Assessing the impact of olfactory dysfunction on eating behavior: A systematic scoping review and call for standardized assessments

Abstract

Olfaction plays a priming role in both the anticipation and consumption phases of eating behavior. Olfactory dysfunction can therefore lead to changes in various aspects of eating behavior, such as food choice, appetite, and food intake. In light of the increasing prevalence of persistent olfactory dysfunction among patients affected by Covid-19, providing proper care and dietary advice to individuals with olfactory dysfunction is imperative. Therefore, this scoping review seeks to gain a better understanding of the impact of olfactory dysfunction on eating behavior. Following the PRISMA guidelines, 49 papers were included, the outcomes were presented by dividing them into two categories: 1) anticipatory eating behavior, including (anticipatory) food liking, appetite and craving, food preferences, food neophobia, and cooking habits; and 2) consummatory behavior, including, food intake, consumption frequency, adherence to dietary guidelines, (experienced) food liking, food enjoyment, and eating habits. Our results show that in the anticipatory phase of eating behavior, food liking, and, food preferences, and in the consummatory phase, food enjoyment is most affected in people who experienced a sudden change in olfactory function rather than a gradual decline. Moreover, changes in food flavor perception due to olfactory dysfunction, result in a shift of food preferences towards more “taste-based” preferences, such as salty or savory (i.e., umami) foods. Subsequently, changes in preferences can affect food intake and adherence to dietary guidelines, but only to a limited extent. Appetite is more likely to be low in individuals with short-term olfactory dysfunction compared to those with long-term changes. Generally, eating behavior is more impacted in individuals with a distorted sense of smell than in those with smell loss, and the effect becomes more pronounced over time. Due to the heterogeneity of methods used to measure different aspects of eating behavior, this review stresses the importance of more research on olfaction and eating behavior using standardized and validated assessments. Such research is essential to better understand the effects of olfactory dysfunction on each aspect of eating behavior and provide effective interventions.