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

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 ± 5.3 year; BMI: 21.7 ± 1.9 kg/m²) 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 30 min, 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 ± 22.84 g) compared to control condition (206.94 ± 24.93 g; p = 0.03). Consistently, salivation was increased significantly during chocolate and beef exposure (mean: 0.494 ± 0.050 g) compared to control condition (0.417 ± 0.05 g; 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.