Evidence-based Dietary Management of Functional Gastrointestinal Symptoms: The FODMAP Approach

Peter R Gibson; Susan J Shepherd


J Gastroenterol Hepatol. 2010;25(2):252-258. 

In This Article

The Low FODMAP Dietary Strategy

The pre-dietary workup is important and is outlined in Figure 1. Breath hydrogen testing, to define who can completely absorb a load of fructose and/or lactose is very useful as it can reduce the breadth of dietary restriction that is necessary. It is not strictly necessary—the fully restricted diet can be initiated—but altering diet carries the risk of nutritional compromise and it is a good principle not to restrict foods if not necessary.

The low FODMAP diet has only been evaluated as a dietitian-delivered diet.[39,42] This has mostly been achieved in a one-to-one setting, but group education sessions have also been used with apparent success. The ability of written literature only to achieve efficacy has not been studied and clinicians should be cautious in undertaking such an approach. Patients often only select the parts of any diet that appeal to them and ignore the rest. This defeats the goals the diet is designed to achieve.

The strategy used at the first consultation is as follows:

  • Define qualitatively the typical eating practices and style of the patient. It is important to understand the likely FODMAPs to which the patient has daily exposure. Pre-completed food recording diaries and direct questioning of the patient during the consultation can be useful methods to obtain such information. This enables individualized dietary advice to be given. For example, if a patient already omits lactose-containing foods from their diet, then this potential FODMAP would not be contributing to ongoing symptoms.

  • The physiological framework for the dietary approach (i.e. the scientific basis of FODMAPs and their malabsorption and subsequent fermentation) is explained to the patient. This is pertinent as it provides the basis for a better understanding of food choice and may increase the likelihood of durable adherence (although this has not been evaluated).

  • Specific dietary instructions are given to the patient:

    • Avoid foods that contain significant free fructose in excess of glucose, unless complete fructose absorption was demonstrated on breath hydrogen testing;

    • Encourage choice of foods where fructose and glucose are 'in balance', or where glucose is in excess of fructose;

    • Co-ingestion of free glucose to 'balance' excess free fructose problematic foods.

    • Limitation of dietary fructose load (in the form of free fructose or sucrose) at any one meal; and

    • Avoidance of foods that are a substantial source of fructans and galactans.

    • Restrict lactose-containing foods, if lactose malabsorption was demonstrated on breath hydrogen or lactose tolerance testing.

    • Avoidance of polyols in, for example, stone fruits and mushrooms.

  • Literature providing food lists and reinforcing instructions are provided.

  • Patients are provided with positive food messages emphasizing suitable food alternatives. To assist in this, verbal descriptions or visual props using packages of commercially available food alternatives are provided, together with suggestions for their use or application, and information regarding retail outlets likely to stock such foods. Several suggestions are provided to cater for a wide spectrum of food preferences, and also to optimize variety, and nutritional adequacy in the diet. A sample meal plan encompassing the dietary principles is also provided.

  • Techniques for handling situations where control of food preparation is limited, such as eating away from home (such as restaurants, school camps and eating at friend's homes) are discussed.

As it is the total dose that will dictate the contribution to symptoms, the accumulated intake of FODMAPs over several days is critical in defining how strict an individual needs to be. In order to ensure symptoms are well-controlled, a strict trial of the low FODMAP diet is warranted for the first 6–8 weeks. On the dietetic review, assessment of symptom response will lead to discussions of individual tolerance, keeping the total FODMAP load in mind. In practice, many patients will manage, for example, occasional ingestion of wheat or rye breads, garlic as a minor ingredient and small serves of broccoli or cauliflower. Testing of tolerance is a vital stage of the dietetic process to ensure maximum variety in the diet.

If the symptomatic response is inadequate, specific questioning is required to determine the adherence to the dietary principles and any deficiencies corrected. If adherence was strict, attention may be needed to modify intake of resistant starch and insoluble and soluble fiber. Other dietary triggers such as food chemicals may need to be considered, as should potential factors such as caffeine, fat, meal size and regularity.


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