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A new study recently carried out at the University of Sheffield has found a significant link between vitamin D deficiency and Irritable Bowel Syndrome (IBS) – a debilitating condition that affects up to 15% of the population in the industrialised world.

51 patients took part in this recent randomized, double-blind controlled trial.

Initial tests showed that 81.8% of people with IBS and constipation, 70% with diarrhea and 81.6% with mixed bowel habits were deficient in vitamin D. Researchers also identified a significant association between vitamin D level and quality of life.

Following initial testing to establish these baseline scores, study participants were randomly allocated to receive either placebo, vitamin D + probiotic supplementation, or just vitamin D supplementation for 12 weeks. Results showed that after 12 weeks of supplementation, all patients with adequate levels of vitamin D showed signs of improvement. More specifically, the group taking vitamin D + probiotic supplementation improved from 25% to 87.5%, the group taking vitamin D on its own improved from 22.2% to 92.3%.  Interestingly, improvements were also noted in the placebo group, from 18.5% to 60%.

The researchers commented on the potential mechanism of action behind vitamin D's role in bowel function,

“Vitamin D receptor (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.”

An estimated 10 million people across England are suffering from low levels of vitamin D – around 1 in 5 adults and 1 in 6 children according to the NICE Centre for Public Health. Many people are unaware that the main source of vitamin D is not food but sunshine. The skin manufactures this essential nutrient upon contact with the sun’s rays; in colder climes however, when people spend more time covered up indoors, production is very limited. In addition, in the UK from mid-October to the start of April, sunlight doesn’t have the correct wavelength to create vitamin D in the skin. Supplementation with vitamin D as cholecalciferol with added vitamin K2 is an effective way to increase levels. 

Tazzyman S et al. Vitamin D associates with improved quality of life in participants with irritable bowel syndrome: outcomes from a pilot trial.  BMJ Open Gastro.  Doi: 10.1136/bmjgast-2015-000052

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