Flavor perception and ingestive behavior in women after metabolic surgery

Nicanor Carreon, Jessica Gabriela

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https://hdl.handle.net/2142/124654 Copy

Description

Title

Flavor perception and ingestive behavior in women after metabolic surgery

Author(s)

Nicanor Carreon, Jessica Gabriela

Issue Date

2024-04-16

Director of Research (if dissertation) or Advisor (if thesis)

Pepino de Gruev, Marta Y

Doctoral Committee Chair(s)

Amengual Terrasa, Jaime

Committee Member(s)

• Cadwallader, Keith R
• Rowitz, Blair

Department of Study

Nutritional Sciences

Discipline

Nutritional Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Flavor
• taste
• smell
• ingestive behavior
• bariatric surgery
• metabolic surgery
• sleeve gastrectomy
• gastric bypass

Abstract

Metabolic surgeries are the most effective evidence-based treatment for severe obesity and its comorbidities. These surgical procedures promote many physiological and ingestive behavior changes that are not fully understood. In Chapter 1, we reviewed the literature on how these surgeries are associated with changes in taste and smell perception. However, we discussed how, despite most patients reporting changes in their “taste” and “smell” perception post-surgery, findings from research studies that assess patients using validated sensory evaluation techniques showed little to no evidence that metabolic surgeries change taste or smell function. For instance, sensory studies in our laboratory found no changes in perceived taste intensity or sensitivity in participants evaluated longitudinally before and 6 months after surgery. However, these studies were conducted using pure gustatory stimuli (e.g., sugar in water or salt in water) without an olfactory component, and participants were assessed after an overnight fast. Therefore, it is uncertain whether patients’ self-reported “taste changes” could be captured 1) when participants are assessed 2 or more years post-surgery (rather than a few months after surgery), 2) when using more complex sensory stimuli closer to food that allows the participation of retronasal smell/“flavor” (not merely gustatory stimulation), or 3) when participants are assessed during the fed state (not after overnight fasting), due to the profound surgery-related changes in postprandial responses. In contrast to the lack of changes in taste sensitivity or the perception of taste intensity post-surgery, we found consistent evidence for reductions in the pleasure derived from tasting sweetness and high-fat foods pre- to post-bariatric surgery among different studies both in patients and in preclinical models which suggest surgery-related changes in central circuits of reward. For example, previous studies in our laboratory found that metabolic surgeries, at least in the short term, can change the hedonic value of sweetness. That is, these previous studies revealed that there was a shift in sweet palatability ratings from pleasantness pre-surgery to unpleasantness 6 months post-surgery, along with improved eating behavior. However, whether these hedonic changes remain in the long term is unknown. Therefore, the overall goal of this dissertation is to investigate flavor perception (taste and retronasal odor interactions), hedonic responses, and ingestive behavior in women who underwent metabolic surgery at least 2 years ago. We aim to better understand changes in flavor perception following metabolic surgery because these changes could influence patients’ food choices, which, in turn, can impact surgery success, weight regain, and quality of life. This knowledge could aid in developing new personalized medical and nutritional therapies against obesity. Our research overcame several challenges imposed by the COVID-19 pandemic; for instance, all laboratories were closed to direct human subject research, and elective surgeries were placed on hold. Therefore, we leveraged the opportunity to investigate associations between maladaptive ingestive behaviors and weight regain in women with a history of metabolic surgery using a web-based survey study design. Our survey study included well-validated questionnaires that assess emotional, external, and restrained eating behavior, food cravings, and other ingestive behaviors such as drinking alcohol. In addition to eating behavior, we were interested in alcohol drinking because these surgeries are associated with an increased risk for alcohol misuse. The findings of this study are described in Chapter 2. In Chapters 3 and 4, we described a research study conducted once direct human research was resumed. Here, we used a cross-sectional study design to compare sensory responses in women who underwent two of the most frequently performed metabolic surgeries in the US and the world: Roux-en-Y gastric bypass (RYGB) and Sleeve gastrectomy (SG) with non-operated controls. The study design included three groups: women who underwent RYGB or SG at least 2 and no more than 6 years ago (n=15; surgery group) and two non-operated control groups: a BMI equivalent group (n=15) and a healthy BMI group (n=15), and two separate sensory visits: one where participants were assessed when fed and one where participants were assessed when fasted. We also aimed to determine whether the perceived interactions between taste and retronasal odors differed between the groups and to what extent the decreased pleasantness for sweets and improved eating behaviors observed within the first year post-surgery remained after 2 years. We hypothesized that taste and odor interactions and the assessment of habituation to the pleasantness derived when repetitively tasting sweets would be more affected by feeding conditions (i.e., fed vs. fasted) in the surgery group than in the control groups due to the profound surgery-related changes in postprandial physiological responses. We also hypothesized that at least some of the changes in the hedonic value of sweetness and the improvements in eating behavior traits observed in previous studies in the short term would still be apparent when patients were evaluated 2-6 years post-surgery. We conclude the dissertation by summarizing our findings and suggesting avenues for future research in Chapter 5.

Graduation Semester

2024-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2024 Jessica Nicanor Carreon

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