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The IBS and FODMAP Diet Connection

Irritable Bowel Syndrome and The Low FODMAP Diet

by LuAnn Scarton, RDN/LDN 

Should I try a Low FODMAP diet to relieve my IBS symptomsMaybe. In their 2020 Clinical Guidelines for the Management of IBS (Irritable Bowel Syndrome), the American College of Gastroenterology recommended a limited trial in patients with IBS to improve symptoms & with proper counseling with a properly trained Dietitian (1). Frequently, I see patients who have either decided to undergo a Low FODMAP diet on their own or have been told by their doctor to trial the diet. They may not have a proper understanding the real purpose of the diet & how to properly follow it.  Everyone has unique diet needs & this diet is far from a one-size-fits-all plan.  A trained Registered Dietitian Nutritionist can assess if you are a candidate for trialing the diet and if adherence to the diet makes sense with your lifestyle your individualized nutritional needs on the diet, assistance with meal planning, recipes, & more. fodmap nutrition ibs approach - new directions

What is the Low FODMAP diet?  The Low FODMAP diet originated in the early 2000s in Australia by a research team that determined certain components of foods contributed to IBS symptoms, such as bloating, abdominal pain or distension, flatulence, constipation & diarrhea.   FODMAP is an acronym that describes the types of carbohydrates found in food that may be poorly absorbed in the intestinal tract.  These carbohydrates eventually make their way into the large intestines where they are rapidly fermented, but poorly absorbed.  The process of fermentation leads to production of gases including hydrogen, methane, & carbon dioxide, causing expansion of the intestines and symptoms for sensitive IBS sufferers.

While it is often referred to as a “diet”, I prefer to think of it as a short-term “plan” that does the necessary detective work to identify food triggers.  A properly implemented Low FODMAP diet can provide significant relief of IBS symptoms in the proper candidate. This plan provides a very systematic approach to identifying problematic foods & building a customized long-term plan.

What does FODMAP mean?   FODMAP stands for Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, And, Polyols. FODMAP categories are determined based on their own chemical makeup. Examples of foods that contain each of the following type of FODMAP include: Oligosaccharides (Fructans & GOS) found in beans, wheat, rye, garlic, & onions.

  • Disaccharides (Lactose) found in milk, yogurt, &certain cheeses.
  • Monosaccharides (Fructose) found in high fructose corn syrup, asparagus, &honey.
  • Polyols (Mannitol & Sorbitol) found in cauliflower, cabbage, & avocado.

How do I know if the Low FODMAP diet is a good idea for me? First things first.  Starting a low FODMAP diet should be discussed with your physician, gastroenterologist &/or a qualified RDN.   If this diet is recommended for your unique needs, a RDN can help you with how to implement the plan so that it will be nutritionally adequate.

If you have a history of “disordered eating”, implementing this type of rigidity in an eating plan will likely do more harm than good. Making these types of changes can be time consuming initially as you are learning new foods to shop & prepare. Ideally, you should not consider trialing this plan if you do not have adequate time or the ability to commit to full compliance. Overall, purchasing different foods, often specialty items, may be more expensive during the initial phase of the diet.

The plan will only be effective in relieving symptoms if it is properly implemented & followed. The Low FODMAP diet is triphasic: Phase 1: Elimination Phase (2-6 weeks), Phase 2: Reintroduction Phase (8-12 weeks), & Phase 3: Modified/Adapted Phase.

Are FODMAP’s bad for you?  This is the puzzling part of a Low FODMAP diet. FODMAP containing foods are generally healthy, nutrient rich carbohydrates, so it doesn’t make sense that these foods could be “harmful” foods. However, due to the nature of IBS & sensitivity of the gut lining, the body is not able to deal with the effects of these fermented carbohydrates. Identifying which specific FODMAPs are problematic reduces long term elimination of all the foods & allows for a more balanced diet.

Generally, I find that most patients tend to react to similar foods in a specific FODMAP category, but able to tolerate others.  For example, someone may be sensitive only to Oligosaccharides & not Polyols.  RDNs will be able to identify which nutrient shortcomings may be of concern for long-term elimination & guide you towards a more nutritionally adequate diet that is also gut friendly.

What are the pitfalls of a Low FODMAP diet?  Since many Gluten-Free foods, but not all, are low FODMAP, many fall into a strictly gluten free diet, which is not always necessary, especially if fructans are tolerated during the re-challenge stage.  Purchasing convenience foods that are low FODMAP can contribute to more of a “junk food” diet & less of a “balanced” diet.

Is a Low FODMAP diet helpful for Ulcerative Colitis & Crohn’s Disease?  Due to the nature of generalized gastrointestinal symptoms patients experience, even those in remission, a low FODMAP diet is a consideration.  There is some evidence that a trial that a low FODMAP diet may provide greater management of symptoms of Inflammatory Bowel Disease.

What would a sample menu on a Low FODMAP diet look like?


Sautéed peppers & Scrambled eggs, Gluten free toast with margarine, banana


Broiled salmon on arugula greens with lemon vinaigrette, Clementine


Rice cake with peanut butter, Almond Milk


Roasted Rosemary Chicken , Baked Potato with margarine, Steamed Carrots

 If your physician has recommended you try the Low FODMAP diet or are wondering if you are a candidate for trialing this diet, schedule an individualized Nutrition Assessment & Counseling session with our registered dietitians at 724-934-3905.

1) Lacy, Brian E. PhD, MD, FACG1; Pimentel, Mark MD, FACG2; Brenner, Darren M. MD, FACG3; Chey, William D. MD, FACG4; Keefer, Laurie A. PhD5; Long, Millie D. MDMPH, FACG (GRADE Methodologist)6; Moshiree, Baha MD, MSc, FACG7 ACG Clinical Guideline: Management of Irritable Bowel Syndrome, The American Journal of Gastroenterology: January 2021 – Volume 116 – Issue 1 – p 17-44