JeffN wrote:However, according to Dr. Michael Holick (one of our nations leading Vit D experts), as little as 5-10 minutes of sun exposure on arms and legs or face and arms three times weekly between 11:00 am and 2:00 pm during the spring, summer, and fall at 42 degrees latitude should provide a light-skinned individual with adequate vitamin D and allow for storage of any excess for use during the winter with minimal risk of skin damage.
Holick MF. Vitamin D deficiency: what a pain it is. Mayo Clin Proc. 2003;78(12):1457-1459.
You said "for use during the winter", and I took that to mean retaining a sufficient amount during the winter. As far as I could tell the article did not mention making it through the winter at such a latitude with adequate levels without supplementation. Did Dr. Holick make this statement elsewhere? I'm unable to find it. Only statements of the percentage of those with deficiencies by the end of winter.
"Tangpricha et al reported that 32% of healthy young white men and women in Boston aged 18 to 29 years were vitamin D–deficient at the end of winter in 2003... Sullivan et al reported that 48% of girls in Maine aged 9 to 11 years were vitamin D–deficient at the end of winter in 2003."
Personally...
Starting in April 2016 we stopped taking vitamin D supplements as a personal experiment to see how well the sun does for us. 10-20 minutes (half that time per side) of midday swimsuit-body sun exposure, 2-4 times per week from April to September at 40 degrees latitude. My wife is of northern European ancestry, I'm of Ireland/England ancestry mostly. Weird Al sang a song about people like us. https://www.youtube.com/watch?v=N9qYF9DZPdw
As of October 25 2016:
Me: 65 ng/mL
Wife: 52 ng/mL
As of January 10 2017 (2.5 months later):
Me: 33 ng/mL (down 20 points, still optimal but getting down there)
Wife: 48 ng/mL (down 4 points, still optimal)
