Modulation of gut microbiota through nutritional interventions in Behçet’s syndrome patients (the MAMBA study): study protocol for a randomized controlled trial

Background: Behçet's syndrome (BS) is a systemic inflammatory disorder of unknown etiology, characterized by a wide range of potential clinical manifestations. Recent evidences suggest that the gut microbiota (GM) in BS shows low biodiversity with a significant depletion in butyrate producers. The aim of the present project is to investigate whether a dietary intervention could ameliorate the clinical manifestations and modulate the GM of individuals with BS. Methods: This is a randomized, open, cross-over study involving 90 BS individuals who will be randomized to follow a 3-months dietary profile with either: lacto-ovo-vegetarian diet (VD), Mediterranean diet (MD) or Mediterranean diet supplemented with butyrate (MD-Bt). The VD will contain inulin and resistant starch-rich foods, eggs and dairy, in addition to plant-based food, but will not contain meat, poultry or fish. The MD will contain all food categories and will provide 2 portions per week of fish and 3 portions per week of fresh and processed meat. The MD-Bt will be similar to the MD but supplemented with 1.8 g/day of oral butyrate. The three different dietary patterns will be isocaloric and related to participants’ nutritional requirements. Anthropometric measurements, body composition, blood and fecal samples will be obtained from each participant at the beginning and at the end of each intervention phase. The primary outcomes will be represented by the change from baseline of the BS gastrointestinal and systemic symptoms. Changes from baseline of GM composition, SCFA production, inflammatory and antioxidant profile will be considered as secondary outcomes. Discussion: BS is a rare disease, and, actually, not all the available treatments are target therapies. A supportive treatment based on dietary and lifestyle issues, able to restore immune system homeostasis, could have a high impact on costs sustainability for the treatment of such a chronic and disabling inflammatory condition.