(NaturalNews) Public health warnings about the skin cancer risks associated with sun exposure have led people to avoid sunlight to such an extent that vitamin D deficiencies have now become widespread, according to a study conducted by researchers from King's College London.The body produces vitamin D upon exposure to the ultraviolet radiation from sunlight. It takes only 15 minutes of sun on the face and hands each day for a fair-skinned person to produce enough vitamin D for their body, although it takes longer for darker-skinned people and those living far from the equator, particularly in the winter. Nevertheless, vitamin D deficiency appears widespread. One recent study from University College London estimated that 12 percent of men and 20 percent of women are clinically deficient in the vitamin, while 57 percent of men and nearly 67 percent of women have insufficient levels.Vitamin D plays a critical role in bone development and health, and is now also believed to help protect against high blood pressure, cancer, autoimmune diseases and asthma."There has been so much effort put into telling people about the damaging effects of ultraviolet light from sunshine, many now take extreme measures to ensure they don't get exposure by wearing moisturizers with factor 15 all year round," said lead researcher Veronique Bataille, calling for new guidelines on sun exposure. "We don't want to say that sunbathing is healthy as there is clearly a risk, but people do need a bit of sunshine to stay healthy."Bataille and colleagues measured blood vitamin D levels of 1,414 white women in the United Kingdom and collected information on their skin type, use of tanning beds, and history of foreign holidays and sunburns. They found that contrary to expectation, the women with the lightest skin actually had the lowest levels of vitamin D. The researchers concluded that this was likely due to lighter-skinned women avoiding the sun over fear of skin cancer Light-skinned women were also less likely to use tanning beds or take vacations out of Britain.Sources for this story include: www.telegraph.co.uk