Vitamin D signaling through the vitamin D receptor has emerged as a key regulator of innate immunity in humans. Investigators at McGill University (Montreal, Canada) extended this observation to the serious autoimmune syndrome known as Crohn's disease.

They reported in the January 22, 2010, edition of the Journal of Biological Chemistry that vitamin D acted directly to stimulate two genes that could be related to the development of Crohn's disease. The first, the beta defensin 2 gene, encodes an antimicrobial peptide that interacts with intestinal bacteria. The second, the NOD2 gene, alerts immune cells to the presence of invading microbes. When vitamin D levels were insufficient, these two genes malfunctioned, which induced the type of inflammatory response found in Crohn's disease.

"Our data suggests, for the first time, that vitamin D deficiency can contribute to Crohn's disease," said Dr. John White, professor of physiology at McGill University. "It is a defect in innate immune handling of intestinal bacteria that leads to an inflammatory response that may lead to an autoimmune condition."

"Siblings of patients with Crohn's disease that have not yet developed the disease might be well advised to make sure they are vitamin D sufficient," said Dr. White. "It is something that is easy to do, because they can simply go to a pharmacy and buy vitamin D supplements. The vast majority of people would be candidates for vitamin D treatment."

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