Assessment of Reward Responses to Erythritol Using Flavor Preference Learning

Assessment of Reward Responses to Erythritol Using Flavor Preference Learning and Its Effects on Gastrointestinal Hormones, Glycemic Control, Appetite-related Sensations and Emotional State

The aim of this project is to investigate the reward responses to oral erythritol compared to sucrose and sucralose using flavor preference learning in healthy participants. In addition, the release of GI hormones, glycemic control, appetite-related sensations, and emotional state in response to erythritol will be investigated.

This trial is a randomized, double-blind, cross-over study; the project set-up will be single-centre, national. The study is composed of six visits: one screening visit, one pre-test visit, three conditioning visits, and one post-test visit. The screening and pre-test will last about two hours, the conditioning days and the post-test day about 4 hours each. During the screening participants take part in a 6-n-propylthiouracil (PROP) sensitivity test to exclude potential supertasters. Moreover, the participants will rate explicit liking and explicit wanting of 10 non-caloric flavored and colored beverages in a randomized order (flavor preference learning). The pre-test visit consists of two parts. First, a chemosensory sweetness matching will be performed, during which we will establish dose-response relationships for perceived sweetness of sucrose, erythritol, and sucralose using equisweet watery solutions across a range of concentrations. Second, the participants will perform a triangle test to ensure that they cannot distinguish the matched erythritol and sucralose solutions from a 10% sucrose solution.

During the 3 conditioning visits, participants will be presented with three conditioning trials (at t = 0, 45, and 90min), each consisting of drinking 100mL of the flavored drink (CS) paired with one of the sweet substances (US = erythritol, sucrose, or sucralose).

In post-test visit, preference for each of the 3 flavored CS drinks will be assessed and a computerized forced choice task will be completed by the participants.

Inclusion Criteria:

• Healthy normal weight participants with a body-mass index (BMI) of 19.0-24.9 kg/m2
• Age 18-55 years
• Stable body weight (±5%) for at least three months
• Able to give informed consent as documented by signature
• 3 drinks rated as neutral and novel (from the flavor preference learning)

Exclusion Criteria:

• Non-taster (deficits of taste and smell) or supertaster
• Fructose intolerance
• Shift worker
• Pre-existing regular consumption of erythritol and/or sucralose and/or aspartame (>1/week)
• Substance abuse (more than 1 glass wine/beer per day; consumption of cannabis, cocaine, heroin, etc.)
• Regular intake of medications, except contraceptives
• Chronic or clinically relevant acute infections
• Pregnancy: although no contraindication, pregnancy might influence metabolic state.
• Participation in another study with investigational drug within the 30 days preceding and during the present study
• Pre-existing diet (vegetarian, vegan, sugar free)
• Inability to follow procedures due to psychological disorders or insufficient knowledge of project language (German)
• Calculated dose of erythritol outside the range of 30-60g (per 300mL) (from the sweetness matching)