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Protocol for the Gut Bugs Trial: a randomised double-blind placebo-controlled trial of gut microbiome transfer for the treatment of obesity in adolescents
  1. Karen S W Leong1,2,
  2. Thilini N Jayasinghe1,
  3. José G B Derraik1,2,
  4. Benjamin B Albert1,
  5. Valentina Chiavaroli1,
  6. Darren M Svirskis3,
  7. Kathryn L Beck4,
  8. Cathryn A Conlon4,
  9. Yannan Jiang5,
  10. William Schierding1,
  11. Tommi Vatanen1,6,
  12. David J Holland7,
  13. Justin M O’Sullivan1,2,
  14. Wayne S Cutfield1,2
  1. 1 Liggins Institute, University of Auckland, Auckland, New Zealand
  2. 2 A Better Start - National Science Challenge, University of Auckland, Auckland, New Zealand
  3. 3 School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
  4. 4 School of Sport Exercise and Nutrition, College of Health, Massey University, Auckland, New Zealand
  5. 5 Department of Statistics, The University of Auckland, Auckland, New Zealand
  6. 6 Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
  7. 7 Department of Infectious Diseases, Counties Manukau District Health Board, Auckland, New Zealand
  1. Correspondence to Professor Wayne S Cutfield; w.cutfield{at}


Introduction Animal studies showed that germ-free mice inoculated with normal mouse gut bacteria developed obesity, insulin resistance and higher triglyceride levels, despite similar food intake. In humans, an association has been found between obesity and gut microbiome dysbiosis. However, gut microbiome transfer has not been evaluated for the treatment of human obesity. We will examine the effectiveness of gut microbiome transfer using encapsulated material for the treatment of obesity in adolescents.

Methods and analysis A two-arm, double-blind, placebo-controlled, randomised clinical trial of a single course of gut microbiome transfer will be conducted in 80 obese [body mass index (BMI) ≥30 kg/m2] adolescents (males and females, aged 14–18 years) in Auckland, New Zealand. Healthy lean donors (males and females, aged 18–28 years) will provide fresh stool samples from which bacteria will be isolated and double encapsulated. Participants (recipients) will be randomised at 1:1 to control (placebo) or treatment (gut microbiome transfer), stratified by sex. Recipients will receive 28 capsules over two consecutive mornings (~14 mL of frozen microbial suspension or saline). Clinical assessments will be performed at baseline, 6, 12 and 26 weeks, and will include: anthropometry, blood pressure, fasting metabolic markers, dietary intake, physical activity levels and health-related quality of life. Insulin sensitivity (Matsuda index), gut microbiota population structure characterised by 16S rRNA amplicon sequencing and body composition (using dual-energy X-ray absorptiometry) will be assessed at baseline, 6, 12 and 26 weeks. 24-hour ambulatory blood pressure monitoring will be performed at baseline and at 6 weeks. The primary outcome is BMI SD scores (SDS) at 6 weeks, with BMI SDS at 12 and 26 weeks as secondary outcomes. Other secondary outcomes include insulin sensitivity, adiposity (total body fat percentage) and gut microbial composition at 6, 12 and 26 weeks. Statistical analysis will be performed on the principle of intention to treat.

Ethics and dissemination Ethics approval was provided by the Northern A Health and Disability Ethics Committee (Ministry of Health, New Zealand; 16/NTA/172). The trial results will be published in peer-reviewed journals and presented at international conferences.

Trial registration number ACTRN12615001351505; Pre-results.

  • obesity
  • paediatric endocrinology
  • microbiology
  • adolescents
  • clinical trials

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:

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  • JMO’S and WSC contributed equally.

  • Contributors WSC, JMO, JGBD, KSWL, BBA, VC, DJH, DMS, TNJ, YJ, KLB, CAC, WS and TV contributed to the conception and design of the study. KSWL, JGBD, WSC, JMO, TNJ, BBA and VC drafted the protocol with input from all other authors.

  • Funding This research received funding from the Rockfield Trust and A Better Start—National Science Challenge. VC was supported (in part) by the European Society for Paediatric Endocrinology (ESPE) Research Fellowship, sponsored by Novo Nordisk A/S; TNJ received a University of Auckland Scholarship, and BBA is supported by a Maurice Paykel Research Fellowship.

  • Competing interests None declared.

  • Ethics approval Ethics approval for this study was granted in November 2016 by the Northern A Health and Disability Ethics Committee (Ministry of Health, New Zealand; 16/NTA/172).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Patient consent for publication Not required.

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