

3 Reasons to Take Vitamin D in the Winter Time - gordonbowman
http://www.drweil.com/drw/u/TIP03934/Vitamin-D-in-Winter-Time.html

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Travis
It's worth noting that the science behind Vitamin D supplements is far from
settled.

On Nov 30, 2010, the USRDA lowered their recommended amount from 2000mg to
600mg for healthy adults. This reflects what the EU publishes as the
recommended amount.

From wikipedia: "There is some disagreement concerning the exact levels of
25-hydroxy-vitamin D needed for good health. A level lower than 10 ng/mL (25
nmol/L) is associated with the most severe deficiency diseases: rickets in
infants and children, and osteomalacia in adults. A concentration above 15
ng/ml (37.5 nmol/L) is generally considered adequate for those in good health.
Levels above 30 ng/ml (75 nmol/L) are proposed by some as desirable for
achieving optimum health, but there is not yet enough evidence to support
this."

That quote is supported by 3 different citations on the wiki page as well.
<http://en.wikipedia.org/wiki/Vitamin_D#Nutrition>

