Effectiveness of vitamin D for irritable bowel syndrome: A protocol for a systematic review of randomized controlled trial

BACKGROUND: Irritable bowel syndrome (IBS) is a prevalent and debilitating condition for patients who experience this disorder. Clinical researches indicate that vitamin D (VD) can help relief the symptoms of IBS. However, no systematic review has addressed this issue yet. Thus, this systematic review aims to investigate the effectiveness and safety of VD for patients with IBS. METHODS: We will retrieve the following databases for randomized controlled trials to assess the effectiveness and safety of VD for patients with IBS: Cochrane Library, EMBASE, MEDICINE, Web of Science, Allied and Complementary Medicine Database, Chinese Biomedical Literature Database, and China National Knowledge Infrastructure. Each database will be retrieved from its inception to January 31, 2019. Two researchers will independently selection studies, extract data and assess methodological quality. RevMan 5.3 software will be used to pool the data, and carry out the meta-analysis if it is possible. RESULTS: This systematic review will evaluate the effectiveness and safety of VD for patients with IBS. The primary outcomes include stool frequency and abdominal pain. The secondary outcomes consist of stool status, quality of life, and adverse effects. CONCLUSIONS: The findings of this systematic review may provide the existing evidence on the effectiveness and safety of VD for patients with IBS. ETHICS AND DISSEMINATION: This systematic review will not require ethical approval, because all data will be extracted from the published literature. The findings of this study will be disseminated at peer-reviewed journals. PROSPERO registration number: PROSPERO CRD42019122641.