Specific food components, such as gluten and FODMAPs, may trigger symptoms in patients with irritable bowel syndrome (IBS). Previous studies suggested that IBS patients with positive anti-gliadin antibodies (AGA) may preferentially respond to a gluten-free diet (GFD). However, GFD removes, apart from gluten, many potential dietary triggers, such as inulin that is part of FODMAPs. To evaluate the dietary patterns and nutrient intake in healthy controls and IBS patients before and after one month of GFD. IBS patients were diagnosed using Rome III criteria and stratified by the presence of AGA (INOVA Inc, San Diego, US). A group of healthy subjects (HV) served as controls. All participants underwent a gluten-free diet (GFD) for one month. Gastrointestinal symptoms were assessed by the IBS Birmingham score. A food frequency questionnaire (FDQ VES2- Victoria, Australia) was used to assess: 1) dietary patterns, 2) nutrient intake, and 3) FODMAP consumption before and after GFD. 41 IBS patients (22 AGA+; 19 AGA-) and 24 HV were recruited. GFD improved symptoms in IBS AGA+, but not in IBS AGA- patients. IBS AGA+ patients had lower baseline intake of specific nutrients including protein, calcium, iron, magnesium, niacin, phosphorus, potassium, and sodium (p<0.05 vs AGA- and HV). IBS AGA+ patients had lower baseline intake of eggs, nuts, yoghurt, fish, fruit, vegetables, and red wine (p<0.05 vs AGA- and HV). The GFD led to increased intake of eggs, bananas, peppers, and lettuce, as well as decreased intake of cakes, meat pies, hamburgers, and beer in IBS AGA+ patients (p<0.05). AGA- patients increased their consumption of bananas and zucchini, and decreased their intake of bread, cakes, meat pies, hamburgers, sausages and pizza (p<0.05). Importantly, there was no overall change on FODMAP intake after the GFD, except for some particular wheat-containing foods. Intake and quality of food differ between subsets of IBS patients, suggesting that patients may already select the food based on the association with their symptoms. IBS AGA+ patients had lower nutritional value intake compared to IBS AGA- patients. The GFD improves gastrointestinal symptoms in AGA+ patients, and this seems to be independent of overall FODMAPs consumption. Boris Family Grant, CIHR Fellowship Grant