Summary: A new Tulane University study finds that a Mediterranean-style diet can improve cognitive performance by reshaping the gut microbiota. In a controlled rodent experiment, rats fed a Mediterranean diet showed distinctive changes in gut bacteria that correlated with better memory, enhanced cognitive flexibility, and stronger working memory compared with rats fed a typical Western diet.
Rats consuming the Mediterranean-style diet experienced increases in several beneficial bacterial groups and decreases in bacteria linked to poorer outcomes. These microbiome shifts were associated with improved performance on learning and memory tests, lower levels of harmful LDL cholesterol, and altered serum cytokine profiles. The findings suggest that dietary patterns influence brain health through gut-brain interactions and point to potential benefits during key developmental periods for young adults.
Key facts:
- Gut–brain connection: A Mediterranean dietary pattern reshaped gut microbiota composition in ways linked to cognitive gains.
- Cognitive benefits: Improved reference memory, working memory, and cognitive flexibility were associated with specific microbiota changes.
- Dietary components: Olive oil, fish, higher fiber, and reduced saturated fat appeared central to the beneficial microbiome and cognitive profile.
Source: Tulane University
Researchers at Tulane University School of Medicine report these results in Gut Microbes Reports. The team compared a Mediterranean-style diet (MeDi) to a Western diet (WD) in young Sprague Dawley rats over 14 weeks to model the effects of diet during a critical developmental window similar to late adolescence and early adulthood in humans.
“We’ve known that what we eat affects brain function, but this study explores how that could be happening,” said lead author Rebecca Solch-Ottaiano, PhD, neurology research instructor at Tulane’s Clinical Neuroscience Research Center. “Our findings suggest that dietary choices can influence cognitive performance by reshaping the gut microbiome.”
In the experiment, ten-week-old male Sprague Dawley rats were assigned to either the Mediterranean-style or Western diet (n = 10 per group) for 14 weeks. Diet compositions were modeled on human eating patterns and used ingredients intended to capture the complexity of real-world diets. Microbiota composition was assessed before behavioral testing, and a series of maze and learning tasks evaluated memory and flexibility.
At the genus level, four bacterial groups increased in abundance in the Mediterranean diet group while five genera decreased relative to the Western diet group. Higher abundance of taxa such as Candidatus Saccharimonas correlated with better cognitive performance on maze tests, whereas higher levels of genera like Bifidobacterium were associated with poorer memory outcomes in this model. Overall, the Mediterranean-fed rats showed improved reference and working memory and superior cognitive flexibility.
Beyond behavior and microbiota, the Mediterranean diet group exhibited lower low-density lipoprotein (LDL) cholesterol and altered serum cytokine levels at the study’s end. However, investigators did not observe group differences in markers for neuroinflammation, blood–brain barrier integrity, glial cell activation, or gene expression related to synaptic plasticity in the brain regions assessed.
These results indicate that the Mediterranean diet modulated gut microbiota, cognitive outcomes, and systemic lipid and immune markers without detectable changes in measured brain gene expression within the timeframe of the study. The authors emphasize that additional research, especially larger human studies, is needed to confirm causality and to map the precise mechanisms linking diet-modified gut communities to cognition and immune function in young people.
The research team suggests the biological effects of a Mediterranean dietary pattern could potentially be harnessed to support academic performance in adolescents or workplace functioning in young adults, though they caution that findings from animal models require confirmation in human trials.
Practical elements of a Mediterranean eating pattern highlighted by the study include:
- Using olive oil as the primary source of fat
- Emphasizing vegetables, fruits, and whole grains
- Including fish and lean proteins regularly
- Limiting red meat and foods high in saturated fat
- Prioritizing high-fiber plant foods to support a healthy microbiome
Other Tulane co-authors include Elizabeth B. Engler-Chiurazzi, Colin Harper, Savannah Wasson, Sharon Ogbonna, Blake Ouvrier, Hanyun Wang, Madison Prats, Katherine McDonald, Ifechukwude J. Biose, Lori A. Rowe, MaryJane Jones, Chad Steele, and Gregory Bix.
About this diet and cognition research news
Author: Keith Brannon (Tulane University)
Source: Tulane University
Contact: Keith Brannon – Tulane University
Image: The image is credited to Neuroscience News
Original research (open access): “Comparison between two divergent diets, Mediterranean and Western, on gut microbiota and cognitive function in young Sprague Dawley rats” by Rebecca Solch-Ottaiano et al., published in Gut Microbes Reports.
Abstract
Comparison between two divergent diets, Mediterranean and Western, on gut microbiota and cognitive function in young Sprague Dawley rats
Clinical studies suggest diet quality influences cognition in youth (ages 15–24). The Mediterranean diet has been associated with cognitive benefits compared with the commonly consumed Western diet, and the gut microbiota may be a key mediator of diet-driven cognitive changes.
In this study, ten-week-old male Sprague Dawley rats were fed either a Mediterranean-style diet or a Western diet (n = 10 per group) for 14 weeks. Microbiota community composition was characterized prior to behavioral testing. At the genus level, four bacterial taxa increased and five decreased in the Mediterranean diet group relative to the Western diet group. Rats on the Mediterranean diet demonstrated improved cognitive flexibility, reference memory, and working memory compared with Western-fed rats. At study end, serum cytokines were elevated and low-density lipoproteins were reduced in the Mediterranean group. Markers of neuroinflammation, blood–brain barrier integrity, glial activation, and synaptic plasticity gene expression in examined brain regions did not differ between groups.
Overall, the Mediterranean diet altered gut microbiota profiles, cognitive performance, and systemic lipid and cytokine measures without detectable changes in the brain gene expression markers assessed. Further work is needed to determine causal links among diet, gut microbiota, immune signaling, and cognition.