Diagnosis and management of FODMAP intolerance

The best way to determine if FODMAP intolerance is present is to trial an exclusion diet in which the intake of foods rich in FODMAPs is reduced for 4 to 8 weeks. Exclusion of FODMAP-rich foods as a group initially is more effective than excluding foods in isolation. For information about the principles of exclusion diets, see here.

Symptom improvement should be evident after 4 weeks. After initial response, FODMAPs should be systematically re-introduced into the diet to identify food triggers and avoid over-restriction. If no improvement is identified, the low-FODMAP diet should be stopped and an alternative cause of symptoms should be sought. FODMAPs are substrates for bacterial metabolism in the gut, and the impact of a low-FODMAP diet on the gut microbiota is yet to be established. Long-term use of a low-FODMAP diet cannot be recommended—the patient should be maintained on the least restrictive diet required to control symptoms.

Although hydrogen breath tests can diagnose fructose malabsorption, there is limited evidence that they aid diagnosis or guide management. More reliable information can be gained from clinical history and dietary manipulation.

More information about low-FODMAP diets is available from the Monash University website and the Gastroenterological Society of Australia website.