The sweet taste study - Physiological role of sweet taste in glucose metabolism

Salame, Clara

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https://hdl.handle.net/2142/120551 Copy

Description

Title

The sweet taste study - Physiological role of sweet taste in glucose metabolism

Author(s)

Salame, Clara

Issue Date

2023-04-26

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

Pepino, Yanina M

Doctoral Committee Chair(s)

Teran-Garcia, Margarita

Committee Member(s)

• de Mejia, Elvira
• Miller, Michael

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)

• Sweet Taste
• Glucose Metabolism
• Obesity
• Sweeteners

Abstract

Low-calorie sweeteners (LCS), widely used as a substitute for sugars, provide sweetness with few, if any, calories. They work by activating sweet taste receptors (STRs) in the tongue. Although previously considered inert, recent studies suggest that by simply activating the sweet taste sensation, they might have metabolic effects. In a recent study, we showed that merely tasting (without swallowing) sucralose – the most used LCS- before consuming 75g of glucose during an oral glucose tolerance test (OGTT) decreased plasma insulin concentration in participants who were non-habitual consumers of LCS. Interestingly, the opposite effect that is people respond with an increase in insulin concentration to an OGTT in a study in which sweetness was inhibited by the presence of lactisole, a broad STR antagonist, in the glucose drink. The combined results of these two studies suggests that LCS have the potential to modify postprandial glucose regulation via the activation of the STR signaling. Remarkably, data from two separate clinical studies in subjects with obesity show that the ingestion of sucralose (rather than merely tasting sucralose) before an OGTT caused an increase in glucose-mediated insulin response. That the ingestion of sucralose affected insulin response to a glucose load goes in line with the possibility that LCS could activate extra-oral STR recently discovered in the gastrointestinal (GI) tract. In the studies described above, the effect of sucralose on glucose-mediated insulin response in people with obesity was not accompanied by a reduction in plasma glucose during the OGTT, suggesting that the acute consumption of sucralose before the glucose load was making insulin resistance get worst. Diets that increase insulin resistance contribute to an increased risk of developing diabetes, especially in people with obesity. Moreover, there are several factors that have been reported to influence glucose responses such as sex-related differences, STR genes, and dietary habits. It is not known, however, if the chronic consumption of LCS is associated with an alteration in the metabolic response to STR activation and taste perception. The long-term goal of this research is to further understand the role of sweet taste perception and the impact of habitual and high consumption of LCS on postprandial glucose responses. The overall objective of this proposal is to assess the extent to which habitual consumption of LCS associates with different metabolic responses to a glucose load in people with obesity. The central hypothesis is that chronic exposure to LCS is associated with a degraded response to an OGTT and a blunted perception of sweetness in people with obesity. The following specific aims will be assessed in people with obesity who are habitual consumers (HC; >5 diet sodas or equivalent per week) or non-habitual consumers (NHC; <1 packet of LCS or equivalent per week) of LCS. Using a randomized crossover design, we will compare glucose and hormonal responses to an OGTT and assess the extent to which sex, STR related genes, dietary habits, and sweet taste perception associate with different metabolic responses to a glucose load in people with obesity. Sweet taste perception will be evaluated in all subjects using a battery of validated human sensory tests, and dietary habits will be assessed using different validated questionnaires. Specific Aim 1: Determine sex-related differences in glucose metabolism in habitual vs non-habitual consumers of LCS who have obesity Habitual and non-habitual consumers will be subject to a 5.5hour long OGTT where they will have to drink a solution containing 75g glucose. The working hypotheses are that habitual consumption of LCS: 1) will increase insulin response without decreasing plasma glucose (i.e reduce insulin sensitivity) in non-habitual consumers of LCS, regardless of the sex 2) compared to females, males will have a higher levers and faster peak early on in NHC, HC will have a decrease in insulin sensitivity Specific Aim 2: Determine sweet taste sensitivity, intensity, and sweet preferences in habitual and non-habitual LCS consumers. Both groups will be subject to different sensory testing to assess the sensitivity, preference, and intensity of the sweet taste. The working hypothesis is that HC will have a blunted perception of sweetness compared to NHC and in turn, prefer higher sweetener concentrations. Specific Aim 3: Determine dietary intake and eating behaviors in people with obesity who are habitual and no-habitual consumers of LCS. All participants will answer questionnaires related to dietary intake and eating behaviors. The working hypothesis is that HC will have similar sugar and calorie intake compared to NHC. Specific Aim 4: Explore the association between individual genetic variation in a sweet taste receptor (TAS1R2) and glucose homeostasis. This will be achieved by analyzing T1R2-Ile191Val variant in participants and their metabolic responses to an OGTT. The working hypothesis is that carriers of the less common variant (T1R2-Ile191Val) will be associated with lower lower glucose, insulin, and c-peptide responses following an OGTT.

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

© 2023 Clara Salamé

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