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 IF you are near the equator
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.
Simple summary chart Oct 2013
Vitamin D Workshop for Seniors contains the following summary chart
- 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
- - - - - - - - - - - - - - - - - - -
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.
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)
- 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 also VitaminDWiki
- Increase your vitamin D from the sun by wearing a tan-through instead of standard shirt
- Equation of IU vs time in the sun - Jan 2012
- 60 minutes of sunlight needed to decrease vitamin D deficiency in sunny climate – Dec 2012
- Complex relationship between UVB and vitamin D – April 2012
This article may result in a re-write of this web page. It questions many of the assumptions made here about:
Amount of skin area, color or skin, obesity, etc. There are several reasons why the study may be wrong however.
- Seniors, like everyone else, need vitamin D but should avoid sunburns – 2011
- All items in Noontime Sun 173 items
- 4X more suburban UV than urban UV – Nov 2010
- all items in category Deficiency of D 276 items
- An overview analysis of the time people spend outdoors – Dec 2010
- Melanoma risk with sunburns - 2010.PDF
- UVB causes sunburn - UVA causes melanoma - 2011.PDF
- Poor knowledge by office workers of vitamin D and sunscreen - July 2010
- Scared Out of the Sun for Fifty Years – Jan 2011
- Overview Suntans and melanoma
- Increased UVB intensity did not increase vitamin D generated – Nov 2010
- Is there a limit as to how much vitamin D the body will produce over a several day time period? replenish cholesterol?
- For small amounts of sunshine the amount of skin exposed may not matter – Jan 2011
- Minutes in the Sun for 1000 IU default 30 degrees North
- Face 3.5%, neck 2%, trunk 26%, hands 6%, arms 14%, legs 14%, thighs 18%
- Sun increases but tanning bed decreases longevity - April 2011 PDF file
- UV calculators on the web
- Many reasons why vitamin D deficiency has become epidemic in past 30-40 years
- Weekly UV almost doubled elderly Vitamin D levels to 20 ng – Dec 2010
- When you get enough vitamin D, be sure to get cofactors too
- Doctor survey: 64 % incorrectly think 10 minutes of sun is enough,
33 % say use sunscreen in the winter – May 2012]
- Ways to increase the amount of vitamin D you get from the sun
- Tanning while getting little vitamin D
- Whites were 2X more likely to be vitamin D deficient if wear long sleeves – Jan 2012
No decrease, however, for reported use of sunscreen
- Vitamin D from psoriasis lamps, tanning beds, and the sun – Jan 2012
- Vitamin D from the sun vs time of day which has the following graphic
Map of annual solar radiation
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
UV Index Minnesota
UV Index Hawaii
Sunshine Prescription June 2012
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