Rosa, please do forget the sun block at least for the first half an hour out in the sun! Because a) a sun block with a protection factor 15 blocks the production of 99% of vitamin D in the skin! b) there's been several studies showing that the ingredients in sunscreens have estrogenic effects on cultured breast cancer cells (i.e. in lab experiments the breast cancer cells enjoyed the sunscreen). I would say if there are natural sun blocks out there it is a good idea to try finding them.
The amount of vitamin D that the skin metabolizes depends on a number of factors including the latitude, the time of the day, season, skin complexion, age, etc. For example, total body exposure (as in naked) out in the sun (at a 30-40 deg latitude, summer time) for about half an hour results in 10.000 IU (250 microgr) – and this seems to be a natural physiological limit, meaning that by longer exposures the skin won’t produce more vitamin D.
Regarding what should be an optimal daily intake of vitamin D - this is a tough question to answer. I've been looking at a LOT of scientific papers on the subject and the dosage was anywhere btw 1.000 IU/day and 10.000 IU/day. My interest with this vitamin peaked during the past few months in connection to its role in preventing colds, flu, diabetes and cancers. If you would like to read more about what is the current knowledge on vitamin D, I'm happy to share my blog post
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Rosa, please do forget the sun block at least for the first half an hour out in the sun! Because a) a sun block with a protection factor 15 blocks the production of 99% of vitamin D in the skin! b) there's been several studies showing that the ingredients in sunscreens have estrogenic effects on cultured breast cancer cells (i.e. in lab experiments the breast cancer cells enjoyed the sunscreen). I would say if there are natural sun blocks out there it is a good idea to try finding them.
The amount of vitamin D that the skin metabolizes depends on a number of factors including the latitude, the time of the day, season, skin complexion, age, etc. For example, total body exposure (as in naked) out in the sun (at a 30-40 deg latitude, summer time) for about half an hour results in 10.000 IU (250 microgr) – and this seems to be a natural physiological limit, meaning that by longer exposures the skin won’t produce more vitamin D.
Regarding what should be an optimal daily intake of vitamin D - this is a tough question to answer. I've been looking at a LOT of scientific papers on the subject and the dosage was anywhere btw 1.000 IU/day and 10.000 IU/day. My interest with this vitamin peaked during the past few months in connection to its role in preventing colds, flu, diabetes and cancers. If you would like to read more about what is the current knowledge on vitamin D, I'm happy to share my blog post
http://ionelu.wordpress.com/2009/08/19/vitamin-d-plan-of-action/
I.A.
August 26, 2009 - 5:16amThis Comment
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