ULTRA-PROCESSED FOODS, MICROBIAL DIVERSITY, AND INTESTINAL HEALTH: A FOOD SCIENCE PERSPECTIVE

Abstract

Over the last two decades, ultra-processed foods (UPFs) have become the staple of the diets of most people in the world today, and the question one now has to ask is: what is happening to the trillions of microbes in the human gut? This review compiled the evidence that has been published mainly between 2022 and 2026 regarding the association between UPF consumption and intestinal microbial diversity and gut health. From the NOVA classification system, the review will examine how the processing of food in industrial settings, whereby dietary fibre is removed, combined with the inclusion of emulsifiers, non-nutritive sweeteners and other synthetic additives, affects the gut ecosystem in several distinct, but interlinked, ways. The results from the cohort studies, randomised feeding trials and animal models suggest a fairly consistent pattern: higher intake of UPF is linked to lower levels of microbial diversity, fewer Faecalibacterium prausnitzii and Akkermansia muciniphila, a thinner protective mucus layer, and a more permeable gut lining. The mechanism of these changes is linked to low-grade inflammation and to increased risk of metabolic syndrome, inflammatory bowel disease, colorectal cancer and mood disorders via the gutbrain axis. Early life seems to be a very sensitive window, with breastfeeding providing some protection against UPF-induced dysbiosis in infants. The review ends with an analysis of the identified gaps in the existing body of literature and recommendations for future uses of processed foods in food science, such as how they can be formulated to better fit into the gut microbiome.