Nutrition in IBS should be individualised

The low FODMAP diet (fermentable oligo-, di-, and monosaccharides and polyols) has been shown to improve symptom management and quality of life in a number of patients with IBS.

But is this type of elimination diet suitable for everyone?


There is a small percentage of patients where eating disorder may be present and this can be associated with functional gut symptoms. There is also emerging research on the comorbidity of functional gut disorders and eating disorders.

Kate Scarlata, along with other authors have written from the dietitian’s perspective about how the Low FODMAP Diet (LFD) may not be suitable for some patients who are at risk for maladaptive eating, eating disorders or with mental health conditions.

The article encourages screening of individuals for eating disorder risk before prescribing an elimination diet, making nutritional approaches for IBS individualised.

Avoidant or restrictive food intake disorder (AFRID)

Avoidant or restrictive food intake disorder is a “diagnosis of eating or feeding disturbance due to lack of interest in eating, avoidance of sensory characteristics of food, or fear of adverse eating consequences (ie. digestive distress)” and was introduced in the DSM-5. (The DSM-5 is a revised Diagnostic and Statistical Manual of Mental Disorders handbook used by health care professionals as a guide to mental disorders assessment and diagnosis).

Feeding disorders like ARFID differs to other eating disorders and the research indicates that patients with IBS are meeting the criteria for ARFID. Prescribing of the LFD in this population needs to be carefully considered along with appropriate screening. Validated screening tools for ARFID in the IBS population need to be developed and with more research in this area is required. Registered dietitians and mental health providers with expertise in this area need to co-ordinate care to reduce risk to nutrient intake and mental health. More about this in our last article here.

Whether a LFD diet is prescribed or not, the overall recommendation is to reduce diet-related anxiety, stabilise or improve nutritional status, and enhance food-related quality of life, all while offering symptom benefit.

The FODMAP-gentle approach

If maladaptive eating is present and a full LFD is not indicated, a FODMAP-gentle approach may be considered. This allows for more flexibility with a reduction a few foods that are highly concentrated in FODMAPs from a patient’s diet.

Reference is made to the review paper by Emma Halmos & Peter Gibson in 2019, where the possible contraindications for diet therapy in IBS populations are discussed.  They describe the basis of a FODMAP-gentle diet, including the main high FODMAP foods to restrict.

A “top-down” approach has been described as a strategy for IBS diet treatment and includes a structured protocol of three phases, namely FODMAP restriction, reintroduction and personalisation involving a long-term plan of dietary manipulation. On the other hand, the FODMAP-gentle approach is a “bottom-up” method where there is mild FODMAP restriction, with a reduction of a few foods very high in FODMAPs and/or a reduction of a few targeted FODMAPs.

Thereafter there will be further restrictions only if required. The authors explain that the traditional published FODMAP protocol should be utilised in the majority of IBS sufferers unless there is indication to use the FODMAP-gentle approach. They note that with the FODMAP-gentle method, there may not be clarity of response which may be due to insufficient FODMAP restriction rather than wrong therapy.

Recognising the patients at risk.

Scarlata et al goes on to describe how to assess good candidates for the LFD diet. Factors to consider include diagnosis; diet and lifestyle history; and behavioural history.

An example of a poor candidate for a LFD would include a patient with current maladaptive eating avoidance. In order to evaluate for maladaptive food avoidance in IBS there are certain key factors that can be considered. These include the following: 

  • Body weight
  • Energy and nutrient intake  
  • Eating behaviours
  • Psychological distress
  • Patient beliefs/attitudes.

These factors can also be used for monitoring a patient during an elimination diet.

Take home messages:

  • Assess emotional and physical health to best select for LFD candidates.
  • Involve an experienced gastro-intestinal dietitian to assist in evaluating whether a patient is a good candidate for the LFD.
  • Encourage first line dietary advice for IBS as a starting point.
  • Refer on to a dietitian or behavioural health specialist with eating disorder expertise for supportive nutrition and psychological care if eating disorders or maladaptive eating are present.

Here is the article.