An Exploration into the Relationship between PROP Taster Status and the Dietary Intake of Sugars

Abstract

Background: The UK population’s intake of sugar greatly exceeds recommendations [1] and this has been linked to an increased incidence of dental caries and obesity [2]. 6-n-propylthiouracil (PROP) is a bitter tasting compound naturally present in foods and recent research suggests that taste sensitivity to PROP varies between individuals. However, the impact of PROP taster status (super-taster, taster or non-taster) upon dietary intakes, particularly sugars, has been poorly investigated [3]. Therefore, this study aimed to investigate whether dietary sugars intake differed between PROP taster status groups. Methods: 44 participants enrolled into a cross-sectional study via purposive sampling during December 2012 - February 2013. Ten participants were excluded due to exclusion criteria, ethical concerns or their withdrawal; 34 data samples were analysed. Exclusion criteria included those who had respiratory infections, diabetes, severe food allergies, ageusia, anosmia (including where caused by medication), been fitted with electronic implantable devices, were pregnant/lactating, suffered from an eating disorder, or ate/smoked/drank in the 2 hours prior to testing. PROP taster status was measured using the three-sample PROP/NaCl suprathreshold-scaling protocol and the general Labelled Magnitude Scale. Dietary sugars intake was assessed using an adapted USDA five-step multiple-pass 24-hour recall technique and analysed using Microdiet dietary assessment software. Data was analysed using all data sets (AD) and then with under-reporters (according to the proxy BMR:EI< 1.1) and miscalculated intakes (i.e. unreliable data) excluded (UDE). Relationships between total sugars intake (grams/day and as a percentage of total daily energy (%TDE)) and PROP taster status were statistically analysed using Shapiro-Wilk normality tests and one-way ANOVAs. Ethical approval was granted by the University of Chester ethics committee. Results: The 34 participants who completed this study were mostly Caucasian (n= 31), female (n= 27), healthy weight (n= 25) and degree-educated (n= 21), with a median age of 23 years, and were classified as super-tasters (n= 20), tasters (n= 6), or non-tasters (n= 8). Data variability was highest within the super-taster group for both sugars as grams/day (166.5 ± 131.9 AD; 193.2 ± 198.7 UDE) and %TDE (25 ± 9.8 AD; 22.7 ± 12.3 UDE), and lowest within the non-taster group (127.7 ± 39.4 AD; 149 ± 17.6 UDE) and taster group (24.8 ± 9.2 AD; 20 ± 0.3 UDE) for sugars as grams/day and %TDE respectively. Sugars intake (grams/day) tended to be highest within the super-taster group, and lowest within the taster group, showing a reverse J-shaped relationship amongst both data sets. This trend however, was not statistically significant (p = 0.288 AD; p = 0.641 UDE). Intake of sugars (%TDE) varied much more between data sets and PROP taster status groups and there were no clear relationships (p = 0.911 AD; p = 0.862 with UDE). Discussion: This study found no relationship betweenPROP taster status and dietary sugars intake, however a number of factors may explain this. These include: the variability in classifying PROP taster status between studies, the low participant sample, and possible confounding variables e.g. the ‘adventurous’ or ‘non-adventurous’ nature of super-tasters, other dietary intakes etc. This study supports findings of similar studies in this area and it is proposed future investigations should recruit a wider range and greater number of participants, limit potential confounding variables and all classify PROP taster status using the same method. Conclusion: Initial findings do not support a relationship between PROP taster status and dietary intake of sugars; at this stage PROP taster status cannot be used to predict sugars consumption.