Context: Functional constipation (FC) and IRRITABLE BOWEL SYNDROME (IBS) represent very common pediatric functional gastrointestinal disorders (FGIDs). Controversial results have suggested a potential role of food allergy as a trigger of functional BOWEL symptoms.Evidence Acquisition: This review summarizes the literature regarding the role of allergic diseases in children with FC and IBS and discusses the hypothesis of the pathogenesis of constipation due to cow’s milk protein allergy (CMPA).We searched systematic reviews, guidelines, or original data in PubMed, MEDLINE, and the Cochrane central register of controlled trials.Results: The pathogenesis of FGIDs remains elusive and is likely multifactorial. Among these factors, adverse reactions to food may play a pathogenic role. Some features, such as abnormal BOWEL motility, visceral hypersensitivity, and changes in mucus composition caused by inflammation of the gastrointestinal wall, have been found both in IBS or FC and in food allergy. Since 1978, an increasing number of reports have suggested a relationship between CMPA and FC. Two randomized controlled studies conducted in children showed that CMPA may induce chronic FC; one study indicated that fermentable oligosaccharide, disaccharide, and monosaccharide polyols (FODMAP) foods may play a role in triggering IBS.Conclusions: Food allergy in children with chronic constipation should be identified using an oral food challenge after being on a diet free of cow’s milk. A diet low in FODMAPs might also be recommended for children with IBS. This approach could be suggested for children with chronic FC and IBS, especially when they do not respond to standard treatment. However, it should also be considered that a minority of patients with FC or IBS could respond to an elimination diet. Further studies are needed to understand the complex pathogenic mechanisms of FGIDs; they also might be helpful to recognize markers for identifying children with IBS and FC caused by foods and to improve their management.

Background: IRRITABLE BOWEL SYNDROME (IBS) has the most common functional gastrointestinal disease and has among the most common reasons for outpatients doctor visit both in primary and specialty clinics. Patients suffer from lifelong chronic abdominal pain, diarrhea, constipation, bloating and flatus often associated with anxiety depression which significant opposing effect on the quality of life and have to use the patients to use the healthcare system and induce a huge cost for health care system. It has also result in abstinence from work and its economic consequences. Treatment of IRRITABLE BOWEL SYNDROME has symptom base which were most challenging aspect of clinical practice. Recently there was accumulating evidence in favor of dietary therapy as one of the cheapest and most effective therapy for IBS. However, there was need for a review which concludes these results.Purpose of this study was to look at the recent literatures about the role of diet in controlling IBS symptoms.Materials and Methods: Studies published in recent 5 years in Pub med and SID databases were searched with relevant keywords. Human studies, English or Persian and original articles were included. Studies which were not relevant to medical nutrition therapy were excluded. From 81 studies, 31 studies were included.Results: Foods containing gluten, lactose, fructose, galactane, sorbitol, fructane and allergen foods should be limited or omitted.Patients should be advised to use fibers, prebiotics and probiotics more often.Conclusion: Medical nutrition therapy is a useful method for controlling symptoms of these patients and should be advised.