A Mediterranean Approach to Low FODMAP Diet (MED-LFD) for Managing IBS Symptoms

Irritable Bowel Syndrome (IBS) is a common functional bowel disorder characterized by absence of any organic cause. The vast majority of patients associate their symptoms with specific food consumption, creating the need for developing a new therapeutic approach based on altering the dietary habits. The aim of the study focuses in the comparison of the efficacy of two dietary patterns, the adjusted to the Mediterranean Diet Low FODMAP Diet (MED-LFD) and the nutritional guidelines of the British National Institute for Health and Care Excellence (NICE) Managing IBS.

Irritable Bowel Syndrome (IBS) is a functional bowel disorder. Patients associate their symptoms with specific foods consumption, creating the need for developing a new therapeutic approach based on altering the dietary intake of these patients. Low FODMAP Diet is often used as a first-line treatment based on observations showing that short-chain carbohydrates are not adequately absorbed in the small intestine and exacerbate the symptoms of IBS. Additionally, the Mediterranean diet is a cultural heritage representative of all the countries surrounded by the Mediterranean Sea, described as a diet rich in herbal foods (cereals, fruits, vegetables, legumes, nuts, olives), with olive oil as the main consumption of fats, high to moderate consumption of fish and seafood, moderate consumption of eggs, poultry, dairy products and alcohol and low consumption of red meat. On the other hand, the nutritional recommendations of British National Institute for Health and Care Excellence (NICE) managing IBS were created on the grounds of systematic reviews and are based on dietary and lifestyle modifications about caffeine, alcohol, fizzy drinks, fiber, resistant starch, fruits, sorbitol, oat and linseed consumption, meal patterns, probiotics and physical activity.

The direct aim of the study is to compare the efficacy of two dietary patterns, the MED-LFD and the nutritional recommendations of NICE managing IBS. Efficacy will be assessed based on the severity of symptoms. Additionally, possible improvements in quality of life and relief of symptoms between the two groups will be evaluated. Finally, the collected fecal samples will be used to assess the effect of each intervention on gut microbiota.

The sample was calculated to 108 participants with prespecified statistical power 80%, level of significance α=0.05 and 10% adjustment for non-compliance in each group to detect an increase in the primary outcome measure (standard deviation of outcome=60). The above hypothesis of the means was based in the meta-analysis of Peter Varju, et al. 2017. Patients will be recruited by the Department of Clinical Nutrition, Attikon University General Hospital, where the nutritional intervention will be carried out.

Eligibility Criteria:
Inclusion Criteria:

* Fulfillment of the Rome IV criteria for IBS (IBS-D, IBS-M, IBS-U)
* Provision of written informed consent.
* Commitment of availability throughout the study period.
* IBS-SSS \> 175

Exclusion Criteria:

* Any concomitant disease requiring specialized nutrition (e.g. renal failure, diabetes, celiac disease, cerebrovascular disease of the central nervous system, major surgical cavity).
* Pregnancy.
* Breastfeeding.
* IBS-C (Bristol Scale type 1 - 2)