Diet is arguably the single most important preventive measure for healthy aging because it affects the functioning of every organ in the body and is a factor both in the development of disease and in recovery.

Nutritional medicine can be simply defined as the relationship of food to the well-being of the human body. It also encompasses the study of environmental effects on the quality of foods, and the impact of nutritional factors on health and disease. Nutritional medicine uses food, and individual nutrients in doses only achievable in supplement form, for medicinal and therapeutic effects.