Why we should all try to eat like people in rural Papua New Guinea – new study
Jens Walter, University College Cork
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.
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.
People in rural Papua New Guinea have extremely limited local-food diets (really local food would be limited to yams, sago and bananas, other staples like sweet potato and taro being imported), no access to safe water (resulting in world-beating rates of stunting and wasting) and prefer a white-rice-and-tinned-meat diet wherever possible. No-one living in Papua New Guinea would recommend that diet. It’s a fiction created by highly selective research from foreigners who have spent limited time day-tripping (this research appears to have lasted only a few weeks in-country).