Diet and Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGD) and related motility issues are among the most prevalent GI disorders in the global population, particularly among children (Park, Mikami, LeClair, et al. 2015). These disorders are also called disorders of gut-brain interaction (Drossman and Hasler 2016).

Complaints such as digestive problems and abdominal pain often continue into adulthood, and the average healthcare costs associated with FGD in the United States may exceed $6,000 per patient (Dhroove, Chogle, and Saps 2010). Among adults presenting FGD, nearly 50% of healthcare economic resources are directed to those with irritable bowel syndrome, which translated to more than $20 billion annually in a 2009 analysis (Brandt, Chey, Foxx-Orenstein, et al. 2009).

Avoidant/restrictive food intake disorder (ARFID) is a relatively new diagnostic category (Fisher, Rosen, Ornstein, et al. 2013). This disorder, which affects children, adolescents, and adults, may initially resemble picky eating, however such food fussiness, unlike ARFID, usually involves only a few food items, and the child’s appetite, overall food intake, and growth and development are normal.

Patients with ARFID may not eat because they lose interest or because they fear that eating will lead to harmful consequences such as choking or vomiting. They may avoid certain foods because of their sensory characteristics. Individuals with ARFID avoid eating food or restrict their food intake to such an extent that they have one or more of the following characteristics: significant weight loss or, in children, failure to grow as expected; significant nutritional deficiency; dependence on enteral feeding or oral nutritional supplements; or markedly disturbed psychosocial functioning. Nutritional deficiencies can be life-threatening, and social functioning can be markedly impaired.

One of the FGDs is Crohn’s disease, which is a complex, chronic inflammatory condition of the GI tract (Torres, Mehandru, Colombel, et al. 2017). A precise etiology of this progressive disease is unknown, although the preponderance of evidence suggests this condition is a result of interactions between individual genetics (~12%), environmental exposures, and possibly intestinal microflora.

 Management of symptoms associated with Crohn’s disease involves an array of therapeutic interventions, depending on the nature, responsiveness, and severity of symptoms. Treating beyond the symptoms as assessed by emerging algorithms has been proposed. Steroid therapy, immunosuppressant interventions, and even nutritional and lifestyle considerations are important factors. “Biologics” may also be valuable in the management of Crohn’s (Cholapranee, Hazlewood, Kaplan, et al. 2017). These agents target specific parts of the immune system. They generally block the action of a specific type of immune cell called a T-cell, or block key inflammatory proteins or cytokines in the immune system, such as tumor necrosis factor-alpha (TNF-α), interleukin 17-A, or interleukins-12 and -23.

A 2017 review of dietary and enteral interventions noted there is limited evidence that some strains of probiotics, at least theoretically, may alter the course of Crohn’s disease (Yamamoto, Shimoyama, and Kuriyama 2017). A 2014 review of six studies, then reduced to two large studies using n-3 polyunsaturated fatty acids, suggested these are probably ineffective in management of Crohn’s disease even though these fatty acids may modulate selected inflammatory processes (Lev-Tzion, Griffiths, Ledder, et al. 2014).

Another unique study suggested a Crohn’s Disease Exclusion Diet and an enteral nutrition product may induce symptom remission among children (Levine, Wine, Assa, et al. 2019). The 6-week crossover study among nearly 80 subjects evaluated regimen tolerance, pediatric Crohn’s disease activity index, C-reactive protein, fecal calprotectin, intestinal permeability, and microbiome profile at the phylum level. Interestingly, each study group presented clinical remission and similar changes in microflora profiles at week 6, however, the group consuming the exclusion diet plus enteral feed demonstrated continued remission of symptoms. Study limitations include study subjects with less than rigorously defined and relatively mild pathology, a sensitive but nonspecific marker for inflammation, and an apparent lack of consideration for the systemic manifestations of autoimmune disease, especially in rheumatologic dimensions.

Certainly, the very broad spectrum of FGDs is daunting in terms of complexity, chronicity, social cost, and degree of human suffering. Further research is required to understand pathologies and develop effective management strategies. Emerging work appears to be intriguing in exploring clinical guidelines that do not necessarily resort to costly remedies.