Food Odours Direct Specific Appetite

Validation of a laboratory craving assessment and evaluation of 4 different interventions on cravings among adults with overweight or obesity

Food cue reactivity (FCR) is an appetitive trait associated with overeating and weight gain. We developed a laboratory craving assessment to objectively evaluate cognitive aspects of FCR. This study examined the preliminary construct and criterion validity of this craving assessment and evaluated 4 different interventions, 2 of which incorporated cue-exposure treatment for food, on craving over treatment and follow-up. 271 treatment-seeking adults with overweight/obesity (body mass index = 34.6[5.2]; age = 46.5[11.8]; 81.2% female; 61.6% non-Latinx White) completed the Food Cue Responsivity Scale and the laboratory craving assessment, during which they alternated holding and smelling a highly craved food and provided craving ratings over 5 min. Participants were subsequently randomized to 26 treatment sessions over 12-months of ROC, Behavioral Weight Loss (BWL), a combined arm (ROC+) and an active comparator (AC), and repeated the craving assessment at post-treatment and 12-month follow-up. Linear mixed-effects models assessed associations between trial type (holding vs. smelling), trial number, pre-treatment FCR, treatment arm, assessment time point, and craving. Cravings were greater when smelling vs. holding food (b = 0.31, p < 0.001), and cravings decreased over time (b = -0.02, p < 0.001). Participants with higher pre-treatment FCR reported elevated cravings (b = 0.29, p < 0.001). Longitudinally, we observed a significant 3-way interaction in which treatment arm modified the relationship between pre-treatment FCR and craving over time (F(17,5122) = 6.88, p < 0.001). An attenuated FCR-craving relationship was observed in ROC+ and BWL from baseline to post-treatment but was only sustained in BWL at follow-up. This attenuation was also observed in ROC and AC from post-treatment to follow-up. The preliminary validity of this laboratory craving assessment was supported; however, greater craving reductions over time in ROC/ROC+ compared to BWL and AC were not consistently observed, and thus do not appear to fully account for the moderating effect of FCR on weight losses observed in the trial.

Olfactory Impairment and Frailty: A Systematic Review and Meta-Analysis

Importance

Olfactory impairment (OI) and frailty are prevalent conditions associated with aging, but studies investigating their association with each other have been discordant.

Objective

To summarize current evidence surrounding the association between OI and frailty.

Data Sources

PubMed, Embase, Cochrane Library, SCOPUS, and CINAHL from inception to November 28, 2023.

Study Selection

This study included observational studies investigating the association between objectively or subjectively assessed OI and objectively evaluated frailty among adults.

Data Extraction and Synthesis

Two independent authors extracted data into a structured template. Maximally adjusted estimates were pooled using a random-effects model, and statistical heterogeneity was evaluated using I2 values. Additional prespecified subgroup and sensitivity analyses were performed. This study used the Newcastle-Ottawa Scale for bias assessment and the Grading of Recommendations Assessment, Development and Evaluation framework for overall evidence quality evaluation.

Main Outcomes and Measures

The primary outcome was the cross-sectional association between OI and frailty, for which the odds of frailty were compared between participants with and without OI. The secondary outcome was the cross-sectional association between frailty and OI, for which the odds of OI were compared between participants with and without frailty.

Results

This study included 10 studies with 10 624 patients (52.9% female; mean [SD] age, 62.9 [9.6] years). The Newcastle-Ottawa Scale score of studies ranged from low to moderate. Grading of Recommendations Assessment, Development and Evaluation scores ranged from low to moderate. OI was associated with a 2.32-fold (odds ratio [OR], 2.32; 95% CI, 1.63-3.31; I2 = 0%) greater odds of frailty compared with individuals with healthy olfactory function. The odds of OI was progressively greater with categorical frailty status, with a 1.55-fold (OR, 1.55; 95% CI, 1.32-1.82; I2 = 0%), 2.28-fold (OR, 2.28; 95% CI, 1.96-2.65; I2 = 0%), and 4.67-fold (OR, 4.67; 95% CI, 2.77-7.86; I2 = 0%) increase in odds for individuals with prefrailty, frailty, and the most frailty, respectively, compared with robust individuals. The results demonstrated stability in subgroup analyses (geographical continent of study, objective vs subjective olfactory assessment) and sensitivity tests.

Conclusions and Relevance

The results of this systematic review and meta-analysis suggest that there is an association between OI and frailty, with an increase in the odds of OI with worsening categorical frailty status among individuals with prefrailty, frailty, and the most frailty. OI may be a potential biomarker for frailty. Future studies could delve into whether OI may be a modifiable risk factor for frailty.

Insights to Study, Understand and Manage Extruded Dry Pet Food Palatability

Pet food production is a fast-growing industry. While extruded dry pet food is the favored pet food due to its convenience of use, it may have poorer palatability than other pet foods such as wet pet foods. However, palatability plays a pivotal role in meeting nutritional requirements or providing therapeutic benefits in cats and dogs, as it ensures food acceptance. Thus, both academics and manufacturers conduct routine palatability tests to assess acceptance and preference of products among pets, alongside sensory analyses involving human panels. Palatability is greatly influenced by species-specific and environmental factors in cats and dogs. The review will hence present the current knowledge on palatability assessment and animal food perception; it will then aim to explore strategies for effectively managing palatability in dry pet food by examining the impact of key ingredients and process parameters on the finished product's palatability. Moreover, the demands and needs for sustainable and healthier products as well as supply constraints present novel challenges and opportunities for academics and manufacturers.

Short-term consumption of highly processed diets varying in macronutrient content impair the sense of smell and brain metabolism in mice

OBJECTIVE

Food processing greatly contributed to increased food safety, diversity, and accessibility. However, the prevalence of highly palatable and highly processed food in our modern diet has exacerbated obesity rates and contributed to a global health crisis. While accumulating evidence suggests that chronic consumption of such foods is detrimental to sensory and neural physiology, it is unclear whether its short-term intake has adverse effects. Here, we assessed how short-term consumption (<2 months) of three diets varying in composition and macronutrient content influence olfaction and brain metabolism in mice.

METHODS

The diets tested included a grain-based standard chow diet (CHOW; 54% carbohydrate, 32% protein, 14% fat; #8604 Teklad Rodent diet , Envigo Inc.), a highly processed control diet (hpCTR; 70% carbohydrate, 20% protein, 10% fat; #D12450B, Research Diets Inc.), and a highly processed high-fat diet (hpHFD; 20% carbohydrate, 20% protein, 60% fat; #D12492, Research Diets Inc.). We performed behavioral and metabolic phenotyping, electro-olfactogram (EOG) recordings, brain glucose metabolism imaging, and mitochondrial respirometry in different brain regions. We also performed RNA-sequencing (RNA-seq) in the nose and across several brain regions, and conducted differential expression analysis, gene ontology, and network analysis.

RESULTS

We show that short-term consumption of the two highly processed diets, but not the grain-based diet, regardless of macronutrient content, adversely affects odor-guided behaviors, physiological responses to odorants, transcriptional profiles in the olfactory mucosa and brain regions, and brain glucose metabolism and mitochondrial respiration.

CONCLUSIONS

Even short periods of highly processed food consumption are sufficient to cause early olfactory and brain abnormalities, which has the potential to alter food choices and influence the risk of developing metabolic disease.

The Role of the Olfactory System in Obesity and Metabolism in Humans: A Systematic Review and Meta-Analysis

Obesity, linked to chronic diseases, poses a global health challenge. While the role of the olfactory system in energy homeostasis is well-documented in rodents, its role in metabolism regulation and obesity in humans remains understudied. This review examines the interplay between olfactory function and metabolic alterations in human obesity and the effects of bariatric surgery on olfactory capabilities in humans. Adhering to PRISMA guidelines, a systematic review and meta-analysis was conducted, focusing exclusively on original human studies. From 51 articles, 14 were selected for the meta-analysis. It was found that variations in olfactory receptor genes influence the susceptibility to odors and predisposition to weight gain and poor eating habits. Bariatric surgery, particularly sleeve gastrectomy, shows significant improvements in olfactory function (SMD 2.37, 95% CI [0.96, 3.77], I = 92%, p = 0.001), especially regarding the olfactory threshold (SMD -1.65, 95% CI [-3.03, -0.27], I = 81%, p = 0.02). There is a bidirectional relationship between olfactory function and metabolism in humans. Bariatric surgery improves olfactory perception in obese patients, but it is still unclear if impacting the olfactory system directly affects eating behavior and the energy balance. However, these findings open novel avenues for future studies addressing the olfactory system as a novel target to alter systemic metabolism in humans.

Orthonasal olfactory influences on consumer food behaviour

It is often suggested in the popular press that food chains deliberately introduce enticing product aromas into (and in the immediate vicinity of) their premises in order to attract customers. However, despite the widespread use of odours in the field of sensory marketing, laboratory research suggests that their effectiveness in modulating people's food behaviours depends on a range of contextual factors. Given the evidence that has been published to date, only under a subset of conditions is there likely to be a measurable effect of the presence of ambient odours on people's food attitudes and choices. This narrative historical review summarizes the various ways in which food odours appear to bias people's food preferences (appetite) and food choices (food consumption and purchase). Emphasis is placed on those experimental studies that have been designed to investigate how the characteristics of the olfactory stimuli (e.g., the congruency between the olfactory cues and the foods, intensity and duration of exposure to odours, and taste properties of odours) modulate the effects of olfactory cues on food behaviour. The review also explores the moderating roles of individual differences, such as dietary restraint, Body Mass Index (BMI), genetic and cultural differences in odour sensitivity and perception. Ultimately, following a review of empirical studies on food-related olfaction, current approaches in scent marketing are discussed and a research agenda is proposed to help encourage further studies on the effective application of scents in promoting healthy foods.

Natural Appetite Control: Consumer Perception of Food-Based Appetite Regulating Aromas

According to the WHO, the number of overweight people (BMI ≥ 25) and obese people (BMI ≥ 30) is constantly growing. On the other hand, the number of elderly people (≥60 years old) in 2020 reached 1.4 billion worldwide. Both mentioned groups demonstrate their individual and characteristic appetite disorders. In light of the side effects of appetite stimulating drugs, which interfere with diabetics, hypertension and thrombosis medicines or diet supplements with doubtful effectiveness in reducing appetite, new and natural alternatives are highly demanded. Therefore, the present study focusses on the search for natural food aromas, which may have potential for appetite regulation. A survey was carried out among consumers with excess body weight (BMI ≥ 25) and the elderly (≥60 years old). Food products and meals pointed out by the survey participants were subjected to volatile analysis by HS-SPME Arrow followed by GC-MS. As a result, a group of volatiles and their odor characteristic were determined for appetite stimulation or reduction, which may suggest that the actual composition of food aroma is more significant than the character of the aroma. Those results may be a basis for designing appetite regulating agents, in which the mechanism of action will be based only on olfaction activity.

Alexithymia modulates the attitudes towards odors but not the olfactory abilities or the affective reactions to odors

Although emotion and olfaction are closely linked, only a few studies have investigated olfactory processing in alexithymia, a condition characterized by altered emotional processing. These results do not allow comprehensive conclusions on whether individuals with alexithymia present lower olfactory abilities or only altered affective reactions and awareness of odors. Three pre-registered experiments were conducted to clarify this relation. We assessed olfactory functions, the affective qualities of odors, the awareness of odors, the attitudes towards them, and the ability to form olfactory images in the mind. Bayesian statistics were used to assess differences between low, medium and high alexithymia groups, and Linear Mixed Models (LMMs) were applied to investigate the modulation of the affective and cognitive components of alexithymia. We observed that individuals with a high level of alexithymia presented the same olfactory abilities, and did not show differences in their rating of odors compared to individuals with low alexithymia levels, while they reported lower levels of social and common odor awareness and a more indifferent attitude towards odors. Olfactory imagery was not affected by alexithymia level, and the affective and cognitive components of alexithymia, when considered separately, modulated olfactory perception differently. Learning more about olfactory perception in individuals with alexithymia leads to a better understanding of how alexithymia impacts the perception of hedonic stimuli coming from different sensory modalities. Our results imply that treatment goals for alexithymia should be the enhancement of the conscious perception of odors, supporting the use of mindfulness-based protocols in the alexithymia treatment.

Appetite-regulating hormones modulate odor perception and odor-evoked activity in hypothalamus and olfactory cortices

Odors guide food seeking, and food intake modulates olfactory function. This interaction is mediated by appetite-regulating hormones like ghrelin, insulin, and leptin, which alter activity in the rodent olfactory bulb, but their effects on downstream olfactory cortices have not yet been established in humans. The olfactory tract connects the olfactory bulb to the cortex through 3 main striae, terminating in the piriform cortex (PirC), amygdala (AMY), olfactory tubercule (OT), and anterior olfactory nucleus (AON). Here, we test the hypothesis that appetite-regulating hormones modulate olfactory processing in the endpoints of the olfactory tract and the hypothalamus. We collected odor-evoked functional magnetic resonance imaging (fMRI) responses and plasma levels of ghrelin, insulin, and leptin from human subjects (n = 25) after a standardized meal. We found that a hormonal composite measure, capturing variance relating positively to insulin and negatively to ghrelin, correlated inversely with odor intensity ratings and fMRI responses to odorized vs. clean air in the hypothalamus, OT, and AON. No significant correlations were found with activity in PirC or AMY, the endpoints of the lateral stria. Exploratory whole-brain analyses revealed significant correlations near the diagonal band of Broca and parahippocampal gyrus. These results demonstrate that high (low) blood plasma concentrations of insulin (ghrelin) decrease perceived odor intensity and odor-evoked activity in the cortical targets of the medial and intermediate striae of the olfactory tract, as well as the hypothalamus. These findings expand our understanding of the cortical mechanisms by which metabolic hormones in humans modulate olfactory processing after a meal.

Insights into the constellating drivers of satiety impacting dietary patterns and lifestyle

Food intake and body weight regulation are of special interest for meeting today's lifestyle essential requirements. Since balanced energy intake and expenditure are crucial for healthy living, high levels of energy intake are associated with obesity. Hence, regulation of energy intake occurs through short- and long-term signals as complex central and peripheral physiological signals control food intake. This work aims to explore and compile the main factors influencing satiating efficiency of foods by updating recent knowledge to point out new perspectives on the potential drivers of satiety interfering with food intake regulation. Human internal factors such as genetics, gender, age, nutritional status, gastrointestinal satiety signals, gut enzymes, gastric emptying rate, gut microbiota, individual behavioral response to foods, sleep and circadian rhythms are likely to be important in determining satiety. Besides, the external factors (environmental and behavioral) impacting satiety efficiency are highlighted. Based on mechanisms related to food consumption and dietary patterns several physical, physiological, and psychological factors affect satiety or satiation. A complex network of endocrine and neuroendocrine mechanisms controls the satiety pathways. In response to food intake and other behavioral cues, gut signals enable endocrine systems to target the brain. Intestinal and gastric signals interact with neural pathways in the central nervous system to halt eating or induce satiety. Moreover, complex food composition and structures result in considerable variation in satiety responses for different food groups. A better understanding of foods and factors impacting the efficiency of satiety could be helpful in making smart food choices and dietary recommendations for a healthy lifestyle based on updated scientific evidence.

Sex difference in human olfactory sensitivity is associated with plasma adiponectin

Energy deprivation as well as hormones that regulate appetite and eating can influence olfactory function. This study investigated olfactory sensitivity for a food-related and a non-food odour prior to and after a meal, and its relationship to the energy-regulating hormones ghrelin and adiponectin. The olfactory sensitivity for orange and rose (PEA) odour in healthy, normal-weight volunteers (19 women, 45 men, 1 undisclosed individual) was not affected by the consumption of a meal. Olfactory sensitivity was not associated with concentrations of circulating ghrelin. However, olfactory sensitivity was higher for women than for men, indicating better olfactory performance. This difference between women and men was related to concentrations of plasma adiponectin, an adipose-specific hormone. Adiponectin may thus explain why sex differences in olfactory sensitivity emerge, and may also account for some of the inconsistencies in previous findings on sex differences. Our findings add to the limited literature on the impact of stomach and adipose tissue-derived hormones on olfactory sensitivity. Further studies are needed to establish a causal link between circulating adiponectin and a sex difference in olfactory sensitivity.

Sensory attributes, dog preference ranking, and oxidation rate evaluation of sorghum-based baked treats supplemented with soluble animal proteins

Treats are offered to dogs to reinforce the animal-owner bond and as rewards. Wheat, which contains gluten (gliadin and glutenin proteins), is often used in treats. The US is a leading producer of sorghum which might be an alternative; however, it does not have functional properties to form viscoelastic doughs, because is mainly composed of kafirin protein. Therefore, the objectives of this study were to determine the effects of supplementing soluble animal proteins in whole sorghum rotary molded baked dog treats on dog preference, sensory attributes, and oxidation rate. The treats were produced in triplicate in a 2x4 + 1 augmented factorial arrangement of treatments. Two whole sorghum flours (WWS and WRS), four protein sources [none (NC), spray-dried plasma (SDP), egg protein (EP), and gelatin (GL)], and a positive control with wheat (WWF-GTN) were evaluated. A preference ranking test with twelve dogs was performed. Additionally, five trained panelists scored the intensity of appearance, aroma, flavor, texture/mouthfeel, and aftertaste attributes. Finally, the treats were stored at 30°C and 60% RH, and hexanal concentrations were measured on days 0, 28, 56, and 112. The data was analyzed using the statistical software SAS for the animal and oxidation rate evaluations with significance considered at P<0.05. The descriptive sensory evaluation data was analyzed using multivariate analysis (XLSTAT). The dogs did not detect differences among WWF-GTN, WWS, or WRS treats when evaluated together. However, the WWF-GTN, WWS-SDP and WWS-EP treatments were preferred among the white sorghum treatments. The EP treatments led to some consumption difficulties by dogs because of their hard texture. The panelists reported a high degree of variation in the appearance and texture across treatments. The WRS and WWS treats with SDP or EP were darker, while NC treats had more surface cracks. Initial crispness, hardness, and fracturability were higher in EP treatments compared to all other sorghum treatments. The predominant flavor and aftertaste identified were "grainy." The hexanal values for all treats were <1.0 mg/kg except for the EP treatments that had higher values (2.0-19.3 mg/kg) across the shelf-life test. This work indicated that the replacement of WWF-GTN by WWS and WRS, along with soluble animal proteins like SDP or GL would produce comparable preference by dogs, oxidation rates, product aromatics, flavor, aftertaste attributes, and, at a lower degree, product texture.

Olfactory stimulation for people with dementia: A rapid review

There is a growing interest in using olfactory (smell) stimulation in dementia care. This study aims to extend current knowledge by synthesising the evidence on the efficacy of interventions using olfactory stimulation for people with dementia and to assess the effects of different types of odours and administration methods using a mixed methods approach. The rapid review was conducted based on searches in six electronic databases. A narrative approach was applied to assess 20 studies included in the review. Fourteen studies used a quasi-experimental design, five studies used an experimental design and one was a case study. High heterogeneity was found on odours and methods of application used, with the majority of studies administering lavender oil using a diffuser. Mixed results were reported on the benefits of olfactory stimulation on responsive behaviours and cognitive function. Although the evidence available is limited, encouraging results were found regarding olfactory stimulation and increased sleep duration, food intake and improved balance. It was not possible to draw any overall conclusion in relation to the effect of olfactory stimulation. However, this review shows promising results that support further investigation of olfactory stimulation as a nonpharmacological intervention for people with dementia. The review is limited due to the low to moderate quality of studies included. Furthermore, the broad range of approaches was employed, and comparison between the studies was difficult. Further high-quality mixed method studies using robust and detailed protocols are needed to clarify the effects of olfactory stimuli and any other factors that may influence the responses of people with dementia.

Using event-related potentials to study food-related cognition: An overview of methods and perspectives for future research

Electroencephalography (EEG), and the measure of event-related potentials (ERPs) in particular, are useful methods to study the cognitive and cerebral mechanisms underlying the perception and processing of food cues. Further research on these aspects is necessary to better understand how cognitive functioning may influence food choices in different populations (e.g. obese individuals, individuals with eating disorders). To help researchers in designing future studies, this article provides an overview of the methods used in the current literature on ERPs and food-related cognition. Several methodological aspects are explored to outline interesting perspectives for future research, including discussions on the main experimental tasks used, the cognitive functions assessed (e.g. inhibitory control, attentional processing), the characteristics of the participants recruited (e.g. weight status, eating behaviors), and the stimuli selected (e.g. food pictures, odors). The issues generated by some of these methodological choices are discussed, and a few guidelines are provided.

Association of Frailty Status and Dietary Patterns in a Nationally Representative Sample of United States Adults with Olfactory Dysfunction

Background: Olfactory dysfunction (OD) is a strong, independent predictor of frailty and mortality risk. This study evaluated the association of dietary patterns and frailty status in older adults with OD. Methods: This cross-sectional study utilized the 2013–2014 National Health and Nutrition Examination Survey. Dietary patterns (DPs) characteristic of OD were derived using exploratory factor analysis (EFA). Multiple logistic regressions adjusted for demographics and frailty risk factors assessed the association of DPs with two frailty metrics: the frailty index (FI) and physical frailty (PF). Results: EFA yielded six distinct DPs in persons with OD. The protein/selenium (OR 0.82 [95% CI 0.74–0.92], p = 0.041) and β-carotene/vitamin A DPs (OR 0.76 [95% CI 0.66–0.88], p = 0.028) were independently associated with frailty by FI. Only the protein/selenium DP (OR 0.82 [95% CI 0.74–0.92], p = 0.036) was associated with frailty by PF. No DPs were associated with either frailty measure in normosmic persons. Conclusions: Dietary patterns high in protein/selenium and β-carotene/vitamin A are associated with lower frailty prevalence in adults with OD. While the relationship between OD and frailty is likely multifaceted, these findings suggest that dietary patterns are uniquely associated with frailty in older adults with OD.

Olfactory and Gustatory Supra-Threshold Sensitivities Are Linked to Ad Libitum Snack Choice

Snacking is a common eating habit in the modern food environment. Individual snack choices vary substantially, with sweet versus savoury snacks linked to differential health outcomes. The role of olfactory and gustatory sensitivities in snack choices and consumption is yet to be tested. A total of 70 Caucasian young males (age: 21−39 years; BMI: 20.5−40.5 kg∙m−2) were tested for their supra-threshold sensitivities to sweet and savoury associated odours and tastants (vanillin, methional; sucrose, NaCl). The participants also attended an ad libitum task in which their intakes of sweet and savoury snacks were recorded and analysed. Univariate and multivariate analyses were used to test for relationships between odour/taste sensitivities and sweet versus savoury snack intake. Results indicated that individual sensitivities to sweet-associated stimuli (e.g., vanillin, sucrose) were negatively linked with intake of the congruent (e.g., sweet) snacks and positively linked with incongruent (e.g., savoury) snacks (p < 0.05). These differences were reflected by energy intake rather than consumption weight (p > 0.05). This study outlines the fundamental roles of olfactory and gustatory sensitivities in snack choices and offers novel insights into inter-individual variability in snack consumption.

Influence of Sensory Properties in Moderating Eating Behaviors and Food Intake

Sensory properties inform likes and dislikes, but also play an important functional role in guiding food choice and intake behavior. Odors direct food choice and stimulate sensory-specific appetites and taste helps to anticipate calorie and nutrient content of food. Food textures moderate eating rate and the energy consumed to satiation and post-ingestive metabolism. We summarize how sensory cues moderate intake, and highlight opportunities to apply sensory approaches to improve dietary behavior. Salt, sweet and savory taste influence liking, but also influence energy intake to fullness, with higher taste intensity and duration linked to lower intake. Psycho-physical studies show it is relatively easy to rank taste intensities at different concentrations but more challenging to discriminate fat contents, and fat discrimination declines further when combined with high-taste intensity. Fat has low impact on sensory intensity, but makes significant contributions to energy content. Combinations of high taste and fat-content can promote passive energy over-consumption, and adding fat also increases energy intake rate (kcals/min), reducing opportunities to orally meter consumption. Consumers adapt their oral processing behaviors to a foods texture, which can influence the rate and extent of energy intake. Understanding how texture influences eating behaviors and bolus formation, affords new opportunities to impact eating rate, energy intake and metabolic response to food. Food formulation has traditionally focused on composition and sensory appeal. Future research needs to consider the role of sensory properties in moderating consumer interaction with their food environment, and how they influence calorie selection, and shape our eating behaviors and intake.

The Effect of Food Odor Exposure on Appetite and Nutritional Intake of Older Adults with Dementia

OBJECTIVES

Dementia can lead to decreased appetite and nutritional intake. Food odor exposure has been shown to increase appetite and nutritional intake in young healthy adults. This study investigates the effect of food odor exposure on appetite, nutritional intake and body weight of Dutch nursing home residents with dementia.

DESIGN

This was a one-armed, non-randomized, non-blinded intervention study consisting of a four-week control period followed by a twelve-week intervention period.

SETTING

Four nursing homes in the Netherlands.

PARTICIPANTS

Forty-five nursing home residents with dementia.

INTERVENTION

During the intervention period, odors were dispersed prior to the main meals.

MEASUREMENTS

General and specific appetite for sweet and savory foods was measured weekly. Nutritional intake was measured once during the control period and three times during the intervention period through a 3-day food record. Body weight was assessed at the start and end of the control period and at the start, end and halfway the intervention period. Data were analyzed with linear mixed models.

RESULTS

Small changes in general and specific appetite were observed after odor exposure. Overall energy intake did not change during the first four intervention weeks, but increased during the second and third (+118kcal/d, p=0.003 and +122kcal/d, p=0.004). Protein intake and body weight did not significantly change during the study.

CONCLUSION

In this study, no clinically relevant changes in appetite, nutritional intake and body weight were observed after food odor exposure. Future studies should assess the effect of natural food odors and/or meal-tailored odors on nutritional intake of older adults with dementia.

Sensory Specific Desires. The Role of Sensory Taste Exposure in Desire for Food with a Similar or Different Taste Profile

The present study investigated how the sensory taste profile of a meal altered the subjective desire, wanting and liking of foods with a sweet, salty, sour, bitter, fatty, and spicy sensory profile, respectively. Participants (n = 85) ate a meal with a pronounced sensory taste profile: (1) sweet, (2) salty, or (3) sweet and salty combined. Self-reports of appetite, pleasantness, and sensory specific desires (SSD) were evaluated over the course of the meal using VAS-scales. SSDs were further studied through alterations in liking and desire for food samples with the main sensory profile being sweet (peach), salty (pretzel), sour (green apple), bitter (dark chocolate), fatty (whipped cream), and spicy (chilli nut), respectively. Consumption of food with a pronounced sensory taste profile was found to suppress the desire for food with a similar sensory taste profile, while the desire for different sensory profiles were enhanced or not affected. Further, when exposed to two pronounced tastes within the same meal, suppression of sensory desires was not only specific for the exposure tastes but tended to go beyond the sensory exposure. The findings suggest that taste variation within a meal holds the potential to create more satisfying meals, which can hinder additional desires after a meal and thus, lower additional calorie intake.

Effect of short-term use of dapagliflozin on impaired awareness of hypoglycaemia in people with type 1 diabetes

AIM

Impaired awareness of hypoglycaemia (IAH) affects about 25% of patients with type 1 diabetes (T1DM). IAH can be reversed by strict avoidance of hypoglycaemia for at least 3 weeks. Adjunctive treatment with sodium glucose cotransporter 2 inhibitors may reduce the risk of hypoglycaemia through reduction of glucose variability. We tested the hypothesis that short-term use of dapagliflozin may improve awareness of hypoglycaemia in people with T1DM and IAH.

MATERIALS AND METHODS

Fifteen patients with T1DM and IAH were included in this randomized double-blind, placebo-controlled cross-over trial (age 49.7 ± 14.6 years, 40% men, disease duration 24.1 ± 14.2 years, glycated haemoglobin 7.5 ± 0.8% (58.6 ± 8.4 mmol/mol). They were treated with dapagliflozin 10 mg once daily or matching placebo, with a washout period of 2 weeks. At the end of each treatment period, participants underwent a modified hyperinsulinaemic normoglycaemic-hypoglycaemic glucose clamp (glucose nadir 2.5 mmol/L). Blinded continuous glucose monitors were used in the final treatment weeks.

RESULTS

Treatment with dapagliflozin significantly improved glycated haemoglobin [-0.32 ± 0.10 vs. 0.22 ± 0.13% (-4.1 ± 0.9 vs. 2.3 ± 1.4 mmol/mol), dapagliflozin vs. placebo, p = .007] and glucose variability (standard deviation, 2.6 ± 0.2 vs. 3.1 ± 0.3 mmol/L, p = .029), but did not affect the frequency of hypoglycaemia. During the hypoglycaemic clamp, dapagliflozin did not affect symptom responses (8.0 ± 3.4 vs. 5.2 ± 1.6, p = .31), but significantly reduced the need for exogenous glucose to maintain hypoglycaemia (3.2 ± 0.3 vs. 4.1 ± 0.4 mg/kg/min, p = .022).

CONCLUSIONS

Eight weeks of treatment with dapagliflozin did not restore hypoglycaemic awareness in people with T1DM and impaired awareness of hypoglycaemia, but ameliorated some clinical aspects.

The Influence of Common Noncommunicable Diseases on Chemosensory Perception and Clinical Implications in Children and Adolescents

An increased incidence of noninfectious chronic diseases, such as obesity, diabetes, and allergies, has been noted in the last century, especially in the last 2 to 3 generations. Evidence suggested that the interrelation among these chronic conditions in pediatric age (e.g., children and adolescents aged 4-16 y) is complex and still unknown, reinforcing the interest of pediatricians in these diseases. Of interest is the need to better understand the link between these pathologies and sensory perception, since the chemical senses of taste and smell, together with chemesthesis, are reported to have a role in food choices and may provide a novel target for intervention in the treatment of these pathologies. This review aims to explore the current evidence on the link between these chronic conditions and chemosensory perception (i.e., taste and smell). In addition, the putative role that chemosensory perception may have on food choices and eating behavior of children and adolescents affected by these diseases are highlighted. Furthermore, the review addresses the unexplored issues that need to be investigated in this area. The literature data search suggested that no clear relation between taste and smell perception and the aforementioned diseases in young population yet exists. However, some possible trends have been highlighted in the adult population, in whom the duration of disease might have affected the relation. There is a need for further, high-quality, hypothesis-led research, with robust measures of taste and smell functions as the primary outcomes, to strengthen or deny this evidence.

The role of an individual's olfactory discriminability in influencing snacking and habitual energy intake

Recent studies have revealed close links between human olfaction, appetite, and food choice. However, it remains unclear whether olfactory sensitivity plays a direct role in determining food and energy intake. The present study addresses this question by assessing relationships between individual olfactory discriminability (at a suprathreshold level), snacking, and habitual energy intake. A total of 92 healthy Caucasian males (mean age = 26.1, SD = 5.8) were tested for their olfactory discriminability (measured by d') to three food-related odorants (O1 - Vanillin, O2 - Methional, and O3 - Maltol/Furaneol mixture) with a 2-AFC method of constant stimuli. These sensory data were then analysed with two separate measures of food consumption - (1) snack energy intake within an ad libitum buffet setting; (2) habitual energy intake using four-day weighed food records. Univariate analyses of variance revealed significant results with regards to O1. Specifically, individuals with higher discriminability consumed significantly less energy from snacking as opposed to their less sensitive counterparts (p = 0.05). However, no significant relationship was found between individual olfactory discriminability and habitual energy intake. While recent years have seen increasing research focus on how external olfactory cues affect food consumption, our study offers particularly novel insights regarding the role of individual olfactory sensitivity in shaping eating behaviour.

Aromachology Related to Foods, Scientific Lines of Evidence: A Review

Smell is the second-most used sense in marketing strategies in the food industry. Sensory marketing appeals to the senses with the aim of creating sensory experiences and converting them into specific emotions associated with a specific product. There is a strong relationship between sensory marketing, aromachology, and neuroscience. In this review, studies were searched on the use of scents in food experiences such as restaurants and food establishments, and a critical evaluation was performed on their aims, target population, place of the study, scents tested, foods tested, and measured parameters, and the main findings were reviewed. Case studies carried out by private companies are also presented. A small number of scientific studies on aromachology related to food are available, and most of them are conducted in artificial laboratory conditions. Methodological procedures largely diverge among studies, making them very difficult to compare and extrapolate results. There is a clear need for research on aromachology related to food in the fields of sensory marketing and appetite modulation. After a brief presentation of the state of the art, we briefly mention future improvements and ideas for future research.

Possibilities for Maintaining Appetite in Recovering COVID-19 Patients

COVID-19 and sequelae thereof are known to cause chemosensory dysfunction, posing a risk for intake and adequate nutrition for recovery. The overall objective of this study was to investigate the subjective strategies for maintaining appetite applied by patients recovering from COVID-19. The study included 19 in-depth interviews, focusing on patients suffering from long-term effects of COVID-19. The results were analysed using a thematic analysis for qualitative data. Results on strategies for maintaining appetite included four key themes: (1) a focus on well-functioning senses, (2) a focus on familiar foods, (3) a focus on the eating environment, and (4) a focus on post-ingestive well-being. It was found that factors prior to, during and after food intake, as well as the context, could influence desire to eat and pleasure related to food intake. As ageusia and anosmia make characterization of food difficult, being able to recognize and memorize its flavour was important to engage in consumption. Under normal circumstances, the hedonic value of food relies predominantly on the flavour of foods. When suffering from chemosensory dysfunction, shifting focus towards the texture of food, including trigeminal stimulation during consumption, were beneficial for maintaining appetite and food-related pleasure. Furthermore, a focus on the holistic satisfying feelings of choosing healthy food, as well as a focus on other people’s enjoyment during meals were reported to boost well-being around food intake. The study elaborated our understanding of the complex consequences of COVID-19, and can be applied in health promoting initiatives targeted patients recovering from COVID-19.

Cognitive and hormonal regulation of appetite for food presented in the olfactory and visual modalities

The ability to regulate appetite is essential to avoid food over-consumption. The desire for a particular food can be triggered by its odor before it is even seen. Using fMRI, we identify the neural systems modulated by cognitive regulation when experiencing appetizing food stimuli presented in both olfactory and visual modalities, while being hungry. Regulatory instruction modulated bids for food items and inhalation patterns. Distinct brain regions were observed for up and down appetite-regulation, respectively the dorsomedial prefrontal cortex (dmPFC) and dorsolateral PFC. Food valuation engaged the ventromedial PFC and bilateral striatum. Furthermore, we identified a neurobiological marker for successful appetite upregulation. Individuals with higher blood levels of ghrelin were better at exercising up-regulation, and engaged the dmPFC more. These findings characterize the neural circuitry regulating food consumption within the healthy population and highlight how cognitive regulation modulates olfactomotor measures of olfaction.

Do Food Odors Differently Influence Cerebral Activity Depending on Weight Status? An Electroencephalography Study of Implicit Olfactory Priming Effects on the Processing of Food Pictures

Attentional automatic processes and cerebral activity may differ between individuals with different weight statuses in the presence of food stimuli (e.g. odors, pictures). In the present study, we used an implicit olfactory priming paradigm to test the influence of non-attentively perceived food odors on the cerebral activity underlying the processing of food pictures, in normal-weight, overweight, and obese adults. A pear odor and a pound cake odor were used as primes, respectively priming sweet low-energy-density foods and high-energy-density foods. Event-related potentials were recorded while the participants passively watched pictures of sweet low and high-energy-density foods, under the two priming conditions plus an odorless control condition. The amplitude and latency of several peaks were measured (P100, N100, P200, N400). As a major result, we found that weight status influences the cerebral activity underlying the processing of food cues outside of consciousness, as early as the first detectable P100 peak.

Aging and the (Chemical) Senses: Implications for Food Behaviour Amongst Elderly Consumers

The growing aging population are increasingly suffering from the negative health consequences of the age-related decline in their senses, especially their chemical senses. Unfortunately, however, unlike for the higher senses of vision and hearing, there is currently nothing that can be done to bring back the chemical senses once they are lost (or have started their inevitable decline). The evidence suggests that such chemosensory changes can result in a range of maladaptive food behaviours, including the addition of more salt and sugar to food and drink in order to experience the same taste intensity while, at the same time, reducing their overall consumption because food has lost its savour. Here, though, it is also important to stress the importance of the more social aspects of eating and drinking, given the evidence suggesting that a growing number of older individuals are consuming more of their meals alone than ever before. Various solutions have been put forward in order to try to enhance the food experience amongst the elderly, including everything from optimising the product-intrinsic food inputs provided to the remaining functional senses through to a variety of digital interventions. Ultimately, however, the aim has to be to encourage healthier patterns of food consumption amongst this rapidly-growing section of the population by optimising the sensory, nutritional, social, and emotional aspects of eating and drinking. An experimental dinner with the residents of one such home where nostalgic-flavoured healthy ice-creams were served is described.

The importance of the olfactory system in human well-being, through nutrition and social behavior

The human sense of smell is still much underappreciated, despite its importance for vital functions such as warning and protection from environmental hazards, eating behavior and nutrition, and social communication. We here approach olfaction as a sense of well-being and review the available literature on how the sense of smell contributes to building and maintaining well-being through supporting nutrition and social relationships. Humans seem to be able to extract nutritional information from olfactory food cues, which can trigger specific appetite and direct food choice, but may not always impact actual intake behavior. Beyond food enjoyment, as part of quality of life, smell has the ability to transfer and regulate emotional conditions, and thus impacts social relationships, at various stages across life (e.g., prenatal and postnatal, during puberty, for partner selection and in sickness). A better understanding of how olfactory information is processed and employed for these functions so vital for well-being may be used to reduce potential negative consequences.

Human spatial memory implicitly prioritizes high-calorie foods

All species face the important adaptive problem of efficiently locating high-quality nutritional resources. We explored whether human spatial cognition is enhanced for high-calorie foods, in a large multisensory experiment that covertly tested the location memory of people who navigated a maze-like food setting. We found that individuals incidentally learned and more accurately recalled locations of high-calorie foods – regardless of explicit hedonic valuations or personal familiarity with foods. In addition, the high-calorie bias in human spatial memory already became evident within a limited sensory environment, where solely odor information was available. These results suggest that human minds continue to house a cognitive system optimized for energy-efficient foraging within erratic food habitats of the past, and highlight the often underestimated capabilities of the human olfactory sense.

Olfactory Perception and Presence in a Virtual Reality Food Environment

Virtual reality (VR)'s effectiveness as a medium for training, education, research, entertainment and other uses is based on the fact that users can be deeply immersed and feel present within virtual environments. Olfaction has received less attention regarding its ability to add realism to VR environments. It is important to investigate under which circumstances olfactory stimuli are likely to add to user experience and help achieve the goals of VR applications. This study examined the role of scent in a VR-based buffet restaurant environment. French fry scented oil was administered while participants made a plate of food in the VR Buffet. Participants were asked afterwards to report on smells they perceived. Only 18% of participants perceived the olfactory stimulus, 78% of whom correctly identified it. Perceiving the olfactory stimulus was associated with higher levels of presence in the VR Buffet. Correctly identifying the olfactory stimulus was associated with heightened presence and increased likelihood of choosing french fries from the VR Buffet. These results demonstrate the potential for variability in scent perception and related user experience in VR. Additionally, this study highlights a need for future research into factors that underlie and moderate olfactory perception in VR environments.

Olfactory Cues of Restaurant Wait Staff Modulate Patrons' Dining Experiences and Behavior

Ambient scents at retail stores have been found to modulate customer perceptions and attitudes toward retail products and stores. Although ambient scent effects have also been observed in restaurant settings, little is known about the scent-related influences of restaurant wait staff on patron perception and behavior. This study aimed to determine whether olfactory cues from restaurant wait staff can affect patrons’ dining experiences and interpersonal behavior with respect to menu choice, flavor perception, overall liking of meal items, meal satisfaction, consumption amount, and tip amount for wait staff. A total of 213 adults with no olfactory impairments were asked to select and consume one of four chicken meat menu items: baked, broiled, fried, and smoked chicken, in a mock restaurant setting, under one of the three most likely scents of wait staff: congruent (smoky barbecue scent), fragrance (perfume scent), and no scent (control) applied to fabric aprons of wait staff. The results showed that menu choice and flavor perception of chicken meat items did not differ in the presence of the three scent conditions. The effects of wait staff scents on overall liking of chicken meat items, meal satisfaction, and tip amount for wait staff were found to differ as a function of patron gender. Female patrons gave higher ratings of overall liking and meal satisfaction under the fragrance scent condition than under the no scent condition, while male patrons showed no effect with respect to overall liking and an opposite result in the meal satisfaction. Female patrons gave larger tips to wait staff under the congruent scent condition than under the no scent condition, while male patrons exhibited no effect. Patrons also were found to consume chicken meat items the least under the congruent scent condition. In conclusion, this study provides new empirical evidence that wait staff scents at restaurants can affect patrons’ dining experiences and interpersonal behavior and that the effects of such scents vary as a function of patron gender.

Associations between olfactory pathway gene methylation marks, obesity features and dietary intakes

Background

Olfaction is an important sense influencing food preferences, appetite, and eating behaviors. This hypothesis-driven study aimed to assess associations between olfactory pathway gene methylation signatures, obesity features, and dietary intakes.

Methods

A nutriepigenomic analysis was conducted in 474 adults from the Methyl Epigenome Network Association (MENA) project. Anthropometric measurements, clinical data, and serum metabolic profiles of the study population were obtained from structured databases of the MENA cohorts. Habitual dietary intake was assessed using a validated semiquantitative food frequency questionnaire. DNA methylation was measured in circulating white blood cells by microarray (Infinium Human Methylation 450 K BeadChips). FDR values (p < 0.0001) were used to select those CpGs that showed the best correlation with body mass index (BMI) and waist circumference (WC). Pathway analyses involving the characterization of genes involved in the olfactory transduction system were performed using KEGG and pathDIP reference databases.

Results

Overall, 15 CpG sites at olfactory pathway genes were associated with BMI (p < 0.0001) and WC (p < 0.0001) after adjustments for potential confounding factors. Together, methylation levels at the15 CpG sites accounted for 22% and 20% of the variability in BMI and WC (r² = 0.219, p < 0.001, and r² = 0.204, p < 0.001, respectively). These genes encompassed olfactory receptors (OR4D2, OR51A7, OR2T34, and OR2Y1) and several downstream signaling molecules (SLC8A1, ANO2, PDE2A, CALML3, GNG7, CALML6, PRKG1, and CAMK2D), which significantly regulated odor detection and signal transduction processes within the complete olfactory cascade, as revealed by pathway enrichment analyses (p = 1.94 × 10^–10). Moreover, OR4D2 and OR2Y1 gene methylation patterns strongly correlated with daily intakes of total energy (p < 0.0001), carbohydrates (p < 0.0001), protein (p < 0.0001), and fat (p < 0.0001).

Conclusions

The results of this study suggest novel relationships between olfactory pathway gene methylation signatures, obesity indices, and dietary intakes.

Effect of the GLP-1 receptor agonist exenatide on impaired awareness of hypoglycemia in type 1 diabetes; a randomized controlled trial

CONTEXT

Impaired awareness of hypoglycemia (IAH), resulting from habituation to recurrent hypoglycemia, can be reversed by strict avoidance of hypoglycemia. Adjunctive treatment with glucagon-like peptide-1 (GLP-1) receptor agonists may reduce glucose variability, hence lower the risk of hypoglycemia and improve awareness. The aim of our study was to investigate the effect of exenatide on awareness of hypoglycemia in people with type 1 diabetes and IAH.

METHODS

This was a randomized double-blind, placebo-controlled cross-over trial. Ten patients with type 1 diabetes and IAH were included (age 38.5±4.4 years, 40% males, HbA1c 7.2±0.4 % (55.2±4.8 mmol/mol)). Patients were treated with exenatide 5µg twice daily (first 2 weeks), followed by 10µg twice daily (remaining 4 weeks) or matching placebo, with a 4-week washout period. Patients wore blinded glucose sensors in the final weeks and modified hyperinsulinemic normoglycemic-hypoglycemic glucose clamps (nadir 2.5 mmol/l) were performed at the end of each treatment period.

RESULTS

Treatment with exenatide caused body weight to fall as compared to placebo (-3.9±0.9 vs. 0.6±1.2 kg, p=0.047). Exenatide did not change mean 24-hour glucose levels (8.3±0.4 vs. 8.5±0.3 mmol/l, exenatide vs. placebo, p=0.64), median (interquartile range) percentage of time spent in hypoglycemia (15.5 [4.5, 25.5] vs. 7.8 [4.4, 17.1]%, p=0.11) and frequency of hypoglycemia (15.8±3.7 vs. 12.1±3.5, p=0.19). Symptom scores in response to clamped hypoglycemia were similar between exenatide (median change 1.0 [-1.5, 7.0]) and placebo (4.5 [1.5, 5.8], p=0.08).

CONCLUSIONS

Six weeks treatment with exenatide did not improve awareness of hypoglycemia in patients with type 1 diabetes and IAH.

Ambient Odor Exposure Affects Food Intake and Sensory Specific Appetite in Obese Women

Food odors are important in food perception not only during consumption, but also in anticipation of food. Even though it is well established that smell is involved in eating behavior, its role in affecting actual food consumption is still unclear, especially in morbidly obese subjects, who are reported to be more affected by sensory cues than lean subjects. The aim of the present study was to investigate the influence of ambient odor exposure on ad libitum food intake and on sensory specific appetite in obese women. Thirty obese women (BMI: 34.9 ± 0.8 kg m^-2; age: 50.8 ± 1.8) attended two sessions in which they were exposed to a bread odor dispersed, in a detectable but mild concentration, in the test room (“scented” condition) and to a control condition (“unscented” condition). Participants filled out a questionnaire on general appetite before entering the test room and completed a sensory specific appetite questionnaire (including 12 specific products) about 10 min after entering the test room. After approximately 15 min of exposure, the ad libitum intake of a low energy dense food product (vegetable soup) was measured. The “scented” condition significantly (p < 0.01) increased the amount of soup eaten compared to the “unscented” condition (466.4 ± 33.1 g; 368.9 ± 33.2 g, respectively). Moreover, the odor exposure induced sensory specific appetite for congruent food products in term of taste and energy density, as well as a significant increase in general appetite scores (p < 0.001). In conclusion, ambient odor exposure to a food odor affected the intake of a low energy food in obese women and stimulated appetite for congruent products. This could have important implications for influencing energy intake of individuals.

Modulation of event-related potentials to food cues upon sensory-specific satiety

Tempting environmental food cues and metabolic signals are important factors in appetite regulation. Food intake reduces liking of food cues that are congruent to the food eaten (sensory-specific satiety). With this study we aimed to assess effects of sensory-specific satiety on neural processing (perceptual and evaluative) of visual and olfactory food cues. Twenty healthy female subjects (age: 20 ± 2 years; BMI: 22 ± 2 kg/m²) participated in two separate test sessions during which they consumed an ad libitum amount of a sweet or savoury meal. Before and after consumption, event-related potentials were recorded in response to visual and olfactory cues signalling high-energy sweet, high-energy savoury, low-energy sweet and low-energy savoury food and non-food items. In general, we observed that food intake led to event-related potentials with an increased negative and decreased positive amplitudes for food, but also non-food cues. Changes were most pronounced in response to high-energy sweet food pictures after a sweet meal, and occurred in early processes of perception (~80-150 ms) and later processes of cognitive evaluation (~300-700 ms). Food intake appears to lead to general changes in neural processing that are related to motivated attention, and sensory-specific changes that reflect decreased positive valence of the stimuli and/or modulation of top-down cognitive control over processing of cues congruent to the food eaten to satiety.