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While it is important to protect the skin from the sun
and the melanomas which can result from over exposure, it is
also critical that people understand the many benefits of
vitamin D - the production of which is stimulated by
ultraviolet radiation, writes Janet Carrington.
Exposure to the sun is known to be responsible for the
initiation of melanoma and other skin cancers.
In New Zealand we have the highest rates of death from
melanoma in the world because our temperate climate means
being out in the sun is taken for granted.
To reduce the incidence of melanoma and other cancers a
trendy mantra - slip, slop, slap and wrap - was introduced
and SunSmart advice provided in schools.
Most could see the logic, were captivated and assiduously
followed the recommendations.
But have the consequences been fully understood? Is the
advice taken too diligently? Recently I saw a television
advertisement for a product containing SPF 80+! Dunedin and
Invercargill have 75% of the sunshine per year that
Christchurch, Auckland and Wellington do.
We have a cooler climate, so there aren't as many days when
it's comfortable to be out in the sun and besides there's
shopping, DVDs and computers keeping us indoors and to make
life more comfortable we're even planning to build a covered
stadium!On the other hand, the sun's ultraviolet radiation
promotes the synthesis of vitamin D in the skin so not
getting enough time in the sun leads to low levels of vitamin
D.
The sun is our main source of vitamin D because the few foods
that contain vitamin D, like oily fish and eggs, provide only
a small amount.
So it is important for everyone to have regular safe sun
exposure.
Because vitamin D is fat soluble, what is made in the summer
can be stored for the winter months, when it is colder and
being out in the sun is less inviting, but that means it's
imperative to be exposed to the sun when appropriate during
the summer.
Vitamin D has an important role in maintaining blood calcium
and phosphate levels by enhancing absorption of these
minerals to promote bone formation and the production of
strong healthy bones.
Low levels of vitamin D have been linked to reduced immunity,
cancers, autoimmune disorders, diabetes, cardiovascular
disease, schizophrenia, depression and autism.
Even now there are pleas for more funds to publicise the
danger of being out in the sun.
But let's be rational - while keeping the danger of
overexposure to the sun in mind, in the South it is essential
to spend some time out in the sun.
Enjoy.
• Dr Janet Carrington is a retired senior lecturer of
the University of Otago's biochemistry department.
