With  their bulging bank balances and the world’s top beauticians on speed  dial, you could be forgiven for thinking that celebrities have it easy  when it comes to skincare. How wrong you’d be. Whether it’s smoking or  overexposure to harmful rays, we take a look at the top skincare sins  and the celebrities who commit them.  
 
Rex Features
Partaking  in the evil weed is one of the quickest routes to a wrinkly,  prematurely aged complexion and rock chick Courtney Love is a classic  example of how smoking can take its toll on the skin. "Smoking causes  premature ageing by damaging the collagen matrix of the skin and  dehydrating skin, which leads to a loss of elasticity," says Shabir Daya  at 
victoriahealth.com.  "Nicotine content restricts blood flow to the skin causing loss of  radiance and resulting in a lacklustre skin. One of the other problems  with smoking is that the whole action of smoking can cause deep  wrinkles, exaggerating frown lines and wrinkles around the lips."
As  the face of countless brands, good skin was a must for Kate Moss, but  years later, now it appears years of piling on various lotions and  potions for make-up shoots has taken its toll on the supermodel's skin.  "The most common mistake people make is over treating their skin on  their quest for perfect skin," says celebrity facialist Ole Henriksen.  "Additionally, when using moisturisers, cleansers or exfoliants you  don't want to rub too vigorously - you don't want to overtreat or  oversensitise your skin. It's important to recognise that by gently  slipping the product across your face in upward circular motions, you're  stimulating the granular ingredients to do the work for you, as they  were designed to do."
We  all love a healthy glow, but spending too long in the sun doesn't just  increase the risk of cancer. Donatella Versace is a classic example of  the effects of sun damage, while sun-loving Geri Halliwell looks set to  follow in the same footsteps. "Sun exposure is the cause of up to 80% of  premature ageing," says Katherine Bell, senior therapist at The  Sanctuary Spa in Covent Garden. "Whilst we often see the effects of the  UVB rays through reddening on the skin, the UVA rays often don't show  themselves until later in life. These rays have an effect on the deeper  layers of our skin where our collagen and elastin are found, and it's  collagen and elastin that help to keep our skin firm and plump." If  you've spent too long soaking up those rays in the past, look for  products that contain phytoestrogens - which are derived from the plants  Pueraria Lobata and Pelvetia and can help stimulate the production of  collagen - such as Clarins' Super Restorative Day Cream (
ciao.co.uk).
While  film star Cameron Diaz probably has access to some of the best  facialists around, her hectic lifestyle could well be the cause of her  acne - finding time to enjoy a balanced nutritional diet is key to  maintaining a healthy complexion. "Poor diet can have a detrimental  effect on the skin, so it's very important to maintain a nutritional  diet rich in fruits and vegetables which will maximise antioxidant  levels in the skin and body to help to fight free radicals," advises  Amanda Watson, brand manager for Neal's Yard Remedies.
 
Rex Features
Although  we love Nicola Roberts for the fact she's finally embraced her  naturally pale complexion, the often flaky appearance of her skin  suggests she could well be skimping on the moisturiser. "The average  person doesn't apply enough moisturiser because they're afraid of  clogging the pores and causing blackhead pimples," says Ole Henriksen.  "But most formulations today are non-comedogenic - they won't clog your  pores. By not applying enough moisturiser, your skin won't bounce back  easily; it may become dry and flaky, or prone to broken capillaries.  Moisturiser acts as a protective shield." Ole Henriksen's Herbal Day  Cream (
ciao.co.uk) instantly infuses skin with long-lasting moisture without clogging pores.
 
Rex Features
California  girl Jessica Simpson has admitted she struggles with her weight, but a  healthy diet and regular exercise isn't just essential for when it comes  to squeezing into those tiny dresses. "Exercise is essential for good  skin because it improves circulation, boosts metabolism, and helps  maintain muscle mass, all of which contribute to a healthy, youthful  appearance," explains Clinique's guiding dermatologist, Dr David  Orentreich.
While  we're not advocating that overly whitened, Hollywood smile, neglecting  your oral hygiene can have a serious effect on your appearance, due to  the fact your teeth have a large part to play when it comes to  supporting your skin. "Proper oral hygiene reduces tooth loss and helps  to prevent facial bone atrophy which leads to wrinkles and sagging of  facial skin," warns David Orentreich. "Prevention of periodontal disease  and gum loss maintains a youthful appearance."
Victoria  Beckham has fought a much publicised battle with acne since she hit the  limelight as a Spice Girl, which wasn't helped by the thick layers of  foundation she piled on. "One of the worst things you can do is simply  not looking after your skin correctly," says Caroline Frazer, skincare  expert at 
simple.co.uk.  "We only have one, so it's important to notice what's happening and  listen to it. Is it dry, greasy or combination? Are the products and  routines used working for your skin? Cleansing, toning and moisturising  every morning and every evening with gentle products without perfume is  one of the best gifts that you can give your skin and ensure that your  skin looks its best for years."
 
Rex Features
We  all love a tipple, but as Amy Winehouse's complexion shows, excessive  consumption of alcohol can play havoc with your skin. "Chronic alcohol  consumption can increase formation of small red facial veins and  contributes to other changes in the skin's appearance," warns Dr David  Orentreich at Clinique.
Too  many sleepless nights and it's only a matter of time before your skin  starts to suffer. "A lack of sleep reduces the regenerative process and  toxin removal from the skin resulting in lacklustre skin and especially  affecting the eyes causing dark circles and bags under the eyes, and can  also affect the hair," says Shabir Daya at 
victoriahealth.com.  "Use a good multitasking mask on the face to plump up the skin and  restore a dewy complexion and perhaps a caffeine-rich eye cream to  minimise eye puffiness and dark circles." Neal's Yard Remedies' Power  Berry Facial Mask (
ciao.co.uk) helps revitalise and refine the skin with a potent blend of antioxidant-rich acai, cranberry and grape.
As  we get older, fine lines start to appear, and while we're certainly not  a fan of that over-botoxed, caught-in-a-wind-tunnel look, the way we  move our face can play a huge part in the development of wrinkles.  "Avoid exaggerated facial expressions," suggests David Orentreich at  Clinique. "Always wear sunglasses when outside to avoid squinting, which  causes crow's feet around the eyes." If you've got a hectic schedule,  invest in a portable eye care product, such as Clinique's All About Eyes  Serum De-Puffing Eye Massage pen (
ciao.co.uk).
 
Rex Features
Kate  Beckinsale might well hate the hordes of paparazzi that follow her  around, but losing her temper with the paps could have some surprising  consequences. "Stress can cause numerous and varying effects on the skin  and causes the release of cortisol - the stress hormone," says Shabir  Daya. "Cortisol causes excessive sebum production as well as causing a  thickening of the cells lining the sebum-producing glands resulting in  acne, blackheads and other similar concerns. Cortisol also causes a lack  of essential fatty acid utilisation by the body and these fatty acids  help to maintain elasticity of the skin as well as maintaining the oils  within the skin - causing a lack of radiance and vitality of skin." If a  packed schedule has left you with dull, tired skin, make time for a  weekly radiance-boosting facial mask, such as A'Kin's Multi Fruit &  Willow Bark Instant Radiance Facial Masque (
victoriahealth.com).
Tamara Hinson, contributor, MSN Life & Style, Updated: 15/04/2011 16:57  MY OWN ARTICLE BELOW
SKIN CARE 
THIS ISN'T A CONVENTIONAL BEAUTY BLOG SO I AM NOT GOING INTO PRODUCTS   OR EVEN ROUTINES BUT RATHER TACKLING THE INNER CORE AND DEALING WITH   THE REAL CAUSES OF SKIN DAMAGE
THE BASICS: UNDERSTANDING HOW THE ENVIRONMENT AND STRESS AFFECTS THE SKIN
Under the 'Stress section' I   talked about how stress hormones such as Adrenalin and Cortisone affect   the skin, if you recall Adrenalin reduces the nourishment delivered by   the blood stream by directing the blood flow away from the extremities   to the heart, lungs and muscles, so the skin and hair wont be so well   nourished. Cortisone damages the fibrocytes, these are specialised cells   within the Dermis that produce collagen and elastin and it is collagen   and elastin that provides support and elasticity within the skin, akin   to the foam and springs in a mattress. When we are young our skin is   plump and elastic but through use from normal facial movements, the   downward pull of gravity, the collagen and elastin tends to bunch   together just like the stuffing in a well used mattress. Now if we   undergo stress for a considerable period as these fibrocytes become   damaged due to the action of Cortisol so the skin will loose its support   structure, its elasticity will suffer and it wont spring back to shape   like it used to, like spent elastic. Cell renewal will suffer due to  the  reduced blood supply there wont be adequate nourishment and the  skin  will take on a greyer pallor and it will loose its healthy rosy  glow.
Now there is another aspect to   this equation, the action of Ultra Violet Light from the sun and of   course sunbeds. The sun produces three types of UV Light UVA UVB and   UVC. The Earth's ozone layer blocks 97-99% of this UV radiation from  penetrating through the atmosphere.  Of the ultraviolet radiation that  reaches the Earth's surface, 98.7% is  UVA  (UVC and more energetic  radiation is responsible for the  generation of the ozone layer, and  formation of the ozone there). Now I  don't want to get to technical  here and want to focus on UVA and UVB.  UVB can only penetrate down  through the skin to the dermis and is  responsible for burning but UVA  is able to penetrate down through the  dermis and like Cortisol damages  the Fibrocytes, those little cells that  plump up our skin and give it  elasticity.
One of the best places on our   bodies to see the affects of gravity and demishing collagen and elastin   especially on women is on the thighs often referred to as 'Cellulite'.
Because we are composed of 70%   water, water is an important component of the skin, therefore it   important we drink adequate water to keep ourselves hydrated. Don't wait   until you feel thirsty before you reach for that drink, it is much   better to sip water at regular intervals as we are constantly loosing   water through bodily processes.
THE EFFECTS OF ALCOHOL, SMOKING AND DRUGS ON THE SKIN
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| TYPICAL SMOKERS SKIN (NOTE THE PURSE LINES) | 
Everything in moderation is something to bear in mind   when it comes to food and drink and that includes alcohol, but alcohol   is a toxin and the liver has to work hard to break it down. The   occasional drink is not going to have too much effect on the skin but it   does cause the peripheral circulation to dilate and one of the   characteristic signs of too much alcohol is the appearance of broken   capillaries across the face, There are other causes of broken   capillaries, sometimes, it's hereditary but often caused by  sudden   changes in temperature i.e. going from very warm central heated homes to   going outdoors without protecting the skin or driving in cars with the   heater blasting against the face. Squeezing spots is another cause.  Too  much alcohol is a depressant too, so you may feel rather jolly at  the  time but you are sure to come back down to earth with a bump.
Many common prescribed drugs have an effect on the skin its something to   be aware of many drugs such as diuretics will cause a loss of moisture   so forewarned you take extra care to apply a good moisturiser to help   counteract this effect. 
Recreational drugs obviously will have an effect on the skin too with   many of them toxic to the body and anything that diverts the body to   spend time detoxifying obviously takes energy away from repairing and   maintaining the body. This is not a blog that discusses drugs I am sure   readers will already know the dangers of such substances.
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| HEALTHY LUNGS | 
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Smoking is one of the worst abuses you can do to your   body, firstly because of its direct effect affect on the lungs, it   impairs the uptake and absorption of oxygen and of course all cells in   the body require oxygen in order to function normally. The nicotine  as   well as being addictive is a powerful vasoconstrictor therefore it   reduces blood flow to the peripheral circulation so the skin and hair   are going to suffer. So as well as impairing oxygen uptake and reducing   blood flow to the skin, the body is also having to use its resources   dealing with all the toxins also inhaled. Poorly nourished skin means it   cannot repair itself adequately. 
Smoking   also leads to more wrinkling, those little purse string lines around   the mouth and crows feet caused by the smoke further research has proven   that smoking causes the skin to age ten years.
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| EFFECTS OF ONE PACK PER DAY FOR 20 YEARS | 
The lungs to the right here are really quite shocking and here you can see the effects of tar from the cigarettes.
IMPROVING THE SKIN BY DIET
IMPROVING THE SKIN PART 1 HOW IT WORKS

Firstly please read the blogs and page on health as this will give an indication on a balanced diet. 
If I were to ask you what is the largest organ in the body what would    you say? It's not the liver or the intestines but the skin, it does a    very important job for us and how many of us take it for granted and    don't look after it.
HOW THE SKIN WORKS
The basics so you will understand how the skin works. The skin is comprised of 3 layers, the Epidermis the layer you can see, the Dermis the true skin and the subcutaneous. Cosmetics only work on the Epidermis    and you can see how deep it is, if you have ever experienced a   blister.  A blister is caused when friction causes the Epidermis and the   Dermis  to separate and the fluid within the blister is lymph. The   Epidermis has  no nerve endings or blood supply that is why removing the   top layer of a  blister is not painful, not to be recommended though  as  it exposes the  Dermis which is rich in nerves and a blood supply to   infection.
The skin  has several functions to secrete sebum that oily    substance on your skin, this is to help keep the skin moisturised by    trapping moisture and forming a barrier together with sweat known as  the   'Acid Mantle' The Acid Mantle is slightly acidic and acts as a Bacteriastat to inhibit bacteria. The skin secretes sebum via the sebaceous glands within the hair follicles and sweat via the Endocrine glands (there are another type of sweat glands know as Apocrine    glands these are found in the axillary and pubic regions unlike    Endocrine sweat bacteria act on Apocrine sweat quickly and this causes    the characteristic Body Odour, these glands only become active after    puberty and have a role to play in pheromones)
Our body temperature is regulated by the skin this is due to the     peripheral circulation either dilating to bring blood to the extremities    of the body like the skin causing flushing to help loose some of the    heat and also by sweating for as the sweat evaporates heat rises with    it. The opposite happens when its cold the body conserves heat to  vital   organs more important than the skin, giving a more white/bluish    appearance and may even induce shivering. At the base of every hair follicle there is a tiny cilary muscle    when its cold and we start to shiver this muscle contracts causing  the   hair to stand up trapping a layer of air next to the skin, giving  the   appearance of goosebumps. Within the Dermis there are sensory nerves that detect temperature. We also have an insulatory layer of fat in the subcutaneous. 
Our skin is waterproof so absorbs very little, the only things that can    permeate the skin are medications, this includes patches such as    Nicotine  and HRT and Essential oils (see Aromatherapy articles on Blog)    COSMETICS CAN NOT. Do not believe the hype and sales talk   ladies  if it could be absorbed by the skin you you have to go to your   Doctor  for it and it would need to be licensed as a Medicine.
Our Skin is protected by sensory nerves that alert us to pain, pressure,    touch, heat and cold, it is waterproof largely impermeable except to    the substances above, fairly tough and it with its layer of fat below    the dermis in the subcutaneous layer keeps us warm, protects our  organs   and bones, gives us shape. As fore mentioned the Acid Mantle  helps   protect from bacteria as bacterial growth is inhibited in its  slightly   acid environment. Melanocytes special little  cells in the   dermis increase as a result of UV light and give us  tanning, the   epidermis also thickens to help protect our skin. Also in  the skin are mast cells and when they are damaged, they produce histomine,    it gives the characteristic itching a weals associated by allergies,    its function is to stimulate blood to the skin to repair and maintain    it. However with allergies the body is hypersensitive producing this    effect.
The skin also excretes some toxins through sweat but this is very very    minimal, so do not believe the hype of some sales people who will    suggest you have a detoxifying foot bath that will rid you of toxins as    it changes the water to a dirty brown colour. Again this is sheer hype    and nonsense for if ridding the body of toxins was that easy we   wouldn't  have a need for Dialysis Machines for those suffering kidney   failure.  It is the Liver, Kidneys and large Intestine that detoxify us.
Vitamin D is also formed in the skin as a result of the    action of UV light acting on 7-dehydrocholesterol present in the skin,    so everything in moderation we do need some sunlight.

So you know know how the skin works and it's functions  and that's great   when everything is in balance. However skin is a very sensitive organ   but as far as the body is concerned it is a lesser important organ that   the heart, lungs, liver etc, so priority is given to important organs  at  times of stress, whether that is emotional stress i.e. worry etc. or   physical stress such as extremes of temperature and its very cold. 
What we put on the skin can throw it off balance, many people use soap   and water, well thats fine for your body, but our face has more   sebaceous glands, is more exposed to the elements and more open to   micro-organisms. Why not soap and water? well soap is alkaline  and   remember the acid mantle is slightly acidic, this maintains an   environment where micro-organisms are less likely to multiply and if you   use an alkaline product you will strip away this protective layer,   making the skin more susceptible to infection. Because our sebaceous   glands tend to be more active on the face, and this increase of sebum in   nature's moisturiser, there may be more of a tendency for them to   become blocked, if infection enters the blocked pores the result it a   spot. There are a number of cleansing bars on the market and water   activated cleansers around for those of you who like the feel of water   on your face.
The trouble and risk of blocked pores is magnified if there is also a   build up of dead skin cells. Now it takes roughly 28 days for new cells   in the basal layer of the epidermis to form and be shed, this time span   increases with age, as we get older our skin becomes more sluggish, if   we don't cleanse our skin adequately enough a layer of dead cells sit  on  the surface making our complexion dull, combined with sebum these  dead  cells can block pores causing blackheads. Inncidently blackheads  are not  dirt but sebum and dead cells form a plug and oxidise  causing  this  this discolouration. In order to keep our complexions fresh and   depending on the type of skin you have exfoliation should be carried out   once to twice a week, with oily skin generally twice. There are  various  products on the market but avoid those exfoliators that are  made from  ground up nutshells and husks as these can be quite scratchy  and can  damage the surface of the skin leading to possible infection.  Rather  choose a product with fine micro beads. Some exfoliators work by   dissolving dead skin cells and are often fruit based containing fruit   acids or enzymes, these may irritate sensitive skin so its a good idea   to patch test an area  before proceeding.
But before choosing what cleanser to use on your skin, you need to know   what type of skin you have. Firstly normal skin is a rarity, normal  skin  is like the skin children have, its neither dry or oily, theres no   visible pores nor shine, it has a good texture and colour, no spots,   blackheads and is plump and has good elasticity. Now how many of us can   say we have normal skin? Oily skin often has visible pores particularly   down the 'T zone' of our faces, it becomes shiny very quickly, it is   prone to blackheads and spots, its doesn't have dry, flaky patches and   often has a sallow colour about it and make up slides of the face quite   quickly. Dry skin, has no obvious pores, doesn't have a tendency to   blackheads or spots, can have flaky itchy areas, often feels tight after   cleansing and a tendency to line and can often be more highly  coloured.  Combination skin is by far the most common type of skin, it  often has  an oil 'T zone' with normal, if your lucky outer areas or dry  cheeks. It  is a combination of either of the aforementioned types. So  you have 4  skin types. Now if only it was that simple but the skin has  different  conditions that affect it. Firstly moisture, it may surprise  you to know  that even oily skin can become dehydrated as this is down  to moisture  content in the skin and not oil. Central heating, changes  in  temperatures, windy weather and not drinking enough water, too much   coffee, tea and cola drinks and alcohol all affect our skin and can  lead  to dehydration. Oily skin favours better than most as sebum can  trap  some moisture but not enough to prevent moisture loss. So its  important  you keep yourself hydrated and drink plenty of water to start  with and  use the correct moisturiser for your skin type. Moisturiser  does what it  says, its job is to trap moisture in the skin, with dry  skin  moisturisers, they generally are more oil based than one designed  for  oily skin and so on.
Cleansing is a matter of preference but your skin type will guide you as   I mentioned early, some people prefer the feel of water on their skin   so a rinse off type of cleanser will suit them. But whatever way you   cleanse your skin, cleanse it twice once to remove make up and the grime   from the day and second to deep cleanse the skin. Which leads me on to   eye make up remover. The skin around the eyes is very delicate and is   the thinest skin thickness on our bodies so treat it with care. Do not   treat it roughly or rub cleanser harshly around the eyes as this will   stretch this delicate skin. Eye make up is designed for this sensitive   area and not all facial cleansers suitable, check the packaging. Which   leads on to all in one cleansers and wipes, these are fine short term   but not ideal in the long term. Many of the wipes contain alcohol and   irritate sensitive eye tissue and certainly the same wipe should not be   used for both eyes due to the risk of cross infection, the same goes  for  cotton wool pads and tissues.
Toners do we need them? well if you use a water based rinse of cleanser   no you don't as the water is suffice to tone and freshen the skin, but   if you use a tissue off cleanser yes you do to remove any residue of   cleanser and grime. These vary from hydrasols (i.e. rose water) to witch   hazel, avoid alcohol on the face as it will remove the acid mantle.
It may surprise you to know that skin after the age of 25 is considered   mature but after the age of 25 ageing signs start becoming apparent.   Prevention is better than cure and a lot easier. We know from Part 1 how   UV light contributes to ageing so be sure your moisturiser contains a   sun protection level of at least 15 thats the first thing to be aware   of. Drink plenty of water to maintain moisture levels and avoid   caffeinated drinks as they are diuretics as encourage the kidneys to   excrete more urine and can lead to dehydration. A good balanced diet   with plenty of fruit and vegetables to give the cells the right   nutrients. Avoid smoking I explained in an earlier article how this ages   the skin and does so by ten years. And there is stress, now that is   difficult to avoid but there are things you can do, you can lessen its   affects by relaxation and I will be giving tips to avoid the damaging   effects due to stress later.
Anti-wrinkle cremes, well if you read the earlier article in Part 1 no   cosmetic can penetrate the epidermis, so I have to say ladies expensive   skin cremes are a total waste of money. The only thing I would say is   that avoid products with mineral oil as this oil sits on the surface of   the skin, yes it traps the evaporation of moisture but it can block the   pores but its fine to use on the body, instead use a vegetable oil  based  product and by that I don't mean 'Crisp and Dry' some examples  are  Almond oil, Jojoba oil, Olive oil. With expensive cremes you are  paying  for the packaging and nice jar. There are temporary anti-wrinkle  fixers  that work by temporarily tightening up the skin or have fillers  and  light reflective powders that soften the appearance of lines.  Simple  things like avoiding squinting in the sun or getting your eyes  checked  if you have difficulty in reading will prevent many a line  forming  around the eyes
Aromatherapy cremes and face masks I will cover in a later article
MPB ©
SKIN CARE THE EFFECTS OF UV LIGHT 
The effects of ultra-violet on the skin are a mixed blessing!
Some is beneficial, necessary for the formation of vitamin D, some is    harmful. Much of what happens to the skin as a result of ultra-violet    light is the result of the skin trying to protect itself and the body    inside from the harmful effects of an excess of the rays; the skin is    quite effective at preventing the rays penetrating deeply into the body.
The Stratum Corneum is a major factor in this prevention (see diagram below)
 
Reflection of rays by layers of the Stratum Corneum
The Stratum Corneum is maintained at such a thickness that with the    ‘usual’ intensity of ultra-violet falling on it, very little passes    through and no damage is caused to the live cells beneath. The Stratum    Corneum of exposed parts of skin such as the face, neck and hands will    be thicker than those parts normally covered by clothing.
However, exposure to higher than normal intensities of ultra-violet will    allow sufficient rays to pass through the epidermis possibly to cause    damage to the living cells underneath.
 
Penetration of Ultra-Violet Rays into the Skin
In a skin, which has active melanocytes producing melanin pigment    granules, this extra ultra-violet will develop the colour of this    melanin, resulting in a Tan.
But not everyone’s skin is in such a state of readiness; their    melanocytes may be inactive, as a result damage will be caused to the    live cells. The result reddening, discomfort, may be even blisters and    peeling i.e. Sunburn.
Regardless, more UVB rays will penetrate to the Stratum Germinativum to    stimulate its dividing cells into greater activity, this will produce    new epidermal cells at a more rapid rate and this will eventually    thicken the Stratum Corneum, thus helping to reflect UV rays.
The general increase in the skin’s metabolism reflects throughout the body in creating ‘a feeling of well-being’.
The physical, physiological and psychological effects of Ultra-Violet
Beneficial effects:
- Vitamin D production
- Stimulation of Metabolism
- Tonic Effect
- Has slight Germicidal effect on the skin
- Causes hyperkeratinisation (thickening described as above), which is    thought to help with some skin conditions such as Acne Vulgaris and    Psoriasis.
Screening responses against excess:
- Suntanning
- The irritant effect of sunburn
- The thickening effect of the Stratum Corneum
Damaging effects:
- Short term – Sunburn
- ***Long term – Premature aging, thickens the epidermis giving a    ‘leathery’ appearance, irreversibly damages Collagen and Elastin    fibres, causes dehydration, can cause allergic reactions, can produce    dark pigmentation patches; Skin Cancer.
Vitamin D ProductionA normal varied diet including dairy    produce will supply all the vitamin D required; however through  sunshine   the vitamin may be made in the body with the help of  ultra-violet.
In the body there are two substances, which can be converted into    vitamin D, these precursor substances are 7-dehydrocholesterol and    ergosterol. When vitamin D is required these substances are moved to    exposed skin where using ultra-violet energy these substances are    converted to Vitamin D.
The potential for making vitamin d in the skin is so enormous that    merely exposing the face for less than an hour on an overcast December    day will make all that is required for the day, the body is able to    regulate this however so a days long sunbathing will not cause over    production.
***How too much sun and UV light damages and ages the skin