How do taste and smell work?
Taste is a sensation that is perceived by the taste buds on the tongue, and smell is a sensation that is detected by olfactory (smell) receptors in the nose. A common misconception is that our tongue can taste flavors such as chocolate, strawberry or mint. However, the tongue can only detect 5 elements: sweet, salty, sour, bitter and umami. It is our olfactory receptors that can detect countless different flavors.
EXPERIMENT: Plug your nose and put a small flavored candy in your mouth. As you eat it, you will notice that you can sense the sweetness but will not be able to identify a flavor. However, if you unplug your nose, the flavor will become detectable.
The aromas that are given off while we eat allow our olfactory receptors to distinguish flavor. Colds and allergies that cause stuffy noses can temporarily decrease our ability to perceive flavors.
Why do taste and smell decrease with age?
Sensations are generated by stimulations. There is a minimum amount of stimulation necessary to produce a sensation, which is known as the threshold. As we age, the thresholds for our senses increase, thereby making it more difficult to produce sensations such as taste and smell.
In addition to increased stimulation thresholds, the number of our taste buds and olfactory receptors decreases with age. Other causes of diminished taste and smell have been linked to medications, health conditions and a history of smoking or alcohol consumption.
In Part 2, we will discuss ways to increase mealtime satisfaction for the elderly who may struggle with a decreased sense of taste and smell.