Personalized Research on Diet in Ulcerative Colitis and Crohn's Disease: A Series of N-of-1 Diet Trials

Am J Gastroenterol. 2022 Jun 1;117(6):902-917.doi: 10.14309/ajg.0000000000001800. Epub 2022 Apr 20.


Heather C Kaplan 1 2 3Lisa Opipari-Arrigan 2 3 4Jiabei Yang 5Christopher H Schmid 5Christine L Schuler 3 6Shehzad A Saeed 7Kimberly L Braly 8Fandi Chang 5Lauren Murphy 2Cassandra M Dodds 2Mason Nuding 9Hao Liu 10Sheri Pilley 11 12Julie Stone 11 13Gisele Woodward 11 14Nancy Yokois 15Alka Goyal 16 17Dale Lee 8Ann Ming Yeh 17Peter Lee 18Benjamin D Gold 14Zarela Molle-Rios 19R Jeff Zwiener 20Sabina Ali 21Mallory Chavannes 22 23Tiffany Linville 24Ashish Patel 25 26Travis Ayers 27Mikelle Bassett 28Brendan Boyle 29Pablo Palomo 30Sofia Verstraete 31Jill Dorsey 32Jess L Kaplan 33Steven J Steiner 34Kaylie Nguyen 35Jennifer Burgis 31David L Suskind 8ImproveCareNow Pediatric IBD Learning Health System


Author information

  • 1Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
  • 2James M. Anderson Center for Health Systems Excellence, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
  • 3Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
  • 4Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
  • 5Department of Biostatistics and Center for Evidence Synthesis in Health, School of Public Health, Brown University, Providence, Rhode Island, USA.
  • 6Division of Hospital Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
  • 7Department of Medical Affairs, Dayton Children's Hospital and Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA.
  • 8Division of Gastroenterology and Hepatology, Seattle Children's Hospital, Seattle, Washington, USA.
  • 9Center for Clinical and Translational Research, Seattle Children's Research Institute, Division of Gastroenterology, Seattle Children's Hospital, Seattle, Washington, USA.
  • 10Division of Applied Mathematics, Brown University, Providence, Rhode Island, USA.
  • 11Parent Working Group, ImproveCareNow Pediatric IBD Learning Health System.
  • 12MUSC Health Shawn Jenkins Children's Hospital, Charleston, South Carolina, USA.
  • 13The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
  • 14Division of Gastroenterology, GI Care for Kids, Children's Healthcare of Atlanta, Atlanta, Georgia, USA.
  • 15Childrens Hospital of the King's Daughters, Division of Pediatric Gastroenterology, Norfolk, Virginia, USA.
  • 16Division of Gastroenterology, Hepatology, and Nutrition, Children's Mercy Hospital, Kansas City, Missouri, USA.
  • 17Division of Gastroenterology, Hepatology, and Nutrition, Department of Pediatrics, Stanford University, Palo Alto, California, USA.
  • 18Division of Pediatric Gastroenterology, Pediatric Specialists of Virginia, Fairfax, Virginia, USA.
  • 19Division of Pediatric Gastroenterology, Nemours Alfred I. duPont Hospital for Children, Wilmington, Delaware, USA.
  • 20Dell Children's Medical Group, Pediatric Gastroenterology, Dell Children's Medical Center of Central Texas, Austin, Texas, USA.
  • 21Division of Pediatric Gastroenterology, Hepatology, and Nutrition, UCSF Benioff Children's Hospital, Oakland, California, USA.
  • 22Division of Gastroenterology, Hepatology, and Nutrition, Children's Hospital Los Angeles, Los Angeles, California, USA.
  • 23Department of Pediatrics, University of Southern California, Los Angeles, California, USA.
  • 24Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Levine Children's Hospital, Charlotte, North Carolina, USA.
  • 25Department of Pediatrics, UT Southwestern Medical Center, Dallas, Texas, USA.
  • 26Pediatric Gastroenterology, Phoenix Children's Hospital, Phoenix, Arizona, USA.
  • 27Division of Pediatric Gastroenterology, Arkansas Children's Hospital, UAMS, Little Rock, Arkansas, USA.
  • 28Division of Pediatric Gastroenterology, Oregon Health Sciences University, Portland, Oregon, USA.
  • 29Division of Gastroenterology, Hepatology, and Nutrition, Nationwide Children's Hospital, Columbus, Ohio, USA.
  • 30Division of Pediatric Gastroenterology, Nemours Children's Hospital, Orlando, Florida, USA.
  • 31Division of Pediatric Gastroenterology, UCSF Medical Center, San Francisco, California, USA.
  • 32Division of Pediatric Gastroenterology, Hepatology, and Nutrition, Nemours Children's Specialty Care, Jacksonville, Florida, USA.
  • 33Division of Pediatric Gastroenterology, MassGeneral Hospital for Children and Harvard Medical School, Boston, Massachusetts, USA.
  • 34Division of Pediatric Gastroenterology/Hepatology/Nutrition, Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Indiana, USA.
  • 35Division of Pediatric Gastroenterology, Hepatology and Nutrition, Lucile Packard Children's Hospital at Stanford, Stanford, California, USA.


Introduction: Evidence about specific carbohydrate diet (SCD) for inflammatory bowel disease (IBD) is limited. We conducted 54 single-subject, double-crossover N-of-1 trials comparing SCD with a modified SCD (MSCD) and comparing each with the participant's baseline, usual diet (UD).

Methods: Across 19 sites, we recruited patients aged 7-18 years with IBD and active inflammation. Following a 2-week baseline (UD), patients were randomized to 1 of 2 sequences of 4 alternating 8-week SCD and MSCD periods. Outcomes included fecal calprotectin and patient-reported symptoms. We report posterior probabilities from Bayesian models comparing diets.

Results: Twenty-one (39%) participants completed the trial, 9 (17%) completed a single crossover, and 24 (44%) withdrew. Withdrawal or early completion occurred commonly (lack of response [n = 11], adverse events [n = 11], and not desiring to continue [n = 6]). SCD and MSCD performed similarly for most individuals. On average, there was <1% probability of a clinically meaningful difference in IBD symptoms between SCD and MSCD. The average treatment difference was -0.3 (95% credible interval -1.2, 0.75). There was no significant difference in the ratio of fecal calprotectin geometric means comparing SCD and MSCD (0.77, 95% credible interval 0.51, 1.10). Some individuals had improvement in symptoms and fecal calprotectin compared with their UD, whereas others did not.

Discussion: SCD and MSCD did not consistently improve symptoms or inflammation, although some individuals may have benefited. However, there are inherent difficulties in examining dietary changes that complicate study design and ultimately conclusions regarding effectiveness.

Trial registration: ClinicalTrials.gov NCT03301311.



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