Low FODMAP diet

History:

In 2004 the research team at Monash University created the Low FODMAP diet.1 Dietary FODMAPs are short-chain carbohydrates that are poorly absorbed in the small intestine and therefore are passed into the colon, digested by bacteria. When bacteria digest these carbohydrates they produce gases and metabolites, which can cause luminal distention, contributing to excess bloating, flatulence, cramping, and diarrhea (1-2). FODMAP represents Fermentable Oligo-, Di-, and Mono-saccharides And Polyols. Many common foods are high in FODMAPs such as apples, watermelon, onion, garlic, high fructose corn syrup, dairy products, and wheat, rye, and barley-based products. There are two mechanisms behind why FODMAPs cause gut symptoms. First, FODMAPs are highly osmotic, drawing excess fluid into the lumen of the intestine leading to symptoms of bloating and diarrhea. Second, colonic bacteria rapidly ferment any unabsorbed FODMAPs, inducing gas production. These mechanisms occur in all people, however, do not cause gastrointestinal symptoms in healthy adults. The difference is that people with IBS can have problems with motility or a highly sensitive gut wall known as colonic hypersensitivity, which exacerbate symptoms. The extra water and gas cause luminal distention, contributing to the excess bloating, flatulence, cramping, and diarrhea seen in IBS.

Purpose:

FODMAPs are small and osmotically active, which increases the liquidity of luminal contents. Luminal distension not only induces the symptoms of pain and the sensation of bloating but may also lead to motility changes. Reducing the consumption of dietary factors that can distend the intestine would hypothetically lead to improvements in global symptoms. Thus, research supports the role of a low FODMAP diet as a treatment to manage global symptoms and improve the quality of life in IBS patients.

General dietary practices:

This dietary approach is a three-step process (3):

  • Step 1: The first step is for patients to follow a low FODMAP diet for two-six weeks. During this time patients will be replacing high FODMAP foods for low FODMAP alternatives, intending to induce symptom control. If symptoms improve during this period, the next step is to reintroduce FODMAPs. 

  • Step 2: As the low FODMAP diet is continued, a gradual stepwise reintroduction of small amounts of individual high FODMAP foods are used to assess tolerance. Each FODMAP group is challenged separately by introducing one food daily for three days to identify which FODMAPs are tolerable and which trigger symptoms. This process is done over eight to twelve weeks, the goal is to determine appropriate tolerance amounts so that some FODMAP foods can be consumed in the diet long term. 

Step 3: After this, the well-tolerated FODMAPs are included in the diet, while poorly tolerated FODMAPs are restricted, but only to a level that provides adequate symptom relief. This method establishes a personalized FODMAP diet for each patient that is minimally restrictive. Since every individual has a different tolerance towards food, the FODMAP diet will differ from patient to patient with IBS.

Alternative: Because the aforementioned method relies on trial-and-error, it can be frustrating for patients to get started. At our facilities, we can empirically test what FODMAPs you are intolerant to using hydrogen breath tests. This can streamline the process of getting started on a low FODMAP diet. More information on hydrogen breath tests here.

Key concerns:

The long-term health effects of a low FODMAP diet are not known. There is thought to be a potential risk of inadequate nutrient intake from such a restrictive diet and potentially unfavorable effects from altered gut microbiota (4). Likewise, as a restrictive diet the low FODMAP diet may foster disordered eating. Further studies of longer duration and adequate sample sizes need to understand any potential adverse effects of long-term restriction of FODMAPs. Moreover, there are no clear cutoff levels for FODMAP content and food labels lack information on these foods. It is important to note that a low FODMAP diet does not alleviate GI symptoms for every IBS subject.

Further Resources:

Apps: Monash University FODMAP Diet

Websites: 

**The information presented provides an overview of the diet along with credible resources to refer to in order to learn more. This is not intended to make any dietary recommendations, rather an education tool for our clients.**

Reference:

  1. Low-FODMAP diet. En.wikipedia.org. https://en.wikipedia.org/wiki/Low-FODMAP_diet. Published 2020. Accessed July 26, 2020.

  2. King K. What Is the Low FODMAP Diet. Eatright.org. https://www.eatright.org/health/allergies-and-intolerances/food-intolerances-and-sensitivities/what-is-the-low-fodmap-diet. Published 2020. Accessed July 26, 2020.

  3. The 3 steps of the FODMAP diet. Monashfodmap.com. https://www.monashfodmap.com/blog/3-phases-low-fodmap-diet/. Published 2018. Accessed July 26, 2020.

  4. Hill P, Muir JG, Gibson PR. Controversies and Recent Developments of the Low-FODMAP Diet. Gastroenterol Hepatol (N Y). 2017;13(1):36-45.