That's because taste and smell work together, giving us the ability to distinguish chocolate ice cream from vanilla, a pear from an apple. On its own, taste only knows salty, bitter, sweet and sour. When we take a bite of chocolate ice cream, taste buds sense that it is sweet, while tiny particles rise up the back of the nose to the olfactory nerves, which identifies that particular sweetness as chocolate. When taste and smell combine, it is flavor. People who complain of a taste loss are actually missing the flavor of food because of an olfactory loss.
Some losses are correctable, others are permanent.
Of the more easily treatable causes of taste and smell loss, the most common are colds, sinus problems, nasal polyps, hormonal disturbances and dental problems. Taste generally returns after treatment with nasal steroids, decongestants, antibiotics, improved oral hygiene or surgery. According to the National Institute on Deafness and Other Communication Disorders, a loss of taste or smell can also be caused by obesity, hypertension, malnutrition, diabetes, Alzheimer's disease and Parkinson's disease. Certain medicines, including penicillin and some antidepressants, can also cause a loss of taste. Age-related loss of taste and smell seems to parallel other kinds of losses such as vision and hearing, says Robert Frank, a University of Cincinnati psychologist specializing in taste and smell perception.