1Burning daylight: balancing vitamin D requirements with sensible sun exposure.
Med J Aust. 2011 Apr 4;194(7):345-8.
Stalgis-Bilinski KL, Boyages J, Salisbury EL, Dunstan CR, Henderson SI, Talbot PL.
Westmead Breast Cancer Institute, University of Sydney, Sydney, NSW, Australia. Kellie.Bilinski at bci.org.au.
OBJECTIVE: To examine the feasibility of balancing sunlight exposure to meet vitamin D requirements with sun protection guidelines.
DESIGN AND SETTING: We 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 µg) 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 < 3 or ? 3 (when sun protection measures are recommended), and whether required duration of exposure was ? 30 min, 31-60 min, or > 60 min.
MAIN OUTCOME MEASURE: Duration of sunlight exposure required to achieve 1000 IU of vitamin D synthesis.
RESULTS: 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 ? 3 before 10 am or after 3 pm. When the UVI was < 3, there were few opportunities to synthesise 1000 IU of vitamin D within 30 min, with either 11% or 17% body exposure.
CONCLUSION: 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.
- Scared Out of the Sun for Fifty Years – Jan 2011
- Melanoma and suncreens Time line -2010
- Melanoma & sunscreen associated in 7 studies - chart 2010
- China has documented that less UV results in more cancer – June 2010
- Most sunscreens actually increase the growth of skin cancer - May 2010
- Dermatologists should not tan – June 2010
- Vitamin D bulb for use in the home - or perhaps office
- All items in Noontime Sun category
- All items in the UV and D category
- Vitamin D from the sun 3 to 12 months of the year in the US
- Introduction to Vitamin D page 6 If shadow TALLER than you are tall, you CANNOT make vitamin D, also UV Index 3
- Minutes in the Sun for 1000 IU
- UV Index guide by US Weather Bureau - 2010 6 pages with lots of graphics
- Map of minutes of sun to get 106 joules in July from: UV in North America with many maps
- UV: The original Source! How to use it April 2010 58 slides, 2 of which are in this File Gallery. Video is on web at http://www.grassrootshealth.net/ and YouTube
- Increased UVB intensity did not increase vitamin D generated – Nov 2010
- Ways to increase the amount of vitamin D you get from the sun
- UV calculators on the web