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Wayne's Story

This page explores Professor Wayne Cutfield's role in the Gut Bugs team and the work he has done as part of the trial.

Wayne Cutfield

Image of Wayne Cutfield
Greenstone TV Ltd and Razor Films Ltd.

“Five years ago we wouldn’t be having this conversation”, says Professor Wayne Cutfield, speaking about the Gut Bugs trial. Gut Bugs is a world-first, cutting-edge research project which, according to Professor Cutfield, examines a “whole new area of biology.” The trial examines the effectiveness of gut microbiome transfer (GMT) as a treatment to support adolescents who are living with obesity to achieve and maintain a healthy weight. Professor Cutfield is a Paediatrician and Professor of Paediatric Endocrinology at the Liggins Institute. He is also the Principal Investigator (PI) for Gut Bugs.


Nature of Science Idea:

  • Science is a collaborative process and scientists often work in teams.


His role as PI is to pull together a large team of researchers and support staff while overseeing what happens in the trial day by day, week by week. He helps with planning the project and with the constant troubleshooting, tweaks and changes that are necessary as the Gut Bugs trial evolves.


The Gut Bugs trial is important because many studies have been carried out on mice which indicate a link (or an association) between the gut microbiome and health conditions such as obesity, diabetes and heart disease. However, as Professor Cutfield says, “man is not a mouse”. Also, he says, association studies do not prove cause and effect. If today is my birthday and it’s raining, I cannot assume that my birthday makes it rain. And the only way to test this is to move my birthday around onto different days and see if it rains. And that is what is happening now with Gut Bugs.”


Nature of Science Ideas

  • Science is innovative, exciting and breaks new ground. Science is about generating and testing new ideas. 
  • Science involves uncertainty and unknowns, you need to find your way, develop techniques, find out how to do things.


Speech bubble with the following quote: "The trial is a dynamic beast that needs to be constantly revised. It's not like making a cake, where you just put everything together and stick it in the oven and wait 40 minutes until it is cooked. It involves taking the cake out of the oven all the time and playing with it, every minute, checking, testing, checking, testing and back in it goes. Every so often there's something that goes wrong, and so we've got to add a little bit of this or that. You do that day after day, week after week, month after month."

Microbiome transfer from one organism to another using faeces is often called FMT - Faecal Microbiome Transplant. However, Professor Cutfield explains why the language needed to change for the Gut Bugs trial from FMT to GMT - Gut Microbiome Transfer:  “A transplant is like a heart or limb transplant. We are transferring bacteria from donor to participant. If you ever try to recruit anybody and say ‘we’re going to do faecal transplant’, or talk to them about ‘faecal’ anything, they’ll run a million miles away.”


We know you can change the type of bacteria in your gut by selectively feeding them - why not just swallow probiotics instead of going through GMT? Prof. Cutfield explains it like this:


“Probiotics and prebiotics are tinkering. Think about renovating your house - you can do a bit of painting or you can change the curtains or you can completely gut the house and re-build it.


It’s a bit like saying ‘if you want a car, why don’t you get a model-T Ford rather than a Ferrari?’ They are that different. Probiotics are a few types of bacteria, GMT is the entire forest. The whole city, not just a couple of families.”

Speech bubble with the following quote: "The more unique the research, the more relevant it is and the more important it is on a world stage. It's weird and interesting and it involves lots of toilet humour."

Nature of Science Idea

  • Clinical trials involving human subjects involve many checks to minimise the risk of harm to participants, but no trial is completely risk-free.


One of the most important considerations in the initial stages of the trial was to prevent the transfer of infectious bugs from donors to recipients. Many infectious bugs don’t have symptoms, so it might not be immediately obvious that a donor is sick or carrying an infectious disease. On a number of occasions, the researchers discovered harmful bacteria in a ‘healthy’ donor gut. These bacteria were not causing the donor any harm, but could not be transferred to a recipient in case they became ill. The researchers were incredibly cautious and designed an extensive screening programme.


Teenagers who were living with obesity were chosen as the test group because many of the treatments on offer to obese adults are not on offer to teens, yet if adolescent obesity can be reversed, they are less likely to develop complications such as heart disease later in life.

Speech bubble with the following quote: "Teenagers are smart enough to know what they want. There are lots of teens out there who have struggled with their weight and they want it fixed - if this can make a difference, why would you not want to try it?"

Nature of Science Ideas

  • Doing science involves accounting for or controlling all kinds of variables. Science is not a linear, step-by-step process, it is often cyclical, and iterative.
  • An important part of scientists’ work is to seek and apply for funding for their research.


The Gut Bugs project is funded by a philanthropist. Gut Bugs is the result of ‘blue sky thinking’ - it is a very novel area of science, and in New Zealand, conventional research funding is generally for projects which are known to some extent and predictable.


Teenagers seemed very open to the idea - according to Prof. Cutfield, when the trial was advertised on Facebook, there was a huge amount of interest. Many participants of different ethnicities are taking part in the trial: European, Pasifika and Maori.


Professor Cutfield explains something that everyone will want to know - how and where did the donors produce the samples? “Donors usually had something to eat before they came to us, they’ve had a coffee. The donor comes in, we collect the fresh stool from them, we immediately take it to the lab, get rid of all the waste out of it, collect up the bacteria, put them in one capsule, put them in a second capsule, and freeze it. And we could do all of that in one hour. Just like making handmade chocolates.“


The Gut Bugs trial has received lots of interest and is the subject of a TV3 series, aptly named “The Good Sh*t.”