subdued said...
I've been taking vitamin D for years--way before I ever had my first flare.
Which means it didn't prevent your first flare.
The main study is only a few months old, March 2010: http://www.nature.com/ni/journal/v11/n4/abs/ni.1851.html
Scientific American said...
From http://www.scientificamerican.com/blog/post.cfm?id=another-reason-vitamin-d-is-importa-2010-03-07
"In order for T cells to become active members of the body's immune system, they must transition from so-called "naive" T cells into either killer cells or helper cells (which are charged with "remembering" specific invaders). And, if ample vitamin D is not around, the T cells do not make that crucial transition, a group of researchers led by Carsten Geisler, head of the Department of International Health, Immunology and Microbiology at the University of Copenhagen, found. They draw this conclusion based on their experiments with isolated naïve human T cells.
"When a T cell is exposed to a foreign pathogen, it extends a signaling device of 'antenna' known as a vitamin D receptor, with which it searches for vitamin D," Geisler said in a prepared statement. If there is an inadequate vitamin D level, he noted, "they won't even begin to mobilize."
Although this vitamin requirement might seem like a handicap to the immune system, the researchers proposed that the additional step involving the vitamin D receptor might actually serve an important evolutionary function: keeping T cells from ravaging healthy tissue. "Given that T cells are capable of explosive proliferation, the lag phase imposed by the vitamin D [receptor step] may diminish the risk of unwanted immunopathology," they noted in the study, which was published online March 7 in Nature Immunology (Scientific American is part of Nature Publishing Group)."
While that says vitamin D is beneficial for the average person because it activates T cells, it also implies (in bold) that vitamin D is harmful for someone with an autoimmune disease like Ulcerative Colitis, for the very same reason.