A five year longitudinal study discovered that low vitamin D levels are associated with worse outcomes in patients with inflammatory bowel disease. The researchers also found that vitamin D supplementation was linked to reduced health care use.
Healio Gastroenterology wrote an article on the study. Take a look.
There have been over 50 studies showing gut problems association with low vitamin D. in addition, several randomized controlled trials have proven that vitamin D treats many gut problems such as IBS http://vitamindwiki.com/tiki-index.php?page_id=3438