Irritable bowel syndrome (IBS) is a relatively common functional disorder of the gastrointestinal tract that is characterized by cramping, abdominal pain, gas, and bloating. It is also characterized by diarrhea, constipation, or both, and can co-occur with mood disorders. Traditionally, IBS has been considered to be idiopathic because there are typically no identifiable structural or biochemical abnormalities; however, recent research is shining a light on potential causes of IBS as well as on increasingly effective integrative treatment approaches. In this article, I'll give a brief overview of what research is suggesting may be potential causes of IBS, and I'll share what I've found to be beneficial with my patients.
Insight into the underlying cause of Irritable Bowel Syndrome
The research suggests that IBS typically begins as a primary dysfunction at the level of the gut that then affects the central nervous system through the gut-brain axis, not the other way around. This dysfunction may be due to multiple factors, including post-infectious gastrointestinal changes (typically linked to gut microbiome balance disturbances), low-grade mucosal disturbances, immune system activation, increased intestinal permeability, serotonin metabolism disruptions, and genetic factors (such as an identified mutation in the SCN5A gene which leads to disruptions in a sodium channel), to name a few. 
Based on the emerging scientific data surrounding the etiology of IBS, it should be clear that a comprehensive treatment plan would address any gastrointestinal pathogens that are present, identify and correct other gut flora imbalances, seek to reduce inflammation and regulate the immune system, seek to heal gut mucus membranes and restore the integrity of the intestinal barrier, and support optimal gut motility.
What I've found to help my IBS patients
In my private practice, I typically start my patients who come in reporting a diagnosis of IBS off on an elimination and challenge protocol. My elimination and challenge protocol involves eliminating common triggers, such as wheat, dairy, fried and processed foods, added sugar, alcohol, caffeine, garlic, onions, and most meats,  each of which can lead to increased gastrointestinal inflammation and further dysregulation of the gut microbiome in the context of IBS. I have patients eliminate these foods for at least a period of 28 days. In my experience, 95%+ of patients experience significant improvement in their gastrointestinal symptoms after the 28-day elimination period; however, in some cases, particularly if the patient's symptoms are very severe and/or debilitating, I may recommend a 6-week elimination phase instead of my typical 4-week phase before initiating the reintroduction phase.
After the elimination period, I have my patients re-introduce foods in a calculated manner, paying special attention to and keeping a physical record of any new symptoms that arise or any previously resolved symptoms that resurface. I have patients reintroduce one food item at a time so that they are able to definitively identify which food is triggering their symptoms, should they experience a symptom flare during the reintroduction phase. Patients continue to reintroduce foods into their diets one-by-one until they are able to identify the foods that trigger their symptoms and the foods that do not lead to a return of symptoms.
During the elimination and challenge protocol, I typically make other recommendations as well, depending on each patient's symptoms and comorbidities. Some of the recommendations I've made for patients to good effect include:
Increasing intake of foods high in soluble fiber, such as freshly ground flaxseed and oatmeal. Soluble fiber can be beneficial in IBS that is characterized by constipation, diarrhea, or both; however, it's important to note that insoluble fiber may aggravate IBS-induced constipation in some patients.
Using herbs to address various symptoms of IBS. For example, I've had good results using Triphala, which is a combination of Terminalia chebula, Terminalia bellerica and Phyllanthus emblica to help ease constipation. Research suggests that Triphala may restore the lining of the gastrointestinal epithelium; it also exhibits anti-inflammatory, antioxidant, and mild laxative properties. 
Using targeted probiotic supplementation. I've used probiotics to help restore balance to the gut microbiome. Research suggests that some probiotic strains may help address mucosal dysfunction and immune activation in cases of IBS. 
Replenish any identified micronutrient deficiencies. As an example, pre-clinical research suggests that elevated homocysteine may play a role in the gastrointestinal epithelium barrier function abnormalities seen in IBS, and that homocysteine-lowering treatment may restore barrier function.  To address hyperhomocysteinemia, I typically recommend a combined supplement including high-dose methyltetrahydrofolate and active B complex. However, as a result of the mucosal disturbances, dysbiotic flora, and increased intestinal permeability, some patients with IBS may have impaired gastrointestinal absorption and may benefit from intramuscular or intravenous nutrient therapy to replenish vitamin stores and address any hyperhomocysteinemia that is identified. [To learn more about incorporating IV nutrient therapy into your practice, click here.]
Other interventions. I've also recommended stress management through both teaching techniques and using adaptogenic herbs to regulate HPA axis function), evaluating for small-intestinal bacterial overgrowth, lifestyle changes aimed at decreasing inflammation, and using other gut healing and intestinal barrier supportive protocols.
In conclusion, although IBS was previously considered to be a condition of unknown etiology, research is elucidating multiple potential causes of the condition. As the cause of IBS may be multifactorial, it makes sense that our treatment approach should be multi-pronged as well. Interventions such as gut-healing nutrients, probiotics, addressing infection and/or dysbiosis, eliminating food sensitivities, addressing homocysteinemia, stress management, immune system regulation, and inflammation reduction should be considered.
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