Grant: Discovery Grants Program - Individual

The flavour of food and beverages strongly influences their liking and consumption, and consequently a range of nutritional and health outcomes. Therefore, differences between individuals in their perception of chemosensory stimuli (taste, smell and touch, which together form the construct of flavour) can associate with differences in habitual dietary intake and risk of diet-related disease. For example, individuals who sense dietary sugar and fat less intensely may require them in higher concentrations to reach optimal liking and thus habitually consume greater amounts, increasing their risk of energy over-consumption, obesity and related disease. Arguably, the most important factor accounting for differences between people in perception of chemosensory stimuli is genetic variation. Two taste phenotypes believed to play important roles in chemosensation are PROP responsiveness and thermal tasting (TT). PROP responsiveness has been used as a marker of genetic variability in the perception of taste for some time. Individuals are often classified as PROP non-tasters (those for whom PROP elicits no or slight bitterness), PROP medium-tasters (those for whom PROP is mildly bitter) or PROP super-tasters (those for whom PROP is intensely bitter). Differential bitterness of PROP associates with variation in the TAS2R38 gene. Importantly, heightened responsiveness to PROP (e.g. supertasting) is associated with greater responsiveness to and discrimination between a wide range of sensations elicited by food and alcoholic beverages. By contrast, TT is a relatively new marker of individual variation in oral sensation, and refers to the capacity of many individuals to experience ?phantom? tastes when a small area of the tongue is heated and/or cooled. Evidence from Trpm5 knockout mice suggests that TRPM5, a TRP superfamily cation channel, plays a role in TT. Importantly, not only do thermal tasters perceive a taste sensation from thermal stimuli, they also rate tastes and chemesthetic sensations more intense than thermal non-tasters; a finding that extends to some alcoholic beverages. How these differences in chemosensation (particularly TT) are reflected in liking, preference and intake of food and alcoholic beverages, has only been partially explored in the literature, and forms the basis of this research proposal. The primary short-term objectives here are to: (1) determine if TT and PROP responsiveness associate with enhanced retronasal olfaction and finer discrimination of oral sensations, (2) characterise TT sub-types, (3) identify the key genetic variations associated with TT in humans, (4) elucidate whether TT predicts liking and perception of sampled foods, and (5) examine the relationships between these taste phenotypes and behaviour towards foods and beverages linked to habitual diet-related disease risk. The long-term objective is to more fully understand biologically based variation in flavour perception of food and beverages between people. Most of the $140 billion of food consumed annually in Canada is produced domestically; the results from this research will eventually assist Canadian producers to optimise the flavour and acceptance of their products, and increase market share through improved selection of raw materials and production practices, and innovative approaches to segmenting the market based on taste phenotypes. Additionally, identifying the genes and taste phenotype characteristics that associate with alcohol use/misuse and habitual diet-related disease will allow Canada to instigate appropriate screening and preventative interventions.