In this section:
Vitamin DSkinThe Ultraviolet IndexFAQ’s
Vitamin D
Adequate vitamin D status is essential for general health. While you can obtain vitamin D from some foods, sunlight is the best source of Vitamin D. We need for Vitamin D for strong bones and general health, and it may also protect against cancers and some auto immune conditions such as multiple sclerosis.
Some UVR exposure is important for vitamin D production. Because of this, a balance is required between avoiding an increased risk of skin cancer and maintaining adequate vitamin D levels. However, sensible sun protection behaviour should not put people at risk of vitamin D deficiency. During the daylight saving months most people get enough UVR exposure to achieve adequate vitamin D levels through incidental sun exposure outside peak UVR times.
The Cancer Society recognises both the very real benefits - and the risks - of sun exposure. Because of this, we are very specific about the hours we advise sun safety.
The Cancer Society sun protection messages are based on the findings of experts’ groups it convened in 2005 and 2007 which concluded that “a balance is required between avoiding an increased risk of skin cancer and maintaining adequate vitamin D levels.”
For these reasons, schools need to promote sun protection during peak ultraviolet radiation (UVR) periods, when the Ultraviolet Index (UVI), which measures the intensity of the ultraviolet radiation (UVR) in the environment, is 3 or above. This is especially important when spending long periods in the sun, particularly for those with fair skin. In most parts of New Zealand, peak UVR times are between October and March, particularly between 11am and 4pm. However, in some parts of New Zealand, such as Northland, the UVI is 3 or above for longer periods of the year.
Sensible sun protection in daylight saving months should not put people at risk of vitamin D deficiency. Someone who burns easily in the sun may only need 5 minutes of daily summer sun exposure, while someone who tans more easily or has darker skin will need more time e.g. up to 20 minutes.( It is likely that in the future, recommendations will become more specifically related to skin type, and length of time in the sun.)
The Society says while sun protection is not generally necessary in winter months, people should protect themselves if at high altitudes or in snow.
In recognition of the importance of the Vitamin D issue, the Society is continuing to review new and emerging research in this area.
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Read the New Zealand Position Statement relating to sun exposure and Vitamin D - (73 KB)
If you have naturally dark skin, you need more UVR exposure to produce adequate levels of Vitamin D.
• Read the Cancer Society's advice about UV radiation & vitaminD_for people with dark skin - (82 KB)
Skin Facts
- Skin’s biggest job is protection. It’s a tough, elastic, flexible and waterproof
covering and maintains the body’s correct temperature.
- Skin is the largest and one of the hardest working organs in the body.
- Skin covers and average area of about 1.8 metres on an adult and makes up 1/6 of your body weight
- Skin continually renews itself. Old skin cells are gradually shed and replaced by new ones every 28 days.
- Skin cells grow and and rejuvenate faster than any other organ.
- You have 19 million skin cells in every square inch of your body.
Skin Types
Skin has been typed into six basic categories:
| Type 1: |
Always burning, never tan; sensitive to exposure; redheaded, freckles, Celtic background |
| Type 2: |
Burns easily, tans minimally; fair-skinned, blue, green or gray eyes, Caucasians |
| Type 3: |
Burns moderately, tans gradually to light brown; average Caucasian skin |
| Type 4: |
Burns minimally, always tans well to moderately brown; olive skin |
| Type 5: |
Rarely burns, tans profusely to dark; brown skin |
| Type 6: |
Rarely burns, least sensitive; deeply pigmented skin |
Skin Layers has 3 layers:
- The outer layer is the epidermis. It’s about 20 cells deep - about as thick as a sheet of paper. The top part of the epidermis is composed of dead cells which are constantly shed. Underneath the dead cells are live squamous cells, and under these are basal cells which are constantly reproducing.
- Below this is the dermis which contains tiny blood and lymph vessels.
- Cells called melanocytes are found the in between. These skin cells produce a brown-black skin pigment called melanin.
There is a subcutaneous layer under this which is mainly fat.
Skin aging causes
Approximately 10% of skin aging is caused by genetic factors or intrinsic factors such as unhealthy diet, sleeping on your stomach and gravity. Over 80% of skin aging is caused by exposure to Ultraviolet radiation.
The Ultraviolet Index
The UVI is a measure of the intensity of Ultraviolet radiation (UVR) in our environment. The higher the number the more intense the UVR. UVR causes damage to our skin and can lead to skin cancer, which kills almost 300 New Zealanders a year.
When the UVI is at 3 or more we need to protect ourselves. This happens almost daily between October and March, and can happen in winter, especially at high altitudes and in snow.
Even when the temperature is not hot the UV radiation levels can be dangerous so temperature is not a good indicator of the need to protect yourself.
UVR can penetrate light cloud cover, so even on cloudy days, and days that may have intermittent showers, you may still be at risk.
The UVI is promoted by the World Health Organization, is scientifically based, and is used internationally. “A Practical Guide' can be downloaded from http://www.who.int/uv/publications/globalindex/en/.
The UV Index Board
FAQ’s
Frequently Asked Questions about sun safety can be viewed on
www.sunsmart.co.nz/sunfaqs.asp
