Food intake and ageing--the role of the gut.

Healthy ageing is associated with decreased appetite and energy intake and this is generally associated with weight loss after about 70 years of age. The mechanisms responsible for this 'physiological' anorexia are not well understood, but it may predispose to the development of protein-energy malnutrition in older people, which is associated with increased morbidity and mortality. Many sensory and social factors, including olfactory changes and economic status, contribute to under-nutrition in older people; however, normal ageing is associated with a number of significant changes in gastrointestinal function. The control of appetite is complex but it is clear that gastrointestinal signals are important in the regulation of appetite and food intake. This review examines the role of small intestinal hormones and gastrointestinal motor function in the observed changes to appetite and food intake in older people.