ARTICLE

The Low-FODMAP Diet Done Right

The low-FODMAP diet is among the most commonly recommended treatments for irritable bowel syndrome. For most patients, the typical experience goes something like this: you leave your gastroenterologist appointment with a handout of high-FODMAP foods to avoid, to see whether cutting them improves your symptoms. Here is the problem. That is not actually how the diet is supposed to work.

The low-FODMAP diet was never intended to be a permanent list of foods to avoid forever. It is a structured, short-term protocol designed to identify your specific individual triggers, with the primary goal of broadening the diet as much as possible while minimizing IBS symptoms.

Here is what you need to know about the low-FODMAP diet to determine whether it is right for you.

1. What are FODMAPs?

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. In simple terms, FODMAPs are short-chain carbohydrates that are poorly absorbed in the small intestine. Because they are not fully absorbed, two things happen. They pull water into the intestine by osmosis, and gut bacteria ferment them and produce gas when they reach the colon. In someone with IBS, this can lead to gas, bloating, cramping, pain and changes in gut motility. Minimizing FODMAPs in the diet removes one of the most common triggers for IBS, but it is not a viable long-term strategy.

There are five main groups of FODMAPs to be aware of:

  1. Fructans - found in wheat, rye, onion and garlic.
  2. Galacto-oligosaccharides (GOS) - found in legumes, cabbage and nuts.
  3. Lactose - found in milk, yogurt, ice cream and soft cheeses.
  4. Fructose - found in apples, pears, mango, honey and high-fructose corn syrup.
  5. Polyols - found in peaches, mushrooms, cauliflower, and sugar-free gum and candy.

2. The three phases of the low-FODMAP diet

The low-FODMAP diet has three phases:

  • Phase 1: Elimination or restriction. During this phase, all high-FODMAP foods are eliminated from the diet. This phase should last approximately two to six weeks. The goal is to see whether symptoms improve with the elimination of FODMAPs.
  • Phase 2: Reintroduction. During the reintroduction phase, foods from each FODMAP group are reintroduced one by one. This helps identify the specific foods that trigger symptoms.
  • Phase 3: Personalization. Using the information on specific triggers identified in Phase 2, non-trigger foods are reintroduced into the diet and an individualized diet plan is created, with the goal of limiting symptoms while minimizing restriction.

The end result should be a diet as liberal and diverse as possible, with only known FODMAP triggers eliminated. Research suggests that most individuals will have only one to two FODMAP triggers.

3. Who should consider the low-FODMAP diet?

The low-FODMAP diet is the most evidence-based dietary therapy for IBS, but it is not for everyone. Approximately a quarter of people will not experience significant symptom improvement from the diet, suggesting that food is not a primary trigger for symptoms in these individuals. Research suggests the low-FODMAP diet is most successful at alleviating symptoms of pain, bloating and distension, and guidelines indicate it may be particularly helpful for the diarrhea-predominant (IBS-D) and mixed (IBS-M) subtypes.

Getting stuck in the elimination phase can be common, but long-term FODMAP elimination is not recommended. Long-term FODMAP restriction risks nutritional deficiencies, negative consequences for the gut microbiome, and the development of fear around eating. Guidelines now explicitly recommend screening for a history of disordered eating, due to the higher prevalence of avoidant and restrictive food intake behaviors among patients with gastrointestinal disease.

If you and your healthcare provider decide the low-FODMAP diet is worth trying for your IBS symptoms, guidelines recommend doing so under the guidance of an experienced GI dietitian. If not, remember that there are many other effective treatment options for IBS, both dietary and non-dietary, beyond the low-FODMAP diet.

This content is educational and is not a substitute for individual medical advice. Talk to your own healthcare team before making any changes to your treatment plan.

References

  1. Monash University. Low FODMAP Diet. monashfodmap.com.
  2. Black CJ, Staudacher HM, Ford AC. Efficacy of a low FODMAP diet in irritable bowel syndrome: systematic review and network meta-analysis. Gut. 2022;71(6):1117-1126. PMID: 34376515.
  3. van Lanen AS, de Bree A, Greyling A. Efficacy of a low-FODMAP diet in adult irritable bowel syndrome: a systematic review and meta-analysis. Eur J Nutr. 2021;60(6):3505-3522. PMID: 33585949.
  4. Van den Houte K, Colomier E, Routhiaux K, et al. Efficacy and findings of a blinded randomized reintroduction phase for the low FODMAP diet in irritable bowel syndrome. Gastroenterology. 2024;167(2):333-342. PMID: 38401741.
  5. Dean G, Chey SW, Singh P, Chey WD. A diet low in fermentable oligo-, di-, monosaccharides and polyols improves abdominal and overall symptoms in persons with all subtypes of irritable bowel syndrome. Neurogastroenterol Motil. 2024;36(8):e14845.
  6. Lacy BE, Pimentel M, Brenner DM, et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2021;116(1):17-44.
  7. AGA Clinical Practice Update on the Role of Diet in Irritable Bowel Syndrome: Expert Review. Gastroenterology. 2022;162(6):1737-1745. PMID: 35337654.