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

背景：人类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被认为与味觉敏感有关，随后与食物偏好和食物摄入量有关。超重/肥胖的人对脂肪酸的检测阈值较高，表明对口腔中的脂肪酸的敏感度降低。事实上，过度肥胖引发的炎症可能会影响口感，并导致过度消费高能量食物。然而，已经证明，控制饮食摄入量可以改变味觉阈值，甚至对口腔的急性刺激(或感觉刺激)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、口感刺激和嗅觉。研究方法：这项研究计划将通过招募拥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、肥胖状况以及味觉和嗅觉之间的关系。本研究的具体目的是：1)进行按基因控制回忆的感官评估实验，以表征具有相似味觉遗传背景的肥胖和消瘦个体之间的味觉敏感性和享乐喜好。2)确定短期膳食脂肪限制对口腔脂肪味觉检测和味觉基因表达的影响。3)根据肥胖状况和遗传特征，确定餐前化学感觉漱口水(或感觉刺激)对食欲、食物摄入量和基因表达的影响。4)检测肥胖和瘦的受试者对甜味和脂肪气味样本的嗅觉，这些受试者具有相同的脂肪和甜味感知基因背景。将检查现有的遗传和身体成分数据，以根据预先指定的标准确定重新接触的潜在合格参与者。那些符合纳入标准的人将被邀请参加一系列研究，根据性别、遗传背景和肥胖状况评估感觉结果。这些研究的特点是：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)餐前食欲和进食行为刺激后的食欲和进食行为结果，以及4)味觉基因和肥胖症状态匹配的嗅觉结果。意义：这项研究将阐明遗传、肥胖和暴露在味觉、嗅觉和食物偏好中的作用，这将有助于理解与化学感官检测和食物偏好有关的多种因素。

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.