Clinical Trials of FODMAP Diet Question Effectiveness

The low-FODMAP diet was developed in Australia by Monash University for those suffering from medically-diagnosed Irritable Bowel Syndrome (IBS) and Functional Gastro-Intestinal Disorder (FGID). While it is increasingly being prescribed by dieticians and GPs as lifestyle treatment for these conditions, a review of the available data has been published in Drug and Therapeutics Bulletin (dtb) showing very little evidence that the diet’s recommendation of avoiding dietary carbohydrate does actually control symptoms.
Take that statement with a grain of salt though.
The study was referring to evidence presented in clinical trials. One study conducted on the UK FODMAP guidelines indicates that the diet changes the profile of the bacteria in the gut, although what the clinical implications of this are, or, indeed, what the long term effects might be, are unclear, says dtb.
But data to back the use of a low FODMAP diet as an effective treatment to control symptoms "is based on a few relatively small, short term unblinded or single blinded controlled trials of varying duration," it cautions.
IBS is characterised by abdominal pain/discomfort and altered bowel frequency in the absence of any obvious gut abnormalities. Symptoms can include abdominal bloating, which eating can worsen.
Up to one in five of the population is thought to be affected, with women twice as likely to develop IBS symptoms as men.
The diet recommends the consumption of foods low in FODMAPs, or Fermentable Oligo-saccharides, Disaccharides, Mono-saccharides (And) Polyols. Patients first start with an elimination diet and slowly introduce foods in singular category under the supervision of a dietician or GP to identify ‘problem’ foods.
The low FODMAP diet, is based on the observation that certain types of short chain carbs are poorly absorbed by the small intestine and that IBS symptoms worsen when these are eaten. These short chain carbs are present in wheat, onions, and legumes; milk; honey, apples, and high fructose corn syrup; and the artificial sweeteners used in confectionery (sorbitol and mannitol). They are rapidly fermented in the gut, increasing water volume and gases.
Like all medical diets, it does require the patient to stick to the guidelines to actually see results. The report’s authors noted the diet may be appropriate for ‘motivated patients for whom other treatments have failed to relieve symptoms, this should only be done under the supervision of a dietitian with specialist expertise in this type of dietary intervention.’
And it concludes: "However, we believe that patients should be advised that there is very limited evidence for its use, the ideal duration of treatment has not been assessed in a clinical trial, and its place in the management of IBS has not been fully established."