Virginie Van Wymelbeke

Does modification of olfacto-gustatory stimulation diminish sensory-specific satiety in humans?

UNLABELLED Alimentary sensory pleasure is an important factor in ingestive behavior. Renewal of olfacto-gustatory pleasure by introducing new foods or through seasoning of previously consumed food might increase intake. OBJECTIVES To explore whether sensory-specific satiety (SSS) for a food could be modulated, either by introducing a novel food or by a modification of sensory stimulation via seasoning the food just eaten. METHODS 180 out of 242 subjects were distributed over 3 experiments involving ad libitum intake of one of 6 fresh foods (cucumber, tomato, pineapple, banana, peanut, pistachio). Blindfolded subjects reported their sensations for the foods on 3 parameters before and after intake of an olfactorily chosen food: Olfactory pleasure (OP), Specific appetite (SA) and Stimulus-Induced Salivation (SIS). EXP. 1: One chosen food was repeatedly presented orthonasally and rated before and after it was eaten. EXP. 2: A second food was olfactorily chosen and ingested after the first one. EXP. 3: The same food was offered again after seasoning. RESULTS 2 min after ingestion, food intake was limited by SSS. OP, SA, SIS correlated with each other for eaten and non-eaten foods. OP for non-eaten foods increased (p<0.01) after ingestion of the chosen food to specific satiety. When the food just eaten was seasoned, OP increased (p<0.01) and led to additional intake (80% of first intake). CONCLUSION A reduction in SSS after introduction of a new flavor or after seasoning an ingested food was observed. Such a reduction has not previously been reported. This could hint at how food sensory variation leads to over-consumption.

Lipid oxidation in overweight men after exercise and food intake

Fat oxidation (FO) is optimized during low- to moderate-intensity exercise in lean and obese subjects, whereas high-intensity exercise induces preferential FO during the recovery period. After food intake during the postexercise period, it is unknown if FO differs according to the intensity exercise in overweight subjects. Fat oxidation was thus evaluated in overweight men after low- and high-intensity exercise during the recovery period before and after food intake as well as during a control session. Ten healthy, sedentary, overweight men (age, 27.9 +/- 5.6 years; body mass index, 27.8 +/- 1.3 kg m(-2); maximal oxygen consumption, 37 +/- 3.9 mL min(-1) kg(-1)) exercised on a cycloergometer (energy expenditure = 300 kcal) at 35% (E35) or 70% (E70) maximal oxygen consumption or rested (Cont). The subjects were fed 30 minutes after the exercise with 300 kcal (1256 kJ) more energy in the exercise sessions than in the Cont session. Respiratory quotient and FO were calculated by indirect calorimetry. Blood samples were analyzed to measure plasma glycerol, nonesterified fatty acid, glucose, and insulin. During exercise, mean respiratory quotient was lower (P < .05) and FO was higher (P < .01) in the E35 than in the E70 session (FO [in mg min(-1)]: E35 = 290 +/- 12, E70 = 256 +/- 38, and Cont = 131 +/- 7). Conversely, FO was higher in the E70 than in both the E35 session and the Cont session during the immediate recovery as well as during the postprandial recovery period (P = .005 for all; FO from the end of the exercise to the end of the session [in grams]: E70 = 45.7 +/- 8.9, E35 = 38.2 +/- 6.8, and Cont = 36.0 +/- 4.3). Blood parameters did not differ between the 3 sessions but changed according to the absorption of the nutrients. In overweight subjects, high-intensity exercise increased FO during the postexercise period even after food intake compared with the low-intensity exercise and the control session.

Alternation between foods within a meal. Influence on satiation and consumption in humans.

Food habituation/dishabituation has been observed in non-human primates in neurophysiological investigations of feeding, and in humans, through salivation or hedonic responses to food. The objective of the study was to evaluate in humans the effect of disruption of habituation by alternation between foods in a meal. Sixteen volunteers (8 males, 8 females; age: 21+/-1 yr; BMI: 21.5+/-0.5 kgm(-2)) ate a two-course meal [meatballs (M) and fries (F), then vanilla cream (C) and brownies (B)] during three randomized sessions. Sessions differed by the alternation of these foods: No-Repetition session with M-F-C-B; Single-Repetition session with F-M-F-B-C-B; Multiple-Repetition session with M-F-M-F-M-F-C-B-C-B-C-B. Final intakes of F and B were ad libitum. Quantities consumed (g, kJ) and ratings of hunger, pleasantness and desire to eat each food were evaluated. Compared to the No-Repetition session, subjects ate 18% more fries and 16% more brownies in the Single-Repetition, and 13% more fries but 20% less brownies in the Multiple-Repetition session. Pleasantness for the food decreased from before to after intake for both fries and brownies with no significant difference between the sessions. It therefore appears that moderate alternation between foods at lunch increases intake, but multiple alternations of foods at the end of the meal may decrease consumption. These differences in intakes could result from differences in sensory-specific satiety via disruption of habituation.

Evidence for Different Patterns of Chemosensory Alterations in the Elderly Population: Impact of Age Versus Dependency

The present experiment aimed to explore the interindividual variability in chemosensory abilities among the elderly population. The chemosensory abilities of 559 subjects, aged from 65 to 99 years, were evaluated. Various categories of the elderly, including people who were living at home either without or with assistance, and people who were living in a nursing home, were interviewed. The results revealed that 43% of the sample presented well-preserved chemosensory abilities, whereas 21% of the participants presented a moderate impairment. Of the sample, 33% presented well-preserved olfactory abilities but strong impairment in gustatory abilities and 3% were nearly anosmic but remained able to perceive the salty taste, demonstrating that gustation and olfaction were not systematically damaged simultaneously. The results showed a link between the level of dependence (free living vs. living at home with help vs. nursing home) and chemosensory abilities, independently of the age effect. These results strengthen the hypothesis that the impairment of chemosensory abilities is not only an effect of age per se; rather, it is related to events that are associated with aging. Factors that lead to increased dependence (such as poor health) also lead to an impairment in chemosensory performance.

Relationships between nutritional status, depression and pleasure of eating in aging men and women

Nutritional health is an essential component of quality of life among older adults. The aim of this study was to identify the predictors of nutritional status in order to identify both common and sex specific predictive pathways in an aging population. A questionnaire was administered to 464 people living at home aged 65 years and above. Part of the questionnaire contained questions about nutritional status (MNA), depression (GDS), pleasure of eating and demographic characteristics. Structural equation modeling was used to examine relationships between the variables. For both sexes, results indicate that depression and pleasure of eating are related to nutritional status. In addition, different pathways were found between men and women. In particular, while pleasure of eating is affected by depression among aging women this is not the case for men. The implications of the findings for nutrition communication are discussed.