Joseph R. Anticaglia MD
Medical Advisory Board
Taste and smell are connected in more ways than we realize. Eighty percent of what we taste is related to the sense of smell. There is virtually no flavor to food or beverages without the sense of smell. This article emphasizes the actions of the Olfactory nerve, i.e. the smell nerve, how it contributes to the enjoyment of food and drink, how it protects us from harmful irritants and how it enhances the quality of our life.
The sensations of taste and smell mingle to bring out the flavors of food and drink. Perhaps the Olfactory nerve is the most underappreciated of the five senses.
The Five Senses
- Taste
- Smell
- Vision
- Sound
- Touch
Olfactory Nerve
The Olfactory nerve is located in the upper and back parts of the nose. It responds to different chemicals in the air allowing the receptor cells in the nose to detect pleasant aromas such as perfumes or foul odors such as a gas leak. They relay these nerve signals to the brain for interpretation. This is labeled Orthonasal Olfaction, the appreciation of pleasant aromas or foul odors when we sniff these volatile chemicals through the nose.
When the receptor cells in the nose are blocked, for example, by nasal polyps, the olfactory cells cannot relay signals to the brain. This prevents the brain from identifying pleasant aromas or alerting us to harmful odors.
We’ve had the experience of having a bad cold while eating and noticing that “This food has no favor.” After the common cold has run its course, our appreciation of flavor returns. The olfactory cells have the capacity to regenerate.
Here’s something you can experiment with: Pinch your nose and chew a jelly bean. What do experience? Most say, “It tastes sweet.” Now let go of your nose, what do you experience? The subjects in the experiment say , “It’s a lemon jelly bean.”
It is the sensation of smell that has transmitted signals to the brain enabling it to get essential bits of information. The brain decodes the signals,, interprets them and produces in a fraction of a second a printout in our consciousness, “Lemon Flavor.”
Some use the term Retronasal Olfaction to mean smelling through the back of your mouth. When you chew a jelly bean, food, or take a sip from a glass of wine, volatile chemicals are delivered to the back of the mouth. The aromas go upwards towards the nose and excite the receptor cells of the Olfactory nerve. When the person in the jelly bean experiment lets go of his nose, he allowed the receptor cells in the nose to receive those chemicals and send signals to the brain allowing it to interpret the lemon flavor of the jelly bean.
Although the Olfactory nerve is the main focus of this article, the five senses contribute to the enjoyment of food albeit it in a minor role when compared to smell and taste. Consider the following illustration:
The look and smell of dark or light chocolates gleaming behind a glass display, the sound it makes as you snap off a piece of it, the feeling you sense as it melts in your mouth (the texture or feel of it), its sweet or slightly bitter taste, the aroma (smell) as it travels up the back of the mouth towards the nose excites a symphony of sensual responses. The brain processes and interprets these sensations using the five senses and most of us don’t give it a second thought.
But there are conditions where the loss of smell prevents you from being aware of harmful situations. They also prevent you from enjoying food and beverages. That’s when your personal history comes into play.
Medical History
Your personal history, often neglected, affects the enjoyment of eating and drinking. It can evoke memories of good times or disappointments. The loss of smell or taste can be partial or complete, temporary or permanent. The complete loss of the sense of smell is called Anosmia.
When you get over the flu, or when nasal polyps are removed, the flavor of food is often restored but not always. A partial list of the disorders is listed below.
Medical History
- Drugs – e.g. Blood pressure medications; Antibiotics, Chemotherapy
- Infections — Sinusitis, Flu. Common cold, nasal polyps
- Zinc deficiency; Thiamin deficiency (Vit B1)
- Poor oral hygiene
- Tobacco smoke
- Rhinoplasty,
- Head injuries – involvement of the olfactory nerve
- Radiation therapy in the head & neck region
- Chemical exposure – insecticides, solvents
- Tumors of nasal cavity or brain
- Aging
- Parkinson’s Disease, Alzheimer’s Disease
- Genetic disorders
The sense of smell helps us enjoy the aromas of food and other pleasures of life. It also serves as an early warning system alerting us to the dangers of moldy food or smoke. In no small way, it determines what we like to eat and what we like to drink.
The loss of the sense of smell can adversely affect the quality of our life. It can make us eat less, be less social, lead to frustration and depression. It seems to make sense that we should pay more attention to this special sense.
REFERENCES
- Anticaglia, Joseph R; Smell and Taste. The Five Tastes, HC Smart.; 2016
- Stuckey, Barb; Taste What You’re Missing; 2012; .Simon and Schuster
Reed, Danielle R.; Diverse Tastes; Genetics of sweet and bitter perception; Physiol. Behav;
Jun30, 2006. - Bromley, Steven M.; Smell and Taste Disorders; Am. Fam. Physician; Jan 15, 2000
- Guyton and Hall, Textbook of Medical Physiology, 2016. W. B. Saunders and Co.
- Costanzo RM; Regeneration of Olfactory Receptor Cells; Pub Med; Ciba Foundation
Symposium, 1991 - Rong-Sab Liang, MD, et al; Medical Treatment of Traumatic Anosmia; Oto. H&N Surg;
Jan. 15, 2015
This article is intended solely as a learning experience. Please consult your physician for diagnostic and treatment options.