A comparative study of the environmentally sustainable EAT-Lancet diet vs. the Mediterranean diet in relation to cognitive function and brain integrity among older adults

Introduction: A higher adherence to a Mediterranean diet (MeDi) has been associated with more brain integrity, and slower cognitive decline. In 2019, the EAT-Lancet commission presented a new, mainly plant-based healthy reference diet, aimed to be environmentally sustainable. However, health benefits of the diet have been questioned, and the impact on cognition and brain health has not been established. This cross-sectional study aims to compare the EAT-Lancet diet vs. the MeDi in relation to cognitive function and neuroimaging markers of neurodegenerative and cerebrovascular alterations among older adults. Methods: The study sample included 615 dementia-free 70-year-olds (54% women) from the Gothenburg H70 Birth Cohort study (examined 2014–16). Dietary adherence was measured with an EAT-Lancet dietary index (score 0–42), and a MeDi index (score 0–9). The scores were transformed into z-scores to enable comparability. Brain magnetic resonance imaging measures included mean total cortical thickness (marker of overall neurodegeneration), and a global small vessel disease score (SVD score, ranged 0–3). Cognitive performance was measured with a global cognitive composite score, derived from eight cognitive tests. Linear and ordinal regression analyses were performed adjusted for sex, and multi-adjusted for potential confounders. Results: The sex-adjusted linear regression analyses showed that higher adherence to the MeDi, and to the EAT-Lancet diet were associated with better cognitive performance. After further adjusting for energy intake, physical activity, smoking status, and education, only the MeDi–cognition association remained (β: 0.071, 95% CI: 0.024–0.117, p=0.003). Furthermore, both adherence to the MeDi (β: 0.007, 95% CI: 0.000–0.013, p=0.046), and to the EAT-Lancet diet (β: 0.009, 95% CI: 0.003–0.016, p=0.005) were positively associated with cortical thickness (less atrophy) in the multi-adjusted model. The EAT-Lancet diet was associated with lower SVD burden in the sex-adjusted model (OR: 0.85, 95% CI: 0.73–0.99, p=0.035), but not in the multi-adjusted model. No association was detected between the MeDi and SVD score. Discussion: Results from this study confirms previously found associations between higher adherence to a MeDi and better cognitive function and brain integrity. The findings also indicate that an environmentally sustainable diet may be beneficial for brain health.