Our sense of taste is important not only for appetite and enjoyment of food, but also for survival: Taste provides an early warning system that can detect when something is spoiled or potentially poisonous.

The tasting process begins when molecules in food or drink stimulate gustatory (taste) cells in the mouth, tongue, or throat. The average person has about 10,000 goblet-shaped taste buds, each containing between 50 and 150 tall, skinny receptor cells. These cells transmit signals through nerve fibers and into the brain’s medulla oblongata, where they meet other signals of temperature, flavor, and texture. The information ascends to the thalamus and then to taste-receiving areas in the cerebral cortex and the limbic system, where it is translated into the sensations we use to recognize and evaluate food.

The brain recognizes these basic tastes: sweet (organic compounds such as alcohols, sugars, and artificial sweeteners), sour (acids), bitter (alkaloids, such as quinine and caffeine), and salty. A more recently identified taste, umami, occurs when we eat foods that contain glutamate—such as potatoes, mushrooms, some cheeses, and meals made with monosodium glutamate, or MSG. Each receptor cell is especially sensitive to one taste, as are the different areas of the tongue where these cells are clustered. Most cells can, however, recognize at least two different tastes.

Taste is only one part of overall flavor, which includes extra details such as the sting of ammonia, the irritation of chile peppers, and the coolness of menthol. Flavor is largely drawn from the sense of smell: If you hold your nose, you may not be able to detect the difference in flavor between apples and pears, for example, but you can still taste that they’re both sweet.

A rare condition, ageusia, causes the loss of taste. Congestion or allergies can cause temporary loss, as can certain medications, exposure to dangerous chemicals, or radiation treatment for cancer. Sensitivity to taste declines with age, because taste and smell cells (which are replaced every 1 to 2 weeks) regenerate at a slower pace as we age.

ADDITIONAL FACTS

  1. Some taste fibers in the tongue travel along the lingual nerve to the chorda tympani, a slender nerve that traverses the eardrum on the way to the brain. When an eardrum is injured and the chorda tympani is damaged, taste buds may begin to die, and sensitivity may be lost at the back of the tongue on the same side.
  2. People generally seem to detect flavors best when food or drink is at or slightly below body temperature.
  3. Taste partially controls even an infant’s sucking response: Babies accept sweet solutions more readily than plain water, and bitter, salty, or sour stimuli tend to stop the sucking reflex.