A comprehensive examination of 27 animal investigations revealed that transitioning to a more health-conscious dietary regimen enhanced memory capabilities. However, the magnitude of these improvements was significantly diminished when prior diets were characterized by high sugar content.
Rehn and associates conducted a systematic review and meta-analysis to evaluate the cognitive and behavioral outcomes of dietary shifts in rodent subjects. The visual attribution belongs to Steve Buissinne.
“Our findings indicate that an uplift in dietary quality does indeed confer benefits upon memory function,” stated Dr. Simone Rehn, a research scientist affiliated with the University of Technology Sydney.
“Nevertheless, these enhancements were not total. Even following several weeks on a wholesome diet, memory recall did not revert to the baseline levels observed in subjects that had consistently maintained a nutritious eating pattern.”
Dr. Rehn, in collaboration with her colleagues, undertook a thorough systematic review and meta-analysis encompassing 27 preclinical studies. The objective was to discern recurrent patterns across the diverse experimental designs.
The primary focus of their investigation was memory function. However, they also assessed behaviors indicative of anxiety and depression, general locomotive activity, and the motivational drive for food consumption.
Across the collective body of research, animal participants that were transitioned to a healthier diet demonstrated superior performance on memory-related assessments compared to those individuals who persisted with unwholesome food choices.
Crucially, the degree of memory recuperation was contingent upon the specific dietary composition. Recovery was documented in studies where high-fat diets were the focus, but this effect was not observed in investigations employing diets excessively high in sugar, nor in those combining high levels of both fat and sugar.
No discernible or consistent improvements were noted in relation to anxiety levels, general activity quotients, or food-seeking motivation. This observation suggests that the observed effects were specifically pertinent to memory rather than a broad spectrum of general behaviors.
“We observed more pronounced improvements in memory after high-fat diets were supplanted by nutritious sustenance,” Dr. Rehn elaborated.
“Conversely, diets laden with added sugars, inclusive of those that were a combination of high fat and high sugar, yielded minimal evidence of recovery.”
“This outcome strongly implies that sugar may represent a pivotal determinant in limiting the extent of memory recovery.”
The memory assessments employed in this analysis are reflective of the functionality of the hippocampus. This particular brain region is indispensable for the processes of learning and memory consolidation. Furthermore, the hippocampus plays a role in the regulation of appetite and the intake of sustenance.
“The utilization of animal models proved instrumental in elucidating the intricate relationship between dietary intake and brain function,” commented Dr. Mike Kendig, also a member of the University of Technology Sydney research team.
“In human subjects, dietary modifications are typically accompanied by concurrent shifts in physical activity, emotional state, and daily routines. These confounding variables render it exceptionally challenging to isolate the specific effects of diet alone on cognitive processes.”
“There exists a prevalent misconception that the detrimental consequences of suboptimal eating habits are readily reversible.”
“These findings suggest that, at least concerning memory function, the situation may be considerably more intricate, particularly in instances where dietary patterns are characterized by high levels of added sugar.”
“While enhancing the quality of one’s diet remains a beneficial endeavor, safeguarding cognitive health may also necessitate the avoidance of prolonged exposure to deleterious dietary regimens, rather than presuming that their adverse effects can invariably be fully mitigated at a later juncture.”
The comprehensive review was officially published on May 17, 2026, within the esteemed journal Nutritional Neuroscience.
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Simone Rehn et al. Cognitive and behavioural effects of high-fat, high-sugar diet reversal: a systematic review and meta-analysis of animal studies. Nutritional Neuroscience, published online May 17, 2026; doi: 10.1080/1028415X.2026.2664635
