The Effect of Olfactory Disorder (and Other Chemosensory Disorders) on Perception, Acceptance, and Consumption of Food

People with changes in the overall sensory experience of food often complain of taste disturbances, although the problem is normally caused by the loss of aroma in the food (thus an olfactory disorder). Olfactory dysfunction is a common sensory impairment affecting a quarter of the population, and this number is likely to increase with our aging population and the advent of the COVID-19 pandemic. Smell plays a pivotal role in food behaviors, being able to perceive distal stimuli involved in food choice, or anticipation and proximal stimuli related to decisions of consumption and enjoyment of food in tandem with other chemical senses (taste and chemesthesis). Starting with the cephalic phase of the digestive process, smell cues a myriad of physiological responses such as saliva, hormones, and digestive enzymes production―typically tailored to the detected nutritional information provided by the smell. Once a food is in close proximity, all the chemical senses continue the cephalic phase and contribute to flavor that acts as a reward (or punishment) to reinforce (or terminate) an eating experience. Not experiencing chemosensory stimuli disrupts many of these processes, leading to an overall change in behaviors with food. These shifts in behaviors may lead to negative physiological changes such as fluctuations in weight and malnutrition. In this chapter, we will discuss interruptions to appetite from chemosensory loss as well as strategies taken by those with chronic smell impairment.