RDA 400 - 1000 IU for adults, Health Canada recommends 400 IU supplementation for 50+. Vitamin D levels are sub-optimal for many Canadians, especially during the winter, but only seriously low for 10%. Ethnic groups with darker skin tend to have a higher rate of deficiency, i.e., the evolution of paler skin lead to greater production of vitamin D at higher latitudes.
The winter sun in Canada doesn't supply vitamin D Oct - Mar. Below the 35 latitude, vitamin D is supplied by the sun all year round, excluding sun screen of course.
http://www.hc-sc.gc.ca/fn-an/nutrition/vitamin/vita-d-eng.php
http://www.cmaj.ca/content/182/12/E610.full
http://www.jabfm.org/content/22/6/698.full
http://www.hc-sc.gc.ca/fn-an/nutrition/vitamin/vita-d-eng.php#a10
http://www.osteoporosis.ca/news/press-releases/new-vitamin-d-guidelines/
http://www.statcan.gc.ca/pub/82-003-x/2010001/article/11131-eng.htm
No comments:
Post a Comment