I knew that there was research going into the role of vitamin D and Crohn's, but didn't know about
the Penn State study. Thanks.
To test for vitamin D deficiency, a blood test needs to be done to check the level of vitamin D 25-hydroxy. (And NOT vitamin D 1,25).
The latest recommendation from the famous Dr. Weil is that everybody should take 1,000IU daily of vitamin D (D3 is best, not D2).
My daughter finds that the only way she can keep her vitamin D from falling is by taking at least 1,800IU daily.
In latitudes from Boston northward, between the months of November and February, most people cannot get enough vitamin D from the sun.