A new University College Cork study finds that high-fat, high-sugar diets in early life can leave lasting marks on the brain’s appetite circuits, but specific probiotics and prebiotics may help protect healthy eating habits into adulthood.
Children today are surrounded by high-fat, high-sugar foods, from birthday parties and school events to sports sidelines and after-school treats. New research from University College Cork (UCC) suggests that this early exposure does more than add extra calories — it can quietly rewire the brain’s control of eating for life.
In a study published in Nature Communications, scientists at APC Microbiome Ireland, a research institute based at UCC, report that an unhealthy diet in early life can cause long-lasting changes in how the brain regulates feeding, even after the junk food stops and body weight returns to normal.
Using a preclinical mouse model, the team showed that a high-fat, high-sugar diet during a critical early-life window led to persistent changes in feeding behavior in adulthood. These changes were tied to lasting disruptions in the hypothalamus, a key brain region that helps control appetite and energy balance.
First author Cristina Cuesta-Martí noted the work underscores how powerful early food experiences can be.
“Our findings show that what we eat early in life really matters,” she said in a news release.
The study adds weight to a growing body of evidence that childhood diets do more than influence short-term weight gain. They can shape food preferences, reward pathways and eating patterns that carry into adult life, potentially increasing the risk of obesity and related diseases.
The researchers found that mice exposed to a high-fat, high-sugar diet when young continued to show altered feeding behavior later on, even when they were switched back to a healthier diet and their body weight normalized. That suggests that early diet can leave behind what are essentially hidden “scars” in the brain’s feeding circuits.
Cuesta-Martí noted that these effects would not necessarily show up on a scale.
“Early dietary exposure may leave hidden, long-term effects on feeding behaviour that are not immediately visible through weight alone,” she said.
But the study also offers a hopeful twist: the gut microbiome — the trillions of microbes living in the digestive tract — may provide a way to protect or even restore healthier eating behaviors.
The UCC team tested microbiota-targeted interventions across the animals’ lives. One approach used a specific beneficial bacterial strain, Bifidobacterium longum APC1472, often referred to as a putative probiotic. The other used a combination of prebiotic fibers, fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS). These fibers occur naturally in foods such as onions, garlic, leeks, asparagus and bananas, and are also added to some fortified foods and supplements.
Both strategies helped counteract the long-term impact of the early junk-food diet, but in different ways.
The probiotic strain Bifidobacterium longum APC1472 produced marked improvements in feeding behavior while causing only minor shifts in the overall gut microbiome. That pattern suggests a relatively targeted mode of action, where one microbe can influence brain circuits involved in appetite without dramatically reshaping the entire microbial community.
In contrast, the FOS and GOS prebiotic combination drove broader changes in the gut microbiome, likely by feeding a wider range of beneficial bacteria. Those changes were also linked to improvements in feeding behavior in adulthood.
Together, the findings point to the gut-brain axis — the two-way communication network between the digestive system and the brain — as a promising target for preventing or reducing the long-term effects of unhealthy early-life diets.
The work highlights the potential of supporting the gut from the very start of life, according to lead investigator Harriet Schellekens, a senior lecturer at the UCC School of Medicine.
“Crucially, our findings show that targeting the gut microbiota can mitigate the long-term effects of an unhealthy early-life diet on later feeding behaviour. Supporting the gut microbiota from birth helps maintain healthier food-related behaviours into later life,” she said in the news release.
While this research was conducted in animals, it aligns with human studies showing that early diet and early microbiome development are closely linked, and that both can influence brain development and behavior. In people, diets high in processed, energy-dense foods have been associated with higher obesity risk, while diets rich in fiber, fruits and vegetables are linked to better metabolic and mental health.
The new study does not claim that a single probiotic or prebiotic is a magic fix for poor diets. Instead, it suggests that microbiota-based strategies, used alongside healthier food environments, could become part of a broader toolkit to support lifelong brain and metabolic health.
“Studies like this exemplify how fundamental research can lead to potential innovative solutions for major societal challenges. By revealing how early-life diet shapes brain pathways involved in the regulation of feeding, this work opens new opportunities for microbiota-based interventions,” added co-author John F. Cryan, UCC’s vice president for research and innovation.
The research was led by UCC in partnership with the University of Seville in Spain, the University of Gothenburg in Sweden and the Teagasc Food Research Centre in Fermoy, Ireland.
For families, educators and policymakers, the message is twofold: protecting children from constant exposure to high-fat, high-sugar foods may help safeguard their brain’s appetite circuits, and nurturing a healthy gut microbiome from birth could offer an extra line of defense.
As scientists continue to explore how specific microbes and fibers influence the developing brain, this work suggests that the choices made at the grocery store and in school cafeterias today may echo in the eating habits and health of the next generation.
Source: University College Cork