Taste

Encyclopedia of Nursing and Allied Health, 20050229 by R.D. Linda Richards

Although certain taste buds seemed to have an affinity for one of the four major flavors, continued research into this intricate biological process has revealed a complex neural and chemical network that precludes simple black and white explanations. For example, each taste bud actually has receptors for sweet, sour, salty, and bitter sensations, indicating that taste buds are sensitive to a complex flavor spectrum similar to the way vision is sensitive to a broad color spectrum grouped into the four major colors of red, orange, yellow, and green. Particular proteins of taste are also under study, like gustducin, which may set off the plethora of chemical reactions that causes something to taste bitter and sweet.

Taste buds for all four taste groups can be found throughout the mouth. A common but mistaken tongue diagram shows areas labeled with basic tastes, such as sweet at the tip of the tongue while bitter is at the back. While specific kinds of buds tend to cluster together, the four tastes can be perceived on any part of the tongue and to a lesser extent on the roof of the mouth. Bitterness does appear to be perceived primarily on the back of the tongue because of several mechanisms.

Role in human health

Taste helps people determine whether potential foods are palatable. It also plays a major role in appetite. People constantly regenerate new taste buds every three to 10 days to replace the ones worn out by scalding soup, frozen yogurt, and the like. As people grow older, their taste buds lose their fine tuning because they are replaced at a slower rate. As a result, middle-aged and older people require more of a substance to produce the same sensations of sweetness or spiciness, for example, than would be needed by a child eating the same food.

Common diseases and disorders

The inability to taste is so intricately linked with smell that it is often difficult to tell whether the problem lies in tasting or smelling. An estimated two to four million people in the United States suffer from some sort of taste or smell disorder. The inability to taste or smell not only robs an individual of certain sensory pleasures, it can also be dangerous. Without smell or taste, for example, people cannot determine whether food is spoiled, making them vulnerable to food poisoning. Also, some psychiatrists believe that the lack of taste and smell can have a profoundly negative affect on a person's quality of life, leading to depression or other psychological problems.

The reasons for taste and smell disorders range from biological breakdown to the effects of environmental toxins; but a clear precipitating event or underlying pathology is often lacking in taste disorders. Here are some of the more common ones:

Cold and flu are the most common physical ailments that can assault the sense of taste and smell. Allergies, viral or bacterial infections can all produce swollen mucous membranes, which diminish the ability to taste. Most of these problems are temporary and treatable.