IBS AND FOOD INTOLERANCE
Irritable bowel syndrome (IBS) is a common and frequently debilitating functional gut disorder. Food-induced symptoms occur in about two-thirds of IBS patients (1). Poorly absorbed carbohydrates have been reported as the most common group of food triggers. Symptom severity correlates with the number of food intolerances (2). The majority of IBS patients are interested in holistic approaches to treatment such as nutritional interventions, probiotic supplements, and hypnotherapy (3). The low fermentable oligo-saccharides, di-saccharides, monosaccharides, and polyols (FODMAP) diet is a novel three-phase nutritional approach shown to be effective in managing symptoms in 50–70% of IBS patients (4,5). FODMAPs are consumed in the Western diet via a number of grains, fruits, vegetables, milk, and sugar-free additives (Table 1). Small-chain FODMAP carbohydrates are commonly malabsorbed resulting in high osmotic activity and rapid fermentation by colonic microbes, contributing to symptom exacerbation in IBS. In this article, I summarize some key considerations when utilizing the low FODMAP diet for gastroenterologists and their IBS patients.
THE FODMAP ELEVATOR PITCH
Educating patients on this nuanced diet with an awkward acronym name can be a task in and of itself. Here is a 30-s FODMAP diet elevator pitch:
FODMAPs are small sugars and fibers found in many everyday foods such as onion, garlic, wheat, watermelon, apples, and milk, to name a few. FODMAP carbohydrates are poorly digested, pull water into the intestines and are rapidly fermented by our gut microbes resulting in gas. Innately, FODMAPs are found in many healthy foods and do not bother most people. In individuals with a sensitive gut, however, FODMAPs can trigger digestive distress. Eating FODMAPs does not cause IBS but the low FODMAP diet can be a solution to managing IBS symptoms.
HOW TO APPLY THE LOW FODMAP DIET
The low FODMAP diet is a learning diet. The end goal of this nutritional approach is to consume as liberal a diet as possible to meet nutrient needs, maintain quality of life, and adequately manage digestive symptoms. The low FODMAP elimination diet is the beginning not the end of this diet therapy. There are three discrete phases: elimination, reintroduction, and personalization (Fig. 1). During the elimination phase, all high FODMAP foods are removed from the diet to determine if FODMAP sensitivities play a role in symptom exacerbation. In the second phase, the reintroduction phase, FODMAPs are systematically added back to the diet via each FODMAP subtype (lactose, excess fructose, etc.), to identify FODMAP triggers. The third phase is the personalization phase during which tolerated FODMAP-containing foods are gently added back into the diet.
Teaching the low FODMAP diet should involve more than providing lists of high and low FODMAP foods. From clinical experience, patients benefit from understanding the basic pathomechanism of FODMAPs in the gut, individualized menu and grocery shopping tips, food label reading guidelines and an overview of the three phases of the diet.
BENEFITS OF WORKING WITH A GI DIETITIAN
The low FODMAP diet is not particularly intuitive and is best guided by a dietitian with GI expertise. GI dietitians provide personalized nutritional interventions that incorporate the patient’s clinical data, nutritional intake, socio-economic status, and lifestyle to create a feasible and nutritionally balanced plan. As self-guided elimination diets can place patients at nutritional risk, referring patients for expert application of the diet is recommended.
Often touted as a highly restrictive diet, a dietitian-guided low FODMAP diet is not complicated for the patient. One study showed that 60% of patients found that when guided by a dietitian, the low FODMAP diet was easy to follow, 65% could easily find suitable products to eat and 43% were able to incorporate the diet easily into their life (6).
Food-related fears are exhibited in the IBS population; a GI dietitian can help patients sort through the hype versus science in effort to maximize nutritional intake and enhance food-related quality of life.
SELECTING THE RIGHT PATIENT FOR THE LOW FODMAP DIET
There are a number of factors that should be considered prior to recommending the low FODMAP diet to your IBS patients (Table 2). Although shared-decision models have shown patients are interested in nutritional approaches to symptom reduction in IBS, not all patients favor dietary interventions or some may not be appropriate for this approach (3).
Individuals with co-morbid conditions such as eating disorders or malnutrition are not suitable candidates for an elimination diet, as dietary restrictions could trigger weight loss or prompt maladaptive eating. The term “nutrachondria” has hit the mainstream media describing self-diagnosis of food intolerance based on inaccurate scientific evidence revealing a need for health practitioners to probe further about diet and rationale for any food restrictions. Avoidant Restrictive Food Intake Disorder (ARFID) is a new diagnosis in the DSM-5. ARFID can result in insufficient caloric and nutrient intake due to concern about problematic symptoms as a consequence of eating. In patients with severe GI symptoms, ARFID should be evaluated and addressed with psychological and nutritional interventions.
To assess whether diet is a potential trigger, simply ask your IBS patient if eating exacerbates GI distress. Most IBS patients experience food-related symptoms, but for those who do not, consider another treatment modality. A review of a patient’s typical eating pattern can help identify if FODMAP-containing foods are present. Certainly, if FODMAPs are not found in the diet, than it is unlikely that FODMAPs are playing a role in GI symptom induction. For those interested in trying the low FODMAP diet, it is best to perform a celiac serology test prior to the advent of the low FODMAP diet as testing post-diet initiation may result in inaccurate testing. The low FODMAP diet is not gluten free but does reduce gluten-containing foods.
WHAT THE LOW FODMAP DIET IS NOT: BUSTING THE MYTHS
There are many common misconceptions about the low FODMAP diet. The low FODMAP diet is not gluten, dairy, or wheat free. Low lactose dairy such as hard and semi-soft cheeses, butter, lactose-free milk, lactose-free yogurt, and lactose-free cottage cheese are suitable on the diet. These dairy foods can easily meet daily calcium needs. The low FODMAP does reduce the protein, gluten—as it minimizes wheat, barley, and rye (gluten sources), however, small amounts of wheat in traditional soy sauce or in a handful (portion size matters) of many wheat-based crackers or pretzels are typically low in FODMAP carbohydrates.
Additionally, the low FODMAP diet is not innately a low fiber or low carbohydrate diet. To support gut health, low FODMAP fiber-rich options include oats, oat bran, strawberries, kiwifruit, baked potato with skin, strawberries, blueberries, quinoa, buckwheat, chia, and hemp seeds. To provide adequate carbohydrate for energy needs, rice, gluten-free pasta, baked potato, suitable low FODMAP fruit, and most gluten-free grains work well for low FODMAP diet followers.
CONFLICTS OF INTEREST
Guarantor of the article: Kate Scarlata, RDN.
Specific author contributions: Kate Scarlata wrote the article.
Financial support: None.
Potential competing interests: KS has a consulting relationship with FODY Foods, a low FODMAP food company.
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