Impact of ambient odors on food intake, saliva production and appetite ratings

Abstract

The aim of this study was to investigate the effect of ambient odor exposure on appetite, salivation and food intake. 32 normal-weight young women (age: 21.4±5.3year; BMI: 21.7±1.9kg/m) attended five test sessions in a non-satiated state. Each participant was exposed to ambient odors (chocolate, beef, melon and cucumber), in a detectable but mild concentration, and to a control condition (no-odor exposure). During each condition, at different time points, participants rated appetite for 15 food products, and saliva was collected. After approximately 30min, ad libitum intake was measured providing a food (chocolate rice, high-energy dense product) that was congruent with one of the odors they were exposed to. A significant odor effect on food intake (p=0.034) and salivation (p=0.017) was found. Exposure to odors signaling high-energy dense products increased food intake (243.97±22.84g) compared to control condition (206.94±24.93g; p=0.03). Consistently, salivation was increased significantly during chocolate and beef exposure (mean: 0.494±0.050g) compared to control condition (0.417±0.05g; p=0.006). Even though odor exposure did not induce specific appetite for congruent products (p=0.634), appetite scores were significantly higher during odor exposure (p<0.0001) compared to the no-odor control condition and increased significantly over time (p=0.010). Exposure to food odors seems to drive behavioral and physiological responses involved in eating behavior, specifically for odors and foods that are high in energy density. This could have implications for steering food intake and ultimately influencing the nutritional status of people.

Changes in Salivary Proteome in Response to Bread Odour

“…For this purpose, a combination of SDS-PAGE, which allowed protein separation in the total of participants, was combined with 2-DE for a deeper separation of the proteins, in a sub-sample. Recently, it was shown that salivary flow rate increases in response to food odours [9,10] and that increase was also observed in the present study, where smelling bread resulted in rise in the volume of saliva produced. This increase in salivation induced by food smelling is part of the cephalic phase response, with the function of preparing the body to optimize nutrient processing throughout the gastrointestinal tract [23].…”

“…There is empirical and scientific evidence that the odour of a palatable food induces saliva secretion. Exposure to odours of chocolate or beef were observed to increase salivation compared to a situation of absence of odours [9] and a recent study demonstrated that this rise in salivary flow rate after food-odour stimulation does not occur in response to non-food odour [10].…”

Olfactory Cues of Restaurant Wait Staff Modulate Patrons’ Dining Experiences and Behavior

“…The odor-enhanced appetite for congruent food items was also found in other studies [23], although the effect has not been consistently observed [25]. Exposure to congruent ambient scents was also found to increase consumers' satiety, i.e., their feeling of fullness ([26], also see [27]), and modulate food intake [24,25]. In addition, when both orthonasal and retronasal pathways were activated by matching scents, the amount of food items consumed was found to diminish [17,21,28].…”

“…For example, Ramaekers et al [21] demonstrated that food odors (e.g., bread or chocolate) increased consumers' appetite and directed their choices toward congruent food items. The odor-enhanced appetite for congruent food items was also found in other studies [23], although the effect has not been consistently observed [25]. Exposure to congruent ambient scents was also found to increase consumers' satiety, i.e., their feeling of fullness ([26], also see [27]), and modulate food intake [24,25].…”

“…Not only does the scent congruency affect satiety, the stimulation of ortho-and retronasal olfactory pathways predictably modulates patron satiety. Research has demonstrated that while olfactory stimuli can affect satiety across a variety of foods, including the chicken entrées used in this study [50], not all scent stimuli influence eating behavior and satiety [25]. A necessary qualification for the scents is that they must be perceived as representing a logical pairing with the food being consumed, implying congruency between food and scent [51].…”