WORCESTER – A new study from University of Massachusetts Medical School finds that the majority of children with irritable bowel syndrome are low on vitamin D. The lead author, pediatric endocrinologist Dr. Benjamin Nwosu, an associate professor of pediatrics at the medical school, called for monitoring and supplementing vitamin D in pediatric IBS patients.

The study, published Monday in the scientific journal PLOS ONE, is the first of its kind to examine such a link in children.

IBS is not a disease but is considered a disabling functional disorder. The cluster of symptoms including cramps, bloating, diarrhea and constipation, affects as many as one in six children, according to a news release from UMass Medical School.

Vitamin D is a nutrient found in some foods, such as salmon, tuna, egg yolks and fortified foods such as milk and orange juice, that is needed for health and to maintain strong bones, according to the National Institutes of Health. It does so by helping the body absorb calcium (one of bone’s main building blocks) from food and supplements.

The body also makes vitamin D when skin is exposed directly to the sun.

Being vitamin D deficient puts individuals at risk for decreased bone mass and muscle weakness. The vitamin is needed to carry messages between the brain and other parts of the body and to help the immune system ward off bacteria and viruses.

In the present study, investigators analyzed medical records of 55 children with IBS and 116 healthy children who didn’t have IBS.

They found 93 percent of the children with IBS had vitamin D deficiency, using the clinical practice definition of deficiency, compared to 75 percent of the healthy children in the control group.

Even using a tighter definition of vitamin D deficiency used by the National Institutes of Health, more than 50 percent of children with IBS had vitamin D deficiency compared to 27 percent of control subjects.

“Vitamin D deficiency is highly prevalent in this area,” Dr. Nwosu said in an interview, pointing to the lack of sun exposure in northern latitudes as a contributing factor. But even so, children with IBS had much higher prevalence of the deficiency.

Dr. Nwosu said people with IBS frequently don’t feel well, with uncomfortable gastrointestinal symptoms, so they may not get out as much to walk or play in the sun.

Also, they typically have limited dietary choices so they may not be getting sufficient vitamin D from food.

People with IBS and other digestive problems tend to avoid a range of foods, whatever provokes their symptoms. Those who avoid fish, eggs and dairy products in particular consume less vitamin D.

“In the general population, meat eaters happen to have higher vitamin D than vegans,” Dr. Nwosu said.

Dr. Nwosu said that given the high prevalence of vitamin D deficiency, the approach that made sense for clinicians would be to routinely screen children with IBS and have them take vitamin D supplements to maintain between 30 and 100 nanograms per milliliter.

He said vitamin D is generally safe at supplementation levels needed to stay within a normal range. In rare cases, constipation, headaches, disorientation and drowsiness are among the risks of heavy supplementation. 

Overall, “Most clinicians tend to gravitate toward 1,000 international units per day,” Dr. Nwosu said about standard daily requirements.

The study published Monday is part of a series of studies looking at children with malabsorption syndromes, including celiac disease and lactose intolerance, to examine what happens to the vitamin D they have in their bodies. Dr. Nwosu said that children with IBS had the highest prevalence of vitamin D deficiency among these groups.

He said the same connection between IBS and vitamin D deficiency has been reported in adults.