Ageing is associated with an increased incidence of diabetes, impaired immunity and numerous physiological, social and economic changes. Another under-recognised change to significantly impact on health outcomes and quality of life is the drastic loss of lean body mass. New concepts have recently emerged which indicate that different types of protein sources supply constituents differentially according to digestion rate, and that amino acids have roles additional to muscle synthesis. This review explores the benefits of higher protein intakes in older people and how the protein source may provide differential benefits. In particular, whey protein is more quickly digested than either casein or soy, and provides a faster and potentially greater net source of available nutrients and essential amino acids essential for maintaining better health.