Balancing vitamin D requirements with sensible sun exposure

January 01, 0001

Balancing vitamin D requirements with sensible sun exposure

The aim of this study by researchers from Australia was to examine the feasibility of balancing sunlight exposure to meet vitamin D requirements with sun protection guidelines. They used standard erythemal dose and Ultraviolet Index (UVI) data for 1 June 1996 to 30 December 2005 for seven Australian cities to estimate duration of sun exposure required for fair- skinned individuals to synthesise 1000 IU (25 microg) of vitamin D, with 11% and 17% body exposure, for each season and hour of the day. Periods were classified according to whether the UVI was less than 3 or greater than or equal to 3 (when sun protection measures are recommended), and whether required duration of exposure was less than or equal to 30 min, 31-60 min, or greater than 60 min.

Duration of sunlight exposure required to synthesise 1000 IU of vitamin D varied by time of day, season and city. Although peak UVI periods are typically promoted as between 10 am and 3 pm, UVI was often greater than or equal to 3 before 10 am or after 3 pm. When the UVI was less than 3, there were few opportunities to synthesise 1000 IU of vitamin D within 30 min, with either 11% or 17% body exposure.

The researchers concluded: "There is a delicate line between balancing the beneficial effects of sunlight exposure while avoiding its damaging effects. Physiological and geographical factors may reduce vitamin D synthesis, and supplementation may be necessary to achieve adequate vitamin D status for individuals at risk of deficiency."

What is the appropriate vitamin D level in humans, allowing for different skin colorations?

For the full abstract, click here.

MJA 194(7):345-348, 4 April 2011
© The Medical Journal of Australia 2011
Burning daylight: balancing vitamin D requirements with sensible sun exposure. Kellie L Stalgis-Bilinski, John Boyages, Elizabeth L Salisbury, Colin R Dunstan, Stuart I Henderson and Peter L Talbot. Correspondence to Kellie Stalgis-Bilinski: [email protected]

Category: S. Skin, T. Endocrine/Metabolic/Nutritional. Keywords: vitamin D, sun exposure, ultraviolet index, journal watch.
Synopsis edited by Dr Stephen Wilkinson, Melbourne, Australia. Posted on Global Family Doctor 12 April 2011

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