Low FODMAPs Diet vs. Specific Dietary Advice in Patients With IBS Diarrheal Variant

Inclusion Criteria: * Rome IV criteria for IBS diarrhea variant (IBS-D). * Low-lactose diet is allowed, provided that patients agree to keep this intake constant throughout the study period, except in the case of randomization in the treatment arm with a low-FODMAPs diet. * The use of probiotic products is permitted, and patients who consume probiotic products must be instructed to continue taking the same amount previously taken throughout the study period. * The drugs used to treat IBS, including antidepressants, will be admitted provided they are used regularly and have a stable dosage for at least one month prior to inclusion in the study. * Patients must be willing to change their current diet to participate in the study for the whole study period. Exclusion Criteria: * Serious cardiac, hepatic, neurological or psychiatric diseases. * GI diseases other than IBS (e.g., inflammatory bowel disease, celiac disease) that could explain current symptoms. * Patients who previously had a low-content diet of particular substances (for example, low FODMAPs content, vegan diet, gluten-free diet). - This last category of subjects will be able to return to the study provided they suspend the gluten-free diet until thes symptoms reappear.