The effect of social norms on vegetarian choices is moderated by intentions to follow a vegetarian diet in the future: Evidence from a laboratory and field study

Social norms could be a tool in dietary transition toward more sustainable diets, but the results of social norms interventions aimed at encouraging the selection of plant-based foods to date have been inconsistent. One reason for this might be because there are important moderating factors that have yet to be investigated. Here we examine social modeling of vegetarian food choices and test whether modeling is dependent upon individual intentions to follow a vegetarian diet in the future in two different settings. In a laboratory study of 37 women, participants with low intentions to become a vegetarian consumed fewer plant-based foods in the presence of a vegetarian confederate, compared to eating alone. In an observational study of 1,037 patrons of a workplace restaurant, participants with a higher score of on vegetarian intentions had a greater likelihood of taking a vegetarian main course or starter, and a vegetarian social norm was associated with a greater likelihood of a vegetarian choice for the main course but not for the starter. These data suggest that participants with low intentions to follow a vegetarian diet may exhibit reactance against an explicit vegetarian norm in an unfamiliar context (as in Study 1) but that general norm following regardless of dietary intentions be more likely when it is conveyed implicitly in a familiar context (as in Study 2).

Principles and Validations of an Artificial Intelligence-Based Recommender System Suggesting Acceptable Food Changes

BACKGROUND

Along with the popularity of smartphones, artificial intelligence-based personalized suggestions can be seen as promising ways to change eating habits toward more desirable diets.

OBJECTIVES

Two issues raised by such technologies were addressed in this study. The first hypothesis tested is a recommender system based on automatically learning simple association rules between dishes of the same meal that would make it possible to identify plausible substitutions for the consumer. The second hypothesis tested is that for an identical set of dietary-swaps suggestions, the more the user is-or thinks to be-involved in the process of identifying the suggestion, the higher is their probability of accepting the suggestion.

METHODS

Three studies are presented in this article, first, we present the principles of an algorithm to mine plausible substitutions from a large food consumption database. Second, we evaluate the plausibility of these automatically mined suggestions through the results of online tests conducted for a group of 255 adult participants. Afterward, we investigated the persuasiveness of 3 suggestion methods of such recommendations in a population of 27 healthy adult volunteers through a custom designed smartphone application.

RESULTS

The results firstly indicated that a method based on automatic learning of substitution rules between foods performed relatively well identifying plausible swaps suggestions. Regarding the form that should be used to suggest, we found that when users are involved in selecting the most appropriate recommendation for them, the resulting suggestions were more accepted (OR = 3.168; P < 0.0004).

CONCLUSIONS

This work indicates that food recommendation algorithms can gain efficiency by taking into account the consumption context and user engagement in the recommendation process. Further research is warranted to identify nutritionally relevant suggestions.

Rats chirp with their mouth full: During an experimental meal, adult male Wistar rats emitted flat ultrasonic vocalisations upon feeding

Rats produce ultrasonic vocalisation (USVs) that are classified into different types, based on their average frequency. In pups 40 kHz USVs are produced upon social isolation, and in adults USVs can be associated with affective states and specific behavioural patterns (i.e., appetitive 50 kHz vocalisations of frequency range 30-100 kHz, or aversive 20 kHz vocalisations of frequency range 18-30 kHz). Generally, USVs of frequency around 50 kHz are linked to activation of brain reward pathways, during anticipation or experience of rewarding stimuli. Previous studies have described several subtypes of 50 kHz USVs, according to their acoustic properties. We asked whether USV production might be relevant to feeding behaviour. We recorded USVs from 14-week old adult rats during the satisfaction of a physiological need: refeeding following mild food deprivation (17 h overnight fast). We analysed a 10 min consummatory phase, preceded by a 10 min anticipatory phase, as a control for the experimental meal. Following identification of USV subtypes, we applied frequentist and Bayesian (Monte Carlo shuffling) statistical analyses to investigate the relationship between USV emission and rat behaviour. We found that it was not total USV quantity that varied in response to food consumption, but the subtype of USV produced. Most importantly we found that rats who feed tend to produce flat USVs of a frequency around 40 kHz. Beyond the previous reports of circumstantial association feeding-flat USVs, our observation directly correlate vocalisation and ingestive behaviour. Our study highlights that, in addition to quantification of the production rate, study of USV subtypes might inform us further on rat consummatory behaviour. Since this vocalisation behaviour can have a communicative purpose, those findings also illustrate nutrition studies might benefit from considering the possible social dimension of feeding behaviour.

Intermittent sucrose solution intake and its schedule of access modulate energy intake and weight gain in response to chronic variable stress in mice

There is a strong relationship between stress and the intake of calorically-dense palatable food. Additionally, intake of sodas is an important contributory factor to obesity, and is often associated with palatable food consumption. We studied the effects of 2-h intermittent access to sucrose-sweetened water (SSW, 12.3%, soda-like) and its schedule of administration on the response to chronic variable stress in mice fed a high-fat, high-sugar diet. C57BL/6 mice (n = 64) had access to water or to both water and 2-h SSW during 5 weeks, in addition to their diet. After the first two weeks, half of the animals from each group were stressed daily using a chronic variable stress (CVS) paradigm, while the other half were kept undisturbed. During the CVS exposure period, 2-h SSW access was either scheduled randomly, right before the stressors or right after the stressors. The effects of SSW and its schedule of administration on dietary intake, stress hormones and adiposity were analyzed. Results showed a larger consumption of SSW and higher bodyweight gain in mice receiving SSW after the stressor. In addition, SSW consumption was shown to affect appetite regulation by reducing CCK sensitivity. The present study suggests that SSW leads to overconsumption and weight gain only if provided after exposure to stress. These findings may implicate a relation between exposure to stress, binge-drinking behaviors of sugar sweetened beverages that ensues, and weight gain in humans consuming a western diet.

Associations between Perceived Social Eating Norms and Initiation and Maintenance of Changes in Dietary Habits during the First COVID-19 Lockdown in France

Changes in dietary habits of the French population have been reported during the national lockdown that was enforced due to the COVID-19 pandemic. This study investigated whether perceived social eating norms were associated with the initiation and maintenance of dietary changes that took place as a result of lockdown. An online study collected information on (1) changes in consumption implemented during the lockdown and the maintenance of these changes, and (2) perceptions about changes in consumption implemented during lockdown by household members, relatives out of home, and the general population. The changes in consumption were classified as foods to increase or to decrease according to French national recommendations. The perception of changes to dietary habits by household members and relatives out of home was related to the changes made by individuals for each of the food categories (all p < 0.05) but not to the perception of changes made the general population. Increased consumption of foods to increase was more likely to be maintained when there was a positive perception of the changes made by household members (p = 0.03). These results highlight the influence of the perception of social eating norms, especially by household members and relatives, on the implementation of dietary changes during lockdown and suggest that social eating norms can have a lasting influence.

Diet Protein Content and Individual Phenotype Affect Food Intake and Protein Appetence in Rats

BACKGROUND

A low-protein diet can induce compensatory intake of excess energy. This must be better evaluated to anticipate the obesogenic risk that may result from the dietary recommendations for reducing animal protein consumption.

OBJECTIVES

We aimed to further characterize the behavioral and physiological responses to a reduction in dietary protein and to identify the determinants of protein appetite.

METHODS

Thirty-two male Wistar rats [4 wk old, (mean ± SEM) 135 ± 32 g body weight] were fed a low-protein (LP; 6% energy value) or normal-protein (NP; 20%) diet for 8 wk. Food intake and body mass were measured during the entire intervention. During self-selection sessions after 4 wk of experimental diets, we evaluated rat food preference between LP, NP, or high-protein (HP; 55%) pellets. At the end of the experiment, we assessed their hedonic response [ultrasonic vocalizations (USVs)] and c-Fos neuronal activation in the olfactory tubercle and nucleus accumbens (NAcc) associated with an LP or HP meal.

RESULTS

Rats fed an LP diet had greater food intake (24%), body weight (5%), and visceral adiposity (30%) than NP rats. All LP rats and half of the NP rats showed a nearly exclusive preference for HP pellets during self-selection sessions, whereas the other half of the NP rats showed no preference. This suggests that the appetite for proteins is driven not only by a low protein status but also by individual traits in NP rats. LP or HP meal induced similar USV emission and similar neuronal activation in the NAcc in feed-deprived LP and NP rats, showing no specific response linked to protein appetite.

CONCLUSIONS

Protein appetite in rats is driven by low protein status or individual preferences in rats receiving adequate protein amounts. This must be considered and further analyzed, in the context of current recommendations for protein intake reduction.

Local Foods Can Increase Adequacy of Nutrients Other than Iron in Young Urban Egyptian Women: Results from Diet Modeling Analyses

BACKGROUND

Nutrition transition and recent changes in lifestyle in Middle Eastern countries have resulted in the double burden of malnutrition. In Egypt, 88% of urban women are overweight or obese and 50% are iron deficient. Their energy, sugar, and sodium intakes are excessive, while intakes of iron, vitamin D, and folate are insufficient.

OBJECTIVE

This study aimed to formulate dietary advice based on locally consumed and affordable foods and determine the need for fortified products to meet the nutrient requirements of urban Egyptian women.

METHODS

Food intakes were assessed using a 4-d food diary collected from 130 urban Egyptian women aged 19-30 y. Food prices were collected from modern and traditional markets to calculate diet cost. Population-based linear and goal programming analyses (Optifood tool) were used to identify "limiting nutrients" and to assess whether locally consumed foods (i.e., consumed by >5% of women) could theoretically improve nutrient adequacy at an affordable cost (i.e., less than or equal to the mean diet cost), while meeting recommendations for SFAs, sugars, and sodium. The potential of hypothetical fortified foods for improving intakes of micronutrients was also assessed.

RESULTS

Iron was the most limiting nutrient. Daily consumption of fruits, vegetables, milk or yogurt, meat/fish/eggs, and tahini (sesame paste) were likely to improve nutrient adequacy for 11 out of 12 micronutrients modeled. Among fortified foods tested, iron-fortified rice, milk, water, bread, or yogurt increased the minimized iron content of the modeled diet from 40% to >60% of the iron recommendation.

CONCLUSIONS

A set of dietary advice based on locally consumed foods, if put into practice, can theoretically meet requirements for most nutrients, except for iron for which adequacy is harder to achieve without fortified products. The acceptability of the dietary changes modeled needs evaluation before promoting them to young Egyptian women.

Social modeling of food choices in real life conditions concerns specific food categories

The social context of eating has a profound effect on consumption choices. Social modeling, that involves using others' behavior as a guide for appropriate consumption, has been well documented for food intake, but less is known about social modeling of food choices. Moreover, social modeling has mainly been studied in laboratory settings. We conducted an observational study in a self-service canteen to examine whether the food choices of an individual were influenced by the choice of the person ahead in the queue. We recorded food choices of 546 individuals (333 men and 211 women) and those of the person in front of them in the queue along a linear buffet. Starters were sub-categorized into salads, mixed starters (e.g. avocado shrimp mayonnaise), and cold meat starters, and desserts were sub-categorized into fruits, dairy products and pastries. There was a significantly higher probability of taking a starter in general (OR = 1.65, IC = 1.06-2.57, p = 0.03), a salad (OR = 1.78, CI = 1.08-2.93, p = 0.02), a mixed starter (OR = 2.98, CI = 1.42-6.05, p < 0.01), but not a cold meat, if the person ahead in the queue also took one compared to when the person ahead did not take one. No significant modelling was found for desserts which may be because almost all participants took a dessert. These results highlight that social modeling influences food choices, and that this phenomenon can be observed in a real life setting. These data also suggest that some food categories, such as starters, could be more susceptible to social modeling than are others. Finally, we observed modeling both between familiar and unfamiliar participants, which suggests that social norms could be used to promote healthier eating in a range of settings including friendship groups.

Protein Status Modulates an Appetite for Protein To Maintain a Balanced Nutritional State-A Perspective View

Protein sufficiency is tightly controlled through different sensing and signaling processes that modulate and adapt protein and energy metabolism and feeding behavior to reach and maintain a well-balanced protein status. High-protein diets, often discussed in the context of body weight management, usually activate anorexigenic pathways, leading to higher satiety, decreased food and energy intake, and decreased body weight and adiposity. Diets marginally low in protein (3-8% energy) or marginally deficient in some indispensable amino acid more often activate orexigenic pathways, with higher appetite and a specific appetite for protein, a response that leads to an increase in protein intake to partially compensate for the deficit in protein and amino acid. Diets severely deficient in protein (2-3% energy as protein) usually depress food intake and induce lower weight and lower fat mass and lean tissues that characterize a status of protein deficiency. The control of protein sufficiency involves various peripheral and central signals, including modulation of both metabolic pathways at the periphery as well as central pathways of the control of food and protein intake, including a reward-driven specific sensitivity to the protein content of foods.

Urban Egyptian Women Aged 19-30 Years Display Nutrition Transition-Like Dietary Patterns, with High Energy and Sodium Intakes, and Insufficient Iron, Vitamin D, and Folate Intakes

BACKGROUND

Recent changes in Egyptian dietary habits can be attributed to more urban and sedentary lifestyles and to alterations in the dietary and economic context. The mean BMI of Egyptian women is one of the highest worldwide, and 50% have iron deficiency.

OBJECTIVE

The aim was to quantify food and nutrient intakes of urban Egyptian women and conduct a detailed analysis of micronutrients commonly consumed in inadequate amounts, such as iron, vitamin D, and folate.

METHODS

Urban Egyptian women aged 19-30 y (n = 130) were recruited during 2016-2017. Energy needs were estimated using the Henry equation, assuming a low physical activity level (1.4). Dietary intakes and iron bioavailability were estimated from a 4-d food diary. Macronutrient intakes were compared with WHO/FAO population goals and micronutrient intakes with Egyptian recommendations. Iron needs were determined for each subject.

RESULTS

The mean BMI (kg/m2) was 27.9 ± 4.9. The mean total energy intake (TEI; 2389 ± 715 kcal/d) was significantly higher than needs (2135 ± 237 kcal/d; P = 0.00018). Total fat (33%TEI) and SFA (11%TEI) intakes were slightly higher than population goals (15-30%TEI and <10%TEI, respectively). Diets provided 18 ± 8 g/d of fiber, 98 ± 54 g/d of total sugars, and nearly twice the recommended sodium intake (intake: 2787 ± 1065 mg/d; recommendation: <1500 mg/d). Estimated dietary iron bioavailability was low (9.2% ± 1.6%), and 79% of women consumed less iron than the average requirement (17.5 ± 7 mg/d). Overall, 82% and 80% of women consumed less vitamin D and folate, respectively, than recommended.

CONCLUSIONS

Egyptian women aged 19-30 y have high intakes of energy and sodium, whereas iron, vitamin D, and folate intakes are insufficient, with only low concentrations of bioavailable iron. These results call for further investigation into measures that would improve this population's diet quality.

Perinatal exposure of rats to a maternal diet with varying protein quantity and quality affects the risk of overweight in female adult offspring

The maternal protein diet during the perinatal period can program the health of adult offspring. This study in rats evaluated the effects of protein quantity and quality in the maternal diet during gestation and lactation on weight and adiposity in female offspring. Six groups of dams were fed a high-protein (HP; 47% protein) or normal-protein (NP; 19% protein) isocaloric diet during gestation (_G) using either cow's milk (M), pea (P) or turkey (T) proteins. During lactation, all dams received the NP diet (protein source unchanged). From postnatal day (PND) 28 until PND70, female pups (n=8) from the dam milk groups were exposed to either an NP milk diet (NPM_W) or to dietary self-selection (DSS). All other pups were only exposed to DSS. The DSS design was a choice between five food cups containing HPM, HPP, HPT, carbohydrates or lipids. The weights and food intakes of the animals were recorded throughout the study, and samples from offspring were collected on PND70. During the lactation and postweaning periods, body weight was lower in the pea and turkey groups (NP_G and HP_G) versus the milk group (P<.0001). DSS groups increased their total energy and fat intakes compared to the NPM_W group (P<.0001). In all HP_G groups, total adipose tissue was increased (P=.03) associated with higher fasting plasma leptin (P<.05). These results suggest that the maternal protein source impacted offspring body weight and that protein excess during gestation, irrespective of its source, increased the risk of adiposity development in female adult offspring.

The Willingness to Modify Portion Sizes or Eat New Protein Foods Largely Depends on the Dietary Pattern of Protein Intake

Promoting a more balanced animal/plant dietary protein ratio by changing portion sizes or introducing new foods is a promising means to improve diet quality, but little is known about the willingness of individuals to adopt such changes. Our objective was to assess the willingness to adopt dietary changes by these means. In a French cross-sectional study in 2018 (n = 2055), we analyzed the association between the willingness to eat smaller or larger portions or to introduce non-consumed protein foods and the current dietary patterns of individuals and their socio-demographic characteristics. These modifications had previously been identified as improving the nutrient adequacy of diets. Participants were more willing to eat smaller portion sizes than to introduce new foods and to eat larger portion sizes. The willingness for any modification varied depending on the food groups concerned. Participants were also more willing to eat larger portions and less willing to eat smaller portions when they were the most frequent consumers of the foods concerned. Participants were more willing to eat a new food if it was consumed in large quantities by individuals with a similar dietary pattern. This study underlines the importance of accounting for individual food habits when issuing nutritional recommendations.

How to Improve Dietary Practices of 19–30yo Egyptian Women Living in Urban Areas? An Optifood Analysis (OR25-04-19)

Objectives

The double burden of malnutrition is rising in several Arab countries due to rapid changes in dietary patterns and lifestyle. Egyptian women have one of the highest BMI worldwide, and nearly one quarter of them suffer from anemia. The objective was to identify changes needed in dietary practices and product offer, which could help to rebalance nutrient intakes for women living in urban Egypt.

Methods

Food intakes were obtained from a 4-days dietary record in 127 women (19–30 yo) and food prices were collected in modern and in traditional trades. Modeling analyses (Optifood software) were used to identify problem nutrients and design affordable food-based recommendations (FBRs): we assessed whether locally and consumed foods could theoretically be combined to ensure nutrient adequacy, at a fixed cost, without exceeding recommendations in energy and SFAs, total sugars and sodium. Fortified foods were included in additional modeling analyses to test their potential to improve intakes of the most problematic micronutrient to cover.

Results

Preliminary results from modeling analyses indicated that iron is the most problematic recommendation to cover from a combination of local and consumed foods. Daily consumption of fruits, vegetables, grains, milk or yoghurt, and tahini associated with smart food choices in the meat-fish-eggs category would result in a low percentage of women at risk for 11 out of 12 micronutrients modeled. Among the fortified foods tested, iron fortified bread, rice, milk and yoghurt would be promising vectors to improve iron intakes.

Conclusions

Local foods can ensure nutrient adequacy of most nutrients. However, strategies are needed to promote acceptable FBRs to rebalance the diet of Egyptian women. Iron fortified products could help to improve iron intakes for this population at risk of anemia.

Funding Sources

Danone Research.

Maternal High-Protein Diet during Pregnancy Modifies Rat Offspring Body Weight and Insulin Signalling but Not Macronutrient Preference in Adulthood

Diet of mothers during gestation may impact offspring phenotype. This study evaluated the consequences of a maternal High-Protein (HP) diet during gestation on food preferences and phenotypic characteristics in adult rat offspring. Dams were fed a HP or a Normal-Protein (NP) isocaloric diet during gestation only. Weaned female pups were divided into 3 diet groups: NP control or one of two dietary self-selection (DSS) conditions. In DSS1, offspring had a free choice between proteins (100%) or a mix of carbohydrates (88%) and lipids (12%). In DSS2, the choice was between proteins (100%), carbohydrate (100%) or lipids (100%). DSS2 groups consumed more of their energy from protein and lipids, with a decreased carbohydrate intake (p < 0.0001) compared to NP groups, regardless of the maternal diet. Offspring from HP gestation dams fed the DSS2 diet (HPDSS2) had a 41.2% increase of total adiposity compared to NPDSS2 (p < 0.03). Liver Insulin receptor and Insulin substrate receptor 1 expression was decreased in offspring from HP compared to NP gestation dams. These results showed the specific effects of DSS and maternal diet and data suggested that adult, female offspring exposed to a maternal HP diet during foetal life were more prone to adiposity development, in response to postweaning food conditions.

Providing a Smart Healthy Diet for the Low-Income Population: Qualitative Study on the Usage and Perception of a Designed Cooking App

Background

Health behaviors among low-income groups have become a major issue in the context of increasing social inequalities. The low-income population is less likely to be receptive to nutritional recommendations, but providing cooking advice could be more effective. In this domain, taking advantage of digital devices can be a bonus with its own challenges.

Objective

The aim of this study was to develop and deploy NutCracker, a social network–based cooking app for low-income population, including cooking tips and nutritional advices, aiming at creating small online communities. We further determined the usefulness, perceptions, barriers, and motivators to use NutCracker.

Methods

The smartphone app, designed jointly with beneficiaries of the social emergency services, was implemented in a disadvantaged neighborhood of Magny, (Paris region, France). Once the app became available, 28 subjects, living in the neighborhood, tested the app for a 6-month period. Logs to the app and usages were collected by the software. In total, 12 in-depth, semistructured interviews were conducted among the users and the social workers to analyze their uses and perceptions of the app relative to their interest in cooking, cooking skills, socioeconomic constraints, and social integration. These interviews were compared with 21 supplementary interviews conducted among low-income individuals in the general population.

Results

NutCracker was developed as a social network–based app, and it includes cooking tips, nutritional advice, and Web-based quizzes. We identified barriers to uses (especially technical barriers, lack of knowledge in the field of new technologies and written comprehension, and search for real contacts) and motivators (in particular, good social integration, previous use of social networks, and help of children as intermediaries). Cooking skills were both a barrier and a lever.

Conclusions

Targeting the low-income groups through a cooking app to promote healthier behaviors offers many advantages but has not been fully explored. However, the barriers in low-income milieu remain high, especially among the less socially integrated strata. Lessons from this intervention allow us to identify barriers and possible levers to improve nutrition promotion and awareness in deprived areas, especially in the time of social crisis.

Differences in BOLD responses in brain reward network reflect the tendency to assimilate a surprising flavor stimulus to an expected stimulus

External information can modify the subjective value of a tasted stimulus, but little is known about neural mechanisms underlying these behavioral modifications. This study used flavored drinks to produce variable degrees of discrepancy between expected and received flavor. During a learning session, 43 healthy young men learned 4 symbol-flavor associations. In a separate session, associations were presented again during an fMRI scan, but half of the trials introduced discrepancy with previously learned associations. Liking ratings of drinks were collected and were analyzed using a linear model to define the degree to which discrepant symbols affected liking ratings of the subjects during the fMRI session. Based on these results, a GLM analysis of fMRI data was conducted to determine neural correlates of observed behavior. Groups of subjects were composed based on their behavior in response to discrepant symbols, and comparison of brain activity between groups showed that activation in the PCC and the caudate nucleus was more potent in those subjects in which liking was not affected by discrepant symbols. These activations were not found in subjects who assimilated unexpected flavors to flavors preceeded by discrepant symbols. Instead, these subjects showed differences in the activity in the parietal operculum. The activity of reward network appears to be related to assimilation of received flavor to expected flavor in response to symbol-flavor discrepancy.

The Protein Status of Rats Affects the Rewarding Value of Meals Due to their Protein Content

Background

Protein status is controlled by the brain, which modulates feeding behavior to prevent protein deficiency.

Objective

This study tested in rats whether protein status modulates feeding behavior through brain reward pathways.

Methods

Experiments were conducted in male Wistar rats (mean ± SD weight; 230 ± 16 g). In experiment 1, rats adapted for 2 wk to a low-protein (LP; 6% of energy) or a normal-protein (NP; 14% of energy) diet were offered a choice between 3 cups containing high-protein (HP; 50% of energy), NP, or LP feed; their intake was measured for 24 h. In 2 other experiments, the rats were adapted for 2 wk to NP and either HP or LP diets and received, after overnight feed deprivation, a calibrated HP, NP, or LP meal daily. After the meal, on the last day, rats were killed and body composition and blood protein, triglycerides, gut neuropeptides, and hormones were determined. In the brain, neuropeptide mRNAs in the hypothalamus and c-Fos protein and opioid and dopaminergic receptor mRNAs in the nucleus accumbens (NAcc) were measured.

Results

Rats fed an LP compared with an NP diet had 7% lower body weight, significantly higher protein intake in a choice experiment (mean ± SD: 30.5% ± 0.05% compared with 20.5% ± 0.05% of energy), higher feed-deprived blood ghrelin, lower postmeal blood leptin, and higher neuropeptide Y (Npy) and corticotropin-releasing hormone (Crh) mRNA expression in the hypothalamus. In contrast to NP, rats fed an LP diet showed postmeal c-Fos protein expression in the NAcc, which was significantly different between meals, with LP < NP < HP. In contrast, in rats adapted to an HP diet compared with an NP diet, energy intake was lower; and in the NAcc, meal-induced c-Fos protein expression was 20% lower, and mRNA expression was 17% higher for dopamine receptor 2 (Drd2) receptors and 38% lower for κ opioid receptor (Oprk1) receptors.

Conclusion

A protein-restricted diet induced a reward system-driven appetite for protein, whereas a protein-rich diet reduced the meal-induced activation of reward pathways and lowered energy intake in male rats.

Fructo-oligosaccharides reduce energy intake but do not affect adiposity in rats fed a low-fat diet but increase energy intake and reduce fat mass in rats fed a high-fat diet

The ingestion of low or high lipid diets enriched with fructo-oligosaccharide (FOS) affects energy homeostasis. Ingesting protein diets also induces a depression of energy intake and decreases body weight. The goal of this study was to investigate the ability of FOS, combined or not with a high level of protein (P), to affect energy intake and body composition when included in diets containing different levels of lipids (L). We performed two studies of similar design over a period of 5weeks. During the first experiment (exp1), after a 3-week period of adaptation to a normal protein-low fat diet, the rats received one of the following four diets for 5weeks (6 rats per group): (i) normal protein (14% P/E (Energy) low fat (10% L/E) diet, (ii) normal protein, low fat diet supplemented with 10% FOS, (iii) high protein (55%P/E) low fat diet, and (iv) high protein, low fat diet supplemented with 10% FOS. In a second experiment (exp2) after the 3-week period of adaptation to a normal protein-high fat diet, the rats received one of the following 4 diets for 5weeks (6 rats per group): (i) normal protein, high fat diet (35% of fat), (ii) normal protein, high fat diet supplemented with 10% FOS, (iii) high protein high fat diet and (iv) high protein high fat diet supplemented with 10% FOS. In low-fat fed rats, FOS did not affect lean body mass (LBM) and fat mass but the protein level reduced fat mass and tended to reduce adiposity. In high-fat fed rats, FOS did not affect LBM but reduced fat mass and adiposity. No additive or antagonistic effects between FOS and the protein level were observed. FOS reduced energy intake in low-fat fed rats, did not affect energy intake in normal-protein high-fat fed rats but surprisingly, and significantly, increased energy intake in high-protein high-fat fed rats. The results thus showed that FOS added to a high-fat diet reduced body fat and body adiposity.

Behavioural measures of child's eating temperament and their link with BMI

Rothbart's model of temperament, defined as individual differences in reactivity and self-regulation, has a strong heuristic value with applications in a wide variety of children's outcomes. Our objective was to test Rothbart's model applied to children's food behaviours and BMI outcome through behavioural measures. Our hypotheses, according to Rothbart's model, were as follows: (i) self-regulation in eating modulates appetite reactivity; (ii) appetite reactivity increases the risk of excess BMI, whereas self-regulation in eating limits this risk. One hundred and four children aged between 7 and 12 years completed four behavioural tasks to assess scores for two components of appetite reactivity (i.e. appetite arousal and appetite persistence) and two components of self-regulation in eating (i.e. self-regulation in eating without hunger and self-regulation in eating speed). Their heights and weights were measured in order to calculate their BMI-for-age. T-tests and regression analysis were used to verify our hypotheses. None of the scores of self-regulation in eating was directly associated with BMI but we observed a significant impact of self-regulation in eating without hunger on appetite arousal (p-value = 0.04), together with a modest but significant association between appetite persistence and BMI (p-value = 0.02). We can thus conclude that our behavioural measures could be used for the determination of the child's eating temperament. Further studies are needed to investigate how to use these measures to improve the treatment of overweight in children.

In-store marketing of inexpensive foods with good nutritional quality in disadvantaged neighborhoods: increased awareness, understanding, and purchasing

BACKGROUND

Consumers often do not understand nutrition labels or do not perceive their usefulness. In addition, price can be a barrier to healthy food choices, especially for socio-economically disadvantaged individuals.

METHOD

A 6-month intervention combined shelf labeling and marketing strategies (signage, prime placement, taste testing) to draw attention to inexpensive foods with good nutritional quality in two stores located in a disadvantaged neighborhood in Marseille (France). The inexpensive foods with good nutritional quality were identified based on their nutrient profile and their price. Their contribution to customers' spending on food was assessed in the two intervention stores and in two control stores during the intervention, as well as in the year preceding the intervention (n = 6625). Exit survey (n = 259) and in-depth survey (n = 116) were used to assess customers' awareness of and perceived usefulness of the program, knowledge of nutrition, understanding of the labeling system, as well as placement-, taste- and preparation-related attractiveness of promoted products. Matched purchasing data were used to assess the contribution of promoted products to total food spending for each customer who participated in the in-depth survey.

RESULTS

The contribution of inexpensive foods with good nutritional quality to customers' total food spending increased between 2013 and 2014 for both the control stores and the intervention stores. This increase was significantly higher in the intervention stores than in the control stores for fruits and vegetables (p = 0.001) and for starches (p = 0.011). The exit survey revealed that 31 % of customers had seen the intervention materials; this percentage increased significantly at the end of the intervention (p < 0.001). The in-depth survey showed that customers who had seen the intervention materials scored significantly higher on quizzes assessing nutrition knowledge (p < 0.001) and understanding of the labeling system (p = 0.024).

CONCLUSION

A social marketing intervention aimed at increasing the visibility and attractiveness of inexpensive foods with good nutritional quality may improve food purchasing behaviors in disadvantaged neighborhoods.

Environmental enrichment alters splenic immune cell composition and enhances secondary influenza vaccine responses in mice

Chronic stress has deleterious effects on immune function, which can lead to adverse health outcomes. However, studies investigating the impact of stress reduction interventions on immunity in clinical research have yielded divergent results, potentially stemming from differences in study design and genetic heterogeneity, among other clinical research challenges. To test the hypothesis that reducing glucocorticoid levels enhances certain immune functions, we administered influenza vaccine once (prime) or twice (boost) to mice housed in either standard control caging or environmental enrichment (EE) caging. We have shown that this approach reduces mouse corticosterone production. Compared with controls, EE mice had significantly lower levels of fecal corticosterone metabolites (FCMs) and increased splenic B and T lymphocyte numbers. Corticosterone levels were negatively associated with the numbers of CD19(+) (r(2) = 0.43, p = 0.0017), CD4(+) (r(2) = 0.28, p = 0.0154) and CD8(+) cells (r(2) = 0.20, p = 0.0503). Vaccinated mice showed nonsignificant differences in immunoglobulin G (IgG) titer between caging groups, although EE mice tended to exhibit larger increases in titer from prime to boost than controls; the interaction between the caging group (control versus EE) and vaccine group (prime versus boost) showed a strong statistical trend (cage-group*vaccine-group, F = 4.27, p = 0.0555), suggesting that there may be distinct effects of EE caging on primary versus secondary IgG vaccine responses. Vaccine-stimulated splenocytes from boosted EE mice had a significantly greater frequency of interleukin 5 (IL-5)-secreting cells than boosted controls (mean difference 7.7, IL-5 spot-forming units/10(6) splenocytes, 95% confidence interval 0.24-135.1, p = 0.0493) and showed a greater increase in the frequency of IL-5-secreting cells from prime to boost. Our results suggest that corticosterone reduction via EE caging was associated with enhanced secondary vaccine responses, but had little effect on primary responses in mice. These findings help identify differences in primary and secondary vaccine responses in relationship to stress mediators that may be relevant in clinical studies.

A cafeteria diet modifies the response to chronic variable stress in rats

Stress is known to lead to metabolic and behavioral changes. To study the possible relationships between stress and dietary intake, male Sprague-Dawley rats were fed one of three diets for 6 weeks: high carbohydrate (HC), high fat (HF), or "Cafeteria" (CAF) (Standard HC plus a choice of highly palatable cafeteria foods: chocolate, biscuits, and peanut butter). After the first 3 weeks, half of the animals from each group (experimental groups) were stressed daily using a chronic variable stress (CVS) paradigm, while the other half of the animals (control groups) were kept undisturbed. Rats were sacrificed at the end of the 6-week period. The effects of stress and dietary intake on animal adiposity, serum lipids, and corticosterone were analyzed. Results showed that both chronic stress and CAF diet resulted in elevated total cholesterol, increased low-density lipoprotein (LDL), and lower high-density lipoprotein (HDL). In addition, increases in body weight, food intake, and intra-abdominal fat were observed in the CAF group compared with the other dietary groups. In addition, there was a significant interaction between stress and diet on serum corticosterone levels, which manifest as an increase in corticosterone levels in stressed rats relative to non-stressed controls in the HC and HF groups but not in the CAF group. These results show that a highly palatable diet, offering a choice of food items, is associated with a reduction in the response to CVS and could validate a stressor-induced preference for comfort food that in turn could increase body weight.

Dietary fibers reduce food intake by satiation without conditioned taste aversion in mice

It is well known that intake of dietary fiber (DF) potently decreases food intake and feelings of hunger and/or promotes satiety ratings. However, the mechanisms explaining these effects are not well characterized. This work was performed to determine which of satiation and/or satiety mechanisms provoke the decrease of food intake induced by DF in mice. We tested in an intra-group protocol a low-viscosity (LV, fructo-oligosaccharide), a viscous (VP, guar gum) and a high-viscosity (HV, mixture of guar gum and fructo-oligosaccharide) preload. These were given to mice by intra-gastric gavage. It appeared that viscous preloads such as VP and HV reduced the daily energy intake by 14% and 21% respectively. The strong effect of HV was mainly due to a large decrease of meal size (by 57%) and meal duration (by 65%) with no effect on ingestion rate during the first 30 min after administration. Therefore, the DF-induced decrease of energy intake was due to a satiation mechanism. This is further supported by a 3-fold increased sensitization of neurons in the nucleus of the solitary tract as observed by c-Fos protein immunolabelling. No compensation of food intake was observed during the rest of the day, a phenomenon that may be explained by the fact that metabolic rate remained high despite the lower food intake. We have also shown that the DF-induced inhibition of food intake was not paired with a conditioned taste aversion. To conclude, this work demonstrates that DF inhibits food intake by increasing satiation during ~1h after administration.

Dietary fibers solubilized in water or an oil emulsion induce satiation through CCK-mediated vagal signaling in mice

This study focused on the fate of the satiating potency of dietary fibers when solubilized in a fat-containing medium. Fourteen percent of either guar gum (GG) or fructo-oligosaccharide (FOS) or a mixture of the 2 (GG-FOS, 5% GG and 9% FOS) were solubilized in water or an oil emulsion (18-21% rapeseed oil in water, v:v) and administered by gavage to mice before their food intake was monitored. When compared with water (control), only GG-FOS solubilized in water or in the oil emulsion reduced daily energy intake by 21.1 and 14.1%, respectively. To further describe this effect, the meal pattern was characterized and showed that GG-FOS increased satiation without affecting satiety by diminishing the size and duration of meals for up to 9 h after administration independently of the solubilization medium. The peripheral blockade of gut peptide receptors showed that these effects were dependent on the peripheral signaling of cholecystokinin but not of glucagon-like peptide 1, suggesting that anorectic signals emerge from the upper intestine rather than from distal segments. Measurements of neuronal activation in the nucleus of solitary tract supported the hypothesis of vagal satiation signaling because a 3-fold increase in c-Fos protein expression was observed in that nucleus after the administration of GG-FOS, independently of the solubilization medium. Taken together, these data suggest that a mixture of GG and FOS can maintain its appetite suppressant effect in fatty media. Adding these dietary fibers to fat-containing foods might therefore be useful in managing food intake.