Mediterranean Diet Linked to Preserved White Matter in Hispanic Adults

Dietary Interventions and the Preservation of Aging White Matter

As the global prevalence of dementia continues to rise, identifying modifiable risk factors has become a clinical priority for physicians managing aging populations [1, 2]. Dietary patterns, particularly the Mediterranean diet, have consistently demonstrated a protective association against Alzheimer’s disease and mild cognitive impairment in large-scale meta-analyses [3, 4]. While the cognitive benefits of plant-based, nutrient-dense diets are well-documented, the specific neuroanatomical mechanisms through which these foods preserve brain function remain a subject of active investigation [5, 6]. Emerging evidence suggests that these benefits may be particularly pronounced in patients with high cardiovascular risk profiles [7, 8]. A new study now offers insights into how specific dietary habits influence the structural integrity of the brain's white matter in a large cohort of Hispanic and Latino adults.

Quantifying Adherence and Neural Integrity in a Large Hispanic Cohort

The researchers analyzed data from the Study of Latinos-Investigation of Neurocognitive Aging-MRI Ancillary Study, focusing on a cohort of 2,642 Hispanic or Latino participants. This group had a mean age of 64.3 years (95% CI 63.4 to 65.1) and was 44% male. To establish a baseline for dietary habits, the study collected intake data between 2008 and 2011 using 24-hour recalls. These reports were used to calculate a Mediterranean diet score (MeDiS) on a scale of 0 to 9, where higher scores indicate closer adherence to the diet's components, such as high intake of vegetables, legumes, and healthy fats. The average MeDiS among participants was 5.0 (95% CI 4.9 to 5.1), reflecting a moderate level of adherence within this community-dwelling population. Between 2017 and 2022, participants underwent brain MRI scans utilizing diffusion tensor imaging (a specialized MRI technique that maps the diffusion of water molecules to assess the microstructural integrity of white matter tracts). This imaging allowed the authors to quantify several key markers of neural health, including total white matter volume (tWM) and white matter hyperintensity (WMH) volume, the latter of which often serves as a clinical marker for small vessel disease and chronic ischemia. Additionally, the researchers measured fractional anisotropy (a metric representing the directionality of water diffusion that reflects the health and organization of axons, known as FA) and free water (a measure of water molecules moving unimpeded by tissue barriers, which can serve as a proxy for neuroinflammation or extracellular edema, known as FW). By correlating these longitudinal imaging findings with the baseline dietary scores, the study aimed to determine how long-term nutritional patterns influence the structural preservation of the aging brain.

Structural Correlates of High Mediterranean Diet Adherence

To evaluate the relationship between dietary patterns and brain health, the researchers utilized linear regression models that controlled for age, sex, and socioeconomic factors. These adjustments allowed for a more precise investigation of the association between the Mediterranean diet score and white matter integrity, independent of common demographic confounders. The analysis demonstrated that higher adherence to a Mediterranean diet is significantly associated with more favorable markers of brain structure, suggesting a protective effect on the neural architecture of aging Hispanic adults. The study identified specific macrostructural benefits associated with nutritional habits; specifically, a higher Mediterranean diet score was associated with lower white matter hyperintensity volume (β = -0.08, 95% CI -0.11 to -0.04). This finding is clinically significant because white matter hyperintensities are a primary imaging marker for cerebral small vessel disease and are frequently linked to an increased risk of stroke and cognitive decline. Furthermore, greater dietary adherence correlated with higher total white matter volume (β = 0.05, 95% CI 0.005 to 0.09), indicating better preservation of overall brain tissue volume and a potential reduction in age-related atrophy. Beyond gross volume, the researchers observed significant associations with microstructural markers of white matter health. Higher Mediterranean diet scores were linked to lower free water (β = -0.04, 95% CI -0.08 to -0.002), a metric representing extracellular fluid that often serves as a proxy for neuroinflammation or vascular leakage into the brain parenchyma. Additionally, the study reported higher fractional anisotropy (β = 0.09, 95% CI 0.05 to 0.13) among those with better dietary adherence. Because fractional anisotropy measures the directionality of water diffusion along axons, these higher values suggest superior axonal integrity and more robust white matter connectivity in participants following the Mediterranean dietary pattern.

The Mediating Role of Cardiovascular Health and Brain Structure

To understand the mechanisms by which nutritional patterns influence neurological outcomes, the researchers conducted a secondary analysis focusing on global cognition and systemic vascular health. Between 2015 and 2018, global cognition was ascertained using a composite score derived from four standardized cognitive tests. The researchers also evaluated cardiovascular health at baseline using the Life's Essential 7 score, a metric ranging from 0 to 100. This score is a modified version of the Life's Essential 8 score that excludes dietary intake to avoid collinearity (a statistical redundancy that occurs when two independent variables are so highly correlated that it becomes difficult to determine their individual effects). Among the study participants, the average Life's Essential 7 score was 66.6 (95% CI 65.6 to 67.6), providing a baseline for the cohort's vascular risk profile. The study utilized mediation analysis (a statistical method used to identify the specific biological or physiological pathways through which an exposure, like diet, affects an outcome, like cognition) to explore whether cardiovascular health and white matter integrity were pathway variables between the Mediterranean diet and global cognition. The findings demonstrated that white matter hyperintensity volume, total white matter volume, and fractional anisotropy mediated the association between the Mediterranean diet score and global cognition. This indicates that the cognitive benefits associated with the diet are significantly tied to the preservation of both the volume and the microstructural directionality of water diffusion within the brain's white matter tracts. A critical finding of the study was the presence of serial mediation from the Mediterranean diet score on global cognition through the Life's Essential 7 score, white matter hyperintensity volume, total white matter volume, and fractional anisotropy. This serial model suggests a multi-step physiological cascade where high adherence to a Mediterranean diet first improves systemic cardiovascular health, which subsequently preserves the structural integrity of the white matter, ultimately resulting in superior cognitive performance. For the practicing clinician, these data suggest that dietary interventions may serve as a foundational strategy for neuroprotection by simultaneously addressing vascular risk factors and the structural decline of the aging brain.

References

1. Zuliani G, Gianfredi V, Veronese N, et al. Efficacy of Mediterranean diet for the prevention of neurological diseases: A systematic review and meta-analysis featured in the Italian National Guidelines "La Dieta Mediterranea".. Nutrition (Burbank, Los Angeles County, Calif.). 2026. doi:10.1016/j.nut.2025.112990

2. Christodoulou CC, Pitsillides M, Hadjisavvas A, Zamba-Papanicolaou E. Dietary Intake, Mediterranean and Nordic Diet Adherence in Alzheimer's Disease and Dementia: A Systematic Review.. Nutrients. 2025. doi:10.3390/nu17020336

3. Fu J, Tan L, Lee JE, Shin S. Association between the mediterranean diet and cognitive health among healthy adults: A systematic review and meta-analysis.. Frontiers in nutrition. 2022. doi:10.3389/fnut.2022.946361

4. Coelho-Júnior HJ, Trichopoulou A, Panza F. Cross-sectional and longitudinal associations between adherence to Mediterranean diet with physical performance and cognitive function in older adults: A systematic review and meta-analysis.. Ageing research reviews. 2021. doi:10.1016/j.arr.2021.101395

5. Gutiérrez-Tordera L, Folch A, Rojas M, et al. Effects of Nutrition on Cognitive Function in Adults with or without Cognitive Impairment: A Systematic Review of Randomized Controlled Clinical Trials. Nutrients. 2021. doi:10.3390/nu13113728

6. Chen X, Maguire B, Brodaty H, O'Leary F. Dietary Patterns and Cognitive Health in Older Adults: A Systematic Review.. Journal of Alzheimer's disease : JAD. 2019. doi:10.3233/JAD-180468

7. Tse JHW, Law QPS, Tsang JTY, Suen LKP, Tyrovolas S, Kwan RYC. The association between the MIND diet and cognitive health in middle-aged and older adults: A systematic review.. The journal of nutrition, health & aging. 2025. doi:10.1016/j.jnha.2025.100630

8. Soest AMVV, Beers S, Rest OVD, Groot LDD. The Mediterranean-Dietary Approaches to Stop Hypertension Intervention for Neurodegenerative Delay (MIND) Diet for the Aging Brain: A Systematic Review. Advances in Nutrition. 2024. doi:10.1016/j.advnut.2024.100184