Here is the design of a clinical trial:

Official Title: Mediterranean Diet Adjusted to Low FODMAP Diet (MED-LFD) vs NICE Guidelines for Improving IBS Symptoms: a New Approach for Managing IBS

Included conditions:
- Irritable Bowel Syndrome With Diarrhea

Study Armgroups:
- {'label': 'Group A', 'type': 'ACTIVE_COMPARATOR', 'description': 'MED-LFD Diet (diet A) for 2 - 6 weeks. After this period there will be a reintroduction phase protocol that will last 6 - 8 weeks.', 'interventionNames': ['Other: Med-LFD']}
- {'label': 'Group B', 'type': 'ACTIVE_COMPARATOR', 'description': 'Diet according to guidelines from the National Institute for Health and Care Excellent (NICE) Managing IBS (diet B) for 4 weeks.', 'interventionNames': ['Other: Nutritional Guidelines of the British National Institute for Health and Care Excellence (NICE) Managing IBS']}

Interventions:
- {'type': 'OTHER', 'name': 'Med-LFD', 'description': 'All participants of this group at phase 1 (elimination phase), will initially follow the Med- LFD (2-6 weeks). At phase 2 (reintroduction phase), patients will gradually reintroduce foods rich in FODMAPs (6-8 weeks) and test their tolerance. At phase 3 (maintenance phase), following the reintroduction of foods rich in FODMAPs, patients will follow an individualized diet based on their personal tolerance (a combination of high and low FODMAPs).', 'armGroupLabels': ['Group A']}
- {'type': 'OTHER', 'name': 'Nutritional Guidelines of the British National Institute for Health and Care Excellence (NICE) Managing IBS', 'description': 'All participants of this group will be informed to follow a diet based on the nutritional guidelines of the British National Institute for Health and Care Excellence (NICE) for Managing IBS for 4 weeks.', 'armGroupLabels': ['Group B']}

Primary Outcomes:
- {'measure': 'Change of symptoms severity pre and post intervention using a specialized questionnaire.', 'description': 'IBS- SSS contains 5 specific questions with instructions on how to score them. Each of the five questions (pain severity, pain frequency, abdominal distension severity, bowel movement satisfaction, quality of life) ranges from 0 to a maximum score of 100 using a visual analog scale (VAS) with total scores ranging from 0 to 500, with higher scores indicating more severe symptoms. Subjects can be categorized as having mild (75-175), moderate (175-300), or severe (\\>300) IBS. A decrease of 50 points is associated with a clinically meaningful improvement.', 'timeFrame': 'Baseline, 4 - 8 weeks and 6 months post intervention'}

Please estimate the sample size based on the assumption: 
Statistical power of 80%, significance level α = 0.05, and 10% adjustment for non-adherence.
2.11.1. Sample Size Calculation
          The sample size was calculated at 108 participants (54 per group) with expected values taken from the meta-analysis of Varju et al. [38] and a pre-specified statistical power of 80%, significance level Î± = 0.05, and 10% adjustment for non-adherence to detect a significant improvement in the primary outcome measure 100 vs. 59 points (estimated standard deviation = 60) in the MED-LFD and NICE groups, respectively.