Sometimes when we talk about taste, we're really talking about smell. Remember holding your nose when about to get as spoonful of medicine? Intuitively we recognize the close association between taste and smell. Much of our experience of the "taste" of food is what we smell of the food in our mouths, experts say.
Our taste buds are important, but smell seems to play a bigger role. Most people who complain of loss of the sense of taste are surprised to learn they are actually having problems with their sense of smell.
Airborne molecules that reach the nose stimulate olfactory cells. Food in the mouth or throat stimulates gustatory (taste) nerve cells. Both types of nerve cells send messages to the brain. The brain assesses the information on smell and taste to identify the source. These nerve cells are the only nerve cells the body replaces when they become old or damaged.
Flavors such as salty, bitter, sweet, and sour can be recognized by the brain without involving the sense of smell. It is the complex flavors that need input from both senses to be experienced.
Other nerve cells in the moist areas of the mouth, nose, throat, and eyes identify other sensations, such as the cool feeling from peppermint or the bite of a chili pepper, that contribute to the experience of taste and smell.
Although aging may seem to affect the taste of food, it's actually the sense of smell that often begins to decline around age 60. Other causes for a poor sense of smell or taste include a head injury; upper respiratory infections, which can cause temporary or permanent loss; polyps in the nose or sinuses; hormone problems; dental problems; dry mouth; head or neck radiation therapy; smoking; prolonged exposure to chemicals; and certain medications.
A popular myth about taste is that we experience sweetness at the tip of the tongue, salt at the sides of the tongue, and bitterness at the back. But experts say that there's no such thing as a "tongue map." Taste cells cluster in the taste buds on the tongue and roof of the mouth and in the throat. You can experience any of the four main tastes--sweet, sour, salty, and bitter--in any of those areas.
When it comes to taste, we're not created equal. Genetically speaking, there's a breed of "super-tasters" who have many more taste buds than most, making them more sensitive to sweet and bitter.
Are you a super-taster? Look in the mirror, and stick out your tongue. Look for red, round structures. (A few drops of milk will make them stand out.) If you've got dozens, you may be a super-taster.
"Supertasters." American Dietetic Association, March 2013. http://www.eatright.org/Public/content.aspx?id=6442476090&terms=supertaster. Accessed 2013.
"Disorders of Smell and Taste." American Rhinologic Society. http://care.american-rhinologic.org/disorders_of_smell_taste. Accessed 2013.
"Smell & Taste." American Academy of Otolaryngology--Head and Neck Surgery. http://www.entnet.org/HealthInformation/smellTaste.cfm. Accessed 2013.
"Taste Disorders." National Institute of Deafness and Other Communication Disorders, National Institutes of Health, July 2009.http://www.nidcd.nih.gov/health/smelltaste/pages/taste.aspx. Accessed 2013.
"Tongue Map." Society of Sensory Professionals. http://www.sensorysociety.org/ssp/wiki/tongue_map/. Accessed 2013.