Treatment and Outcome

Multiple treatment options were presented to the patient, including both medications and lifestyle changes. The patient chose nonpharmacologic therapies and the addition of a vitamin D supplement and a probiotic. Lifestyle changes included a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP).

Within 8 weeks of starting the strict low-FODMAP diet, her abnormal bloodwork values returned to normal limits and her diarrhea resolved. The abdominal bloating was greatly reduced and she felt much more motivated to take walks and exercise. Her overall anxiety level improved due to the lack of nervousness about having digestive problems in public.

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The patient’s current presentation after adhering to treatment.


IBS is a functional gastrointestinal disorder that affects between 10% and 20% of the population.1 IBS is associated with a mosaic of factors, all of which contribute to different manifestations of the syndrome. For example, impaired or abnormal colonic transit time, impaired rectal evacuation, irritants to the lumen of the intestines, alterations in gut flora, genetic predisposition, and psychosocial stress all play a role in IBS.2  These factors can lead to altered mucosal permeability, immune activation, or inflammatory response, which in turn leads to a diarrhea-predominant or constipation-predominant disorder.

In diarrhea-predominant IBS, studies have shown higher concentrations of short-chain fatty acids in the colon. This may be due to increased bile acid secretion or the inability to absorb bile acid in the small intestines. These fatty acid chains have <6 carbon atoms and cause the colon to contract at a faster pace, with contractions spanning a larger surface area than normal. Ileocolonic contractions reached highest amplitude of strength after a high-fat meal containing over 500 kcal. A high-FODMAP diet is poorly absorbed in the intestine of patients with IBS and contributes to higher levels of these diarrhea-inducing short-chain fatty acids.2

IBS is more common in women and symptoms may fluctuate over time, often mimicking other conditions and may result in diagnosis delays or misdiagnosis, which can delay treatment, ultimately reducing quality of life and increasing overall healthcare costs.3  Most patients present to their PCP; up to 68% are diagnosed by a PCP, while 13% will be referred to gastroenterology and diagnosed by the specialist.3  Today, up to 48 million Americans are living with IBS and nearly 75% of people may be undiagnosed.4 

As noted, alterations in the natural microbiota of the gut have also been considered a potential factor in the etiology of IBS.1 A higher ratio of firmicutes to bacteroides bacteria is often seen in patients with constipation-predominant IBS (IBS-C). These lower levels of bacteroides bacteria are associated with IBS-C and cause a longer colonic transit time and higher rates of depression.2 

Pharmaceutical Treatments

In many cases, pharmacologic treatment may be traditionally prescribed. To treat abdominal pain, anticholinergic/antispasmodic medications are recommended. For IBS- C, if increasing dietary intake of fiber to 25 g/day does not provide relief, the provider may prescribe psyllium. For IBS-D, loperamide before meals (2 to 4 mg, PRN up to 4 times a day) can aid in providing relief. Additional medications include bile acid sequestrant agents such as cholestyramine if there is a history of cholecystectomy or bile acid malabsorption. Newer 5-HT4 receptor agents have been proven effective as well, including alosetron for IBS-D and tegaserod for IBS-C.5 

Psychological Support

In some cases of IBS, patients may be refractory to treatment. In such cases, psychological support or pain management is recommended. According to the American Gastroenterological Association, cognitive behavioral therapy, hypnosis, relaxation therapy, and stress management can be especially effective in patients with a history of abuse or comorbid depression.5 Psychiatric medications may also improve IBS pain. Tricyclic antidepressants are the treatment of choice in these cases, as selective serotonin reuptake inhibitors have not been studied adequately but are safe to use for comorbidities. Anxiolytics, however, are not recommended due to their addictive qualities, which may lead to abuse.5

Diet Modification

Diet modification usually includes advising a patient to eat smaller, more frequent meals to reduce fat intake and to avoid gas-producing foods, such as onions. One Swedish study compared this traditional dietary advice to a low FODMAPs diet, finding that both were equivalent in reducing signs and symptoms of IBS.6 The study speculated that a combination of the 2 methods would be most beneficial.


Physical activity can also lesson symptoms of IBS. A recent trial found that patients who maintained a low level of activity (control group) experienced worsening symptoms compared with the intervention group, who exercised 20 to 60 minutes 3 to 5 days a week.7 This exercise regimen is recommended by the Swedish National Institute of Health’s Physical Activity in the Prevention and Treatment of Disease. The study also showed that increased activity improves existing IBS and also hypothesized that in a healthy subject, increased activity would aid in preventing the development of the disease. Existing research proves that physical activity normalizes colonic transit time and reduces bloating, which is the goal in the prevention and treatment of IBS.7


Numerous studies have shown that probiotics reduce the occurrence and intensity of IBS symptoms and may potentially lead to full recovery. Based on the results of a meta-analysis with 1793 patients, the consistent daily use of probiotics is beneficial in the prognosis of IBS compared with control groups that did not use probiotics.8

The addition of certain microorganisms may lead to a better prognosis, including Bifidobacterium longum and Lactobacillus acidophilus.9-11 Probiotics are not the same as prebiotics, and prebiotics are not useful in the treatment of IBS.9 B longum was found to reduce overactive limbic activity and even reduce the symptom of depression in many patients with IBS.10 L acidophilus can mitigate abdominal pain and reduce visceral hypersensitivity when given shortly after the first signs of IBS.11 Probiotics containing more than 1 strain of bacteria may be the most beneficial, and a combination of 3 bacteria is ideal, according to a study conducted over a 6-week span.12

Probiotics also provide a long-term management option that encourages compliance more than a low-FODMAPs diet, which is difficult to follow consistently and can lead to malnourishment if the patient does not take care to consume an appropriate variety of food.9 Overall, patients taking probiotics have a better prognosis regarding their IBS symptoms compared with patients not taking probiotics.

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Vitamin D

Vitamin D deficiency is extremely common in patients with IBS.13 A deficiency can lead to worsening or development of IBS symptoms and a multitude of systemic complications including poor regulation of the natural flora, incorrect operation of cellular mechanisms, problems with peptide release, and issues with immune regulation.14 It is important to educate patients on the dangers of vitamin D deficiency and to provide the treatment they need in order to prevent complications of IBS or otherwise. Studies show that in deficient patients, vitamin D replacement can reduce IBS symptoms. If levels are raised to normal range within 6 months, patients may experience full recovery from symptoms.13

Vitamin D deficiency has also been linked to depression.15 A study explored the connection to estrogens and adipose tissue, finding that when soy isoflavones and vitamin D were administered together, gastrointestinal symptoms and overall total quality of life in women were greatly improved.16 This may suggest that the mosaic of contributing factors to IBS, including excess adipose tissue, low physical activity, depression, psychologic distress, and vitamin D deficiency, are intertwined to create a complex disorder. Overall, correcting a vitamin D deficiency with supplementation will prevent further complications of IBS.17


IBS can be caused by a variety of etiologies and may appear slightly different from one patient to another. Therefore, the plan of care and treatment should be catered to the patient’s individual needs and lifestyle. While traditional medication may serve certain patients well, there are many alternatives that are proven to treat IBS symptoms as effectively as or better than prescription medications. These options should be considered and employed in order to provide the best care possible for patients with IBS.


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