Influence of age on mastication: effects on eating behaviour.

The present review covers current knowledge about the ageing of oral physiology related to mastication and its effects on eating behaviour. Mastication is the first process undergone by a food during feeding. It has a key role in the maintenance of nutritional status in two respects. First, the perceptions of food's sensory properties elicited during chewing and swallowing are one of the major determinants of the pleasure which drives us to eat; second, the properties of the swallowed bolus are affected by oral conditions and this may modulate the subsequent phases of digestion. Ageing in healthy dentate subjects induces moderate changes in oral physiology. Changes in neuromuscular activity are partly compensated by changes in chewing behaviour. No clear age effect is seen in texture perception, although this does impact on food bolus properties. In contrast, great alterations in both chewing behaviour and food bolus properties are observed when ageing is associated with a compromised dentition, general health alterations and drug intake. Eating behaviour is far more complex than just chewing behaviour and the concerns of the elderly about food cannot be explained solely by oral physiology. Discrepancies are often noticed with older subjects between various objective measurements of oral performance and corresponding measures of self-perception. In addition, although more foods are recognised as hard to chew with increasing age, there is no clear shift in preference towards food that is easy to chew. Food choices and food consumption are also driven by memory, psychology and economic factors. Advances in the understanding of food choice in the elderly need a sustained collaborative research effort between sensory physiologists, nutritionists, and food scientists.