Findings from a recent study found that young adults who eat lots of refined sugar and saturated fat struggled more to remember locations in a virtual maze.
This effect held true even after adjusting for BMI and general working-memory ability.
Promisingly, experts believe these cognitive changes are reversible by choosing healthier foods.
Researchers at the University of Sydney wanted to understand how “Western-style” diets — rich in refined sugars and saturated fats — affect spatial navigation (the ability to learn and remember routes).
While previous animal studies pointed to problems with the hippocampus (a brain region tied to memory), this is the first human study to test that directly.
Participants were 55 university students, aged 18–38, who self-reported their diets, had their BMIs measured, and took a basic working‑memory test.
The goal? To isolate the effects of diet on navigation skills, rather than body weight or memory capacity.
“We’ve long known eating too much refined sugar and saturated fat brings the risk of obesity, metabolic and cardiovascular disease, and certain cancers,” researcher Dr. Dominic Tran said in a news release. “We also know these unhealthy eating habits hasten the onset of age-related cognitive decline in middle age and older adults.
“This research gives us evidence that diet is important for brain health in early adulthood, a period when cognitive function is usually intact.”
The study
Participants completed a diet questionnaire, focusing on frequency of high-sugar and high-fat food intake. They then entered a virtual‑reality maze with landmarks scattered around.
Six practice runs: They searched for a treasure chest in under four minutes — or else got teleported to it and studied its position for 10 seconds.
Seventh trial (memory test): The chest was removed. Participants had to point out where it had been — relying purely on memory.
By comparing performance on that final test against diet, BMI, and memory scores, researchers isolated the impact of diet on spatial recall.
The findings
Clear pattern: Participants who reported higher fat and sugar consumption were significantly less accurate in pinpointing the former treasure location — even after adjusting for BMI and working memory.
Hippocampus in the spotlight: The deficits were specific to spatial navigation, linking back to hippocampal functioning — not overall cognition.
Reversible impact? Dr. Tran emphasizes that the effect is likely reversible: “The good news is we think this is an easily reversible situation,” he said. “Dietary changes can improve the health of the hippocampus, and therefore our ability to navigate our environment, such as when we’re exploring a new city or learning a new route home.”
Why it matters for you
You don’t need to wait until mid-life to think about diet and brain health. This study shows cognitive performance can be affected now — even in young adults with normal weight and good short-term memory. But the bright side is that the negative impact isn’t permanent and can likely be improved with better food choices.
“It’s likely our participants were a little healthier than the general population and we think, if our sample better represented the public, the impact of diet on spatial navigation would likely be even more pronounced,” Dr. Tran said.