Visceral Adiposity, Vagal Tone and Food Preferences: a Pilot Study

Study Overview
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Brief Summary
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Food preferences are defined by a number of measurable parameters, such as per se food choices, sensitivity of taste and olfactory sensory perceptions, hedonic appreciation of foods (liking) and motivation to consume them (wanting). These food preferences are fundamental to the quality of food intake, and are therefore a key factor influencing weight loss or maintenance of a stable weight. Obesity is also associated with reduced sensory sensitivity to taste and smell, as well as disturbances in the responses of the food reward system. However, the internal, or physiological, mechanisms impacting these food preferences are still poorly understood. To date, several studies seem to point to the role of body composition, in particular visceral adiposity, or adiposity surrounding the digestive organs. Indeed, a high level of visceral adiposity is associated with the onset of numerous cardiometabolic disorders, but also with altered sensory perceptions. This relationship could be mediated by the vagus nerve, which connects the digestive organs to the brain, enabling the perception of internal signals sent by the body, such as feelings of hunger or satiety. Low vagal activity is associated not only with abdominal obesity, but also with reduced sensory sensitivity to taste and smell, and changes in food choices in favor of energy-dense foods (rich in fats and/or sugars). Electrical stimulation of the vagus nerve is now recognized as a possible treatment for morbid obesity in the USA, but the mechanisms leading to the expected weight loss are still debated. Similarly, an increase in vagal tone has been found in patients who have undergone bariatric surgery for the treatment of severe complicated to morbid obesity, in parallel with sensory disturbances. The overall aim of this project is to explore and confirm the relationship between visceral adiposity and various food preference parameters, such as olfactory and gustatory perceptions and reward system responses, involving liking and wanting certain foods and associated behaviors. This project also aims to shed light on the possible mediation of the vagus nerve in this relationship.

Official Title
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Adiposité viscérale, Tonus Vagal et préférences Alimentaires : Une étude Pilote

Conditions
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Adiposity, Food Preferences, Eating Behavior

Intervention / Treatment
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* Other: Visceral adiposity


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Have a BMI between 18.5 and 35 kg/m²; French-speaking; Be able to travel to the Research Center of the Institut Universitaire de Cardiologie et Pneumologie de Québec for an investigative visit. Exclusion Criteria: Smokers ; Women who know they are pregnant, breastfeeding or menopausal; Who have been diagnosed with type I or type II diabetes; Having undergone bariatric surgery or obesity medication (GLP1 analogue, naltrexon-bupropion combination, etc.); Presenting an allergy or intolerance to one of the products used in the sensory tests (taste test: sucrose, sodium chloride, citric acid, quinine hydrochloride dihydrate; olfactory test: citrus, lemongrass, cinnamon, mint, peppermint, banana, anise, turpentine, garlic, coffee, apple, clove, pineapple, rose, geranium, eucalyptus, wormwood, fennel, caraway, leather, n-butanol, linalool, pyridine, diethyl phthalate, propylene glycol); Have a history of pathologies which, in the investigator's opinion, could interfere with the study criteria, such as ENT, neurological, upper digestive or cardiac pathologies; Receiving long-term pharmacological treatment, in particular antidepressants, antipsychotics, benzodiazepines, beta-blockers, etc. ; Presenting or having presented in the last 6 months a thymic episode such as depression, bipolar disorder, etc. ; Wearing a cardiostimulator (pacemaker); Minors or adults under guardianship.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Visceral Adiposity<br>No intervention to be adminstrated. Participants will be considered based on their visceral adiposity (ctageorial and continous). Visceral adiposity index is computed with BMI, waist circumference, triglyceridemia, HDL-cholesterol levels, and biological sex. | Other: Visceral adiposity<br>* Visceral adiposity assess by the visceral adiposity index<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Taste Strips total score | Taste identification score for sweet, salty, bitter, and sour (/16). The test used is Taste Strips (ODOFIN, Burghart Messtechnik GmbH, Holm, Germany). | Baseline | 
| TDI score, or Sniffin Sticks total score | Olfaction score based on odor detection (Threshold), Discrimination, and Identification (/48). The test used is Sniffin Sticks (ODOFIN, Burghart Messtechnik GmbH, Holm, Germany). | Baseline | 
| Explicit liking score for high-fat/sweet foods | Explicit liking will be measured using visual analog scales anchored at each end with not at all and extremely to answer the question How pleasant would it be to taste this food now? while seeing pictures of food items. (/100) The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Explicit liking score for high-fat/savoury foods | Explicit liking will be measured using visual analog scales anchored at each end with not at all and extremely to answer the question How pleasant would it be to taste this food now? while seeing pictures of food items. (/100) The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Explicit liking score for low-fat/high-sweet foods | Explicit liking will be measured using visual analog scales anchored at each end with not at all and extremely to answer the question How pleasant would it be to taste this food now? while seeing pictures of food items. (/100) The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Explicit liking score for low-fat/savoury foods | Explicit liking will be measured using visual analog scales anchored at each end with not at all and extremely to answer the question How pleasant would it be to taste this food now? while seeing pictures of food items. (/100) The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Explicit wanting score for high-fat/sweet foods | Explicit wanting will be measured using visual analog scales anchored at each end with not at all and extremely to answer the question How much would like to eat some of this food now? while seeing pictures of food items. (/100) The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Explicit wanting score for high-fat/savoury foods | Explicit wanting will be measured using visual analog scales anchored at each end with not at all and extremely to answer the question How much would like to eat some of this food now? while seeing pictures of food items. (/100) The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Explicit wanting score for low-fat/sweet foods | Explicit wanting will be measured using visual analog scales anchored at each end with not at all and extremely to answer the question How much would like to eat some of this food now? while seeing pictures of food items. (/100) The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Explicit wanting score for low-fat/savoury foods | Explicit wanting will be measured using visual analog scales anchored at each end with not at all and extremely to answer the question How much would like to eat some of this food now? while seeing pictures of food items. (/100) The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Implicit wanting score for high-fat/sweet foods | Implicit wanting will be calculated using a forced-choice task. It involves the presentation of successive pairs of food pictures, each pair being the object of a spontaneous preferential choice by the volunteer. A score is calculated from the frequency of choice and non-choice of said category and the reaction time of the participants. This score ranges from -100 to 100 and is interpreted in relation to the scores for the other food categories assessed in the task. A positive score indicates that the food category under consideration was chosen more often and more quickly than the others. A negative score indicates the opposite. The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Implicit wanting score for high-fat/savoury foods | Implicit wanting will be calculated using a forced-choice task. It involves the presentation of successive pairs of food pictures, each pair being the object of a spontaneous preferential choice by the volunteer. A score is calculated from the frequency of choice and non-choice of said category and the reaction time of the participants. This score ranges from -100 to 100 and is interpreted in relation to the scores for the other food categories assessed in the task. A positive score indicates that the food category under consideration was chosen more often and more quickly than the others. A negative score indicates the opposite. The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Implicit wanting score for low-fat/sweet foods | Implicit wanting will be calculated using a forced-choice task. It involves the presentation of successive pairs of food pictures, each pair being the object of a spontaneous preferential choice by the volunteer. A score is calculated from the frequency of choice and non-choice of said category and the reaction time of the participants. This score ranges from -100 to 100 and is interpreted in relation to the scores for the other food categories assessed in the task. A positive score indicates that the food category under consideration was chosen more often and more quickly than the others. A negative score indicates the opposite. The task used is the Leeds Food Preference Questionnaire. | Baseline | 
| Implicit wanting score for low-fat/savoury foods | Implicit wanting will be calculated using a forced-choice task. It involves the presentation of successive pairs of food pictures, each pair being the object of a spontaneous preferential choice by the volunteer. A score is calculated from the frequency of choice and non-choice of said category and the reaction time of the participants. This score ranges from -100 to 100 and is interpreted in relation to the scores for the other food categories assessed in the task. A positive score indicates that the food category under consideration was chosen more often and more quickly than the others. A negative score indicates the opposite. The task used is the Leeds Food Preference Questionnaire. | Baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Standard deviation of the N-N interval (SDNN) | Parameter of the heart rate variability, indirect indicator of the vagal tone (ms). Standard deviation of NN intervals. Measured using a 48 hours Holter monitor. | Baseline | 
| pNN50 | Parameter of the heart rate variability, indirect indicator of the vagal tone (%). Percentage of successive R-R intervals that differ by more than 50 ms. Measured using a 48 hours Holter monitor. | Baseline | 
| Root mean square of successive N-N interval difference (RMSSD) | Parameter of the heart rate variability, indirect indicator of the vagal tone (ms). Root mean square of successive R-R interval differences. Measured using a 48 hours Holter monitor. | Baseline | 
| Low Frequency (LF) | Parameter of the heart rate variability, indirect indicator of the vagal tone (ms²). Power spectral density of low frequencies. Measured using a 48 hours Holter monitor. | Baseline | 
| High Frequency (HF) | Parameter of the heart rate variability, indirect indicator of the vagal tone (ms²). Power spectral density of high frequencies. Measured using a 48 hours Holter monitor. | Baseline | 
| LF/HF ratio | Parameter of the heart rate variability, indirect indicator of the vagal tone (a.u.). Measured using a 48 hours Holter monitor. | Baseline | 
| Sweet Perceived Intensity | Measured during the Taste Strips using 9 Likert scales ranging from no taste to intense will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Salty Perceived Intensity | Measured during the Taste Strips using 9 Likert scales ranging from no taste to intense will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Bitter Perceived Intensity | Measured during the Taste Strips using 9 Likert scales ranging from no taste to intense will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Sour Perceived Intensity | Measured during the Taste Strips using 9 Likert scales ranging from no taste to intense will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Sweet Perceived Appreciation | Measured during the Taste Strips using 9 Likert scales ranging from extremely unpleasant to extremely pleasant will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Salty Perceived Appreciation | Measured during the Taste Strips using 9 Likert scales ranging from extremely unpleasant to extremely pleasant will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Bitter Perceived Appreciation | Measured during the Taste Strips using 9 Likert scales ranging from extremely unpleasant to extremely pleasant will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Sour Perceived Appreciation | Measured during the Taste Strips using 9 Likert scales ranging from extremely unpleasant to extremely pleasant will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Odors Perceived Intensity | Measured during the Sniffin Sticks (identification test) using 9 Likert scales ranging from no odor to intense will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Odors Perceived Appreciation | Measured during the Sniffin Sticks (identification test) using 9 Likert scales ranging from extremely unpleasant to extremely pleasant will be used. A score ranging from 1 to 9 will be calculated. | Baseline | 
| Satiety volume as a percentage of total volume (Water Load Task) | Indicator of gastric interoceptive capacities obtained during the Water Load Task. | Baseline | 
| Beck Depression Inventory II (BDI-II) score | Evaluates severity of depressive symptoms using a validated questionnaire. Minimum score : 0; Maximun score : 63; Higher scores mean a worse outcome. | Baseline | 
| State-Trait Anxiety Inventory (STAI) score | Evaluates severity of anxiety symptoms using a validated questionnaire. The questionnaire includes two scales (20 items) consisting of a total of 40 questions. For each scale the minimum score is 0 and the maximun score is 80. Higher scores mean a worse outcome. | Baseline | 
| Eating Disorder Examination Questionnaire (EDE-Q) score | Evaluates presence of eating disorders using a validated questionnaire. The measure provides four attitudinal subscale scores: Restraint (5 items), Eating Concern (5 items), Shape Concern (8 items), and Weight Concern (5 items). An overall Global score is the mean of the four subscale scores. Responses are on a 7-point ordinal response; minimum score : 0, maximun score: 6; higher scores mean a worse outcome. | Baseline | 
| Food Craving Trait Questionnaire (FCQ T) score | Evaluates severity of cravings using a validated questionnaire. Minimum : 39; Maximum : 234; Higher scores mean a worse outcome. | Baseline | 
| Food Craving State Questionnaire (FCQ S) score | Evaluates severity of cravings using a validated questionnaire. Minimum : 15; Maximum : 75; Higher scores mean a worse outcome. | Baseline | 
| Body Awareness Questionnaire (BAQ) score | Evaluates attention to intern signals (interoception) using a validated questionnaire. Minimum score: 18; Maximun score: 126; Higher scores mean a better outcome. | Baseline | 
| CCK fasting blood levels | Fasting blood sample. (mmol/L) | Baseline | 
| PYY fasting blood levels | Fasting blood sample. (mmol/L) | Baseline | 
| GLP-1 fasting blood levels | Fasting blood sample. (mmol/L) | Baseline | 
| Glicentine fasting blood levels | Fasting blood sample. (mmol/L) | Baseline | 
| Oxytomodulin fasting blood levels | Fasting blood sample. (mmol/L) | Baseline | 
| LPS fasting blood levels | Associated with adipose tissue dysfunction. Fasting blood sample. (mmol/L) | Baseline | 
| IL-6 fasting blood levels | Associated with adipose tissue dysfunction. Fasting blood sample. (mmol/L) | Baseline | 
| Fasting Glycemia | Fasting blood sample. (mmol/L) | Baseline | 
| Fasting Insulinemia | Fasting blood sample. (pmol/L) | Baseline | 
| Appetite scores | Calculated on the basis of a rating from 0 to 10 for each of the following parameters: sensation of hunger, desire to eat, satiation and prospective consumption. These ratings will be estimated using 100 mm-long visual analog scales annotated with not at all and extremely, on the left and right of the scale respectively, to answer the following questions: At the moment, how hungry are you?, At the moment, how hungry are you?, At the moment, how hungry are you? and At the moment, how hungry do you think you are?. Before each tests on the exploration day (taste, olfaction, LFPQ, Water Load Task, questionnaires) | Baseline |