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Irritable Bowel Syndrome

I have heard physicians say that food and nutrition are not important in the management

of IBS and other gastrointestinal conditions. As infuriating as that sounds, many other dietitians have shared similar experiences with me. In honor of IBS Awareness Month, let’s learn about this condition and the tremendous effects that food, nutrition, and lifestyle change can have for those with IBS.

Approximately 12% of people in the United States have Irritable Bowel Syndrome (IBS),

a chronic, functional bowel disorder characterized by symptoms such as bloating, abdominal

pain, diarrhea, or constipation. There is no specific test for IBS but at least two of the following must occur once a week for 3 months: pain and discomfort related to defecation, a change in the frequency of defecation, or a change in stool consistency (1). There are three main types of IBS: diarrhea predominant (IBS-D), constipation predominant (IBS-C), and a mixture of the two (IBS-M). Various conditions may need to be ruled out such as Intestinal Bowel Disease (Crohn’s and Ulcerative Colitis) or Celiac Disease.

Underlying Causes

Etiologies of IBS may be elusive but several that have been proposed by research

include foodborne illness, “visceral hyperalgesia [hypersensitivity], intestinal permeability,

immune activation, altered gastrointestinal motility, autoimmunity, and alteration of the gut

microbiome” (1). Every case is unique, so a general recommendation such as “eat more fiber” could have detrimental repercussions while a suggestion to only “eat what you tolerate” is not very helpful. A comprehensive nutrition and lifestyle assessment is essential. That is why someone with a gastrointestinal disorder should add a registered dietitian to their healthcare team.

Conventional Treatments

Examples of medications that may be used to control symptoms include

antidepressants, prokinetics, antibiotics, pain medications, and laxatives. Their effectiveness

varies, and they are often unsuitable for long-term use and carry a risk of side effects.

Medications for IBS have often been categorized as “band-aids'' which do not address the root cause of the issue. The relapse rate of symptoms is high, and it is common for someone to spend decades searching for the right treatment and tens of thousands of dollars on tests.

You may be asking: “Do you have any good news, then, Nathan?” Yes, I do, but I think it

is important to validate the experiences of each and everyone’s health journey and the long road that many with IBS travel to find symptom relief. It breaks my heart to see so many dismissed by their healthcare providers and given lackluster nutrition advice.

Flare Ups

Before diving into strategies that can address the root causes of IBS, let’s discuss some

basic steps to manage symptoms through a food and nutrition lens. After all, it is important to address what to do in a flare up.

It is essential to replace fluids and electrolytes lost during periods of frequent diarrhea or

vomiting. For constipation, proper hydration is important to help soften stools and encourage their progression through the GI tract. Avoid alcohol, caffeine, and smoking which can irritate the gut and worsen IBS symptoms. Avoid high fat foods (such as fried food, full fat dairy, and processed meat) and spicy foods. Ask your dietitian how much fiber to consume and choose cooked vegetables over raw and softer fruits such as bananas. Eat small, frequent meals and snacks, opting for pureed or liquid consistency (like a meal replacement shake) as needed. Watch out for sugar alcohols (sorbitol, erythritol, mannitol, xylitol, isomalt, maltitol, lactitol) which are one of the most common triggers for gastrointestinal symptoms. They are often used in place of sugar in sugar-free foods and beverages. Eat sitting down in a relaxed setting, chewing food thoroughly, and taking deep breaths. Try to reduce stress as much as possible and consider a free guided meditation video. Avoid strenuous exercise and get plenty of sleep and rest.


The Low Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols

(FODMAP) diet is one of the most popular dietary approaches to reduce IBS symptoms, though it is certainly not the only one. Monash University, which created the Low FODMAP diet, explains that FODMAPs are short-chain carbohydrates that may not be absorbed properly in the gut, drawing water into the intestines. They are also highly fermented by gut bacteria, which cause gas. Let me be clear, the FODMAP content alone does not determine if a food is nutrient-dense or not. Some of the healthiest foods (beans, mango, mushrooms, avocado, watermelon, etc.) are high in FODMAPs while some processed food products are high in FODMAPs (like high fructose corn syrup). The goal of the Low FODMAP diet, like any

elimination diet, is to reintroduce foods to keep as many foods as possible in someone’s diet

moving forward. Some limitations of the low FODMAP diet include that 1) it is restrictive and can be challenging to follow 2) around 30% do not achieve significant symptom relief and 3) it still does not determine the “root cause” of what is triggering symptoms in the first place.


If you have heard of gut bacteria, probiotics, or the gut microbiome, then you may know

that bacteria in the intestines provide many essential health benefits from improved function tobetter digestion to improved cardiovascular health. Many trillions of these bacteria are located in the large intestine while not so many reside in the small intestine. If you have an improper balance of the different types of gut bacteria, it is called gut dysbiosis. If there are too many bacteria in the small intestine, it is a condition called small intestinal bacterial overgrowth (SIBO). Research suggests that as many as half of people with diarrhea-predominant irritable bowel syndrome have SIBO (2). Recently, a new condition (intestinal methanogenic overgrowth) was identified that is related to but different from small intestinal bacterial overgrowth. Intestinal methanogen overgrowth (IMO) is more often associated with constipation while SIBO is often associated with IBS-D or IBS-M. The practical way of testing for SIBO or IMO is a breath test that detects levels of hydrogen, methane, and hydrogen sulfide. Identifying the presence of SIBO or IMO is very helpful for determining treatment options for IBS, but the road to symptom relief can still be quite difficult. There are two antibiotics that can be effective for the treatment of SIBO or IMO: xifaxan and nystatin. Sadly, the relapse rate is very high. Limited research indicates that herbal antimicrobials may work just as well (3). Probiotics can help, and three brands in particular have many supporting studies: VSL#3, LacClean, and Visbiome.

However, there should be caution since probiotics can also make symptoms worse.

Yet once again, what is the root cause? What caused the bacterial overgrowth in the first

place? There are multiple proposed etiologies including motility problems, overuse of proton pump inhibitors, and adhesions caused by abdominal surgeries. Addressing the root cause can help prevent relapse of symptoms.


The gut and brain are connected via the vagus nerve, part of the parasympathetic

nervous system, which plays a major role in controlling digestion. There is no doubt that stress can greatly affect IBS. For instance, nerves in the gut may be hyper-sensitive, registering more pain from bloating for someone with IBS than for someone without the condition. Stress-reducing approaches, such as yoga, have been studied extensively with good success in reducing IBS symptoms.


There are a multitude of approaches for treating IBS and each one claims to be “the

best.” However, the best approach for alleviating the symptoms of irritable bowel syndrome is to determine the root cause and that varies from person to person. Long-term symptom relief requires a lot of patience, but my hope is that it will not require more blood, sweat, and tears than is absolutely necessary. Medications might bring short-term relief, but their use should be evaluated critically with the knowledge that they could even make symptoms worse over time. Complementary approaches that address food, lifestyle, and stress are essential, and a registered dietitian is a valuable addition to the treatment team.

Schedule your appointment with Nathan today!

Call 501-225-5454


1. Takakura W andPimentel M (2020)Small Intestinal Bacterial Overgrowth And Irritable

BowelSyndrome–An Update.Front. Psychiatry 11:664.doi:

10.3389/fpsyt.2020.00664REVIEWpublished: 10 July 2020doi:


2. Small intestinal bacterial overgrowth is associated with Diarrhea-predominant irritable

bowel syndrome by increasing mainly Prevotella abundance.

3. Chedid V, Dhalla S, Clarke JO, Roland BC, Dunbar KB, Koh J, Justino E, Tomakin E,

Mullin GE. Herbal therapy is equivalent to rifaximin for the treatment of small intestinal

bacterial overgrowth. Glob Adv Health Med. 2014 May;3(3):16-24. doi:

10.7453/gahmj.2014.019. PMID: 24891990; PMCID: PMC4030608.

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