The effects of hedonically acceptable red pepper doses on thermogenesis and appetite

Abstract

Previous studies suggest consumption of red pepper (RP) promotes negative energy balance. However, the RP dose provided in these studies (up to 10 g/meal) usually exceeded the amount preferred by the general population in the United States (mean=~1 g/meal). The objective of this study was to evaluate the effects of hedonically acceptable RP doses served at a single meal in healthy, lean individuals on thermogenesis and appetite. Twenty-five men and women (aged 23.0 ± 0.5 years, BMI 22.6 ± 0.3 kg/m(2), 13 spicy food users and 12 non-users) participated in a randomized crossover trial during which they consumed a standardized quantity (1 g); their preferred quantity (regular spicy food users 1.8 ± 0.3 g/meal, non-users 0.3 ± 0.1 g/meal); or no RP. Energy expenditure, core body and skin temperature, and appetite were measured. Postprandial energy expenditure and core body temperature were greater, and skin temperature was lower, after test loads with 1 g RP than no RP. Respiratory quotient was lower after the preferred RP dose was ingested orally, compared to in capsule form. These findings suggest that RP's effects on energy balance stem from a combination of metabolic and sensory inputs, and that oral exposure is necessary to achieve RP's maximum benefits. Energy intake was lower after test loads with 1 g RP than no RP in non-users, but not in users. Preoccupation with food, and the desire to consume fatty, salty, and sweet foods were decreased more (or tended to be decreased more) in non-users than users after a 1 g RP test load, but did not vary after a test load with no RP. This suggests that individuals may become desensitized to the effects of RP with long-term spicy food intake.

Figure 1

Test visit timeline.

Figure 2

Mean (± SEM) changes in energy expenditure measured over the 270 min after test loads (n=25) were greater with 1 g RP than no RP (p<0.05). *p<0.05, **p<0.01

Figure 3

Mean (± SEM) respiratory quotient (RQ) measured over the 270 min after test loads (n=25) was lower when RP was consumed orally, compared to in capsule form (p<0.05). *p<0.05

Figure 4

Mean (± SEM) core body temperature measured over the 270 min after test loads (n=25) was greater with 1 g RP than no RP (p<0.05).

Figure 5

AUC (± SEM) change in appetite ratings for preoccupation with food and desire to eat fatty, salty, and sweet foods measured over the 270 min after test loads (n=25) was decreased more (or tended to be decreased more) in non-users than users after test loads with 1 g RP (a), but did not vary significantly after test loads with no RP (b) (p = 0.097, p<0.01, p<0.01, and p = 0.061, respectively).

Figure 6

Mean (± SEM) energy intake at a challenge meal served 270 min after test loads (n=25) was lower in non-users after test loads with 1 g RP compared to no RP, but did not vary significantly in users (p<0.05). *p<0.05