Changing demography towards older populations requires nutritionists to review food--health relationships in regard to older age groups, to the ageing process, to precursors of disability and survival, and to the changeability of health status through diet in later life. Nutritional status in later life may be complex with combined features of under-, over- and disordered nutrition -- dysnutrition. Further, beyond food components (essential nutrients and more), foods themselves, integrals of food intake and the socio-cultural aspects of food intake play a significant role in the health and well-being of the aged and require measurement. Ageing socio-biology provides opportunities and imposes limitations on the usual food intake instruments. However, rapid assessment procedures can be particularly valuable as highlighted in the Food Habits in Later Life project of the International Union of Nutritional Sciences. There are critical issues to which dietary methodology can be applied to the aged: a disappearing knowledge base, relevant health-enhancing strategies and the creation of new food--health opportunities. Many communities now wish to use such information to develop food-based dietary guidelines for their aged members.