A diet rich in fat and sugar may do more than harm your waistline—it could impair brain function, according to new research from the University of Sydney.
The study found that high-fat, high-sugar (HFHS) diets negatively affect the hippocampus, a seahorse-shaped structure deep within the brain’s temporal lobe, crucial for forming long-term memories and guiding spatial navigation.
“Our findings suggest this is a reversible condition,” said lead author Dr. Dominic Tran. “Improving your diet can restore hippocampal health and boost your ability to navigate new environments, such as finding your way through an unfamiliar city.”
Researchers assessed the cognitive performance of 55 university students aged 18 to 38. Participants completed dietary surveys detailing their intake of sugary and fatty foods, had their body mass index (BMI) recorded, and underwent memory tests, including a virtual reality maze challenge.
In the maze, participants had to locate a treasure chest six times. Those who found the chest within four minutes progressed immediately; those who didn’t were shown the correct location briefly before the next round. In a final test, the chests were removed, and participants were asked to recall and mark where the treasures had been.
Results revealed a stark difference: students who consumed lower-fat, lower-sugar diets were significantly more accurate at identifying previous chest locations than their HFHS-eating counterparts.
“Even after accounting for working memory and BMI, sugar and fat intake remained a strong predictor of performance on the final memory task,” said Dr. Tran.
He stressed the broader implications: “We’ve long known excessive consumption of refined sugars and saturated fats increases the risk of obesity, cardiovascular disease, metabolic issues, and certain cancers. Now, it’s clear these eating patterns also accelerate cognitive decline—not just in later life, but potentially starting in young adulthood when mental function should be at its peak.”
Dr. Tran concluded that because the study group—young, relatively healthy university students—likely represented a fitter subset of the population, the true impact of diet on brain health across the general public may be even more profound.
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