"Comparing people with a level less than 20ng/ml with those over 20ng/ml builds in a limited comparison. If we knew the levels of the comparison cohort then we might be able to deduce the validity of the comparison."
Join the discussion
Vitamin D deficiency
How to know if you get enough
How to get sun safely and supplement effectively
If you have a question about vitamin D and you can't find an answer on the Vitamin D Council website, then send us your question!
Ask a question