Plasticity of sweet taste: importance of diet and receptor expression in taste buds

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PROJECT SUMMARY Consumers report taste as the number one driver of food choice. Yet, taste perception can vary greatly across individuals and is associated with dietary preferences and food choice, with potential to impact nutrition and health. Conversely, dietary habits are known to impact taste response. For example, diets high in sugary foods and beverages are associated with reduced sweet taste function. However, the pathway in which humans experience plasticity of the sweet taste perception has yet to be elucidated. A recent study in a mouse model suggests that dietary exposure to saccharin modulates gene expression of a sweet taste receptor. The overall research goal of the present proposal is to establish fundamental knowledge of sweet taste receptor biology in humans, in terms of dietary intake, taste perception, and individual characteristics. Our hypothesis is that greater exposure to sweet foods and beverages will be associated with lower sweet taste function and reduced expression of the sweet taste receptor gene. Thus, our Aims are to investigate the expression of the sweet taste receptor in human taste buds in regards to 1) intake of sweet foods and beverages, 2) modulation due to exposure to sweet stimulus, and 3) individual characteristics (e.g., taste genetics). We will achieve these aims by combining interdisciplinary approaches between biology and sensory psychophysics. Using a non-invasive biopsy procedure, we can collect taste buds from human lingual tissue by harvesting fungiform papillae. Using these tissues, we can quantify expression levels of taste receptor genes, allowing for qualifying the relationship with taste function and explore how exposure modulates expression levels over time. This proposal includes two human subject studies, a cross-sectional study looking between high and low consumers of sweet foods and beverages and a 5-week longitudinal exposure study. Both studies include measures of taste intensity and sensitivity, intake and preferences for sweet foods and beverages, fungiform papillae density, taste receptor genetics, and taste receptor expression. The proposed study will provide new information regarding the molecular and cellular mechanisms regulating sweet taste receptor expression and further establish a link between dietary intake, taste psychophysics, and food behavior. A greater understanding of the plasticity of sweet taste and its underlying mechanism may contribute to clinical significance in understanding of the health implications linked with consumption of sweet foods and beverages, such as obesity and diabetes. Long-term objectives include identifying strategies to improve taste perception through dietary modification. This would be impactful for individuals with reduced or altered taste function in order to improve dietary quality and nutrition.