Irritable bowel syndrome (IBS) is the most common gastrointestinal disorder in the U.S. An estimated $1.6 billion is spent on treatments each year.^1,2 Depending on the source, data suggests anywhere from 10 to 25 percent of Americans struggle with this condition.^3,4

IBS is completely different from another condition with a similar name: inflammatory bowel disease (IBD), which is an autoimmune disease that can have very serious consequences. While it can cause debilitating pain, IBS is a functional bowel disorder, meaning there are no significant physical conditions that contribute to the problem. Common signs and symptoms of IBS include frequent: 

• Abdominal discomfort and/or pain

• Spastic colon (spastic contractions of the colon)

• Gas and/or bloating

• Diarrhea

• Constipation

IBS is frequently treated with drugs such as antispasmodics and even antidepressants. While these drugs may help control symptoms, they do not address the underlying problem, which is primarily diet related. Typically, simply avoiding gluten will result in significant improvement. Recent research has also highlighted the importance of vitamin D optimization in this condition.

IBS Strongly Associated With Vitamin D Insufficiency

A recent review^5,6,7 in the European Journal of Clinical Nutrition notes that of the seven published studies looking at vitamin D status and IBS prevalence, four observational studies concluded vitamin D deficiency is prominent among those with IBS — with about 75 percent having insufficient levels — and two intervention studies reported “improvement in IBS symptom severity scores and quality of life” among those given vitamin D supplements. In one, 70 percent of IBS patients improved on the vitamin D regimen. According to the authors:

“The available evidence suggests that low vitamin D status is common among the IBS population and merits assessment and rectification for general health reasons alone. An inverse correlation between serum vitamin D and IBS symptom severity is suggested and vitamin D interventions may benefit symptoms.”

Lead author Bernard Corfe, Ph.D.,⁸ a senior lecturer in oncology at the University of Sheffield in the U.K., told reporters, “It is evident from the findings that all people with IBS should have their vitamin D levels tested and a large majority of them would benefit from supplements.”⁹

Another recent study¹⁰ looking at gene expression and variations in patients’ serotonin pathways also concluded that IBS patients tend to have lower vitamin D levels, and that expression of genetic biomarkers for IBS are modulated by vitamin D. According to the authors:

“Strikingly, the direction of gene regulation elicited by vitamin D in colonic cells is ‘opposite’ to the gene expression profile observed in IBS patients, suggesting that vitamin D may help ‘reverse’ the pathological direction of biomarker gene expression in IBS. Thus, our results intimate that IBS pathogenesis and pathophysiology may involve dysregulated serotonin production and/or vitamin D insufficiency.”

Football Players Sidelined by Low Vitamin D

In related news, other recent research¹¹ found nearly 60 percent of National Football League players have low vitamin D levels, placing them at increased risk for injury. Fifty-six percent of those with insufficient levels of vitamin D (a serum level of 20 to 31 ng/mL) suffered some form of lower extremity muscle strain or muscle injury while playing, and 73 percent of those with severe deficiency (a vitamin D level of 20 ng/mL or lower) ended up with muscle injuries.

For comparison, only 40 percent of those with “normal” vitamin D levels reported injuries, defined here as a vitamin D level of 32 ng/mL or greater. Analysis revealed inadequate vitamin D levels nearly doubled a player’s odds of suffering lower extremity strain or core muscle injury, and raised their odds of hamstring injury nearly fourfold.

Considering the research showing 40 ng/mL is really the cutoff point for general health, and that 60 ng/mL is likely a more ideal level, one wonders if sports injuries might not be reduced even more were the players to maintain levels of 40 to 60 ng/mL. In a hospital news release, Dr. Brian Rebolledo, orthopedic surgeon specializing in sports medicine at the Scripps Clinic in La Jolla, California, and the lead author of the study said:¹²

“We were interested in vitamin D in this population because it’s been shown to play an important role in muscle function and strength, which is critical to the high-performance athlete. Most of the past research into the harmful effects of low vitamin D has focused on the elderly, but relatively few studies have examined this association in the elite athlete. This study suggests that monitoring and treating low vitamin D may potentially be a simple way to help prevent certain muscle injuries.”