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Potential relief for IBS through vitamin D

Vitamin D isn’t just for bone health. Its role in dampening inflammation and regulating immune responses suggest that it may help in treating IBS, which is directly tested in this randomized trial.

Study under review: Effect of Vitamin D on Gastrointestinal Symptoms and Health-Related Quality of Life in Irritable Bowel Syndrome Patients: a Randomized Double-Blind Clinical Trial


Irritable Bowel Syndrome[1] (IBS) is a chronic condition characterized by abdominal pain, altered bowel habits, flatulence, and abdominal distension, with symptoms ranging from mild to severe. Abnormalities in the biochemical signaling between the GI tract and the nervous system, the immune system, organ pain, and disturbances in bowel habits are commonly associated with IBS. Moreover, symptoms are often associated with psychological distress[2], which can hamper quality of life and sense of well-being. Psychological symptoms are theorized to be both potential causes and effects of having IBS. Other IBS risk factors are shown in Figure 1.

Figure 1: Risk factors for IBS

Vitamin D is a fat-soluble compound known for its ability to regulate calcium and phosphorous metabolism. It plays a role in cognitive function, immune health, bone health, and well-being. In the context of IBS, evidence shows an association between vitamin D status and anxiety, depression, and fibromyalgia[3], with greater association[4] observed in IBS patients - though a cause and effect relationship has yet to be identified. The rate of vitamin D deficiency is estimated to be 30-50%[5] worldwide, a percentage similar to vitamin D deficiency in patients with GI disorders.

Recent studies have further investigated vitamin D’s beneficial effects in modulating the immune response and inflammation[6], two factors believed to be contributors to the onset of altered gut function and IBS symptoms. One recent case study[7] investigating the effects of vitamin D supplementation on symptoms of IBS showed that participants taking 3,000 IU of vitamin D per day experienced improvements in their symptoms, and that the symptoms recurred after supplementation ceased. Additionally, anecdotal evidence suggests that participants who report themselves as vitamin D deficient have experienced improvements in their symptoms following high-dose[7] vitamin D supplementation.

While the exact association between vitamin D status and IBS has yet to be determined, vitamin D3 supplementation has been shown to aid in the overall health and function of the intestinal mucosal barrier, which is relevant because damage to this barrier commonly occurs during IBS. This information, coupled with the observed effect of vitamin D in improving homeostasis of the intestinal mucosal barrier, gives way to the study under review, which sought to determine the effects of vitamin D supplementation on symptoms, severity score, and quality of life scores (QoL) in people with IBS.

Vitamin D has shown promising anti-inflammatory and immune-modulating effects in recent human and animal studies, and has shown to be effective in improving intestinal barrier integrity, thus supporting healthy gut barrier function and permeability. The purpose of the present study was to investigate the effect of high-dose vitamin D supplementation on symptoms, severity, and quality of life in patients with IBS.

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