Groundbreaking research reveals why one-size-fits-all diets don't work

Your genes can remind you what your ancestors ate, your culture shapes what you choose to eat now, and your gut bacteria help to determine how well you digest what you eat.

The study, carried out by scientists from the University of Tartu and KU Leuven, have connected dots together to reveal that optimal nutrition is not found in any single superfood or diet trend, but in the complex interplay between our genetic heritage, cultural and religious dietary traditions, and the trillions of bacteria living in our gut. Their comprehensive article, published in Frontiers in Nutrition, presents the integrated framework for understanding how these factors work together—and why this matters for the future of personalised healthcare.

“Think of nutrition like a three-part symphony. Your genes provide the basic melody - shaped by what your ancestors ate over thousands of years. Your culture, religion, and tradition add the harmony - determining what foods you actually choose and how you prepare them. Your gut bacteria provide the rhythm - breaking down your food and creating the compounds your body needs. When all three parts play together, you get beautiful music. When they're out of sync, you get disease,” explains Dr. Ajai Kumar Pathak, the lead author of the study.

Instead of studying just one instrument, an international team led by Dr. Ajai Kumar Pathak, Prof. Elin Org, and Prof. Toomas Kivisild, looked at the whole orchestra. They analysed results of previous studies on genetics, traditional diets, religious food practices, and gut bacteria from two very different regions with contrasting climate: temperate/tropical South Asia and extremely cold Arctic. What they found was a remarkably coordinated system that's been fine-tuned over millennia.

Carefully balanced systems are falling apart

The traditional South Asian vegetarian diet, consumed mostly by Hinduism and Jainism religious people, is rich in complex carbohydrates, dietary fibre, and plant-derived nutrients, and facilitates adaptations of certain genes that efficiently process starches and convert plant fats into brain-healthy nutrients. While Arctic peoples, whose ancestors survived on high-fat diets from marine mammals and fish in some of Earth's harshest environments, have genetic "recipes" for burning animal fats (for energy and body heat in extreme cold) and maintaining stable blood sugar without any carbohydrates, says Anna Kolesnikova, also involved in the study.

The research doesn't stop at genes. The scientists also discovered that gut microbiota - our internal ecosystem - co-evolved with these dietary patterns. For example, traditional South Asian vegetarians harbor microbiota specialised for fermenting plant fibers and producing beneficial compounds. In contrast, Arctic populations developed gut microbes optimised for processing animal fats and proteins.

Here's where the story takes a troubling turn. These finely tuned genetic adaptations, perfected over millennia, are now being challenged by the globalisation, urbanisation and spread of Western processed foods.

As traditional diets give way to processed foods, the carefully balanced relationship between genes, culture, and microbes falls apart - leading to epidemics of diabetes, heart disease, and obesity in populations that were historically healthy.

Take South Asians, for example. Despite having "efficient" starch-processing genes, they are now facing epidemic rates of diabetes and heart disease when exposed to refined sugars and processed foods. Arctic populations, whose ancestors never encountered high-carb foods, develop diabetes at alarming rates when traditional diets are replaced with processed foods. Both populations are experiencing rising obesity and cardiovascular disease as their genetic adaptations clash with contemporary diets. Modern processed diets also disrupt the ancient microbial partnerships, contributing to inflammation and disease

Precision Nutrition may help resolve this crisis

This research isn't just about understanding the past - it's about revolutionising the future of nutrition. The findings suggest we need to move beyond "one-size-fits-all" dietary guidelines toward precision nutrition that considers genetic ancestry, individual genetic variants, microbiome composition, but also cultural food traditions to honour traditional dietary wisdom while adapting to modern life.

This research emphasises a shift toward treating food as personalised medicine. Just as we're moving toward precision medicine based on individual genetics, we're now entering the era of precision nutrition that might help resolve human health by considering the gene-traditional diet-microbiota axis.

See the Full article available at: https://doi.org/10.3389/fnut.2025.1638843