Exploring the neural correlates of fat taste perception and discrimination: Insights from electroencephalogram analysis.

Understanding neural pathways and cognitive processes involved in the transformation of dietary fats into sensory experiences has profound implications for nutritional well-being. This study presents an efficient approach to comprehending the neural perception of fat taste using electroencephalogram (EEG). Through the examination of neural responses to different types of fatty acids (FAs) in 45 participants, we discerned distinct neural activation patterns associated with saturated versus unsaturated fatty acids. The spectrum analysis of averaged EEG signals revealed notable variations in δ and α-frequency bands across FA types. The topographical distribution and source localization results suggested that the brain encodes fat taste with specific activation timings in primary and secondary gustatory cortices. Saturated FAs elicited higher activation in cortical associated with emotion and reward processing. This electrophysiological evidence enhances our understanding of fundamental mechanisms behind fat perception, which is helpful for guiding strategies to manage hedonic eating and promote balanced fat consumption.

Orosensory Detection of Dietary Fatty Acids Is Altered in CB1R-/- Mice.

Obesity is one of the major public health issues, and its prevalence is steadily increasing all the world over. The endocannabinoid system (ECS) has been shown to be involved in the intake of palatable food via activation of cannabinoid 1 receptor (CB1R). However, the involvement of lingual CB1R in the orosensory perception of dietary fatty acids has never been investigated. In the present study, behavioral tests on CB1R-/- and wild type (WT) mice showed that the invalidation of Cb1r gene was associated with low preference for solutions containing rapeseed oil or a long-chain fatty acid (LCFA), such as linoleic acid (LA). Administration of rimonabant, a CB1R inverse agonist, in mice also brought about a low preference for dietary fat. No difference in CD36 and GPR120 protein expressions were observed in taste bud cells (TBC) from WT and CB1R-/- mice. However, LCFA induced a higher increase in [Ca2+]i in TBC from WT mice than that in TBC from CB1R-/- mice. TBC from CB1R-/- mice also exhibited decreased Proglucagon and Glp-1r mRNA and a low GLP-1 basal level. We report that CB1R is involved in fat taste perception via calcium signaling and GLP-1 secretion.

Effects of CD36 Genotype on Oral Perception of Oleic Acid Supplemented Safflower Oil Emulsions in Two Ethnic Groups: A Preliminary Study.

Previous studies demonstrate humans can detect fatty acids via specialized sensors on the tongue, such as the CD36 receptor. Genetic variation at the common single nucleotide polymorphism rs1761667 of CD36 has been shown to differentially impact the perception of fatty acids, but comparative data among different ethnic groups are lacking. In a small cohort of Caucasian and East Asian young adults, we investigated if: (1) participants could detect oleic acid (C18:1) added to safflower oil emulsions at a constant ratio of 3% (w/v); (2) supplementation of oleic acid to safflower oil emulsions enhanced perception of fattiness and creaminess; and (3) variation at rs1761667 influenced oleic acid detection and fat taste perception. In a 3-alternate forced choice test, 62% of participants detected 2.9 ± 0.7 mM oleic acid (or 0.08% w/v) in a 2.8% safflower oil emulsion. Supplementation of oleic acid did not enhance fattiness and creaminess perception for the cohort as a whole, though East Asians carrying the GG genotype perceived more overall fattiness and creaminess than their AA genotype counterparts (P < 0.001). No differences were observed for the Caucasians. These preliminary findings indicate that free oleic acid can be detected in an oil-in-water emulsion at concentrations found in commercial oils, but it does not increase fattiness or creaminess perception. Additionally, variation at rs1761667 may have ethnic-specific effects on fat taste perception.

Detection thresholds for four different fatty stimuli are associated with increased dietary intake of processed high-caloric food.

BMI-specific differences in food choice and energy intake have been suggested to modulate taste perception. However, associations between body composition and fat taste sensitivity are controversial. The objective of this study was to examine the association between body composition, dietary intake and detection thresholds of four fatty stimuli (oleic acid, paraffin oil, canola oil, and canola oil spiked with oleic acid) that could be perceived via gustatory and/or textural cues. In 30 participants, fat detection thresholds were determined in a repeated measurements design over twelve days. Weight status was examined by measuring the participants' BMI, waist circumference and waist-to-hip ratio. The habitual food intake was assessed via several questionnaires and twelve, non-consecutive 24-hour food diaries. In this study, a negative correlation was found between fat detection thresholds and the intake of food rich in vitamins and fibre. Moreover, a positive correlation was identified between the intake of high-fat food and fat detection thresholds. No differences in fat detection thresholds were observed due to variations in BMI or waist-to-hip ratio. These findings indicate that a regular intake of fatty foods might decrease an individuals' perceptual response to fats which might lead to excess fat intake on the long term.

Oil Perception-Detection Thresholds for Varying Fatty Stimuli and Inter-individual Differences.

Multiple lines of research have demonstrated that humans can perceive fat in the form of free fatty acids (FFAs). However, the dietary concentration of FFAs is generally very low and fat is mainly consumed as triacylglycerol (TAG). The aim of this study was to examine the perception of different fatty stimuli and possible associations between them. Therefore, detection thresholds for 4 fatty stimuli (oleic acid [FFA], paraffin oil [mixture of hydrocarbon molecules], canola oil [TAG-rich], and canola oil spiked with oleic acid [rich in TAGs and FFAs]) were determined in 30 healthy participants. Additionally, inter-individual differences in fat perception were examined. It was observed that oleic acid was perceivable at significantly lower concentrations than all other stimuli (P < 0.001). Similarly, canola oil with oleic acid was detectable at lower concentrations than canola oil alone (P < 0.001). Moreover, canola oil detection thresholds were significantly lower than paraffin oil detection thresholds (P = 0.017). Participants who were sensitive for low concentrations for oleic acid showed lower detection thresholds for canola oil with and without oleic acid, compared with participants that were less sensitive for oleic acid. The results of this study demonstrate that the higher the concentrations of FFAs in the stimuli, the lower the individual fat detection threshold. Moreover, participants being sensitive for lower concentrations of FFAs are also more likely to detect low concentrations of TAG-rich fats as it is found in the human diet.

Fat Taste Sensitivity Is Associated with Short-Term and Habitual Fat Intake.

Evidence suggests individuals less sensitive to fat taste (high fat taste thresholds (FTT)) may be overweight or obese and consume greater amounts of dietary fat than more sensitive individuals. The aims of this study were to assess associations between FTT, anthropometric measurements, fat intake, and liking of fatty foods. FTT was assessed in 69 Australian females (mean age 41.3 (15.6) (SD) years and mean body mass index 26.3 (5.7) kg/m²) by a 3-alternate forced choice methodology and transformed to an ordinal scale (FT rank). Food liking was assessed by hedonic ratings of high-fat and reduced-fat foods, and a 24-h food recall and food frequency questionnaire was completed. Linear mixed regression models were fitted. FT rank was associated with dietary % energy from fat ( ß ^ = 0.110 [95% CI: 0.003, 0.216]), % energy from carbohydrate ( ß ^ = -0.112 [-0.188, -0.035]), and frequency of consumption of foods per day from food groups: high-fat dairy ( ß ^ = 1.091 [0.106, 2.242]), meat & meat alternatives ( ß ^ = 0.669 [0.168, 1.170]), and grain & cereals ( ß ^ = 0.771 [0.212, 1.329]) (adjusted for energy and age). There were no associations between FT rank and anthropometric measurements or hedonic ratings. Therefore, fat taste sensitivity appears to be associated with short-term fat intake, but not body size in this group of females.

Zizyphin modulates calcium signalling in human taste bud cells and fat taste perception in the mouse.

Zizyphin, isolated from Zizyphus sps. leaf extracts, has been shown to modulate sugar taste perception, and the palatability of a sweet solution is increased by the addition of fatty acids. We, therefore, studied whether zizyphin also modulates fat taste perception. Zizyphin was purified from edible fruit of Zizyphus lotus L. Zizyphin-induced increases in [Ca2+ ]i in human taste bud cells (hTBC). Zizyphin shared the endoplasmic reticulum Ca2+ pool and also recruited, in part, Ca2+ from extracellular environment via the opening of store-operated Ca2+ channels. Zizyphin exerted additive actions on linoleic acid (LA)-induced increases in [Ca2+ ]i in these cells, indicating that zizyphin does not exert its action via fatty acid receptors. However, zizyphin seemed to exert, at least in part, its action via bile acid receptor Takeda-G-protein-receptor-5 in hTBC. In behavioural tests, mice exhibited preference for both LA and zizyphin. Interestingly, zizyphin increased the preference for a solution containing-LA. This study is the first evidence of the modulation of fat taste perception by zizyphin at the cellular level in hTBC. Our study might be helpful for considering the synthesis of zizyphin analogues as 'taste modifiers' with a potential in the management of obesity and lipid-mediated disorders.