# Vitamin D **URL:** \ **Category:** Factual Questions\ **Created:** [November 28, 2006, 4:52am UTC](https://boards.straightdope.com/t/vitamin-d/382037 "2006-11-28T04:52:01Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![fifty-six](https://avatars.discourse-cdn.com/v4/letter/f/5daacb/32.png) [@fifty-six](https://boards.straightdope.com/u/fifty-six)\ **Post date:** [November 28, 2006, 4:52am UTC](https://boards.straightdope.com/t/vitamin-d/382037/1 "2006-11-28T04:52:01Z")
I was hoping for a little insight on vitamin D synthesis. I live in a northern lat., 59 degrees or so. And was wondering how much exposure to the sun I would need in order to produce a healthy amount of vitamin D. Most importantly in the winter months I have been told that there is not sufficient sun to produce any at all this time of year. Is that correct? What is it in the sun that helps us make vitamin D? UV? Is there a graph or chart to see the relative amount of vitamin producing rays month to month. I do understand that there are other factors potentially blocking Vitamin D producing rays. Elevation, smog, cloud cover? Assume that in my town we generally have snow on the ground, little or no air pollution, and live close to sea level. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 28, 2006, 5:20am UTC](https://boards.straightdope.com/t/vitamin-d/382037/2 "2006-11-28T05:20:33Z")
[Journal of Clinical Endocrinology & Metabolism, Vol 67, 373-378; 1988](http://jcem.endojournals.org/cgi/content/abstract/67/2/373) > [@](#): > > Human skin or [3 alpha-3H]7-dehydrocholesterol exposed to sunlight on cloudless days in Boston (42.2 degrees N) from November through February produced no previtamin D3. In Edmonton (52 degrees N) this ineffective winter period extended from October through March. Further south (34 degrees N and 18 degrees N), sunlight effectively photoconverted 7- dehydrocholesterol to previtamin D3 in the middle of winter. Wikipedia has a nice summary on [vitamin D](http://en.wikipedia.org/wiki/Vitamin_D1) , including a description of the photolysis of 7-dehydrocholesterol by ultraviolet light. 59 degrees is a long way up there, so milk in winter might be a good idea, no matter how much sun you get. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [November 28, 2006, 11:30am UTC](https://boards.straightdope.com/t/vitamin-d/382037/3 "2006-11-28T11:30:21Z")
Various seafood products that have traditionally been part of the Inuit diet are also high in vitamin D.