Gut Bugs Trial launches in Auckland

21 March 2017
Gut Bugs Trial

A team of New Zealand researchers are embarking on a study that could lead to a breakthrough treatment for serious weight problems.

The team, led by Professor Wayne Cutfield and Dr Justin O’Sullivan at the Liggins Institute within the University of Auckland, will take the gut bacteria from healthy lean young people and give them in capsules to teenagers who are clinically obese.

In overweight mice, this has been shown to lead to dramatic weight loss.

The Gut Bugs Trial lies at an explosive new research frontier that is redefining our understanding of nutrition and health. It’s all to do with the bacteria that live inside and on the surface of our bodies, collectively known as our microbiome.

We each carry our own unique population of about 30-40 trillion tiny microbes – that’s 1.5 kg of bacteria. These microscopic creatures interact in many different, intricate, and mainly unknown ways with our body systems. Recent technological advances mean scientists are now beginning to discover just how crucial our microbiome is to our overall health and wellbeing.

The Auckland study focuses on the gut microbiome: the bacteria deep in our gut which accounts for 95 percent of our total microbiome.

“What we eat affects the community of bacteria in our gut; and this gut microbiome affects how we digest and metabolise (convert into energy) what we eat,” says Dr O’Sullivan, a molecular microbiologist.

“There’s evidence that the more diverse your gut microbiome, the healthier you are, in general,” he says.

 “The basic idea behind our trial is that by introducing more kinds of gut bacteria to obese young people, it will enable their bodies to metabolise food better, potentially leading to weight loss and other health benefits.”

The Liggins Institute trial is believed to be the first in the world to study gut microbiome transfer in obese teenagers. The transfer involves safely isolating the gut bacteria from the stools of healthy lean donors, and putting it into capsules which are then taken by overweight teenagers. The capsules will be odourless and flavourless.

Half the teenagers will be given the bacteria capsules and half will receive placebo capsules in a double-blind study (meaning neither participants nor researchers will know who gets the real capsules until after the trial is finished – the “gold standard” of clinical trial designs).

 “There are three possible outcomes,” says Professor Wayne Cutfield, a paediatric endocrinologist. “The recipients could lose weight and keep it off for a long time, or the weight loss may last only weeks, or we could see no effect at all.

“Another question we expect the study will answer is if it does initially work, will the recipients need to adopt a healthy diet in order to maintain the health benefits?” he says.

“We’re at the proof of concept stage. We need to show this safe technique works before we develop it further - that’s why we’re being so meticulous in our study design. If it does work, it could be further developed into a large scale treatment for one of our biggest health crises.”

One in three children and 65 percent of adults in New Zealand are overweight or obese, and at increased risk of serious weight-related diseases such as type 2 diabetes, heart and liver disease.

Dr O’Sullivan, with the help of postgraduate students, will track the donors’ bacteria, and the changes in the recipients’ gut over six months after they take the capsules – data that will greatly enrich scientists’ understanding of gut microbes and their effects.

The human clinical trial – dubbed the “Gut Bugs Trial” – will simultaneously be making history of another kind, as acclaimed documentary-makers Razor Films follow its progress for a NZ On Air-funded television documentary series.

Razor Films is the team behind international hit “Why Am I?” about the Dunedin Study, “The Hard Stuff with Nigel Latta”, and a new Simon Gault-fronted series called “Why Are We Fat?”

Producer Mark McNeill says Professor Cutfield mentioned the Gut Bugs Trial when he was being filmed for the Simon Gault-fronted series, to screen on Prime this year.

“It is such a fascinating out-there idea, but based on real science,” says McNeill.

“Plus it was a unique opportunity to observe a world-first clinical trial. I was immediately interested.”

The study is now recruiting donors and recipients. The donors need to be lean, aged 18-24 years, not on medication, lead a healthy lifestyle with regular exercise, and ideally a mix of vegetarians and omnivores.

You can find out more about joining the study here, or email



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