[chessplayer]

“Vitamin D deficiency tied to host of dangers”

“For most people, she said, 10 minutes a day of sun exposure to the face and arms without sunblock protection is enough to trigger vitamin D production in the skin during warm weather. However, from mid-October to mid-March, the sun’s rays in northern cities such as Boston are too weak to generate vitamin D, causing a regionwide drop-off in blood levels through the winter.”

http://www.boston.com/news/globe/health_science/articles/2004/12/30/vitamin_d_deficiency_tied_to_host_of_dangers/

[metmom]

However, from mid-October to mid-March, the sun’s rays in northern cities such as Boston are too weak to generate vitamin D, causing a regionwide drop-off in blood levels through the winter.”

That would either be about mid-March to mid-Sept, OR mid-February to mid-Oct. It doesn't depend on the climate and temp. It depends on the position of the sun in the sky. Look at the equinoxes and when they occur.

Some people who claim to be scientists should be more careful.

[metmom]

Another factor I heard is important in Vitamin D production in the body is the presence of the skins oils on the skin. If that’s true, then going out in the sun after a shower would not result in the production of Vit D. I’ve always wondered if the rise in skin cancer is because people are getting the damage from the UV exposure and not the vit D because of being *too* clean. (so to speak)

[Aquinasfan]

However, from mid-October to mid-March, the sun’s rays in northern cities such as Boston

That's where I live, and historically, that's the period when I've been zonked out. Seasonal fatigue doesn't happen with everybody, but it sure happened with me. I've been taking Vitamin D for the last couple of years, beginning in November and ending in spring.