Cell: Vitamin D May Reduce Intestinal Inflammation

In people with inflammatory bowel disease, taking vitamin D enhances the immune system’s protective response to gut bacteria and reduces inflammation, according to researchers at the Mayo Clinic. The findings were published in the journal Cell Reports Medicine.

The scientists studied people with Crohn’s disease, a chronic inflammation of the digestive tract, and ulcerative colitis, which causes inflammation of the lining of the large intestine. All volunteers initially had low vitamin D levels. For 12 weeks, participants took a weekly supplement, after which the researchers compared blood and stool measurements.

Vitamin D supplementation was found to alter the balance of the immune response. Levels of protective IgA antibodies, which help control bacteria on the surface of the intestinal lining, increased in the gut, while levels of inflammatory IgG decreased. At the same time, fecal calprotectin, a marker of intestinal inflammation, also decreased, falling by an average of 722 micrograms per gram.

Additional cell experiments revealed a possible mechanism behind the effect. Vitamin D acted on immune-system dendritic cells and stimulated the production of IgA. The immune response to different groups of gut bacteria also changed: the protective response increased toward microorganisms associated with maintaining the intestinal barrier, while the inflammatory response decreased.

“Vitamin D may not simply suppress inflammation but help the immune system interact more appropriately with the gut microbiota. This could represent a new avenue for adjunctive therapy for inflammatory bowel disease,” the researchers said.

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