Irish Examiner│Discovering the benefits of the NiMe diet – the unprocessed foods that are good for the gut

First pubished in the Irish Examiner on 11 April 2025.

Ditch the processed food and focus on high fibre for a healthier microbiome: this is advice from scientific researchers who have just launched a book which includes a meal plan and recipes for those interested in embarking on a new eating system. The kicker is that this is not a new way of eating. It’s something based on research into traditional eating patterns in non-industrialised societies like rural Papua New Guinea.

Cork-based Dr Jens Walter, Professor of Ecology, Food, and the Microbiome at UCC and the APC Microbiome Ireland, along with registered dietitian Dr Anissa Armet, a postdoctoral researcher at the University of Alberta, collaborated on the research that led to their writing a book on this newly devised diet. The NiMe Diet: Scientific Principles and Recipes was inspired by Walter’s research into what Papua New Guineans eat, with Armet coming on board to devise recipes and test the findings on human volunteers.

Walter, a graduate of the University of Hohenheim in his native Germany, took up his UCC post in 2020 after 20 years of microbiome research experience at universities in New Zealand, America and Canada. His interest in Papua New Guinea dates back to when he was a small child, watching a documentary on the country that, he says “really stuck with me”. As a researcher specialising in the gut microbiome – the community of microbes that lives in our intestines – he realised that Papua New Guinea was one of the few places in the world where it was possible to study microbiomes that had not been affected by the kind of industrialised food that we consume in our Western-style diets. This modern dietary pattern, dominant in many high-income countries, is characterised by its reliance on industrially produced foods: high in saturated fats and carbohydrates and low in fibre.

Papua New Guinea is a predominantly rural population. According to the World Bank in 2023, 86.28% of the people live in rural communities, are heavily reliant on subsistence farming and eat mainly fibre-rich, unprocessed plant-based foods. “So I sent them an email asking for poop samples,” says Walter, matter-of-factly. By studying the faecal samples from indigenous communities in rural Papua New Guinea, he was able to discover that their gut microbiomes were much more diverse than those of people in industrialised countries. This kind of diversity is what we all hope to achieve as it has links to many health benefits, including gut health and a strong immune system.

Not only that, but there was also a commonality between findings in non-industralised populations throughout the world, in places as far apart as Malawi, Venezuela and even the Tanzanian Hadza hunter-gatherers. “They eat different plant sources and different animal sources,” says Walter, “but their diets are mostly plant-based and their food has not been industrialised.” Processing – like pasturisation, canning and freezing – “has made food more secure and safe and stable,” says Walter, but when it becomes industrialised that comes with a cost: a reduction in the nutritional value of food. The food we eat shapes our gut microbiome and unless it is nourished, it can’t do its job and keep us healthy.

“Our main motivation is actually the prevention of chronic diseases,” says Walter, who notes that the disquieting increase in diseases like colon cancer, heart disease and type 2 diabetes has been linked to “industrialisation and urbanisation, and to the western diet in general”. This is where the NiMe – non-industrialised microbiome restore – diet comes in. Walter had the hypothesis; Armet put it into practice. Using scientific principles established from the research, she devised recipes that focused on whole-plant foods, vegetables, legumes and fruit and included a single small serving of salmon, chicken or pork animal protein per day. Highly processed foods were avoided, as was dairy, beef and wheat, on the grounds that none of these would be available as part of a Papua New Guinean traditional non-industralised diet.

With a rotation of dishes that included rice pudding, yellow pea soup and baked chicken breast, Armet conducted a strictly controlled nutritional trial with 30 participants. The people involved had a daily consumption of around 45g of fibre. The Irish Heart Foundation recommends that we should consume between 24-35g of fibre a day; the most recent National Adult Nutrition Survey found that Irish adults only consume about 19g.

Although the sample was small, the results were significant. LDL, or “bad” cholesterol, dropped by 17%, blood sugars reduced by 6% and there was a 14% decrease in C-reactive Protein, an indication of inflammation and heart disease. Participants also lost weight, despite not changing their calorie intake.

With the recipes and a meal plan all shared in the free-to-download book, this scientifically trialled, verifiably healthy diet can be followed by anyone. “That was very important for us,” says Walter. “All the research was funded through foundations and public sources so we thought that this information should be available to as many people as possible [and] it should be free.” Most ingredients can be easily found in supermarkets and none of them are on the expensive end of the shopping basket. “We weren’t trying to radically push certain ingredients,” Walter notes. “These are not the only healthy recipes in the world but they are the ones that have been tested in a human trial. It’s more important to follow the overall principles: eat more whole foods, a diversity of vegetables and more fibre. It’s striking how much you can achieve with fibre.”

More information, including recipes and a link to download the book, at www.instagram.com/nimediet

Yellow pea soup
Serves 2.

Ingredients
1 ¼ cups (250 g) raw yellow split peas
2 Tbsp (30 mL) olive oil
½ cup (60 g) carrots, chopped
⅓ cup (35 g) celery, chopped
3 Tbsp (30 g) onion, chopped
1 ½ tsp (3 g) minced garlic (~2 cloves)
1 ⅓ cups (250 g) canned cannellini beans (white beans), drained and rinsed
½ tsp (1 g) low-sodium vegetable bouillon
½ tsp (1 g) salt
¼ tsp (0.5 g) black pepper
⅛ tsp (0.25 g) cayenne pepper

Directions
1. Using a strainer, rinse yellow split peas with cool running water.
2. Add rinsed peas to a large pot and fill with cold water until about 2” of water is above the peas.
3. Bring water to a boil and cook yellow peas on medium heat until softened, ~30-35 minutes. Once cooked, drain any remaining water and set aside.
4. While the split peas cook, add olive oil to another large pot and heat on medium-high heat.
5. Once oil is hot, add carrots, celery, and onion and cook for 10 minutes, stirring occasionally, until browned.
6. Add in garlic and cook for ~1-2 minutes.
7. Add the white beans, vegetable bouillon, salt, black pepper, cayenne, cooked yellow peas, and 600 ml water and stir well.
8. Simmer soup for ~30 minutes, until vegetables are softened.
9. Once vegetables are softened, if desired, use immersion blender to blend smooth. Serve warm, with artichoke and bean salad if desired.
From: The NiMe Diet: Scientific Principles and Recipes by Anissa Armet and Jens Water.