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No – 10 minutes per day of sun-UVB is NOT enough

Many people and doctors believe that 10 minutes a day in the sun a few days of the week provides enough vitamin D

WRONG most of the time


5-10 minutes is enough 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.

Update April 2014 - we made a video Vitamin D in 5 minutes

Simple summary chart Oct 2013

at is.gd/timeinsun

Vitamin D Workshop for Seniors contains the following summary chart

Image
Assumes

  • 2X more minutes going to Seattle which is at a higher latitude (47 instead of 32)
  • 3X more for senior instead of youth
  • 2X more for standing than lying down
  • All items multiply

Does not include

  • Obese (2X more minutes)
  • Black Skin (5X more minutes)
  • Early morning or late afternoon sun (2X more minutes)
  • Sun during Spring or Fall ( shoulder season >2X more minutes)
  • Urban haze - perhaps 2X or 4x more minutes
  • Light clouds

Vitamin D lasts in your body for about a month
There are ways to increase the amount of vitamin d you get from the sun
If you can't sunbathe all year, consider taking supplements, use a sunbed, or get your own UVB lamp


A study was published May 2011 of the amount of sun needed to get 20 ng/ml of vitamin D

Note: many recommend much more: 30, 40, and even 50 ng/ml

  • Got sun/UV 3 times per week for 6 weeks
    • Danger of skin cancer if all tanning done just once per week instead of spread over three times
  • Assumed 30% of skin exposed (shorts and T shirt)
  • Assumed summer sun intensity
    • There is such a thing as a vitamin D winter
    • Very little vitamin D when your shadow is longer than you are

For white, thin, youth living more than 30 degrees away from the equator

  • 20–40 minutes if STANDING
  • 10-20 minutes if LYING DOWN

But, 20 ng/ml only prevents Rickets

If want to achieve, say 36ng/ml, then about 2X longer is needed
Standing – but be aware that any time over 30 minutes may cause skin cancer

  • 1 hour if white, young, and thin
  • 3 hours if white, elderly and thin
  • 5 hours if dark, young and thin
  • 30 hours if dark, elderly and obese
    • totally impossible - longer than a day
    • perhaps the factors do not multiply - we have no data

Tables from the paper - which assumes 3 times per week

  • Vertical = standing
  • Horizontal = lying down
  • Better still would be on a slant board - to place body perpendicular to the rays of the sun

Image
Image

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Abstract of study

The vitamin d debate: translating controlled experiments into reality for human sun exposure times.

Photochem Photobiol. 2011 May;87(3):741-5. doi: 10.1111/j.1751-1097.2011.00898.x. Epub 2011 Feb 14.
Webb AR, Kift R, Berry JL, Rhodes LE.
School of Earth Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK Vitamin D Research Laboratory, School of Biomedical Sciences, University of Manchester, Manchester Royal Infirmary, Manchester, UK Photobiology Unit, Dermatological Sciences, School of Translational Medicine, University of Manchester, Manchester Academic Health Science Centre, Salford Royal NHS Foundation Hospital, Manchester, UK.

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.

Results from both model and experimental data show that relatively short exposures of a modest amount of unprotected skin to summer sunlight in northern climes, on a regular basis during lunchtime hours, increases vitamin D to sufficiency status (?20?ng?mL(-1) ) in the white Caucasian population. While both sun exposure conditions and human skin responses are variable in real life, these quantitative findings provide a guide for authorities devising sunlight exposure recommendations.

Registered readers can CLICK HERE to see the PDF file


Vitamin D sun time suggestions condensed from Translated German website

Time vs skin type (on each side of body – in Southern Europe/US, June-August, 11 – 2PM)

  • 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.

used on wikipage:http://www.vitamindwiki.com/tiki-index.php?page_id=1689

Add 5 minutes if in Northern Europe/US

2X times in shoulder seasons = March-May, September

2X times in non-noon = 10-11 AM or 3-5 PM

3X times if both shoulder season and non-noon (not 4X)

Tips:

  • 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

Added by VitaminDWiki

  • 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


see wikipage http://www.vitamindwiki.com/tiki-index.php?page_id=1689
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See also VitaminDWiki

see wikipage: http://www.vitamindwiki.com/tiki-index.php?page_id=3152

Map of annual solar radiation

Accounts for latitude and clouds, but not altitude (e.g. Colorado)

from http://www.lenzing.com/en/plastics/thermoplastics/artifical-turf/uv-stability.html

SED = “standard erythema dose” = approximately the UV Index.


Erythemal dose = amount of sun to create a slight reddening of skin

For light skin 1.5 SED ==> slight reddening
The darker the skin, the more SED needed (black skin needs 5X more)

UV index for a light skinned person

1.5 = 1 hour
3.0 = 1/2 hour
6.0 = 1/3 hour

UV index for a person with black skin

1.5 = 5 hour
3.0 = 2.5 hour
6.0 = 5/6 hour

Note: SED is defined for UVA (tanning), not UVB (vitamin D), so it overestimates the amount of vitamin D at high latitudes or non-noon.

alternate term: MED =“minimal erythemal dose” – varies with darkness of skin

UV Index scale

used on wikipage:  http://www.vitamindwiki.com/tiki-index.php?page_id=1689

UV Index Minnesota

2009

UV Index Hawaii

from http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/uv_annual.shtml

Sunshine Prescription June 2012

 see webpage http://www.is.gd/timeinsun

A half hour or more sun a day is a human right and should become a lifestyle habit like tooth brushing

Comment to an article in Mercola July 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

Pick Your Poison – Sunscreens vs. Sunburns Green Med Info June 2013



Short url = http://www.is.gd/timeinsun


Page last modified on 23 April, 2014


List of attached files
ID Name desc uploaded Size Downloads Actions
3571 pdf Shade.pdf PDF - 2014 23 Jan., 2014 by admin 305.38 Kb 89 View Download  
566 jpg skin types.jpg Skin Types Chart 10 June, 2011 by admin 6.98 Kb 3664 View Download  
549 jpg time for daily exposure.jpg time for daily exposure 02 June, 2011 by admin 24.26 Kb 15030 View Download  
548 jpg sun exposure needed for get 20 ng of vitamin D.jpg sun exposure needed for get 20 ng of vitamin D 02 June, 2011 by admin 38.36 Kb 15089 View Download  

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