Dementia in Alzheimer’s disease leads to the loss of independence and the onset of disability, which, combined with the deficits common in old age, creates a barrier to maintaining good nutritional status and represents a risk factor to the development of malnutrition. The aims of this synthesis were to collect data on the role of diet in the prevention of dementia and discuss the appropriate nutrition for patients at different stages of Alzheimer’s disease. In addition, the study aimed to provide an overview of methods for assessing nutritional status to allow the selection of an appropriate management strategy for patients with dementia. Findings on the role of diet in dementia prevention have identified certain dietary patterns that can be considered beneficial. The article also discusses the European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines published in 2015, which address nutritional care for dementia patients. These include recommendations for dietary assessment, dietary modifications, and nutrient supplementation. An important aspect of the article is the subject of dysphagia, which affects a significant number of Alzheimer’s disease sufferers. The paper highlights selected recommendations for dietary modification from the European Society for Swallowing Disorders (ESSD) and the European Geriatric Medicine Society (EuGMS).