For years the sun has been considered public enemy number one, causing skin damage, premature aging, skin pigmentations and increasing our risk of skin cancer. But before you head for the shade when the sun is out, consider the fact that those so called nasty UV rays are needed in the production of vitamin D and by blocking out the sun, you are risking a deficiency that could leave you open to all sorts of ailments.
An increasing number of scientific studies are now pointing to vitamin-D deficiency as a factor in a catalogue of illnesses including colds and flu, heart disease, strokes, diabetes, auto-immune disorders, depression, osteoporosis and numerous cancers. It has even been suggested as one possible cause of autism.
At the root of the rate of deficiency is the modern-day habit of avoiding sun exposure. Add to that busy lifestyles such as city-living which mean we actually spend more time indoors than our ancestors did. Because of that you have a population that is not getting enough exposure to uv light to produce the vitamin D their body needs.
Around 50 per cent of Americans are believed to have insufficient levels of vitamin D - and living in sunny climates doesn't necessary make you less prone to deficiencies. Studies in Australia have noted similar deficiencies, especially among the darker skinned and the elderly, while a recent study by the University of Hong Kong revealed more than 60 per cent of Hong Kong people were insufficient in vitamin D.
Professor Annie Kung Wai-chee, who led the study, said part of the problem was the common misconception that people living in sunny climates get all the sun and therefore the vitamin D they need without trying.
In addition, dark-skinned people are more at risk because the melanin that colours the skin works like a sun-block preventing the UVB rays being synthesized into vitamin D.
The truth is vitamin D is not a vitamin but a type of hormone that plays an important role in the control of calcium. It has long been known to encourage healthy bones, reduce inflammation, and prevent the bone disease rickets in children and osteoporosis later in life.
Since time began, humans have gotten most of their vitamin D from the sun. Just 15-20 minutes in bright sunshine produces 10,000 to 20,000 IU (international units) of vitamin D - some 50 times the amount you can get in many Vitamin D supplements.
Remember that 20 minutes in the tanning unit of your choice is equal to two hours in the sun.