Alzheimers disease (AD) is the most common cause of dementia in patients over 60 years of age. It is characterized by progressive degradation of cognitive function. It is a disease that affects one of every 10 individuals over the age of 65 and 50% of individuals over the age of 85. The estimated number of people with AD could be well over 14 million by the year 2050, unless a clear understanding of AD pathogenesis is gained and new AD prevention and/or treatment is developed. Concomitantly, the proportion of elderly, nondemented individuals is growing at a rapid rate. It is a well-known fact that reduced amounts of certain dietary nutrients are associated with memory loss and other thinking problems, especially in older individuals. And reduced levels of vitamins C and E have been associated with increased severity of AD. High intake of cholesterol and saturated fats is also associated with an increased risk of AD. In this review, we consider general dietary essential nutrients and non-essential nutrients, including various resources and their biological functions. Moreover, we discuss how nutrition in terms of various intake doses affects brain function, including "normal" aging, age-related dementia, and AD. We also gather together and present recent evidence on how to retard aging, and perhaps prevent AD by adopting a nutritional approach. We believe that the exciting and intriguing information will stimulate great interest in research on what constitutes a healthy diet and research on healthy aging, and the prevention of AD.