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ULTRAVIOLET LIGHT Man’s best friend. Dr. D. Czarnecki MD MBBS. Ultraviolet light. Sunlight has many beneficial effects on men and it has been known for a long time that sunlight is good for you – even though exactly what sunlight did was unknown until recently

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Ultraviolet light man s best friend

ULTRAVIOLET LIGHTMan’s best friend

Dr. D. Czarnecki MD MBBS

Ultraviolet light
Ultraviolet light

  • Sunlight has many beneficial effects on men and it has been known for a long time that sunlight is good for you – even though exactly what sunlight did was unknown until recently

  • 1385 BC - Echnaton (Egypt) praised sunlight

  • Hippocrates noted that sunlight leads to faster healing of fractures

  • 135 AD - Anthyllos (Greece) stated that exposure to sunlight made bodies stronger and activated brain function

  • 20th century - it was found that the sun prevents rickets

  • Ultraviolet light (UVL) is the part that of the sun’s spectrum that causes the most benefit

Ultraviolet light1
Ultraviolet light

  • Ultraviolet light (UVL) is the part of the sun’s spectrum lying between 200 and 400 nm

  • It is divided into three components based on certain properties

  • UVC does not penetrate through ozone

  • UVB does not penetrate through glass or sunscreens. It is attenuated by ozone

  • UVA does not penetrate through opaque materials

Ultraviolet light

200nm 290 320 400nm







opaque material

Ultraviolet light2
Ultraviolet light

  • UVC is the strongest component – most likely to burn

  • UVB is strong and causes sunburn

  • It produces a tan

  • It damages DNA

  • It causes the skin to produce chemicals

  • UVA is weak

  • It darkens existing pigment but does not produce new pigment

  • It penetrates deeply into the skin – may cause wrinkles

Ultraviolet light






The epidermal cells (Keratinocytes)

are chemical power houses

Vitamin d
Vitamin D

  • Vitamin D is one of the most important chemicals produced by the skin

  • 7 dehydrocholesterol is converted into previtamin D by UVL

  • Previtamin D moves into the circulation, to the liver where it is converted into 25 hydroxy vitamin D (25 OHD)

  • 25 OHD is transported into the kidneys where it is converted into 1 25 dihydroxy vitamin D (1 25OHD) – the active form



7 dehydrocholesterol

previtamin D







Ultraviolet light is the most important source of vitamin D

Vitamin d1
Vitamin D

  • Dietary precursors enter the liver to be converted into 25OHD

  • People cannot obtain enough vitamin D via their diets

  • People cannot produce too much vitamin D from the sun


  • 7 dehydrocholesterol previtamin D inert substance

Vitamin d2
Vitamin D

  • It was only recently discovered that he skin also produces the active form of vitamin D (1 25 OHD)

  • UVL

  • 7 dehydrocholesterol previtamin D 1 25 OHD

  • Many other organs, apart from the kidneys, also produce 1 25 OHD

Vitamin d3
Vitamin D

  • The current recommendations – vitamin D intake

  • <13 yrs – 200 IU (international units)

  • 51 – 70 yrs – 400 IU

  • >70 yrs – 600 IU

  • Studies of people who are covered in clothing when outside, and studies of submariners, suggest that 1000 IU a day are needed if people do not get some sun on their skins

Vitamin d4
Vitamin D

  • Dietary sources of vitamin D

  • 1 teaspoon of cod liver oil – 1360 IU

  • 100 g of salmon – 360 IU

  • 1 egg – 20 IU

  • 1 cup of fortified milk – 98 IU

  • There is little in breast milk

  • People cannot obtain enough vitamin D from their ordinary diets

Vitamin d5
Vitamin D

  • It is needed to maintain normal body calcium levels

  • It promotes calcium absorption from the small intestine

  • It promotes re-absorption from the kidneys

  • A fall in serum calcium triggers the parathyroid gland to produce parathyroid hormone

  • The kidneys produce more 1,25 vitamin D

  • Bone is resorbed

Vitamin d6
Vitamin D

  • Needed for healthy bones

  • Needed for healthy muscles

  • Prevents osteoporosis?

  • Prevents cancers

  • Reduces the incidence of auto-immune diseases

  • Reduces the incidence of multiple sclerosis

  • Reduces hypertension and myocardial infarction

  • Alleviates depression?

  • Deficiency – causes poor spermatogenesis?

Vitamin d musculoskeletal system
Vitamin D musculoskeletal system

  • Vitamin D deficiency is associated with osteomalacia and increased bone turnover – a risk for fractures

  • Deficiency might be associated with osteoporosis

  • Deficiency – poor muscle co-ordination might be present

  • Deficiency – muscle pain might be present. Deficiency might be the cause of “fibromyalgia” in older patients

Hip fractures
Hip fractures

  • Thin bones, and poor muscle co-ordination – a risk for fractures

  • About 20,000 hip fractures a year in Australia

  • 87% are older than 55 years

  • 6% die – inpatients

  • 15 – 20% die within 12 months

  • 50% have some disability

  • Double blind, placebo controlled studies have found that vitamin D and calcium reduce falls and reduce the number of fractures when falls occur

Vitamin d cancer
Vitamin DCancer

  • The closer to the equator people live, the less risk of internal cancers and dying of cancer

  • Women given vitamin D in Nebraska developed fewer cancers over 4 years compared to controls – a prospective study

  • Double blind, placebo controlled studies of calcium and vitamin D

    Reduced the risk of colonic adenomas

    Rats given vitamin D then carcinogens developed fewer cancers of the colon

Vitamin d cancer1
Vitamin DCancer

  • In tissue culture – vitamin D kills cancer cells (prostate cancer, melanoma)

  • It has anti-proliferative effects

  • Blocks the cell cycle

  • Promotes the differentiation of cells

  • Induces apoptosis

  • Boosts the immune response

  • Reduces angiogenesis

Vitamin d cancer2
Vitamin DCancer

  • Improves the response to chemotherapy

  • Improves the response to radiotherapy

  • Causes hypercalaemia

  • Analogues are being developed

  • These will have some of the benefits without the hypercalaemia side effect

Vitamin d death prevention
Vitamin D – death prevention

  • Norway – surgery for CA in winter is more likely to kill you than if it is undertaken in the summer

  • Boston – lung CA surgery in the winter is more likely to result in death than if it is in the summer

  • Similar findings with cardiac surgery in the UK – higher death rate in winter

  • It may be more than the surgeon’s winter depression

Vitamin d melanoma
Vitamin D – melanoma

  • The role of sunlight in the genesis of melanoma is still being debated. Sunburn is the common finding in studies through out the world

  • Indoor workers have a higher incidence than outdoor workers – through out the world

  • Melanoma excised in the summer in Australia - live longer (adjusted for age, sex, thickness, site, type) than if a melanoma is excised in the winter

  • Melanoma survival is better in regions closer to the equator

Vitamin d diabetes
Vitamin DDiabetes

  • UK children given 2000IU of vitamin D – 80% less diabetes than their control group

  • Diabetes-prone mice given 25 OHD – 80% less diabetes

  • Obesity is associated with lower vitamin D – it is a risk factor for diabetes

  • Insulin resistance is more common in vitamin D deficient people – can be corrected with supplements

Sun exposure
Sun Exposure

  • The sun is good for you in small doses

  • Too much sun exposure damages the skin. It causes thinning, wrinkles, brown macules, burst blood vessels – an aged appearance

  • People have to be educated about safe sunbathing

  • The aim is not to get sun burnt. Wear appropriate clothes and put sunscreen on exposed skin after a certain period of exposure

Too much UVL damages the skin – thin wrinkled, bruised

The skin of his stomach is what his skin should look like. Note the difference

The demarcation line is visible. The skin looks aged. Note the normal skin in the unexposed sites – this is his age

How many minutes it takes for untanned skin to burn at noon on a clear day
How many minutes it takes for untanned the normal skin in the unexposed sites – this is his ageskin to burn at noon, on a clear day.

Sun exposure1
Sun Exposure the normal skin in the unexposed sites – this is his age

  • The average white Australian’s tan has an SPF of 3 – he can stay outside three times as long as someone with out a tan

  • The average Indian has an SPF of 15 – he will burn every day in Darwin if he stays outside all day

    4 months of the year in Melbourne

  • Even Blacks burn – Viv Richards will tell you that sunburn is just as painful in blacks as whites

  • Some Asians have pale skin - 14% of Koreans have light skin– they easily burn

How many minutes it takes for untanned and an average tanned skin to burn
How many minutes it takes for untanned the normal skin in the unexposed sites – this is his ageand (an average tanned skin) to burn

Sunscreens the normal skin in the unexposed sites – this is his age

  • Slow down sun damage

  • Prevent new solar keratoses (SKs) – Australia, USA, Europe

  • Prevent new SKs even in renal transplant recipients – if they are applied every day

  • Prevent SCCs – a Queensland prospective study

  • Prevent skin cancer in renal transplant recipients (German study)

  • Sunscreens prevent vitamin D formation

Sunscreens the normal skin in the unexposed sites – this is his age

  • Some studies suggest that sunscreen use is associated with an increased risk of melanoma

  • These were not always well designed studies.

  • Some facts that need to be addressed in future studies

  • People who sunburn easily – more likely to use a sunscreen (also more likely to get a melanoma)

  • People may apply a sunscreen when at the beach, but what about the rest of the time? A lot of exposure occurs during activity e.g. walking around

  • Some studies were retrospective therefore biased – people are more likely to use a sunscreen after a melanoma was diagnosed

Vitamin D deficiency is largely a cultural problem the normal skin in the unexposed sites – this is his age.

Moslem women

Women who work in offices

Nursing home patients

African immigrants


Expose the head and forearms to the sun for 15 minutes, five times a week at noon

Vitamin d7
Vitamin D the normal skin in the unexposed sites – this is his age

  • For adequate levels of vitamin D

  • People need to expose 20% of the body, at noon, for

    10 minutes if they do not tan

    for 15 minutes if they tan

  • Three days a week (no sunscreen)

  • After this exposure, cover up or put a sunscreen on

Vitamin d8
Vitamin D the normal skin in the unexposed sites – this is his age

  • Why not take vitamin D and avoid the sun?

  • UVL induces the skin to produce many other chemicals including hormones

  • These hormones have many properties such as:

    producing a tan

    anti-inflammatory properties

    appetite suppression

    influence lipid metabolism

    influence mood

Hormones the normal skin in the unexposed sites – this is his age

  • Keratinocytes produce a large hormone called


  • This enters the circulation and is cleaved into other hormones in different tissues

  • These hormones have many beneficial effects. The endorphins make people feel better and is possibly why sunbathing is addictive to some

UVL the normal skin in the unexposed sites – this is his age






Ultraviolet light3
Ultraviolet Light the normal skin in the unexposed sites – this is his age

  • Damages the epidermis and dermis (in big doses)

  • Suppresses the immune system

  • Causes the epidermal cells to produce many chemicals

  • Produces a tan

  • Causes skin cancer

ULTRAVIOLET LIGHT the normal skin in the unexposed sites – this is his age

Melanocyte - DNA damage

Keratinocyte - DNA damage, p53 damaged

Langerhans cells inactive

UVL damages DNA, DNA repair enzymes, and causes cutaneous immunosuppression (it damages Langerhans cells)