There is very little evidence to show that a diet often followed by people with irritable bowel syndrome (IBS) actually works, a study has found.
IBS is a common, long-term condition that causes stomach cramps, bloating, diarrhoea and/or constipation and is thought to affect up to one in five people at some point in their life. Around twice as many women are affected as men.
Sufferers are usually advised to adjust their fibre intake, to have regular meals and to limit fresh fruit to three portions a day among other measures.
Many people also follow the low FODMAP diet, which was developed in Australia, and is based on the observation that many short-chain carbohydrates are poorly absorbed in the small intestine and have been identified by patients as exacerbating IBS symptoms.
Examples of short-chain carbohydrates include apples, pears, artichoke, asparagus, chickpeas and lentils.
An article in the Drug and Therapeutics Bulletin (DTB), which describes itself as the independent review of medical treatment, said the aim of the diet is not to exclude the particular foods altogether, but to adjust consumption to a level that controls symptoms.
But it said recent reviews of studies carried out into its effects have not found that it improved some symptoms, but not others.
The piece also suggested that people on it could be suffering from nutritional deficiencies due to cutting certain foods out.
“Evidence for the efficacy of the low FODMAP diet to improve symptoms of irritable bowel syndrome (IBS) is based on a few relatively small, short-term unblinded or single-blinded controlled trials of varying duration,” it concluded.
“All the trials provide some evidence of efficacy in terms of improved symptom score with few reports of adverse events. One study has shown that a low FODMAP diet can have an impact on gut microbiota, although the clinical implications of this are unclear. The long-term effect of this type of dietary manipulation is unknown.
“Some guidelines suggest that a low FODMAP diet may be appropriate for motivated patients for whom other therapies have not offered sufficient symptomatic relief; and that advice on a low FODMAP diet should be provided by a dietitian with specialist knowledge of this type of intervention.
“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.”