There is growing evidence - and increasing debate surrounding this data -that many people in the northern hemisphere, especially the elderly and and darker-skinned individuals, may be lacking sufficient vitamin D.
However experts gathered recently by the American Academy of Dermatology Association say that recommending increased exposure to sunlight is "highly irresponsible".
Speaking at the Academy's Melanoma/Skin Cancer Detection and Prevention Month news conference, dermatologist Vincent A. DeLeo from Columbia University in New York said: "It is known that there is a high risk of developing skin cancer from repeated and intentional ultraviolet B exposure to boost vitamin D levels; the latter can be safely achieved by nutritional supplements."
"Skin cancer is an epidemic in this country and recommending increased UV exposure with claims that sunlight somehow promotes good health is highly irresponsible."
Findings from the conference white paper are published in the May 2005 issue of the Journal of the American Academy of Dermatology (vol 52, no 5, p 868).
The benefits of vitamin D are well documented and include, most notably, improved bone health and fracture prevention, better muscle health and a reduced risk of falling in older individuals.
However research suggest that many elderly are lacking in the vitamin. A study done by Danish health authorities last year found that in the oldest age-groups close to 80 per cent have vitamin D insufficiency and 25 per cent are vitamin D deficient.
Some researchers have caused controversy by suggesting that increased exposure to sun could help remedy such deficiencies. But the US authors noted that photosynthesizing vitamin D through natural sunlight is maximized after 20 minutes of ultraviolet B (UVB) exposure, with extended sun exposure providing no additional benefit but instead increasing the likelihood of photodamage and skin cancer.
"There is certainly ample scientific evidence proving that vitamin D does not need to be produced from UVB exposure to be effective," said Dr DeLeo.
"Under no circumstances should anyone be misled into thinking that natural sunlight or tanning beds are better sources of vitamin D than foods or nutritional supplements. The only thing they are proven to be better at is increasing your risk of developing skin cancer."