Western diets - high in processed foods and low in fibre - are associated with obesity, diabetes and heart disease . These diets don't only harm our bodies, they also harm our gut microbiomes, the complex community of bacteria, fungi and viruses found in our intestinal tract that are important for our health.
Author
- Jens Walter
Professor at the School of Microbiology, University College Cork
Scientists, including my colleagues and me, are actively searching for ways to create healthy microbiomes to prevent chronic diseases. And my search has taken me to Papua New Guinea.
I have long been fascinated by this country, with its remote valleys almost untouched by the modern world until 1930, more than 800 languages, an ancient system of sustenance agriculture and entire communities living a non-industrialised lifestyle. This fascination kicked off a thrilling nine-year research project involving researchers from eight countries, which led to a paper published in the scientific journal Cell .
In previous research , my team studied the gut microbiomes of rural Papua New Guineans. We discovered microbiomes that are more diverse than their westernised counterparts, enriched in bacteria that thrive on dietary fibre, and with lower levels of inflammation-causing bacteria that are typically found in people who eat highly processed foods.
This information provided hints on how to perhaps redress the damage caused to our gut microbiomes.
The traditional diet in rural Papua New Guinea is rich in unprocessed plant-based foods that are full of fibre but low in sugar and calories, something I was able to see for myself on a field trip to Papua New Guinea. Determined to create something everyone could use to benefit their health, our team took what we saw in Papua New Guinea and other non-industrialised societies to create a new diet we call the NiMe (non-industrialised microbiome restore) diet.
What sets NiMe apart from other diets is that it is dominated by vegetables (such as leafy greens) and legumes (such as beans) and fruit. It only contains one small serving of animal protein per day (salmon, chicken or pork), and it avoids highly processed foods.
Dairy, beef and wheat were excluded from the human trial because they are not part of the traditional diet in rural Papua New Guinea. The other characteristic distinction of the diet is a substantial dietary fibre content. In our trial, we went for around 45g of fibre a day, which exceeds the recommendations in dietary guidelines.
One of my PhD students got creative in the kitchen designing recipes that would appeal to a person used to typical western dishes. These meals allowed us to develop a meal plan that could be tested in a strictly controlled study in healthy Canadian adults.
Remarkable results
We saw remarkable results including weight loss (although participants didn't change their regular calorie intake), a drop in bad cholesterol by 17%, decreased blood sugar by 6%, and a 14% reduction in a marker for inflammation and heart disease called C-reactive protein. These benefits were directly linked to improvements in the participants' gut microbiome, specifically, microbiome features damaged by industrialisation.
On a western diet low in dietary fibre, the gut microbiome degrades the mucus layer in the gut, which leads to inflammation . The NiMe diet prevented this process, which was linked to a reduction in inflammation.
The diet also increased beneficial bacterial metabolites (byproducts) in the gut, such as short-chain fatty acids, and in the blood, such as indole-3-propionic acid - a metabolite that has been shown to protect against type 2 diabetes and nerve damage.
Research also shows that low dietary fibre leads to gut microbes ramping up protein fermentation, which generates harmful byproducts that may contribute to colon cancer.
In fact, there is a worrying trend of increased colon cancer in younger people , which may be caused by recent trends towards high-protein diets or supplements . The NiMe diet increased carbohydrate fermentation at the expense of protein fermentation, and it reduced bacterial molecules in the participants' blood that are linked to cancer.
The findings from our research show that a dietary intervention targeted towards restoring the gut microbiome can improve health and reduce disease risk. The NiMe diet offers a practical roadmap to achieve this, by providing recipes that were used in our study . It allows anyone interested in healthy eating to improve their diet to feed their human cells and their microbiome.
Jens Walter has received honoraria and/or paid consultancy from PrecisionBiotics/Novonesis A/S. NiMe is a trademark of Anissa M. Armet and Jens Walter. The research described in this article was supported by the Weston Family Microbiome Initiative, PrecisionBiotics Group Ltd., the "Hundred Talents Program" Research Start-up Fund of Zhejiang University, Alberta Innovates Postgraduate Fellowship, Izaak Walton Killam Memorial Scholarship, the Alberta Innovates Graduate Student Scholarship, the Frederick Banting and Charles Best Canada Graduate Scholarship, the Walter H. Johns Graduate Fellowship, the University of Alberta Doctoral Recruitment Scholarship, the Campus Alberta Innovates Program, the Canada Research Chairs Program, the Science Foundation Ireland Centre grant to APC microbiome Ireland (APC/SFI/12/RC/2273_P2) and a Science Foundation Ireland Professorship (19/RP/6853). I would like to thank the people of Papua New Guinea whose way of life has been an inspriation for the development of the NiMe diet, and the participants of the human trial. I am deeply indepted to all the collaborators and the scientific institutions that have contributed to the research (please see author list and affiliations on publication). I would like to thank Prof. Andrew Greenhill (Federation University, Australia) and Prof William Pomat (Papua New Guinea Institute of Medical Research) for hosting me in Papua New Guina in 2019. I would further like to thank Jessica Stanisich and Tina Darb from the APC Microbiome Ireland for their help with this article.
