Int J Environ Res Public Health. 2017 Aug 16;14(8). pii: E920. doi: 10.3390/ijerph14080920.
|Spring||head + hands||7% of skin||1400 IU|
|Summer||head + hands + arms||20% of skin||250 IU|
- Assumes White skin
Dark skin can be 2X to 5X less responsive
- Assumes not obese
more than half of Vitamin D goes to fat cells, not to the body
- Assumes young
only about 1/3 as much vitamin D is generated by elderly skin
- Assumes same amount generated by each skin area
see Little Vitamin D generated by face and hands - June 2015
- Assumes an unspecified amount of head hair
- Assumes same skin response regardless of the time of year
- Vitamin D winter does not appear to exist
- Time in sun (in Spain) to get 4,000 IU of vitamin D: half hour in July , 2 hours in October – Sept 2016 A small amount more skin area 25% summer, 10% Oct
- Optimize vitamin D from the sun - 14 ways
- Increase your vitamin D from the sun by wearing a tan-through instead of standard shirt
About 2,100 IU in summer with tan-thru shirt (1.5 X 1400 IU)
- Vitamin D from phototherapy lamps, tanning beds, and the sun – Jan 2012
- Getting Vitamin D into your body the sun is just one of many ways
- Founder of VitaminDWiki uses a UVB bulb in the winter - next to exercycle
No – 10 minutes per day of sun-UVB is NOT enough contains the following summary
- 5-10 minutes provides only 1,000 IU ONLY IF you are near the equator
- AND young
- AND not obese
- AND have light skin
- AND it is summer
- AND it is the middle of the day
- AND you have lots of skin exposed to the sun
- AND you are lying down
- AND you are not wearing sunscreen.
- AND you have a healthy Liver
Exposure to sunlight, specifically the ultraviolet radiation, has both positive and negative health effects. Maximizing the benefits (vitamin D synthesis) while minimizing the damage is a multifaceted problem in which many of the elements are poorly quantified. Here we show how rigorously conducted large sample size laboratory studies of the effect of ultraviolet radiation dose on vitamin D status can be applied to real-life situations. This was achieved by modeling the radiation incident on different surfaces for different solar locations, and equating with the controlled exposures in the laboratory studies.
Registered readers can CLICK HERE to see the PDF file
Vitamin D sun time suggestions condensed from Translated German website
- Type 1 may get 5 minutes per day.
- Type 2 can get 10 minutes per day.
- Type 3 may get 15 minutes per day.
- Type 4 should get 20 minutes per day.
- Type 5 should get 25 minutes per day.
- Type 6 should get 30 minutes per day.
- When first tanning reduce the following times by half.
- Lie down so that you get into a shadow at the time alloted.
- Always take a short-time with the sun.
- Do not exceed these times, it will redden your skin, and cause skin damage and sunburn
- Increase times 3X if elderly
- Increase times 2X if overweight
- Increase times 3X if cloudy or you are in the shade
- Increase times 2X if hazy
- Increase times 2X if standing
- Add 10 minute? if very far from equator: Alaska/Finland
- Decrease times ( 1/2 ?) if near equator
- The times above assume
- % of body exposed to sun - we guess 30% = shorts and T shirt
- Daily? rather than 3 days a week
McKenzie - 2009.pdf has the following graph
Erythemal dose = amount of sun to create a slight reddening of skin
1.5 = 1 hour
3.0 = 1/2 hour
6.0 = 1/3 hour
1.5 = 5 hour
3.0 = 2.5 hour
6.0 = 5/6 hour
alternate term: MED =“minimal erythemal dose” – varies with darkness of skin
Sunshine Prescription June 2012
Experiment in getting 20 minutes of mid-day sun every weekday in Korea ( same latitude as Washington DC)
Exposure on hands, forearms and face every weekday for four weeks. Facial sunblock and sunglasses were permitted.
Vitamin D levels DECREASED. But it was October/November
Experiment reported in Vitamin D Council Jan 2013
Schrempf M1, Thuns N2, Lange K3, Seckmeyer G4.
1 Institute of Meteorology and Climatology, Leibniz Universität Hannover, 30419 Hannover, Germany. schrempf at muk.uni-hannover.de.
2 Institute of Meteorology and Climatology, Leibniz Universität Hannover, 30419 Hannover, Germany. thuns at muk.uni-hannover.de.
3 Institute of Meteorology and Climatology, Leibniz Universität Hannover, 30419 Hannover, Germany. lange at muk.uni-hannover.de.
4 Institute of Meteorology and Climatology, Leibniz Universität Hannover, 30419 Hannover, Germany. seckmeyer at muk.uni-hannover.de.
The vitamin D₃-weighted UV exposure of a human with vertical posture was calculated for urban locations to investigate the impact of orientation and obstructions on the exposure. Human exposure was calculated by using the 3D geometry of a human and integrating the radiance, i.e., the radiant energy from the direct solar beam and the diffuse sky radiation from different incident and azimuth angles. Obstructions of the sky are derived from hemispherical images, which are recorded by a digital camera with a fisheye lens. Due to the low reflectivity of most surfaces in the UV range, the radiance from obstructed sky regions was neglected. For spring equinox (21 March), the exposure of a human model with winter clothing in an environment where obstructions cover 40% of the sky varies by up to 25%, depending on the orientation of the human model to the sun. The calculation of the accumulated vitamin D₃-weighted exposure of a human with winter clothing walking during lunch break shows that human exposure is reduced by the obstruction of buildings and vegetation by 40%.
PMID: 28813022 PMCID: PMC5577621 DOI: 10.3390/ijerph14080920