J Clin Immunol. 2009 Jul;29(4):470-8. doi: 10.1007/s10875-009-9277-9. Epub 2009 Feb 14.
Plasma 1,25 dihydroxy vitamin D3 level and expression of vitamin d receptor and cathelicidin in pulmonary tuberculosis.
STUDY SUBJECTS AND METHODS:
In combination with the information I posted about below--Vitamin D receptors are essential to avoiding colitis (inflammation and soreness in the intestines)--I think there's a very solid basis to suspect a connection between Vitamin D supplementation and the uptick in people suffering with intestinal problems in the USA.
It takes only 4 cups of milk to get all the Vitamin D you need. For adults. A tablespoon of cod liver oil has more than three times the RDA of Vitamin D. Again, that's for adults. Unless you have reason to think you need supplemental vitamin D, I recommend you don't take it. And be even more cautious when dosing a child.