Here is the design of a clinical trial:

Official Title: ModulAtion of Gut Microbiota Through Nutritional Interventions in Behcet's Syndrome pAtients: the MAMBA Study

Included conditions:
- Behcet Syndrome

Study Armgroups:
- {'label': 'VD group', 'type': 'EXPERIMENTAL', 'description': 'Group that starts with Vegetarian diet (VD)', 'interventionNames': ['Behavioral: Vegetarian diet', 'Behavioral: Mediterranean diet with butyrate', 'Behavioral: Mediterranean diet']}
- {'label': 'MD+Bt group', 'type': 'EXPERIMENTAL', 'description': 'Group that starts with Mediterranean diet with oral supplementation with butyrate (MD+Bt)', 'interventionNames': ['Behavioral: Vegetarian diet', 'Behavioral: Mediterranean diet with butyrate', 'Behavioral: Mediterranean diet']}
- {'label': 'MD group', 'type': 'ACTIVE_COMPARATOR', 'description': 'Group that starts with Mediterranean diet (MD)', 'interventionNames': ['Behavioral: Vegetarian diet', 'Behavioral: Mediterranean diet with butyrate', 'Behavioral: Mediterranean diet']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Vegetarian diet', 'description': '7-days dietary profile with a Vegetarian diet (VD), containing inulin and resistant starch-rich foods and including no meat and fish, but containing eggs and dairy, for 3 months', 'armGroupLabels': ['MD group', 'MD+Bt group', 'VD group'], 'otherNames': ['VD']}
- {'type': 'BEHAVIORAL', 'name': 'Mediterranean diet with butyrate', 'description': '7-days dietary profile with Mediterranean diet with oral supplementation with butyrate (MD+Bt), 2 g/day, for 3 months', 'armGroupLabels': ['MD group', 'MD+Bt group', 'VD group'], 'otherNames': ['MD+Bt']}
- {'type': 'BEHAVIORAL', 'name': 'Mediterranean diet', 'description': '7-days dietary profile with Mediterranean diet (MD), including 2 portions per week of fish and 3 portions per week of fresh and processed meat (2 of which fresh or processed red meat), for 3 months', 'armGroupLabels': ['MD group', 'MD+Bt group', 'VD group'], 'otherNames': ['MD']}

Primary Outcomes:
- {'measure': 'Disease severity of Behcet syndrome assessed by Behçet Disease Current Activity Form', 'description': 'The disease activity will be assessed by the use of the validated Behçet Disease Current Activity Form (BCDAF), at the baseline and after the dietary intervention. The BCDAF will assess the presence of oral and genital ulceration, skin, joint and gastrointestinal involvement, presence of fatigue and headache with a 5-point scale according to the duration of symptoms, with 0 meaning no symptoms and 4 meaning symptoms for 4 weeks. The presence of eyes, large vessels or central nervous system (CNS) involvement are document with "yes/no" answers. In addition, patients will be asked to rate on a 7-point scale how active they felt. Similarly, the clinicians will complete a 7-rating scale to assess their opinion of overall activity of the disease, with lower scores representing better outcomes.', 'timeFrame': '1 year'}
- {'measure': "Behcet disease's improvement of symptoms assessed by the Global Assessment of Improvement Scale (GAI) modified form", 'description': 'The Global Assessment of Improvement Scale (GAI) modified form will assess Behcet disease\'s improvement of symptoms using a 7-point scale, with higher scores meaning an improvement of the symptoms. The severity of abdominal pain, severity of abdominal distention, satisfaction with bowel habits, severity of headache, severity of exhaustion, severity of nausea, attention disorder, muscle/joint pain, and quality of life will be investigated in response to the following question: "Compared to the way you felt before you entered the study, have your symptoms over the past 7 days been: 1) "Substantially Worse", 2) "Moderately Worse, 3) "Slightly Worse", 4) "No Change", 5) "Slightly Improved", 6) "Moderately Improved" or 7) "Substantially Improved".', 'timeFrame': '1 year'}
- {'measure': "Behcet disease's severity of gastrointestinal symptoms assessed by the Symptom Severity Scale (SSS) modified form", 'description': "The Symptom Severity Scale (SSS) modified form is a multidimensional rating scale assessing overall symptoms' severity on a Visual Analogue Scale (VAS). An overall score will be calculated from six items: pain severity, pain frequency, abdominal bloating, bowel habit dissatisfaction, abdominal heaviness, and life interference. The modified SSS ranges from 0 to 600, with higher scores meaning more severe symptoms.", 'timeFrame': '1 year'}

Please estimate the sample size based on the assumption: 
power of 80% (beta), significance level (alpha) of 0.05, and allowance for non-compliance and loss to follow-up
Sample size calculation
        Due to the lack of dietary intervention trials on BS and to the fact that gastrointestinal symptoms are quite similar in BS and inflammatory bowel disease, based on a previously published trial [24], a sample size of 80 individuals with BS is required to achieve power of 80% (beta) with alphaâ=â0.05, to detect a 50-point difference in the mean of SSS (the primary outcome), between VD and MD interventions. We will recruit an extra 10 volunteers (for a total of 90), as we assume that not all individuals would be compliant with the treatments and in case of loss to follow up. Losses will be included in the intention-to-treat but not in the per-protocol analyses.