The study sheds light onto an often forgotten condition that affects 10–15% in the industrialised world and highlights the need for nationwide screening programs as well as possible vitamin D supplementation for IBS sufferers.
IBS refers to a relapsing condition that has a large social impact and is associated with significant health care costs, both direct through IBS symptoms and associated disorders and indirect through time taken off work. Estimates have placed annual direct and indirect management costs to be $8bn (€7.44bn) and $25bn (€23.27bn), respectively.
The study used a randomised, double blinded, three-arm parallel design trial of vitamin D, placebo or a combination of vitamin D and probiotics. 51 IBS patients were enrolled.
Tests revealed that vitamin D deficiency was high across different IBS symptoms: 81.8% of those with IBS with constipation, 70% of IBS with diarrhoea and 81.6% of IBS with mixed bowel habits.
Results also revealed a significant association in the baseline data between circulating vitamin D level and quality of life. Supplementation was found to significantly improve vitamin D level versus placebo.
Supplementation studies
The role of vitamin D supplementation in other gastrointestinal conditions is also supported by other studies which show associations between a vitamin D deficiency and inflammatory bowel disease. Vitamin D has recently been linked to lowering blood pressure and reducing the risks of heart and kidney disease.
A study to assess patient data from 37 IBS sufferers commented on the effect of vitamin D supplementation on their condition. The paper reported that approximately 70% of those that received high-dose supplementation improved their IBS symptoms.
A role for vitamin D supplementation in gastrointestinal health is also supported by a study showing associations between vitamin D deficiency and inflammatory bowel disease (IBD).
IBS is a chronic and debilitating functional disorder of the gastrointestinal tract. Little is known about why and how the condition develops, although it is known that diet and stress can make symptoms worse.
The symptoms often cause embarrassment for patients meaning many live with the condition undiagnosed. The disorder accounts for 10% of visits to GP surgeries and the condition has a significant and escalating burden on society as a consequence of lost work days and time spent on regular hospital appointments.
Study details
Scientists from the University of Sheffield adopted a double-blind randomised controlled trial that set out to assess if vitamin D would benefit IBS patients. Participants provided a blood sample to assess vitamin D levels. An IBS symptom questionnaire was also used.
Participants were randomly allocated to receive a placebo, vitamin D supplementation and probiotic placebo, or probiotic and vitamin D supplementation. Participants took their assigned supplement for the next 12 weeks filling in their questionnaire fortnightly. Participants were asked to take a blood test to determine vitamin D levels during their final visit.
After 12 weeks of supplementation, participants with satisfactory levels of vitamin D improved in all groups. The group, which took vitamin D and the probiotic, improved from 25% to 87.5%. Those who received vitamin D alone improved from 22.2% to 92.3%. Most noticeably, an improvement was also noted in the placebo group, with a jump from 18.5% to 60%.
Vitamin D receptor key
The researchers pointed out that vitamin D had been implicated in neurological developments in previous studies and the vitamin D receptor (VDR) had been expressed throughout the nervous system where its activation was linked to neurotransmitter levels and serotonin synthesis.
“VDR is also expressed in the gut and regulates epithelial barrier function and bowel inflammation suggesting that a vitamin D deficient diet may directly impact bowel function and hence IBS symptomology,” the paper commented.
“Our attempt to distinguish the effects of circulating and ingested vitamin D did not support either model, likely due to underpowering of the study.”
Source: BMJ Open Gastro
doi:10.1136/bmjgast-2015-000052
“Vitamin D associates with improved quality of life in participants with irritable bowel syndrome: outcomes from a pilot trial.”
Authors: S. Tazzyman et al.