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Diet plays a fundamental role in irritable bowel syndrome (IBS), as it triggers or aggravates symptoms in around two-thirds of patients. Many patients spontaneously adopt dietary changes. These patients often restrict dairy products, fruits, and vegetables. Three diets are supported by scientific evidence in the management of IBS: the standard dietary advice from the National Institute for Health and Care Excellence (NICE), the low FODMAP diet, and, more recently, the Mediterranean diet. The low FODMAP diet targets fermentable sugars potentially responsible for digestive symptoms, with effectiveness demonstrated in several studies. It is structured in three phases: restriction, reintroduction, and personalization. The Mediterranean diet, for its part, is a less restrictive alternative, particularly in patients with associated anxiety or depressive disorders. Other diets, such as the low-gluten diet or those based on dietary IgG testing, lack scientific validation and are not recommended. An exclusion regimen based on in vivo testing using confocal laser endomicroscopy has shown promising results, but further study is required before clinical application. Finally, although some dietary restrictions can be effective on the symptoms and severity of IBS, they carry risks, including nutritional deficiencies and eating disorders, such as avoidant/restrictive food intake disorder (ARFID). It is therefore crucial to carefully evaluate patients with IBS who are candidates for these diets, taking into account their nutritional status, psychiatric history, and vulnerability factors in order to avoid adverse effects.