Interindividual variability in appetitive sensations and relationships between appetitive sensations and energy intake.

BACKGROUND: Appetitive sensations (AS) are signals that guide eating behaviors. Marked short-term inter-individual variability in AS has been reported but the long-term stability of individual ratings and their dietary implications are not well characterized. OBJECTIVES: This study explored the stability of inter-individual ratings of hunger, fullness and thirst for 17 weeks; determined the relationships between these sensations, eating patterns and energy intake (EI); as well as the associations between ratings and selected individual characteristics (age, gender, BMI). METHODS: A 17-week observational study collected hourly appetitive ratings and dietary intake data from 97 (90 completers, 7 partial completers) healthy adults at weeks 1, 9, and 17. RESULTS: There were marked and stable inter-individual differences over the 17 weeks for hunger (week 1 vs. week 9, r = 0.72 (p < 0.001); week 1 vs. week 17, r = 0.67 (p < 0.001); week 9 vs. week 17, r = 0.77 (p < 0.001)); fullness (week 1 vs. week 9 r = 0.74 (p < 0.001); week 1 vs. week 17, r = 0.71 (p < 0.001); week 9 vs. week 17, r = 0.81 (p < 0.001)); and thirst (week 1 vs. week 9 r = 0.82 (p < 0.001); week 1 vs. week 17, r = 0.81 (p < 0.001); week 9 vs. week 17, r = 0.88 (p < 0.001)). Cross-correlation functions revealed EI and eating pattern exerted stronger effects on AS than the reverse. However, the absolute effect sizes were small. Path analyses also indicated that there were weak relationships between AS and EI. No robust effects of the studied individual characteristics were observed. CONCLUSION: This study found that acute and chronic sensations of hunger, fullness and thirst are relatively stable within individuals but vary markedly between individuals. In addition, the present data indicate AS are poorly associated with dietary patterns or with EI under conditions of relatively stable energy balance.

Positive nutrition: shifting the focus from nutrients to diet for a healthy lifestyle.

PURPOSE AND METHODS: This summary is based on a scientific symposium organized by the Mediterranean Diet Roundtable and the American Italian Food Coalition titled, 'Positive Nutrition: shifting focus from nutrients to diet for a healthy lifestyle.' It was held at the Embassy of Italy in Washington DC in September of 2022. The panel of experts discussed how science can inform policy, what insights may be gleaned from different countries' approaches to healthy eating and what principles of the Mediterranean diet will inform strategies for a healthy future. Recognizing that isolated actions have limited impact on the complex relationship between diet and obesity, the panel discussed the importance of a system approach. In particular, the panel emphasized that focusing on single ingredients, isolated food categories and narrow approaches to policy have had limited success across the globe. RESULTS AND CONCLUSION: The panel agreed that there is a need for change of perspective that embraces complexity and emphasizes more positive nutrition messaging and policies. LEVEL OF EVIDENCE: V, Opinions of respected authorities, based on descriptive studies, narrative reviews, clinical experience, or reports of expert committees.

Almond consumption decreases android fat mass percentage in adults with high android subcutaneous adiposity but does not change HbA1c in a randomised controlled trial.

The purpose of this study was to determine if the mixed evidence of almond consumption on HbA1c stems from testing people with different body fat distributions (BFD) associated with different risks of glucose intolerance. A 6-month randomised controlled trial in 134 adults was conducted. Participants were randomly assigned to the almond (A) or control (C) group based on their BFD. Those in the almond group consumed 1·5 oz of almonds with their breakfast and as their afternoon snack daily. Those in the control group continued their habitual breakfast and afternoon snack routines. Body weight and composition were measured and blood samples were collected for determination of HbA1c, glycaemia and lipaemia at 0 and 6 months. Appetite ratings, energy intake and diet quality were collected at 0, 2, 4 and 6 months. Participants consuming almonds ingested 816 (sem 364) kJ/d more than participants in the control group (P = 0·03), but this did not result in any differences in body weight (A: -0·3 (sem 0·4), C: -0·4 (sem 0·4); P > 0·3). Participants in the almond, high android subcutaneous adipose tissue (SAT) group had a greater reduction in android fat mass percentage (A: -1·0 (sem 0·6), C: 1·1 (sem 0·6); P = 0·04), preserved android lean mass percentage (A: 0·9 (sem 0·6), C: -1 (sem 0·6); P = 0·04) and tended to decrease android visceral adipose tissue mass (A: -13 (sem 53) g, C: 127 (sem 53) g; P = 0·08) compared with those in the control, high SAT group. There were no differences in HbA1c between groups (A: 5·4 (sem 0·04), C: 5·5 (sem 0·04); P > 0·05). Thus, BFD may not explain the mixed evidence on almond consumption and HbA1c. Long-term almond consumption has limited ability to improve cardiometabolic health in those who are overweight and obese but otherwise healthy.

Effects of whole peanut within an energy-restricted diet on inflammatory and oxidative processes in obese women: a randomized controlled trial.

BACKGROUND: Peanut consumption has little effect on body weight, despite its high energy density and is associated with reduced cardiovascular disease risk. Based on previous research, we hypothesized that the consumption of whole peanut would be associated with greater improvements in body composition, lipid profile, and biomarkers of inflammation and oxidative stress. METHODOLOGY: Twenty-four women with obesity [body mass index (BMI) > 30 kg m-2 ], 33.1 ± 8.7 years old, were assigned to three groups and consumed 56 g of whole peanut (WP), skinned peanut (SP), and no peanut (NP) and consumed energy-restricted diets (250 kcal d-1 less than their customary diet) for 8 weeks. RESULTS: WP group lost an average of 3.2 kg, while SP group lost 2.6 kg and the NP group 1.8 kg. However, only the groups that consumed peanuts showed a significant reduction in BMI. WP group presented lower body weight, BMI, waist circumference, total lean mass, and total body fat than the SP group in the eighth week. There was a significant reduction in total cholesterol and low-density lipoprotein (LDL) after 4 weeks of intervention, which was maintained in week-8 for the WP and SP groups. In addition, there was an improvement in platelets and plasma homocysteine with WP group. CONCLUSION: Our results suggest that the regular intake of the whole peanut as part of an energy-restricted diet showed health benefits since it enhanced body weight loss, besides improving body composition and reducing cholesterol, platelets, and homocysteine concentrations. © 2021 Society of Chemical Industry.

Perceptual Quality of Nonesterified Fatty Acids Varies with Fatty Acid Chain Length.

Nonesterified fatty acids (NEFA) are effective taste stimuli. The quality they impart has not been well characterized. Sourness, and "fattiness" have been reported, but an irritation component has also been described and how these transition with gradations of aliphatic chain length has not been systematically studied. This study examined intensity and quality ratings of NEFA ranging from C2 to C18. Oral sites and the time course of sensations were also monitored. Given all NEFA contain carboxylic acid moieties capable of donating hydrogen ions, the primary stimulus for sour taste, testing was conducted with and without sour adaptation to explore the contribution of sour taste across the range of NEFA. Short-chain NEFA (C2-C6) were rated as predominantly sour, and this was diminished in C2 and C4 by sour adaptation. Medium-chain NEFA (C8-C12) were rated as mainly irritating with long-chain NEFA (C18) described mostly as bitter. The latter may reflect the lack of "fatty" lexicon to describe the sensation. Short-chain NEFA were mostly localized to the anterior tongue and were of rapid onset. The sensation from medium-chain NEFA was attributed to the lateral tongue, whereas medium- and long-chain NEFA sensations were predominantly localized to the back of the tongue and throat and had a longer lag time. The findings indicate there is a systematic transition of NEFA taste quality and irritation with increments in chain length and this is consistent with multiple modes of transduction.

A workshop on 'Dietary Sweetness-Is It an Issue?'

This report summarises a workshop convened by ILSI Europe on 3 and 4 April 2017 to discuss the issue of dietary sweetness. The objectives were to understand the roles of sweetness in the diet, establish whether exposure to sweetness affects diet quality and energy intake, and consider whether sweetness per se affects health. Although there may be evidence for tracking of intake of some sweet components of the diet through childhood, evidence for tracking of whole diet sweetness, or through other stages of maturity are lacking. The evidence to date does not support adverse effects of sweetness on diet quality or energy intake, except where sweet food choices increase intake of free sugars. There is some evidence for improvements in diet quality and reduced energy intake where sweetness without calories replaces sweetness with calories. There is a need to understand the physiological and metabolic relevance of sweet taste receptors on the tongue, in the gut and elsewhere in the body, as well as possible differentiation in the effects of sustained consumption of individual sweeteners. Despite a plethora of studies, there is no consistent evidence for an association of sweetness sensitivity/preference with obesity or type 2 diabetes. A multifaceted integrated approach, characterising nutritive and sensory aspects of the whole diet or dietary patterns, may be more valuable in providing contextual insight. The outcomes of the workshop could be used as a scientific basis to inform the expert community and create more useful dialogue among health care professionals.

Aspartame Consumption for 12 Weeks Does Not Affect Glycemia, Appetite, or Body Weight of Healthy, Lean Adults in a Randomized Controlled Trial.

Background: Low-calorie sweeteners are often used to moderate energy intake and postprandial glycemia, but some evidence indicates that they may exacerbate these aims. Objective: The trial's primary aim was to assess the effect of daily aspartame ingestion for 12 wk on glycemia. Effects on appetite and body weight were secondary aims. Methods: One hundred lean [body mass index (kg/m2): 18-25] adults aged 18-60 y were randomly assigned to consume 0, 350, or 1050 mg aspartame/d (ASP groups) in a beverage for 12 wk in a parallel-arm design. At baseline, body weight and composition were determined, a 240-min oral-glucose-tolerance test (OGTT) was administered, and measurements were made of appetite and selected hormones. Participants also collected a 24-h urine sample. During the intervention, the 0-mg/d ASP group consumed capsules containing 680 mg dextrose and 80 mg para-amino benzoic acid. For the 350-mg/d ASP group, the beverage contained 350 mg aspartame and the 1050-mg/d ASP group consumed the same beverage plus capsules containing 680 mg dextrose and 700 mg aspartame. Body weight, blood pressure, heart rate, and waist circumference were measured weekly. At weeks 4, 8, and 12, participants collected 24-h urine samples and kept appetite logs. Baseline measurements were repeated at week 12. Results: With the exception of the baseline OGTT glucose concentration at 60 min (and resulting area under the curve value), there were no group differences for glucose, insulin, resting leptin, glucagon-like peptide 1, or gastric inhibitory peptide at baseline or week 12. There also were no effects of aspartame ingestion on appetite, body weight, or body composition. Compliance with the beverage intervention was ∼95%. Conclusions: Aspartame ingested at 2 doses for 12 wk had no effect on glycemia, appetite, or body weight among healthy, lean adults. These data do not support the view that aspartame is problematic for the management of glycemia, appetite, or body weight. This trial was registered at www.clinicaltrials.gov as NCT02999321.

The Macronutrients, Appetite, and Energy Intake.

Each of the macronutrients-carbohydrate, protein, and fat-has a unique set of properties that influences health, but all are a source of energy. The optimal balance of their contribution to the diet has been a long-standing matter of debate. Over the past half century, thinking has progressed regarding the mechanisms by which each macronutrient may contribute to energy balance. At the beginning of this period, metabolic signals that initiated eating events (i.e., determined eating frequency) were emphasized. This was followed by an orientation to gut endocrine signals that purportedly modulate the size of eating events (i.e., determined portion size). Most recently, research attention has been directed to the brain, where the reward signals elicited by the macronutrients are viewed as potentially problematic (e.g., contribute to disordered eating). At this point, the predictive power of the macronutrients for energy intake remains limited.

Taste Responses to Linoleic Acid: A Crowdsourced Population Study.

Dietary fats serve multiple essential roles in human health but may also contribute to acute and chronic health complications. Thus, understanding mechanisms that influence fat ingestion are critical. All sensory systems may contribute relevant cues to fat detection, with the most recent evidence supporting a role for the sense of taste. Taste detection thresholds for fat vary markedly between individuals and responses are not normally distributed. Genetics may contribute to these observations. Using crowdsourced data obtained from families visiting the Denver Museum of Nature & Science, our objective was to estimate the heritability of fat taste (oleogustus). A pedigree analysis was conducted with 106 families (643 individuals) who rated the fat taste intensity of graded concentrations of linoleic acid (LA) embedded in taste strips. The findings estimate that 19% (P = 0.043) of the variability of taste response to LA relative to baseline is heritable at the highest concentration tested.

Effects of almond consumption on the post-lunch dip and long-term cognitive function in energy-restricted overweight and obese adults.

The post-lunch dip in cognition is a well-established phenomenon of decreased alertness, memory and vigilance after lunch consumption. Lunch composition reportedly influences the post-lunch dip. Moreover, dieting is associated with cognitive function impairments. The negative effects of dieting have been reversed with nut-supplemented diets. The aims of this study were to (1) evaluate the acute effect of an almond-enriched high-fat lunch or high-carbohydrate lunch on the post-lunch decline in cognitive function, and (2) evaluate the effects of chronic almond consumption as part of an energy-restricted diet on the memory and attention domains of cognitive function. In total, eighty-six overweight and obese adults were randomised to consume either an almond-enriched diet (AED) or a nut-free control diet (NFD) over a 12-week weight loss intervention. Participants were also randomised to receive either an almond-enriched high-fat lunch (A-HFL) (>55 % energy from fat, almonds contributing 70-75 % energy) or a high-carbohydrate lunch (HCL) (>85 % energy from carbohydrates) at the beginning and end of the weight loss intervention. Memory and attention performance indices decreased after lunch consumption (P<0·001). The A-HFL group ameliorated the decline in memory scores by 57·7 % compared with the HCL group (P=0·004). Both lunch groups had similar declines in attention. Moreover, memory and attention performance indices increased after the 12-week intervention period (P<0·05) with no difference between the AED and NFD groups. In conclusion, almond consumption at a midday meal can reduce the post-lunch dip in memory. However, long-term almond consumption may not further improve cognitive function outcomes in a weight loss intervention.

Almond Consumption during Energy Restriction Lowers Truncal Fat and Blood Pressure in Compliant Overweight or Obese Adults.

BACKGROUND: The inclusion of almonds in an energy-restricted diet has been reported both to enhance or to have no effect on weight loss. Their effects specifically on visceral body fat stores during energy restriction have not been widely examined. In addition, almond consumption has been associated with reduced blood pressure (BP), but whether this is linked to or independent of changes in body composition has to our knowledge not been examined. OBJECTIVE: We evaluated the effects of consuming almonds as part of an energy-restricted diet on body composition, specifically visceral adipose tissue (VAT) and BP, compared to a nut-free energy-restricted diet. METHODS: A randomized controlled 12-wk clinical trial of 86 healthy adults [body mass index (in kg/m2): 25-40] was conducted. Participants were randomly assigned to 1 of 2 energy-restricted (500-kcal deficit/d) diets: an almond-enriched diet (AED) (15% energy from almonds) or a nut-free diet (NFD). A linear mixed-model analysis on primary outcomes such as body weight, body fat, VAT, and BP was performed on all participants [intention-to-treat (ITT) analysis] and compliant participants (complier analysis). RESULTS: Body weight, truncal and total fat percentage, VAT, and systolic BP decreased after 12 wk of energy restriction in both the ITT and complier analyses (P < 0.05). The complier analysis (but not the ITT analysis) indicated a greater mean ± SEM reduction in truncal fat (AED: -1.21% ± 0.26%; NFD: -0.48% ± 0.24%; P = 0.025), total fat (AED: -1.79% ± 0.36%; NFD: -0.74% ± 0.33%; P = 0.035), and diastolic BP (AED: -2.71 ± 1.2 mm Hg; NFD: 0.815 ± 1.1 mm Hg; P = 0.029), and a greater tendency for VAT loss (AED: -8.19 ± 1.8 cm2; NFD: -3.99 ± 1.7 cm2; P = 0.09) over time in the AED group than the NFD group. CONCLUSIONS: Moderate almond consumption by compliant overweight and obese individuals during energy restriction results in greater proportional reductions of truncal and total body fat as well as diastolic BP and hence may help to reduce metabolic disease risk in obesity. This trial was registered at clinicaltrials.gov as NCT02360787.

Trends and determinants of discretionary salt use: National Health and Nutrition Examination Survey 2003-2012.

OBJECTIVE: To examine temporal trends and determinants of discretionary salt use in the USA. DESIGN: Multiple logistic regression was used to assess temporal trends in discretionary salt use at the table and during home cooking/preparation, adjusting for demographic characteristics, using data from the National Health and Nutrition Examination Survey 2003-2012. Prevalence and determinants of discretionary salt use in 2009-2012 were also examined. SETTING: Participants answered salt use questions after completing a 24 h dietary recall in a mobile examination centre. SUBJECTS: Nationally representative sample of non-institutionalized US children and adults, aged ≥2 years. RESULTS: From 2003 to 2012, the proportion of the population who reported using salt 'very often' declined; from 18 % to 12 % for use at the table (P<0·01) and from 42 % to 37 % during home cooking (P<0·02). While one-third of the population reported never adding salt at the table, most used it during home cooking/preparation (93 %). Use of discretionary salt was least commonly reported among young children and older adults and demographic and health subgroups at risk of CVD. CONCLUSIONS: While most people reported using salt during home cooking/preparation, a minority reported use at the table. Reported 'very often' discretionary salt use has declined. That discretionary salt use is less common among those at risk of CVD suggests awareness of messages to limit Na intake.

Satiety effects of psyllium in healthy volunteers.

Controlling hunger between meals is a challenge for many individuals. This manuscript comprises 2 sequential clinical trials investigating the effects of psyllium (Metamucil) on satiety, both using a randomized, double-blind, placebo-controlled cross-over design. The first study determined the effects of 3.4 g, 6.8 g, and 10.2 g of psyllium taken before breakfast and lunch for 3 days. The second study determined the effects of 6.8 g (taken before breakfast and lunch on Days 1 and 2 and before breakfast on Day 3) on the satiety of participants receiving an energy restricted meal in the morning (breakfast) for 3 days. Efficacy endpoints were mean inter-meal hunger, desire to eat, and Satiety Labeled Intensity Magnitude Visual Analog Scale scores. In Study 1, all 3 psyllium doses resulted in directional or statistically significant mean reductions in hunger and desire to eat, and increased fullness between meals compared to placebo, with both higher doses better than placebo or 3.4 g. The 6.8 g dose provided more consistent (p ≤ 0.013) satiety benefits versus placebo. In Study 2, satiety was assessed similarly to Study 1. A significant (p ≤ 0.004) decrease in the 3-day mean hunger and desire to eat, as well as an increase in fullness for psyllium relative to placebo was observed. Most adverse events were mild gastrointestinal symptoms and were similar for psyllium compared to placebo. These results indicate that psyllium supplementation contributes to greater fullness and less hunger between meals.

Humans are more sensitive to the taste of linoleic and α-linolenic than oleic acid.

Health concerns have led to recommendations to replace saturated fats with unsaturated fats. However, addition of unsaturated fatty acids may lead to changes in the way foods are perceived in the oral cavity. This study tested the taste sensitivity to and emulsion characteristics of oleic, linoleic, and α-linolenic acids. The hypothesis tested was that oral sensitivity to nonesterified fatty acids would increase with degree of unsaturation but that in vitro viscosities and particle sizes of these emulsions would not differ. Oral taste thresholds were obtained using the three-alternative, forced-choice, ascending method. Each participant was tested on each fat 7 times, for a total of 21 study visits, to account for learning effects. Viscosities were obtained for the blank solutions and all three emulsions. Results indicate lower oral thresholds to linoleic and α-linolenic than oleic acid. At higher shear rates, 5% oleic and linoleic acid were more viscous than other samples. More-dilute emulsions showed no significant differences in viscosity. Particle sizes of the emulsions increased very slightly with increasing unsaturation. Together, the emulsion characteristics and oral sensitivity data support a taste mechanism for nonesterified fatty acid detection.

Oleogustus: The Unique Taste of Fat.

Considerable mechanistic data indicate there may be a sixth basic taste: fat. However, evidence demonstrating that the sensation of nonesterified fatty acids (NEFA, the proposed stimuli for "fat taste") differs qualitatively from other tastes is lacking. Using perceptual mapping, we demonstrate that medium and long-chain NEFA have a taste sensation that is distinct from other basic tastes (sweet, sour, salty, and bitter). Although some overlap was observed between these NEFA and umami taste, this overlap is likely due to unfamiliarity with umami sensations rather than true similarity. Shorter chain fatty acids stimulate a sensation similar to sour, but as chain length increases this sensation changes. Fat taste oral signaling, and the different signals caused by different alkyl chain lengths, may hold implications for food product development, clinical practice, and public health policy.

No Difference in Perceived Intensity of Linoleic Acid in the Oral Cavity between Obese and Nonobese Individuals.

Findings from studies examining interactions between fat taste and dietary fat intake or body weight are mixed. A convenience sample of 735 visitors to the Denver Museum of Nature & Science ≥8 years old rated the taste intensity of edible taste strips impregnated with varying concentrations (%v/v) of linoleic acid (LA) (blank = 0.0, low = 0.06, medium = 0.15, high = 0.38). Percent body fat (BF%) was measured using bioelectrical impedance. Fat taste intensity was rated as significantly different across all concentrations (P < 0.001) except between the blank and low concentrations (P = 0.1). Ratings increased monotonically across concentrations. Children (<18 years; N = 180) rated all concentrations as more intense than adults (P < 0.001 for all). Women and girls rated the highest concentration as more intense than men and boys (P < 0.02 for all). BF% was not correlated with fat taste intensity ratings. Self-reported dietary intake indicated that obese individuals' intensity ratings for medium and high concentrations of LA were inversely related to recent mono- and poly-unsaturated fat exposure (r = -0.19 to -0.27; P < 0.03 for all). No such associations were observed in the nonobese group. Findings suggest that factors other than simple adiposity status influence fat taste intensity ratings, and that participants in fat taste studies should receive standardized meals prior to testing.

Higher plasma lipopolysaccharide concentrations are associated with less favorable phenotype in overweight/obese men.

PURPOSE: Lipopolysaccharide (LPS) from the outer membrane of gram-negative bacteria might be an inflammation trigger in adipose tissue. It has recently been proposed that there is a link between adipose tissue distribution and blood LPS. However, the number of studies on this topic is scarce, and further investigation in humans is required. In this study, we explored the association between plasma LPS concentrations and body fat distribution, as well as the biochemical parameters that may indicate the presence of metabolic disorders. METHODS: Sixty-seven young adult men with body mass index of 26-35 kg/m(2) were evaluated. Anthropometry, body composition and body fat distribution, blood pressure, energy expenditure, physical activity level, dietary intake, and biochemical parameters were assessed. RESULTS: Men with median plasma LPS ≥ 0.9 EU/mL presented higher sagittal abdominal diameter, trunk fat percentage, and android fat percentage, and mass, insulin and alanine aminotransferase concentrations, homeostasis model assessment of insulin resistance (HOMA-IR), and beta cell dysfunction (HOMA-B) than those with lower plasma LPS. LPS correlated positively with the trunk fat percentage, and android fat percentage, and mass, insulin, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase concentrations, as well as HOMA-IR and HOMA-B. CONCLUSION: Our results suggest that a higher plasma LPS concentration is associated with a less favorable phenotype as characterized by higher central adiposity, higher values of HOMA-IR, and beta cell function impairment in overweight/obese men.

Different oral sensitivities to and sensations of short-, medium-, and long-chain fatty acids in humans.

Fatty acids that vary in chain length and degree of unsaturation have different effects on metabolism and human health. As evidence for a "taste" of nonesterified fatty acids (NEFA) accumulates, it may be hypothesized that fatty acid structures will also influence oral sensations. The present study examined oral sensitivity to caproic (C6), lauric (C12), and oleic (C18:1) acids over repeated visits. Analyses were also conducted on textural properties of NEFA emulsions and blank solutions. Oral thresholds for caproic acid were lower compared with oleic acid. Lauric acid thresholds were intermediate but not significantly different from either, likely due to lingering irritating sensations that prevented accurate discrimination. From particle size analysis, larger droplets were observed in blank solutions when mineral oil was used, leading to instability of the emulsion, which was not observed when emulsions contained NEFA or when mineral oil was removed from the blank. Rheological data showed no differences in viscosity among samples except for a slightly higher viscosity with oleic acid concentrations above 58 mM. Thus, texture was unlikely to be the property used to distinguish between the samples. Differences in oral detection and sensation of caproic, lauric, and oleic acids may be due to different properties of the fatty acid alkyl chains.

Lingual lipase activity in the orosensory detection of fat by humans.

Lingual lipase generates nonesterified fatty acids (NEFA) from dietary fats during oral processing by lipolysis. Lingual lipase in rodents has strong lipolytic activity and plays a critical role in oral detection of fats. The functional activity of lingual lipase during oral processing of high-fat foods in humans remains poorly characterized. Five commonly consumed high-fat foods varying in physical states and fatty acid composition (almond, almond butter, olive oil, walnut, and coconut) were masticated by 15 healthy human subjects at the rate of one chew per second with and without lipase inhibitor orlistat. Salivary NEFA concentrations were measured. To determine the role of lingual lipase in oral fat detection, sensory ratings were obtained from the same 15 human subjects for almond butter with and without orlistat. Lingual lipase was active during oral processing of almond and coconut. No activity of lingual lipase was detected during processing of almond butter. There was only weak evidence lingual lipase is a determinant of oral fat detection. Lingual lipase may only contribute to NEFA generation and oral fat detection of fatty foods that require stronger oral processing effort.

Associations between BMI and fat taste sensitivity in humans.

The objective of this study was to examine the reliability of associations between fat taste, hunger, dietary fat intake, and body mass index (BMI). Detection thresholds for oleic acid (OA) were obtained during each of 7 consecutive visits using a modified staircase procedure. Participants were 48 (N = 17 male; N = 31 female) healthy adults (mean age: 28.5 ± 10.4 years) with BMI's ranging from 18.9 to 47.2 (≥ 25 kg · m(-2), N = 24). OA detection thresholds and self-reported hunger (100-mm visual analog scale) were assessed at each visit. BMI and dietary fat intake (Block Rapid Fat Screener) were determined at baseline. There was a significant decrease of threshold concentration over repeated trials among lean and overweight (BMI between 25.0 and 29.9 kg · m(-2)) participants but not in the obese. Combining the lean and overweight and contrasting their responses to the obese revealed the lean plus overweight group to be significantly more sensitive at visits 6 and 7. No change of threshold sensitivity or correlation with fat intake was observed in the obese participants unlike findings in the lean and lean plus overweight participants. Correlations between saturated fat intake and threshold sensitivity were positive (greater intake associated with higher thresholds) at baseline for the group, with additional correlations observed among the lean plus overweight but not in the obese, leaving open questions about the nutritional significance of the association. No significant associations were observed between sensitivity to OA and hunger. Repeated testing is required to assess associations between fat taste and other outcome variables.