಗಬಹುದು.

6. ಸಾಕಷ್ಟು ನೀರಿನಲ್ಲಿ ತೊಳೆಯಿರಿ: ಹಾಗೇ ಬಿಟ್ಟ ಉಳಿಕೆಗಳು ಚರ್ಮದ ರಂಧ್ರಗಳನ್ನು ಮುಚ್ಚಬಹುದು.

7. ಪದೇ ಪದೇ ಮೇಲ್ಚರ್ಮವನ್ನು ತೆಗೆಯಬೇಡಿ: ತ್ವಚೆಯ ಮೇಲ್ಪದರವನ್ನು ತೆಗೆದು ಸ್ವಚ್ಛಗೊಳಿಸುವ ನೆಪದಲ್ಲಿ ಸ್ಕ್ರಬ್‍ಗಳನ್ನು ಅತಿಯಾಗಿ ಬಳಸಿದರೆ ತ್ವಚೆಯು ದೊರಗಾಗಿ ಅಂದಗೆಡುತ್ತದೆ. ಅಂತಹ ಸ್ಕ್ರಬ್ ಗಳನ್ನು ಬಳಸದಿರುವುದೇ ಲೇಸು!

8. ಟವೆಲ್‍ನಿಂದ ಮುಖವನ್ನು ತಿಕ್ಕಬೇಡಿ: ತೊಳೆದಾದ ಬಳಿಕ ಟವೆಲ್‍ನಿಂದ ಮುಖವನ್ನು ಮೃದುವಾಗಿ ಒತ್ತಿ ನೀರನ್ನು ತೆಗೆಯಿರಿ.

ನೆನಪಿಡಿ! ನೀವೇನು ಮಾಡುವುದಿದ್ದರೂ ಸರಳವಾದ, ಸುಲಭವಾದ ವಿಧಗಳನ್ನೇ ಬಳಸಿರಿ.
ನಿಮ್ಮ ತ್ವಚೆಯ ಮೇಲೆ ಹರಿಹಾಯಬೇಡಿ; ತಾಳ್ಮೆಯಿಂದ, ಮೃದುವಾಗಿ ವರ್ತಿಸಿ.
ಸದಾ ನಿಮ್ಮ ಅತ್ಯುತ್ತಮವಾದ ವದನವೇ ಮುಂದೆ ಬರಲಿ!