Carotid intima-media thickness (CIMT), measured by ultrasound, is a validated marker of subclinical atherosclerosis and an early predictor of cardiovascular and cerebrovascular disease. Increasing evidence links vascular aging and oxidative stress to cognitive decline, particularly among older adults and individuals with neurodegenerative disorders. Dietary antioxidants and polyphenols-abundant in fruits, vegetables, olive oil, tea, and red wine-exert protective effects on vascular and brain health through anti-inflammatory, antioxidant, and endothelial-supportive mechanisms. This narrative review synthesizes current evidence on the influence of dietary antioxidants and polyphenols on ultrasound-measured CIMT and cognitive function, with emphasis on aging and early neurodegenerative disease. A narrative review of clinical trials, cohort studies, and mechanistic investigations published between 2000 and 2024 was conducted. Studies exploring antioxidant-rich diets and individual polyphenols (e.g., resveratrol, epigallocatechin gallate, punicalagin) and their effects on CIMT, oxidative stress, neuroinflammation, and cognitive outcomes were included. Evidence from randomized controlled and observational studies shows that polyphenol-rich interventions-such as the Mediterranean diet and pomegranate juice-are associated with reductions in CIMT and improvements in cognitive domains, including memory, attention, and executive function. These benefits are mediated through reduced oxidative stress, suppression of pro-inflammatory cytokines, improved lipid metabolism, and enhanced nitric oxide bioavailability. Some studies also demonstrate favorable changes in brain imaging biomarkers and cerebrovascular perfusion. Dietary antioxidants and polyphenols show potential to mitigate vascular aging and cognitive decline. These nutritional strategies may serve as safe, cost-effective adjuncts in preventing atherosclerosis and neurodegenerative disorders. However, further long-term, high-quality studies are needed to define optimal doses, formulations, and personalized dietary approaches.
