The roles of genetic variation, adiposity, and diet in sensory perception and food preferences.

背景：人的摄食行为是一个复杂的过程，在分子水平上受多种因素的影响。几种常见的基因变异与味觉敏感性有关，随后与食物偏好和食物摄入量有关。超重/肥胖个体对脂肪酸的检测阈值较高，表明口腔对脂肪酸的敏感性降低。事实上，过度肥胖引起的炎症可能会损害味道，导致过度食用高能量食物。然而，对饮食摄入的控制已被证明可以改变味觉阈值，甚至对口腔的急性刺激（口腔感觉刺激）也会影响包括食欲在内的生理结果。此外，味觉基因在嗅觉组织中表达，但之前没有研究评估味觉基因变体的嗅觉能力。因此，有机会通过考虑暴露、肥胖和基因组因素来更全面地评估味觉、外感刺激和嗅觉。方法：本研究计划将通过招募已有全基因组基因分型数据的先前研究参与者来评估遗传学、肥胖状况、味觉和嗅觉感知之间的关系。具体目的是：1)在味觉遗传背景相似的肥胖个体和瘦弱个体之间，通过基因型记忆控制感官评价实验来表征其味觉敏感性和享乐喜好。2)确定短期限脂饮食对口腔脂肪味觉检测及味觉基因表达的影响。3)根据肥胖状况和基因谱，确定餐前化学感官漱口水（口腔感官刺激）对食欲、食物摄入和基因表达的影响。4)在具有相同的脂肪和甜味感知遗传背景的肥胖和苗条参与者之间，检查甜味和脂肪气味样本的嗅觉感知。将检查现有的遗传和身体成分数据，以根据预先规定的标准确定潜在的合格参与者进行再接触。那些符合纳入标准的人将被邀请参加一系列的研究，根据性别、遗传背景和肥胖状况来评估感官知觉结果。研究将描述1)基线味觉检测阈值，2)短期饮食脂肪限制后的味觉检测阈值，3)使用交叉设计的化学感觉漱口水进行餐前味觉刺激后的食欲和摄食行为结果，以及4)味觉基因和肥胖状态匹配的嗅觉结果。意义：本研究将阐明遗传、肥胖和暴露在味觉、嗅觉和食物偏好中的作用，这将有助于理解化学感觉检测和食物偏好的多重因素。

Background: Human ingestive behaviour is a complex process influenced by many factors at molecular levels. Several common genetic variants have been implicated in taste sensitivity with subsequent links to food preferences and food intake. Overweight/obese individuals demonstrate higher detection thresholds for fatty acids, indicating reduced sensitivity to fatty acids in the oral cavity. Indeed, inflammation induced by excess adiposity may compromise taste and lead to overconsumption of energy-dense foods. However, manipulation of dietary intake has been demonstrated to alter taste thresholds and even acute stimulation of the oral cavity (oro-sensory stimulation) impacts physiological outcomes including appetite. Moreover, taste genes are expressed in olfactory tissues, but no previous work has evaluated olfactory abilities across taste gene variants. Thus, opportunities exist to more comprehensively evaluate taste perception, oro-sensory stimulation, and olfaction by considering exposure, adiposity, and genomic factors. Approach: This research program will evaluate relationships between genetics, adiposity status, and taste and olfactory perception by recruiting previous research participants who have genome-wide genotyping data available. The specific aims are to: 1) Conduct a recall-by-genotype controlled sensory evaluation experiment to characterize taste sensitivities and hedonic liking between obese and lean individuals with similar taste genetic backgrounds. 2) Determine the effect of short-term dietary fat restriction on fat taste detection and expression of taste genes in the oral cavity. 3) Determine the effect of pre-meal chemosensory mouth rinses (oro-sensory stimulation) on appetite, food intake, and gene expression according to adiposity status and genetic profiles. 4)Examine olfactory perception of aromas from sweet and fat odor samples between obese and lean participants with the same genetic background for fat and sweet taste perception. Existing genetic and body composition data will be examined to identify potential eligible participants for recontact according to prespecified criteria. Those who meet the inclusion criteria will be invited to participate in a series of studies to evaluate sensory perception outcomes according to sex, genetic background and adiposity status. The study sessions will characterize 1) baseline taste detection thresholds, 2) taste detection thresholds after a short-term period of dietary fat restriction,  3) appetite and ingestive behaviour outcomes following pre-meal oro-sensory stimulation with chemosensory mouth rinses using a crossover design, and 4) olfactory outcomes matching for taste genes and adiposity status. Significance: This research will clarify the roles of genetics, adiposity, and exposure in taste, olfaction, and food preferences, which will be relevant for understanding the multiple factors implicated in chemosensory detection and food preferences.