Dr. John Cannell has spent significant time in reviewing research from the 30’s in using extreme amounts of vitamin D to treat disease. This is well worth the read.
I am amazed at the amounts of vitamin D and the fact that all did not die. In particular since they were using D2 and ran the risk of over irradiation and forming toxisterols.
Check it Out: Gary Null and Vitamin D Toxicity
Vitamin D in large amounts can be toxic. If you want to try more than a million IU for an infection or other disease then you should see your doctor. It is not the amount that you take, it is keeping your serum level consistently under 200 ng/ml. See last line table one NIH Fact Sheet Of course that argument fails when you start to take in the millions of IU’s.
For best results in treating chronic disease then keep your 25(OH)D3 level to that of a sunny country 54 to 90 ng/ml. (Grant and Holick) Please notice that I said D3 in the 25(OH)D3.
Typical amounts of vitamin D3 from all sources should be around 40 IU of D3 per pound of body weight per day. This should keep you under 10,000 IU per day unless you are reallly large.