Vitamin D supplements are not an effective treatment for easing painful symptoms of Irritable Bowel Syndrome (IBS), a new study from the University of Sheffield reveals.

• New research from University of Sheffield reveals vitamin D supplementation does not improve painful IBS symptoms
• Scientists nonetheless noted a high prevalence of poor vitamin D status in people with IBS, so the authors still recommend testing and remedy to support overall health
• The definitive study is the largest to provide evidence on effect of vitamin D on IBS symptoms
• IBS is a chronic and sometimes debilitating condition which affects over 10% of the population, costing the NHS in excess £11 million per year

Scientists from the University’s Department of Oncology and Metabolism - in conjunction with health supplement company, BetterYou - carried out trials on participants who suffer with the chronic condition of the digestive system to assess whether vitamin D reduced the severity of their symptoms, and whether it could improve their quality of life.

Results of the study - published today (30 July 2021) in the European Journal of Nutrition - found that despite an improvement in vitamin D status in the participants in response to a vitamin D3 oral spray supplementation over a 12 week trial, there was no difference to their IBS symptom severity over the same period, nor a reported change in the participants’ quality of life.

IBS is a common functional bowel disorder, characterised by chronically relapsing perturbed bowel habit. It causes symptoms such as stomach cramps, bloating, diarrhoea and constipation. For some, symptoms will come and go, but for others it can severely affect their quality of life, often causing embarrassment leading to many living with the condition undiagnosed, affecting both mental health and wellbeing.

Carried out in collaboration with Sheffield Teaching Hospitals NHS Foundation Trust, the study also identified that although vitamin D supplements do not ease symptoms of IBS, a vitamin D deficiency is widespread amongst the IBS population, potentially leading to an increased risk of suffering from fractures and osteoporosis in the long-term.

Co-author of the study Dr. Liz Williams, a Senior Lecturer in Human Nutrition at the University of Sheffield, said: “There has been interest from researchers and from patient groups in the potential of high dose vitamin D to alleviate symptoms of IBS, but there haven’t been many properly controlled trials in this area. What our research shows is that supplementing vitamin D at a safe dose did not reduce the severity of IBS symptoms.

“It is worth noting however, that the vitamin D supplementation did correct deficiencies in those people who were found to have poor vitamin D status, and this is important for other aspects such as bone and muscle health.”

Lead-author Professor of Human Nutrition and Health at Newcastle University and Honorary Fellow at the University of Sheffield, Bernard Corfe, said: “For some people living with severe IBS, low vitamin D levels may be attributable to changes in diet and lifestyle. Some may feel due to the severity of their symptoms that they limit their outdoor activities due to the anxiety their symptoms can cause, or alter their diet to avoid certain foods triggering their symptoms.

“Unfortunately all of these coping mechanisms can be detrimental to overall health and wellbeing and reduce exposure to valuable sources of vitamin D.

“Given that vitamin D is essential for overall health and wellbeing, it is still important people with IBS get tested and treated and seek dietary advice so it does not impact on their long term health.”

The research team at Sheffield were the first to suggest a possible link between people living with IBS and low vitamin D levels in 2012, and have since followed the issue closely. The study published today is the largest, and most definitive study to date showing clearly that vitamin D supplementation does not ease severe IBS symptoms.

Although little is known about why and how the debilitating condition develops, and there is currently no cure for IBS, further research is trying to identify better ways to support and manage people living with the chronic condition.

Professor Corfe added: “There is a range of management strategies that people living with IBS can seek help with from their GP, but because of the heterogeneity of the syndrome, managing IBS can be trial and error for each individual patient.

“As it is estimated that between five and 15% of the population could be living with IBS - some undiagnosed due to the anxiety and embarrassment their symptoms can cause - it is vitally important we continue with research to find new ways to diagnose, treat and understand the impact of IBS on the population.”