Is it time to rethink the burden of non-coeliac gluten sensitivity? A systematic review

INTRODUCTION: Non-coeliac gluten sensitivity (NCGS) is still a poorly defined clinical condition. This review aims to describe the clinical features of subjects with a symptomatic response to gluten intake, and to estimate the prevalence of NCGS. EVIDENCE ACQUISITION: Literature search was conducted in accordance with PRISMA recommendations. The PubMed database was searched for original articles until 1st June 2020. EVIDENCE SYNTHESIS: We identified 30 relevant articles, including 14 studies that investigated NCGS through a double-blind, placebo-controlled crossover trial (DBPCC), and 16 that examined the role of gluten in causing symptoms without a DBPCC. We found that regardless of the diagnostic work up, gluten-sensitive patients were predominately middle-aged females complaining of abdominal pain, bloating and diarrhea. The pooled prevalence of NCGS after DBPCC was 24% (5-34%). Subjects with irritable bowel syndrome or self-reporting gluten intolerance accounted for the vast majority of the patients who did not start a DBPCC. A symptomatic response to a gluten-free diet (GFD) occurred in between 7% and 93% of patients. No data on long-term outcomes of NCGS individuals were reported. CONCLUSIONS: Clinical features of NCGS patients did not differ among all the included studies, whereas prevalence figures are rather heterogeneous. Long-term benefit of a GFD on these patients still needs to be ascertained.