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Taste and Smell

Aging And The Olfactory System, Smell And Disease, Aging And Taste, Taste And Disease

The sense of taste influences food preferences and food choices. When people describe how food tastes, they are actually talking about food flavor, and not just the basic tastes of sweet, sour, salty and bitter. The range of flavor experiences also includes aroma, texture, and mouth ‘‘feel’’—and, some would say, even the pleasantness of foods.

Much of food flavor is perceived through taste and smell. The four taste qualities are perceived through receptors located on the tongue and elsewhere in the oral cavity. Some scientists count the taste of monosodium glutamate (MSG) as a fifth basic taste quality known as umami. Mouths also detect the texture and temperature of foods, and the chemical burn of chili peppers and other irritants. Other components of flavor (such as the aroma of vanilla or orange) are airborne particles that come directly through the nasal passages, or enter the nose from the back of the mouth through what is known as retronasal transport.

Scientists have always assumed that taste and smell would undergo dramatic declines with age, much as vision and hearing do. However, it now appears that the chemical senses are much more robust in older people than are vision, hearing, and even touch. Generally, age-related deficits in the sense of smell are more dramatic than taste deficits. These losses do not occur suddenly at any given age. Instead, a progressive decline begins by thirty or forty years of age and continues gradually in later life. Because of the very slow progression of sensory losses, an older person may not even be aware that a decline in taste or smell acuity has occurred.

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Medicine EncyclopediaAging Healthy - Part 4