Dementia, especially Alzheimer’s disease, is a major global health concern, and dietary patterns play a significant role in its development and progression. The Mediterranean diet, rich in fruits, vegetables, whole grains, seafood, and healthy fats, is strongly associated with a reduced risk of dementia. Specific nutrients like omega-3 fatty acids, vitamins, and antioxidants contribute to cognitive protection. Evidence from population-based studies and clinical trials strongly supports the cognitive protective effects of this diet. Other dietary interventions, including calorie-controlled regimens, intermittent fasting, and the MIND diet (Mediterranean–DASH Intervention for Neurodegenerative Delay), have also shown promise in preserving cognitive function. The nutritional challenges faced by individuals with dementia often include difficulties with eating, swallowing, and dietary management. Customized dietary interventions can improve the quality of life and potentially slow the progression of cognitive decline in affected individuals. While the exact mechanisms are still being investigated, healthy dietary patterns are beneficial. The Mediterranean diet, and possibly the ketogenic diet, emerges as compelling approaches for both the prevention and management of dementia. Continued research is essential to clarify the causal links and biological mechanisms involved further. However, these dietary modifications represent a promising strategy for mitigating the global burden of dementia. Emerging evidence emphasizes the role of nutrition beyond early development, focusing on age-related decline. Protective diets, such as Mediterranean and MIND, rich in micronutrients and polyphenols, alongside gut microbiome modulation, show promise. Crucially, addressing cardiovascular risk factors in middle age is vital for preventing later dementia, suggesting integrated management within existing noncommunicable disease programs.