The potential impact of dietary manipulation on the maintenance of physical and cognitive function between middle and old age has profound consequences for optimization of health, independence and well-being for the latter years. This review article considers four key areas: the role of diet and longevity; potential dietary measures to prevent sarcopenia; diet and cognitive function; and dietary interventions with regard to primary or secondary prevention of age-related chronic disorders. Caloric restriction has been shown to slow ageing and maintain health status in both primates and rats. The evidence has limited applicability to humans, since it is unlikely that 30% reduced diets could be maintained long-term. The causes of sarcopenia, which manifests as loss of strength, disability and reduced quality of life, are multifactorial. However, resistance with ageing to regulatory amino acids known to modulate translation and initiation, particularly leucine, raise possibilities with regard to dietary intervention. The pattern of protein intake appears to be important in whole-body protein retention in older adults. A body of evidence is emerging that associates various dietary factors with a reduction in cognitive decline with age, or a delay in the progression of Alzheimer's disease, particularly with regard to intake of vitamin E and C-containing foods, as well as fish intake. Epidemiological evidence demonstrates a role for dietary intervention in the primary prevention of chronic diseases, even in old age. However, the potentially harmful effects of micronutrient supplementation in the secondary prevention of coronary heart disease raise concern regarding appropriate dietary messages for the elderly. The role of the antioxidants, lycopene, lutein and zeaxanthin, in the prevention of cataracts and age-related macular degeneration support the almost universal dietary guideline ‘eat more fruit and vegetables’. In future dietary guidelines for the elderly need to be evidence-based and take into account protective food patterns, rather than target specific foods.