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@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.

PMID: 21470084

UVI <3 = GREEN

See also VitaminDWiki

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• 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

In January most of the Northern portion of the world gets no vitamin D from the sun

UV Index less than 3 = Blue and Purple on this map