Researchers at the University of Sheffield discovered that low levels of vitamin D decreases the quality of life in sufferers of irritable bowel syndrome (IBS). They recommend that all people with IBS be screened for vitamin D deficiency. Everyone should be screened for vitamin D status regardless of whether or not they have IBS. In Functional Medicine we look at vitamin D deficiency as just one of many nutritional factors that can contribute to IBS. Other factors may be food sensitivities, gastrointestinal imbalances, adrenal hormone issues along with stress.