Irritable Bowel Syndrome and Vitamin D: Is There a Connection?
Common symptoms of IBS are constipation, diarrhea, or alternating diarrhea and constipation with or without abdominal pain.
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Irritable bowel syndrome (IBS) is the most common functional bowel disorder in the general population, affecting approximately 25 to 45 billion people in the United States.1 There is no known etiology, which makes identifying treatment for IBS a frustrating task for healthcare providers. Common symptoms of IBS are constipation, diarrhea, or alternating diarrhea and constipation with or without abdominal pain. Approximately 10% to 15% of the western population is affected by IBS, which results in an increase in direct and indirect health costs through loss of work productivity, frequent office and hospital visits, and testing to rule out more serious diseases.2 The total cost of IBS in the United States is approximately $30 billion annually, with an estimated $1.6 to $10.5 billion in direct costs and $20 billion in indirect costs.3 IBS can be life-altering for patients and often leads to avoidance of social situations and emotional distress. It is not life-threatening, has different degrees of severity, and treatment is based on symptomology. Due to no known cause of IBS, treatment may not be successful and patients may experience a lifetime of frustration and depression.
Vitamin D deficiency symptoms can be vague and may lead to underdiagnosis of the condition. Low vitamin D levels have been linked to multiple diseases including some cancers, neurologic disorders, decrease in bone density, and cognitive decline in the elderly. There is research that suggests a possible inflammatory response in the gut when vitamin D levels are low, making the connection between vitamin D and IBS a feasible speculation.
Vitamin D is most often acquired through sunlight, which can vary throughout the United States. The stronger the radiation, the longer an individual is exposed to radiation, and the more body area exposed to radiation, the more vitamin D that can be produced.4 Due to research noting the benefits of vitamin D, healthcare professionals are more aware of the importance of maintaining normal vitamin D levels in their patients.
What Is IBS?
IBS is a functional bowel disorder that was first documented 150 years ago.5 A functional bowel disorder is defined as changes in intestinal motility, intestinal nerve sensitivity, and the way the brain controls the normal function of the gut.1 As mentioned, there is no known etiology for IBS, nor is there specific testing to secure the diagnosis. The diagnosis of IBS is determined through application of the Rome criteria for functional bowel disorders.
The Rome classification system was introduced by an international group of gastrointestinal experts at the University of Rome, Italy, and is used in daily practice for patients with gastrointestinal complaints.6 The Rome IV criteria were introduced in May 2016 and are currently used to diagnose IBS by healthcare providers in daily practice today.7 The Rome IV criteria consist of recurrent abdominal pain on at least 1 day a week over the previous 3 months accompanied by 2 or more of the following symptoms: abdominal pain related to defecation, associated with a change in stool frequency, and associated with a change in stool form. All symptoms should be present for the past 3 months with the onset of symptoms occurring 6 months prior.8 By meeting these criteria, a diagnosis of IBS can be established.
Symptoms of IBS include diarrhea, constipation, and a mix of diarrhea alternating with constipation. The Rome IV diagnoses for bowel disorders include IBS constipation (IBS-C), IBS diarrhea (IBS-D), IBS mixed (IBS-M), IBS unclassified (IBS-U), functional constipation, functional diarrhea, functional abdominal bloating and distension, unspecified functional bowel disorder, and opioid-induced constipation.7 Treatment for IBS consists of prescription and over-the-counter medications, dietary modifications, and behavioral therapy. Treatment is based on a patient's symptoms and may need to be altered according to a patient's needs. Stating this, changes in treatment can be costly and time-consuming due to lost days of work and adjustments in medication or behavioral therapy.
Studies have been conducted that investigate the cognitive and emotional aspects of IBS. Up to 50% of patients with IBS meet the criteria for a psychiatric diagnosis including depression, anxiety, hostility, phobia, somatization, and paranoia.9 Due to symptoms of IBS, avoidance of certain foods, eating out with others, social situations, work situations where a toilet may not be available, intimate relationships, and personal relationships that would entail others finding out about IBS are common and significant concerns.10
The American College of Gastroenterology Functional GI Disorders Task Force recommends against extensive testing for IBS because these patients do not seem to have a higher prevalence of organic disease.5 However, there are alarm features outside of the Rome IV criteria that should alert the healthcare provider to investigate for more serious diseases. These alarm features include anemia, nocturnal symptoms, rectal bleeding, weight loss, recent antibiotic use, onset of symptoms after age 50, family history of colon cancer, inflammatory bowel disease, or celiac sprue disease.11 It is not uncommon for patients with IBS to wander through the medical system for years with multiple diagnoses because of lack of interest or frustration by the healthcare provider due to lack of treatment; the psychiatric component of the disease; or lack of clinical, physical, and/or laboratory criteria for the diagnosis.5