Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Systematic review of the evidence for sustained efficacy of dietary interventions for reducing appetite or energy intake
Halford, J.C.G. ; Masic, U. ; Marsaux, C.F.M. ; Jones, A.J. ; Lluch, A. ; Marciani, L. ; Mars, M. ; Vinoy, S. ; Westerterp-Plantenga, M. ; Mela, D.J. - \ 2018
Obesity Reviews 19 (2018)10. - ISSN 1467-7881 - p. 1329 - 1339.
Appetite - energy intake - satiety - study duration

We assessed evidence for changes in efficacy of food-based interventions aimed at reducing appetite or energy intake (EI), and whether this could be used to provide guidance on trial design. A systematic search identified randomized controlled trials testing sustained efficacy of diets, foods, supplements or food ingredients on appetite and/or EI. Trials had to include sufficient exposure duration (≥3 days) with appetite and/or EI measured after both acute and repeated exposures. Twenty-six trials met the inclusion criteria and reported data allowing for assessment of the acute and chronic effects of interventions. Most (21/26) measured appetite outcomes and over half (14/26) had objective measures of EI. A significant acute effect of the intervention was retained in 10 of 12 trials for appetite outcomes, and six of nine studies for EI. Initial effects were most likely retained where these were more robust and studies adequately powered. Where the initial, acute effect was not statistically significant, a significant effect was later observed in only two of nine studies for appetite and none of five studies for EI. Maintenance of intervention effects on appetite or EI needs to be confirmed but seems likely where acute effects are robust and replicable in adequately powered studies.

Food reward from a behavioural and (neuro)physiological perspective
Bruijn, Suzanne E.M. - \ 2017
University. Promotor(en): Kees de Graaf; Renger Witkamp, co-promotor(en): Gerry Jager. - Wageningen : Wageningen University - ISBN 9789463436748 - 154
food - physiological functions - feeding behaviour - food preferences - perception - hormones - responses - neurohormonal control - stomach bypass - gastric bypass - satiety - voedsel - fysiologische functies - voedingsgedrag - voedselvoorkeuren - perceptie - hormonen - reacties - neurohormonale controle - maag bypass - buik bypass - verzadigdheid

Food reward is an important driver of food intake and triggers consumption of foods for pleasure, so-called hedonic eating, even in the absence of any energy deficits. Hedonic eating can trigger overeating and may therefore lead to obesity. Given the rise in obesity rates and the health risks associated with being obese, hedonic eating and food reward are important phenomena to study. This thesis aimed to add on to the existing knowledge on food reward. The phenomenon was approached from a behavioural, sensory and (neuro)physiological perspective in healthy, lean and in obese gastric bypass populations.

For the behavioural perspective, the main outcome measure used in this thesis was food preferences. To be able to study food preferences for four macronutrient and two taste categories, a new food preference task was developed. In chapter 2, the development and validation of the Macronutrient and Taste Preference Ranking Task (MTPRT) were described. The MTPRT uses a ranking method to determine preferences for four macronutrient (high-carbohydrate, high-fat, high-protein, low-energy) and two taste (sweet and savoury) categories.

For the sensory and physiological perspective, focus was put on the endocannabinoid system (ECS): a neuromodulatory system that plays a role in food reward. To gain more insight into this role, the effect of ECS modulation with pharmacological challenges on sensory perception of sweet taste and on food preferences were studied, as well as endocannabinoid responses to food intake. In chapter 3 it was shown that inhaling Cannabis with low doses of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) does not alter sweet taste intensity perception and liking in humans, nor does it affect food preferences. Vice versa, in chapter 4 it was found that liking of a food taste does not affect endocannabinoid responses to food intake, after controlling for expectations. When palatability of the food is unknown until the first bite, response of endocannabinoids, ghrelin and pancreatic polypeptide did not differ between a palatable and a neutral food across anticipatory, consummatory and post-ingestive phases of food intake. Endocannabinoid and ghrelin plasma concentrations decreased after food intake, which suggests an orexigenic function for endocannabinoids.

In chapters 5, 6 and 7, studies with patients who underwent Roux-en-Y gastric bypass surgery were described. These studies were intended to gain more insight into alterations in food reward in relation to (morbid) obesity and in response to surgical treatment by RYGB surgery.

First, in chapter 5 food preferences were assessed before, and at two months and one year after RYGB. It was shown that patients have decreased preference for high-carbohydrate and high-fat foods, and increased preference for low-energy foods after compared with before surgery. In addition, liking ratings for the high-carbohydrate and high-fat foods were decreased after RYGB surgery, whereas liking of low-energy products changed minimally. Potential mechanisms behind these alterations in food preferences include changes in neural processing of food cues and changes in appetite-related gut hormones.

In chapter 6, it was shown that alterations in food preferences after RYGB surgery are indeed related to changes in neural activation in response to food cues. With regards to the appetite-related hormones it was shown that plasma concentrations of the endocannabinoid anandamide were increased after compared with before surgery. Plasma concentrations of other endocannabinoids and ghrelin did not change. Moreover, changes in endocannabinoid or ghrelin concentrations did not correlate with changes in food preferences or neural response to food cues. Together, these results suggest that changes in neural processing of food cues contribute to changes in food preferences towards low-energy foods, and provide a first indication that the endocannabinoid system does not seem to play a role in this process.

To gain more insight into behavioural responses to food cues, a response-inhibition paradigm was used in chapter 7, in which response-inhibition to high-energy and low-energy food cues was assessed during brain imaging. The behavioural data did not show differences in performance when comparing before and two months after RYGB surgery. The brain imaging data showed that activation in reward-related brain areas was decreased in response to both high- and low-energy food pictures after RYGB surgery. Also, prefrontal brain areas were more activated in response to the high-energy pictures, which suggests improved response inhibition.

In conclusion, the findings in this thesis show that modulating the ECS with low doses of THC and CBD does not influence sweet taste perception and liking and food preferences, and vice versa, food taste liking in the absence of expectations does not affect endocannabinoid responses to food intake. With regards to RYGB surgery it was uncovered that changes in food preferences after RYGB surgery are related to altered brain reward processing, but no relation with changes in endocannabinoid tone was found. The success of RYGB surgery and the changes in food choice might in part be caused by an improved inhibitory response to high-energy foods.

Between odours and overeating : behavioural and neurobiological mechanisms of olfactory food-cue reactivity
Zoon, Harriët F.A. - \ 2017
University. Promotor(en): Kees de Graaf, co-promotor(en): Sanne Boesveldt. - Wageningen : Wageningen University - ISBN 9789463431675 - 178
geurstoffen - overeten - neurobiologie - voedingsgedrag - reukstimulatie - obesitas - eetlust - overgewicht - buik bypass - verzadigdheid - odours - overeating - neurobiology - feeding behaviour - olfactory stimulation - obesity - appetite - overweight - gastric bypass - satiety

The obesogenic environment we live in is characterized by an abundance of available foods and food cues that tempt us to eat. Throughout our lives we learn to associate these food cues (odours, pictures) with physiological consequences of food consumption. The sense of smell is suggested to be very important for determining food quality, guiding us away from spoilt food and towards rewarding foods. Increased sensitivity to environmental cues of rewarding food, decreased sensitivity to physiological cues of hunger and a decreased ability to control impulses are thought to contribute to overeating and obesity. With the research in this thesis we aimed to elucidate the role of odours in (over)eating, to better understand how sensory food cues and hunger feelings are involved in determining our eating pattern.

We assessed the appetizing effects of exposure to odours signalling food with a certain taste (sweet/savoury) and energy density (high/low). Our findings show that smelling a food odour increases appetite for foods that are similar to the odour, both in terms of taste and energy density. These appetizing effects were present when participants were hungry but also when they had just eaten, indicating a possible role in overeating.

Further, consumption of a high-energy food with a certain taste (sweet/savoury) led to a decrease in liking and wanting of foods with a similar taste and energy density. Next to this, we observed more pronounced changes in early neural processing of pictures of high-energy/sweet food after consumption of a high-energy/sweet meal.

Food preferences and -intake after ambient exposure to odours signalling high-energy food, low-energy food and non-food were not different. Odours did not affect these measures of eating behaviour differently in a hungry or satiated state and in normal-weight or overweight participants.

In a group of patients who underwent Roux-en-Y Gastric Bypass weight-loss surgery, we found a shift in food preferences away from high-fat/high-sugar and towards low-fat/low-sugar foods and altered activation in the frontoparietal neural network during (food) cue processing. After compared to before surgery we also found altered prefrontal neural responses when patients inhibited their responses to pictures of high-energy food. These results suggest that RYGB leads to changes in cognitive control of attention and increased neural inhibitory control over behavioural responses.

In conclusion, odours have a specific appetizing function in the anticipatory phase of eating. They are important in determining the taste quality and energy-density and may be involved in the selection of foods for macronutrient regulation. Orthonasal odours should be used to guide food selection towards a healthier eating pattern.

External cues challenging the internal appetite control system—Overview and practical implications
Bilman, Els ; Kleef, Ellen van; Trijp, Hans van - \ 2017
Critical Reviews in Food Science and Nutrition 57 (2017)13. - ISSN 1040-8398 - p. 2825 - 2834.
Food environment - food intake - obesity - satiation - satiety
Inadequate regulation of food intake plays an important role in the development of overweight and obesity, and is under the influence of both the internal appetite control system and external environmental cues. Especially in environments where food is overly available, external cues seem to override and/or undermine internal signals, which put severe challenges on the accurate regulation of food intake. By structuring these external cues around five different phases in the food consumption process this paper aims to provide an overview of the wide range of external cues that potentially facilitate or hamper internal signals and with that influence food intake. For each of the five phases of the food consumption process, meal initiation, meal planning, consumption phase, end of eating episode and time till next meal, the most relevant internal signals are discussed and it is explained how specific external cues exert their influence.
The interplay between mouth and mind : explaining variation in taste-related brain activation
Rijn, Inge van - \ 2016
University. Promotor(en): Kees de Graaf, co-promotor(en): Paul Smeets. - Wageningen : Wageningen University - ISBN 9789462579040 - 156
taste research - magnetic resonance imaging - brain - patterns - satiety - hunger - calories - smaakonderzoek - kernspintomografie - hersenen - patronen - verzadigdheid - honger - calorieën

Food does not always ‘taste’ the same. During hunger, for example, food may be tastier compared to during satiety. Many other internal and external factors affect the way we experience our food and make it a dynamic process. Our brain is responsible for weighing and integrating these factors and forms the final consumption experience. Mapping the impact of all factors that influence the consumption experience is of fundamental importance for understanding why we eat the way we eat. Important drivers for food consumption are its rewarding capacity, healthiness and caloric content. Furthermore, in the current supermarket environment, advertisements and food claims are omnipresent, and may exert influence on our consumption experience by triggering all kinds of cognitive processes. Therefore, in this thesis we aimed to assess the effect of food content (caloric content and sugar type), character (personality trait reward sensitivity and attitude health-interest) and cognitive effects (labeling/claim effects and selective attention to food properties) on brain activation during tasting. Such taste-related brain responses were obtained with the use of functional Magnetic Resonance Imaging while administering small sips of liquid to young, normal weight female participants in a MRI scanner.

To begin with, we focussed on the effect of caloric content on taste responses (Chapter 2). An important function of eating is ingesting energy, and the ability to sense energy in the oral cavity would therefore be biologically relevant. However, in this thesis we showed that oral exposure to caloric (maltodextrin and maltodextrin + sucralose) and non-caloric (sucralose) stimuli does not elicit discriminable responses in the brain when averaged over hunger and satiety. Nevertheless, energy content did interact with hunger state in several brain regions involved in inhibition (approach-avoidance behaviors) and gustation: the middle cingulate cortex, ventrolateral prefrontal cortex, anterior insula and thalamus. Thus, brain activation in response to oral calories, irrespective of sweetness, seems to be dependent on hunger state.

In addition to the detection of oral calories in general, we examined whether different sugar types, glucose and fructose, can be sensed in the oral cavity (Chapter 3). Tasting glucose compared to fructose evoked greater food reward (anterior cingulate cortex, ACC) activation during hunger and greater food motivation (precentral gyrus) activation during hunger and satiety. Responses to oral fructose relative to glucose were greater only during satiety in an area associated with inhibitory control (superior frontal gyrus). It appears that oral glucose and fructose evoke differential brain responses, independent of sweetness.

Secondly, we investigated in how far reward sensitivity, a personality trait, affected brain responses to calories in the oral cavity (Chapter 4). This because a food’s reward value is highly dependent on its caloric content. Sensitivity to rewards was measured with the Behavioral Activation System Drive scale and was correlated with oral calorie activation from a simple maltodextrin solution and a sucrose sweetened soft drink. Oral calorie activation was obtained by subtracting activation by a non-caloric solution (sucralose solution/non-caloric soft drink) from that by a caloric solution (maltodextrin + sucralose/sucrose sweetened soft drink). We found that neural responses to oral calories from a maltodextrin solution are modulated by reward sensitivity in reward-related areas such as the caudate, amygdala, and ACC. For soft drinks, we found no correlations with reward sensitivity in any reward related area. This discrepancy may be due to the direct detection of maltodextrin, but not sucrose in the oral cavity. However, the absence of this effect in a familiar soft drink warrants further research into its relevance for real life ingestive behavior.

In the last part of this thesis we explored how cognitions modulate the consumption experience. Perceived, rather than actual caloric content, inflicted by calorie food labels, induces cognitive processes that may influence the consumption experience on their own. We tested this in an experiment and found that receipt of a beverage perceived as low- compared to high-caloric induced more activation in the dorsal striatum, a region involved in coding food reward (Chapter 5). As low-calorie labels may appeal especially to the health-minded consumers, we correlated brain responses to the receipt of a beverage perceived as low- compared to high-caloric with health interest (measured with the General health interest subscale of the Health and Taste Attitude Scales). Indeed, health interest scores correlated positively with activation in the dorsal striatum.

Rather than focussing participants’ attention on differences within one food aspect, in Chapter 6 we focussed on selective attention to different food aspects, i.e. pleasantness versus taste intensity versus calories. In the supermarket, food labels and claims often do the same. In the first place, paying attention to hedonics, caloric content or taste intensity predominantly resulted in common brain activation in regions involved in the neural processing of food stimuli, e.g. the insula and thalamus. This likely resulted from ‘bottom-up’ sensory effects, which are more prominent than ‘top-down’ attentional effects. However, small differences were also observed; taste activation was higher during selective attention to intensity compared to calories in the right middle orbitofrontal cortex and during selective attention to pleasantness compared to intensity in the right putamen, right ACC and bilateral middle insula. Overall, these results indicate that statements regarding food properties can alter the consumption experience through attention-driven effects on the activation of gustatory and reward regions.

Finally, the general discussion (Chapter 7) describes main finding and conclusions of this thesis. In sum, we showed that food energy content, sugar type, trait reward sensitivity, health interest, food labels and selective attention all modulate taste-related brain activation. In conclusion, these findings indicate that the formation of the final consumption experience is a very multifaceted process that dependents on numerous factors integrated by the brain, of which we are just beginning to grasp its complexity.

Small intestinal targets involved in food intake regulation : 'from nutrient to satiety signal'
Ripken, D. - \ 2016
University. Promotor(en): Renger Witkamp; H.F.J. Hendriks. - Wageningen : Wageningen University - ISBN 9789462576438 - 180 p.
obesity - preventive nutrition - small intestine - ileum - duodenum - jejunum - satiety - appetite control - food intake - safflower oil - vagus nerve - casein - stevia rebaudiana - sucrose - macronutrients - serotonin - animal models - human feeding - obesitas - preventieve voeding - dunne darm - verzadigdheid - eetlustcontrole - voedselopname - saffloerolie - nervus vagus - caseïne - macronutriënten - serotonine - diermodellen - humane voeding

Background and aim: The worldwide increasing prevalence of overweight and obesity raises concerns for health. There is a clear need for preventive strategies, because current preventative interventions have proven to be unsuccessful in the long term. New strategies may be developed based on targets in the small intestine by activating satiety signals. The thesis aimed to investigate small intestinal targets contributing to food intake regulation. These targets included serotonin, the vagal nerve and the intestinal brake mechanism.

Methods: The effects of ileal stimulation with safflower oil (lipid mixture), casein (protein), sucrose (carbohydrate) and rebaudioside A (non-caloric sweetener) on GLP-1 and PYY release were investigated by applying an porcine ex vivo intestinal segment model. The same model was also used to investigate if serotonin is involved in (non-)nutritional-induced GLP-1 and PYY release.

The contribution to satiation of GLP-1 and CCK receptors at the vagal nerve, was studied by investigating the effects of GLP-1 and CCK receptor antagonists on ad libitum food intake in a pig model of subdiaphragmatic vagotomy.

Two placebo controlled randomized crossover studies were performed in healthy volunteers to investigate the effects of small intestinal macronutrient delivery on ad libitum food intake and satiety signals. The first study compared the effects of duodenal, jejunal and ileal casein delivery on ad libitum food intake and satiety signals. The second study investigated if ileal delivery of all three macronutrients results in activation of satiety signals and reduction in ad libitum food intake. In addition, it was investigated if ileal delivery of native casein is efficiently digested and absorbed and does not result in adverse effects. In both studies the nutrients were delivered to the small intestine by inserting a nasointestinal feeding tube in healthy volunteers.

Results: All macronutrients and rebaudioside A stimulated GLP-1 and PYY release from ileal tissue segments. Protein and fat stimulated serotonin release. Inhibiting the reuptake of serotonin resulted in enhanced nutrient induced GLP-1, PYY and CCK release. Serotonin stimulated GLP-1 release from enteroendocrine cells via a serotonin receptor mediated process.

Results of the in vivo pig study showed that antagonism of the CCK receptor increased food intake in both vagotomized and sham operated pigs. Blocking the GLP-1 receptor did not affect food intake in both groups.

The human studies showed that ileal protein delivery inhibited food intake and activated satiety signals as compared to duodenal or jejunal protein delivery. Also, ileal delivery of small quantities (51.7 kcal) of each macronutrient decreased food intake and activated satiety signals. In addition, it was shown that ileal delivery of native casein resulted in a time and concentration depended increase in plasma concentrations of amino acids and did not result in activation of immune responses nor in gastrointestinal complaints.

Conclusions: The data presented in this thesis show that ileal delivery of all macronutrients results in activation of satiety signals and reduction of food intake. Stimulation of the ileum resulted in the strongest activation of satiety signals and inhibition of food intake compared to duodenal and jejunal stimulation. Besides direct nutrient-receptor interaction, the ileum senses (non-)nutritional stimuli via serotonin mediated processes resulting in GLP-1 release. In conclusion, these results demonstrate that targeting the ileum with small amounts of macronutrients is safe and has potential as a weight management strategy.

The appetizing and satiating effects of odours
Ramaekers, M.G. - \ 2014
University. Promotor(en): Tiny van Boekel, co-promotor(en): Pieternel Luning; Catriona Lakemond. - Wageningen : Wageningen University - ISBN 9789461739995 - 164
geurstoffen - eetlust - verzadigdheid - sensorische evaluatie - voedingsgewoonten - odours - appetite - satiety - sensory evaluation - feeding habits
Background and aim

Unhealthy eating habits such as unhealthy food choices or overeating increase the prevalence of obesity, diabetes, cancer, cardiovascular and other diseases. Therefore, it is important to understand how separate factors, such as sensory processes, influence our eating behaviour. As one of the sensory modalities, olfaction has a relationship with food intake regulation. Previous research reveals that food odours can induce both appetite and satiation. In this thesis, we split appetite and satiation into a ‘general’ part and a ‘food specific’ part. General appetite and general satiation refer to the desire to eat in general. General satiation measured by subjective ratings (e.g. by using line scales) is also named ‘subjective satiation’. The specific part refers to the desire to eat a specific food: e.g. the appetite for a banana or the appetite for tomato soup.

The main objective of this thesis was to investigate under which circumstances odours are appetizing or satiating in order to identify factors that influence our eating behaviour.Odours arrive at the odour receptors via two routes: the orthonasal route via the nose to perceive the outside world or retronasally via the mouth to ‘taste’ the food. The appetizing and satiating effects of ortho- and retronasally smelled odours were investigated by varying the odour exposure time, the odour concentration(retronasal only), the odour type, passive versus active sniffing (orthonasal only) and by switching between odour types.

Methods

We conducted six within-subject experiments. All participants were healthy normal-weight women (age 18-45 y and BMI 18.5-26 kg/m2). In four experiments (studies 2A, 2B, 3A and 3B), we investigated the appetizing and satiating effects of orthonasal odours, with two experiments addressing odours that were smelled passively in rooms with ambient odours (chapter 2) and two addressing actively smelled odours by sniffing the contents of a cup (chapter 3). In studies 2A (passive, n=21), 2B (passive, n=13) and 3A (active, n=61), we investigated the effects of exposure timeand odour typeon appetite, the appetite for specific foods, food preference and food intake. Differences between passiveand active exposure were investigated by comparing the data from 2A and 3A. In the fourth experiment (n=30) using a similar set-up, sweet and savoury odours were presented directly after each other, to explore the effects of daily encounters with a variety of food odours (i.e. switching). In all orthonasal studies, general appetite and the appetite for specific foods were monitored over time, using visual analogue scales. General appetite comprised hunger and desire-to-eat ratings. The appetite for specific products addressed the appetite for smelled products and the appetites for a set of other products that were congruent and incongruent with the odour (studies 2A, 2B, 3A and 3B). Food preference was assessed using a computerised program offering pairs of food pictures (studies 2A, 2B and 3B).

Furthermore, two experiments addressed the satiating effects of retronasal odours while consuming tomato soup ad libitum (studies 4A and 4B). The retronasal odour exposure was disconnected from the soup base consumptionby use of a retronasal tube that was connected to an olfactometer. The odours were delivered directly into the nasal cavity at the moment a sip of soup base was swallowed. In study 4A (n=38), the satiating effects of odour exposure time(3 and 18 s) and odour concentration(5x difference) were investigated. In study 4B(n=42),we investigated whether addition of cream odourto tomato soup, in combination with a low or high viscosity, affected satiation. Hunger and appetite ratings were monitored over time during odour exposure, by using 100 mm visual analogue scales (VAS).

Results

The results showed that orthonasalexposure to food odours influenced the appetite for specific foods via a typical pattern: the appetite ratings for the smelled foods increased by +6-20 mm(SSA; all P<0.001), the appetite for congruent sweet and savoury foods increased by +5 mmand the appetite for incongruent sweet and savoury foods decreased by -5 mm (all P<0.01), measured by using 100 mm VAS (studies 2A, 2B, 3A and 3B). This typical pattern was found in all studies, independently of passive or active smelling, exposure time or switching between odours (studies 2A, 2B, 3A and 3B). Results in study 3B showed that the appetite for specific products adjusted to the new odour within one minute after a switch between sweet and savoury odours. Similar results were found with a computerised food preference program, in which participants chose repeatedly between pairs of foods (studies 2A, 2B and 3B). Food preference shifted in circa 20% of the choices. Furthermore, passively smelled food odours had a large effect on the appetite for the smelled foods (+15 mm; P<0.001) and a small effect on general appetite (+4 mm; P=0.01; study 2A). Actively smelled food odours had nosignificant effect on general appetite or food intake (studies 3A and 3B). Non-food odours appeared to suppress general appetite slightly (-2 mm, P=0.01). The appetizing effects did not change over timeduring a twenty-minute odour exposure (studies 2A, 2B, 3A and 3B) and the typical pattern of odour effects on the appetite for specific foods was not affected by switching between sweet and savoury odours (study 3B). The pleasantness of the odour decreased by -4 mmduring active smelling (P=0.005), whereas the appetite for the smelled food remained high (P<0.001; study 3B).

Furthermore, the results from the retronasalstudies showed that an increase in both retronasal odour exposure time and concentration reduced ad libitum intake by 9 % (i.e. 3 sips and 22 kJ; P=0.04) and had no effect on subjective satiation (study 4A). Adding cream odour decreased subjective satiation with circa 5 %between 7 and 13 minutes after the start of consumption (P=0.009), but did not affect ad libitumintake (study 4B). Retronasally smelled odour significantly contributed to the development of sensory-specific satiety (study 4A).

Conclusions

Orthonasally smelled odours affect to a larger extend what you eat, than how much you eat. They influence the appetite for specific foods via a typical pattern: the appetite for the smelled foods and for congruent sweet or savoury foods increases, whereas the appetite for incongruent sweet or savoury foods decreases. This typical pattern is independent of exposure time, passive or active smelling and switchingbetween odours. The reason for this pattern is unknown, however, it may be caused by the preparation of the body for the intake of the smelled food, as food odours may provide information about the nutrient composition of their associated foods. Furthermore, passiveodour exposure may enhance general appetite (how much), whereas activesmelling appears to have no effect. Interestingly,the appetite for the smelled foods remained elevated during the 20-minute smelling, althoughthe pleasantness of the smelled odour decreased a little over time. This shows an earlier assumption from literature incorrect: a decrease in pleasantness of the odour does not lead to less appetite for the smelled food. This seeming contradiction may result from different mechanisms, such as a decrease in hedonic value during prolonged sensory stimulation on the one hand and anticipation of food intake on the other hand. Furthermore, food odours were found to change preference in circa 20% of the cases. Probably, food odours shift food preference, but do not overrule strong initial preferences in circa 80% of the cases.

Moreover, retronasally smelled odours probably have a small influence on satiation, though the evidence is not very strong. An increase in both retronasal odour concentrationand odour exposure timemay enhance satiation. Adding cream odourmay temporarily affect subjective satiation but does not affect food intake. However, the satiating effects that were found in these studies with retronasal odour exposure were borderline significant and data on food intake and subjective appetite ratings were not consistent, which probably reflects thesmall effect size.

Orthonasal odours influence food preference and could potentially be used to encourage healthy eating behaviour. The studies in this thesis were conducted under controlled circumstances and the results possibly deviate from behaviour in daily life. Therefore, it is unclear how strong the influence of odours is on our eating behaviour in daily situations. Finally, we advise product developers not to focus on changing retronasal odour characteristics in order to enhance satiation of products, seen the small effects that were found in this thesis.

Sensory-specific appetite is affected by actively smelled food odors and remains stable over time in normal-wight women
Ramaekers, M.G. ; Boesveldt, S. ; Lakemond, C.M.M. ; Boekel, M.A.J.S. van; Luning, P.A. - \ 2014
The Journal of Nutrition 144 (2014)8. - ISSN 0022-3166 - p. 1314 - 1319.
cephalic phase responses - cue exposure - unrestrained eaters - olfactory-bulb - chewing gum - satiety - hunger - humans - perception - attention
Understanding overconsumption starts with knowledge of how separate factors influence our eating behavior. Food cues such as food odors are known for their effect on general appetite and sensory-specific appetite (SSA). Active sniffing rather than passive exposure may induce satiation over time. The objective of this study was to investigate how actively sniffing banana odors affects general appetite, SSA, and subsequent food intake. In a crossover study, 61 women actively smelled cups containing natural banana, artificial banana odor, or water (no odor) for 10 min. Treatment order was randomly assigned as much as possible. General appetite and SSA were monitored by using 100-mm visual analog scales during the 10 min of active sniffing, followed by ad libitum intake of banana milkshake. Results showed that SSA was consistently high (+12 mm) during actively sniffing natural or artificial banana odors, with no decrease in SSA over time. Sniffing both banana odors increased the appetite for banana (+11 mm) and other sweet products (+4 mm), whereas the appetite for savory products decreased by 7 mm (all P <0.01) compared with no odor. Actively sniffing banana odor did not significantly influence food intake (P = 0.68) or general appetite scores (P = 0.06). In conclusion, SSA scores during active sniffing were identical to the SSA found in a similar study that used passive smelling, suggesting that SSA is independent of the manner of sniffing and exposure time. Moreover, sweet/savory categorization may suggest that food odors communicate information about the nutrient composition of their associated foods. These data clearly show the appetizing effects of food odors.
Human protein status modulates brain reward responses to food cues1–3
Griffioen-Roose, S. ; Smeets, P.A.M. ; Heuvel, E.M. van den; Boesveldt, S. ; Finlayson, G. ; Graaf, C. de - \ 2014
American Journal of Clinical Nutrition 100 (2014)1. - ISSN 0002-9165 - p. 113 - 122.
leverage hypothesis - energy-intake - taste - breakfast - appetite - satiety - carbohydrate - mechanisms - receptors - choice
Background: Protein is indispensable in the human diet, and its intake appears tightly regulated. The role of sensory attributes of foods in protein intake regulation is far from clear. Objective: We investigated the effect of human protein status on neural responses to different food cues with the use of functional magnetic resonance imaging (fMRI). The food cues varied by taste category (sweet compared with savory) and protein content (low compared with high). In addition, food preferences and intakes were measured. Design: We used a randomized crossover design whereby 23 healthy women [mean SD age: 22 +/- 2 y; mean +/- SD body mass index (in kg/m(2)): 22.5 +/- 1.8] followed two 16-d fully controlled dietary interventions involving consumption of either a low-protein diet (0.6 g protein center dot kg body weight(-1) center dot d(-1), similar to 7% of energy derived from protein, approximately half the normal protein intake) or a high-protein diet (2.2 g protein center dot kg body weight(-1) center dot d(-1), similar to 25% of energy, approximately twice the normal intake). On the last day of the interventions, blood oxygen level-dependent (BOLD) responses to odor and visual food cues were measured by using fMRI. The 2 interventions were followed by a 1 -d ad libitum phase, during which a large array of food items was available and preference and intake were measured. Results: When exposed to food cues (relative to the control condition), the BOLD response was higher in reward-related areas (orbitofrontal cortex, striatum) in a low-protein state than in a high-protein state. Specifically, BOLD was higher in the inferior orbitofrontal cortex in response to savory food cues. In contrast, the protein content of the food cues did not modulate the BOLD response. A low protein state also increased preferences for savory food cues and increased protein intake in the ad libitum phase as compared with a high-protein state. Conclusions: Protein status modulates brain responses in reward regions to savory food cues. These novel findings suggest that dietary protein status affects taste category preferences, which could play an important role in the regulation of protein intake in humans. This trial was registered at www.trialregister.nl/trialreg/admin/rctview.asp?TC=3288 as NTR3288.
Snel vol door stevig kauwen
Ramaker, R. ; Bolhuis, D.P. - \ 2014
Resource: weekblad voor Wageningen UR 8 (2014)17. - ISSN 1874-3625 - p. 10 - 10.
voedselconsumptie - verzadigdheid - eetlust - voeding en gezondheid - voedingsonderzoek - food consumption - satiety - appetite - nutrition and health - nutrition research
Mensen eten minder van hamburgers op een hard broodje dan op een zachte bol. Eten dat ons flink laat kauwen, zo blijkt, zorgt dat we eerder vol zitten. Dit inzicht kan helpen voedselproducten te ontwerpen die overeten – en daarmee overgewicht – voorkomen.
The Sum of lts Parts-Effects of Gastric Distention, Nutrient Content and Sensory Stimulation on Brain Activation
Spetter, M.S. ; Graaf, C. de; Mars, M. ; Viergever, M.A. ; Smeets, P.A.M. - \ 2014
PLoS One 9 (2014)3. - ISSN 1932-6203 - 10 p.
body-weight regulation - food-intake - feeding-behavior - eating behavior - human amygdala - appetite - humans - satiety - taste - fat
During food consumption the brain integrates multiple interrelated neural and hormonal signals involved in the regulation of food intake. Factors influencing the decision to stop eating include the foods' sensory properties, macronutrient content, and volume, which in turn affect gastric distention and appetite hormone responses. So far, the contributions of gastric distention and oral stimulation by food on brain activation have not been studied. The primary objective of this study was to assess the effect of gastric distention with an intra-gastric load and the additional effect of oral stimulation on brain activity after food administration. Our secondary objective was to study the correlations between hormone responses and appetite-related ratings and brain activation. Fourteen men completed three functional magnetic resonance imaging sessions during which they either received a naso-gastric infusion of water (stomach distention), naso-gastric infusion of chocolate milk (stomach distention + nutrients), or ingested chocolate-milk (stomach distention + nutrients + oral exposure). Appetite ratings and blood parameters were measured at several time points. During gastric infusion, brain activation was observed in the midbrain, amygdala, hypothalamus, and hippocampus for both chocolate milk and water, i.e., irrespective of nutrient content. The thalamus, amygdala, putamen and precuneus were activated more after ingestion than after gastric infusion of chocolate milk, whereas infusion evoked greater activation in the hippocampus and anterior cingulate. Moreover, areas involved in gustation and reward were activated more after oral stimulation. Only insulin responses following naso-gastric infusion of chocolate milk correlated with brain activation, namely in the putamen and insula. In conclusion, we show that normal (oral) food ingestion evokes greater activation than gastric infusion in stomach distention and food intake-related brain areas. This provides neural evidence for the importance of sensory stimulation in the process of satiation.
Pectin is not pectin: A randomized trial on the effect of different physicochemical properties of dietary fiber on appetite and energy intake
Wanders, A.J. ; Feskens, E.J.M. ; Jonathan, M.C. ; Schols, H.A. ; Graaf, C. de; Mars, M. - \ 2014
Physiology and Behavior 128 (2014). - ISSN 0031-9384 - p. 212 - 219.
body-weight - food-intake - guar gum - satiety - viscosity - glucose - meal - satiation - glycemia - humans
An increased intake of dietary fiber has been associated with reduced appetite and reduced energy intake. Research on the effects of seemingly identical classes of dietary fiber on appetite has, however, resulted in conflicting findings. The present study investigated the effects of different fiber properties, including methods of supplementation, on appetite and energy intake. This was a randomized crossover study with 29 subjects (21 ± 2 y, BMI: 21.9 ± 1.8 kg/m2) consuming dairy based liquid test products (1.5 MJ, 435 g) containing either: no pectin, bulking pectin (10 g), viscous pectin (10 g), or gelled pectin (10 g). The gelled pectin was also supplemented as capsules (10 g), and as liquid (10 g). Physicochemical properties of the test products were assessed. Appetite, glucose, insulin and gastric emptying were measured before ingestion and after fixed time intervals. Energy intake was measured after 3 h. Preload viscosity was larger for gelled > viscous > bulking > no pectin, and was larger for gelled > liquid > capsules. Appetite was reduced after ingestion of gelled pectin compared to bulking (p <0.0001), viscous (p = 0.005) and no pectin (p <0.0001), without differences in subsequent energy intake (p = 0.32). Gastric emptying rate was delayed after gelled pectin (82 ± 18 min) compared to no pectin (70 ± 19 min, p = 0.015). Furthermore, gelled (p = 0.002) and viscous (p <0.0001) pectin lowered insulin responses compared to no pectin, with minor reductions in glucose response. Regarding methods of supplementation, appetite was reduced after ingestion of the gelled test product compared to after capsules (p <0.0001) and liquid (p <0.0001). Energy intake was lower after ingestion of capsules compared to liquid (- 12.4%, p = 0.03). Different methods of supplementation resulted in distinct metabolic parameters. Results suggest that different physicochemical properties of pectin, including methods of supplementation, impact appetite and energy intake differently. Reduced appetite was probably mediated by preload physical properties, whereas inconsistent associations with metabolic parameters were found.
Claiming satiety: consumer perception, interpretation & subsequent food
Bilman, E.M. - \ 2014
University. Promotor(en): Hans van Trijp, co-promotor(en): Ellen van Kleef. - Wageningen : Wageningen University - ISBN 9789461738660 - 172
verzadigdheid - voedselopname - voedselconsumptie - voedselvoorkeuren - voedselverpakking - consumenteninformatie - consumenten - consumentengedrag - satiety - food intake - food consumption - food preferences - food packaging - consumer information - consumers - consumer behaviour

For many people, food intake management is a challenging process, as food is always in abundance and the appetite control system is challenged and potentially overpowered by habits, routines and cues in the external environment. The present thesis focuses on satiation and satiety expectations and inferences as a guide for food intake, both within and across consumption episodes. More specifically, the role of physiological cues, claims on food packages and packaging design in the development of satiation/ satiety expectations and their effect on food intake is studied. This thesis takes as a starting point that feedback from previous consumption experiences is important for the development of satiety and satiation expectations. In addition, it is expected that satiation and satiety expectations also can be inferred ‘on the spot’, either explicitly (as from satiety claims), but potential also implicitly and more intuitively (as from packaging design and other factors in the eating context).

Both a higher number of sips and a longer oral transit time reduce ad libitum intake
Bolhuis, D.P. ; Lakemond, C.M.M. ; Wijk, R.A. de; Luning, P.A. ; Graaf, C. de - \ 2014
Food Quality and Preference 32 (2014)Part C. - ISSN 0950-3293 - p. 234 - 240.
food-intake - energy-intake - young-adults - eating rate - bite size - body-weight - appetite - consumption - satiety - meal
Background - A higher eating rate leads to a higher food intake, possibly through shorter orosensory exposure to food. The transit time in the oral cavity and the number of bites or sips per gram (inversely related to bite or sip size) are main contributors that affect eating rate. The separate role of these two aspects on satiation and on orosensory exposure needs further clarification. Objective - The objective of the first study was to investigate contributions of the number of sips per gram (sips/g) and oral transit time per gram (s/g) on ad libitum intake. The objective of the second study was to investigate both aspects on the total magnitude of orosensory exposure per gram food. Methods - In study 1, 56 healthy male subjects consumed soup where the number of sips and oral transit time differed by a factor three respectively: 6.7 vs. 20 sips/100 g, and 20 vs. 60 s/100 g (2 × 2 cross-over design). Eating rate of 60 g/min was kept constant. In study 2, the effects of number of sips and oral transit time (equal as in study 1) on the total magnitude of orosensory exposure per gram soup were measured by time intensity functions by 22 different healthy subjects. Results - Higher number of sips and longer oral transit time reduced ad libitum intake by respectively ~22% (F(1, 157) = 55.9, P <0.001) and ~8% (F(1, 157) = 7.4, P = 0.007). Higher number of sips led to faster increase in fullness per gram food (F(1, 157) = 24.1, P <0.001) (study 1). Higher number of sips and longer oral transit time both increased the orosensory exposure per gram food (F(1, 63) = 23.8, P <0.001) and (F(1, 63) = 19.0, P <0.001), respectively (study 2). Conclusion - Higher number of sips and longer oral transit time reduced food intake, possibly through the increased the orosensory exposure per gram food. Designing foods that will be consumed with small sips or bites and long oral transit time may be effective in reducing energy intake.
Effect of Replacing Sugar with Non-Caloric Sweeteners in Beverages on the Reward Value after Repeated Exposure
Griffioen-Roose, S. ; Smeets, P.A.M. ; Weijzen, P.L.G. ; Rijn, I. van; Bosch, I. van den; Graaf, C. de - \ 2013
PLoS One 8 (2013)11. - ISSN 1932-6203
body-weight - artificial sweetener - energy density - food-intake - satiety - brain - choice - flavor - adults - taste
Background: The reward value of food is partly dependent on learned associations. It is not yet known whether replacing sugar with non-caloric sweeteners in food is affecting long-term acceptance. Objective: To determine the effect of replacing sugar with non-caloric sweeteners in a nutrient-empty drink (soft drink) versus nutrient-rich drink (yoghurt drink) on reward value after repeated exposure. Design: We used a randomized crossover design whereby forty subjects (15 men, 25 women) with a mean +/- SD age of 21 +/- 2 y and BMI of 21.5 +/- 1.7 kg/m(2) consumed a fixed portion of a non-caloric sweetened (NS) and sugar sweetened (SS) versions of either a soft drink or a yoghurt drink (counterbalanced) for breakfast which were distinguishable by means of colored labels. Each version of a drink was offered 10 times in semi-random order. Before and after conditioning the reward value of the drinks was assessed using behavioral tasks on wanting, liking, and expected satiety. In a subgroup (n=18) fMRI was performed to assess brain reward responses to the drinks. Results: Outcomes of both the behavioral tasks and fMRI showed that conditioning did not affect the reward value of the NS and SS versions of the drinks significantly. Overall, subjects preferred the yoghurt drinks to the soft drinks and the ss drinks to the NS drinks. In addition, they expected the yoghurt drinks to be more satiating, they reduced hunger more, and delayed the first eating episode more. Conditioning did not influence these effects. Conclusion: Our study showed that repeated consumption of a non-caloric sweetened beverage, instead of a sugar sweetened version, appears not to result in changes in the reward value. It cannot be ruled out that learned associations between sensory attributes and food satiating capacity which developed preceding the conditioning period, during lifetime, affected the reward value of the drinks.
Relying on satiety cues in food consumption : studies on the role of social context, appearance focus, and mindfulness
Veer, E. van de - \ 2013
University. Promotor(en): Hans van Trijp, co-promotor(en): Erica van Herpen. - S.l. : s.n. - ISBN 9789461736895 - 240
voedselconsumptie - sociale psychologie - consumenten - voedselopname - verzadigdheid - eetlust - eetlustcontrole - honger - fysiologie - bewustzijn (consciousness) - eten - maaltijden - snacks - food consumption - social psychology - consumers - food intake - satiety - appetite - appetite control - hunger - physiology - consciousness - eating - meals
Consumers eat at various sequential occasions throughout the day. The current thesis addresses the question of how one consumption episode can affect the amount of consumption at a subsequent episode. The thesis focuses specifically on how the social context during a consumption episode affects subsequent consumption, and on when consumers rely on hunger and satiety cues in sequential consumption episodes.
Molecular effects of fermentation in the gut and its relevance for metabolism and satiety
Haenen, D. - \ 2013
University. Promotor(en): Michael Muller, co-promotor(en): Guido Hooiveld; Bas Kemp. - S.l. : s.n. - ISBN 9789461736673 - 210
dikke darm - fermentatie - voedingsvezels - verzadigdheid - darmmicro-organismen - vetzuren met een korte keten - metabolisme - large intestine - fermentation - dietary fibres - satiety - intestinal microorganisms - short chain fatty acids - metabolism

Dietary fibres, the edible parts of plants that are resistant to digestion and absorption in the human small intestine, were shown to be important in the prevention of obesity and the metabolic syndrome. This association can partially be attributed to a fibre-induced increase in satiety. Dietary fibres can be fermented by bacteria, collectively referred to as the microbiota, in the large intestine (i.e. caecum and colon), resulting in the production of the short-chain fatty acids (SCFAs) acetate, propionate and butyrate. Part of the effect of dietary fibres on satiety is thought to be mediated via the production of SCFAs.

The objective of the research described in this thesis was to reveal the effects of fermentation in the large intestine using comprehensive approaches with focus on metabolism and satiety.

The effect of 2-wk-consumption of resistant starch (RS), a dietary fibre highly fermentable by the gut microbiota, was studied in 2 pig experiments. In the first experiment, performed in adult female pigs, intestinal samples were collected from different areas of the gastrointestinal tract to measure luminal microbiota composition, luminal SCFA concentrations and the expression of host genes involved in SCFA uptake, SCFA signalling, and satiety regulation in mucosal tissue. In an additional study the effects of RS were investigated in young growing pigs fitted with a cannula in the proximal colon for repeated collection of tissue biopsies for whole-genome expression profiling and luminal content for measurement of SCFA concentrations and microbiota composition. To limit inter-individual variation, the RS diet was provided to the pigs in a 2 x 2 crossover design for 2 wk per diet. Furthermore, the behaviour of the pigs was monitored and the postprandial plasma response of satiety-related hormones and metabolites was measured at the end of each 2 wk period using repeated peripheral blood sampling via catheters.

In order to determine the potential differences in post-prandial plasma protein profiles, minipigs were assigned to a control (C) diet or a diet containing the bulky fibre lignocellulose (LC), the viscous and fermentable fibre pectin (PEC) or RS for periods of 8 d in a 4 x 4 Latin square design. Portal and carotid blood samples were collected from catheters on d 8 of each treatment, both before and at several time points after an ad libitum morning meal.

Male C57BL/6J mice were used to study the effect of background diet and SCFAs on colonic gene expression. Mice were fed a semi-synthetic low fat or high fat diet starting 2 wk before the treatment period. During treatment, mice received a rectal infusion of either an acetate, propionate, butyrate, or a control saline solution on 6 consecutive days, after which colon was collected to perform comprehensive gene expression profiling.

RS enhanced satiety based on behavioural observations, as RS-fed pigs showed less feeder-directed and drinking behaviours than pigs fed a digestible starch (DS) diet. In both caecum and colon, differences in microbiota composition were observed between RS-fed pigs and DS-fed pigs. In the colon these included the induction of the healthy gut-associated butyrate-producing Faecalibacterium prausnitzii, whereas potentially pathogenic members of the Gammaproteobacteria were reduced in relative abundance in RS-fed pigs. Caecal and colonic SCFA concentrations were significantly higher in RS-fed pigs. Geneexpression profiling of the proximal colon revealed a shift upon RS consumption from the regulation of immune response towards lipid and energy metabolism. The nuclear receptor PPARG was identified as a potential key upstream regulator. At plasma level, SCFA concentrations were higher in RS-fed pigs throughout the day. Postprandial glucose, insulin and glucagon-like peptide 1 (GLP-1) responses were lower in RS-fed than in DS-fed pigs, whereas triglyceride levels were higher in RS-fed than in DS-fed pigs.

In minipigs, plasma protein profiles were found to be most similar with C and LC consumption and with PEC and RS consumption, indicating that the consumption of diets with fermentable fibres results in a different plasma protein profile compared to a diet containing non-fermentable fibres or a diet without fibres.

In mice we observed that dietary fat content had a major impact on colonic gene expression responses to SCFAs, especially after propionate treatment. Moreover, the diet- and SCFA-dependent gene expression changes pointed towards the modulation of several metabolic processes. Genes involved in oxidative phosphorylation, lipid catabolism, lipoprotein metabolism and cholesterol transport were suppressed by acetate and butyrate treatment, whereas propionate resulted in changes in fatty acid and sterol biosynthesis, and in amino acid and carbohydrate metabolism.Furthermore, SCFA infusion on the high fat diet background appeared to partially reverse the gene expression changes induced by high fat feeding without SCFA infusion.

In conclusion, this thesis showed that the consumption of RS changed the microbiota composition in the colonic lumen, with a decrease in the abundance of potentially pathogenic bacteriaand an increase in the abundance of SCFA-producing populations. Furthermore, colonic gene expression changes were observed after RS consumption and after colonic administration of SCFAs. With both treatments,among the changes inthe transcriptional profileof the host were adaptations inmetabolic processes, such as energy and lipid metabolism, and immune response.We also showed that fat content in the background diet had a major impact on gene expression responses to SCFAs in colon. Overall, this thesis supports the implementation of fermentable dietary fibres into the human diet to improve colonic health and to reduce energy intake and body weight gain, which ultimately may prevent obesity and type 2 diabetes. Additional research is required to further elucidate the mechanisms via which fermentable dietary fibres can improve human health.

Fermentation in the gut to prolong satiety : exploring mechanisms by which dietary fibres affect satiety in pigs
Souza Da Silva, C. - \ 2013
University. Promotor(en): Bas Kemp, co-promotor(en): Liesbeth Bolhuis; Walter Gerrits. - S.l. : s.n. - ISBN 9789461736321 - 268
voedingsvezels - fermentatie - spijsvertering - verzadigdheid - varkens - voedingsgedrag - dietary fibres - fermentation - digestion - satiety - pigs - feeding behaviour

Obesity has become a major health problem in humans and companion animals. Although obesity is not common in farm animals, food restriction is often used to maintain low feeding costs and performance of, for instance, pregnant sows and fattening pigs. Food restriction may result in hunger and increased feeding motivation, which are associated with behavioural problems. Knowledge on the regulation of satiety is thus crucial to aid in the control of food intake in humans, and to improve welfare in food-restricted farm animals. Dietary fibres are believed to enhance satiety, but the effectiveness varies with the physicochemical properties of the fibre sources concerned. Therefore, the objective of this thesis was to identify whether and how dietary fibres with different physicochemical properties, such as bulkiness, viscosity, gelling and fermentability, affect satiety in the domestic pig, which was used both as a model for humans and as a target animal. In a study focusing on behavioural measures of satiety, pectin (viscous fibre) was the least satiating, whereas lignocellulose (bulking fibre) and resistant starch (fermentable fibre) were the most satiating fibres tested. In a subsequent study, increasing levels of guar gum, inulin, and resistant starch (all fermentable fibres), when replacing digestible starch, enhanced satiety throughout the day. Resistant starch was the most satiating fibre among all fibres tested, and used, in a subsequent study, to assess possible physiological and molecular mechanisms by which fermentation may affect satiety. Also in this study, resistant starch appeared to enhance satiety based on behavioural observations, i.e. reduced feeder-directed and drinking behaviours during 24 h. As expected, the satiating effects of resistant starch coincided with increased 24 h plasma short-chain fatty acids (SCFA) levels and decreased postprandial glucose and insulin plasma levels. Glucagon-like peptide-1 (GLP-1) plasma levels were lower in pigs fed resistant starch, whereas peptide tyrosine tyrosine (PYY) plasma levels were not affected by resistant starch, suggesting that these hormones do not play a role in the increased satiety induced by fermentation. Resistant starch consumption led to downregulation of genes involved in immune responses, and upregulation of genes involved in metabolic processes such as fatty acid and energy metabolism in the proximal colon. Moreover, correlation analysis inversely linked potential pathogenic microbial groups with plasma SCFA concentrations and with genes involved in fatty acid metabolism. These findings suggest that besides satiating effects, resistant starch has a beneficial effect on colonic health. In the last study, the long-term effects of a gelling fibre promoting satiation (alginate) and a fermentable fibre promoting satiety (resistant starch) on feeding patterns and growth performance were assessed. In the long-term, growing-finishing pigs compensated for a reduced dietary energy content by increasing voluntary food intake (alginate), or they became more efficient in the use of digestible energy (resistant starch). Moreover, dietary fibres increased the relative weight of the gastrointestinal tract and led to changes in body composition (less fat more muscle), which may be relevant for the maintenance of lean weight in humans. In conclusion, fermentable fibres are more satiating than viscous and bulking fibres. The satiating effects of fermentable fibres are likely mediated by an increased SCFA production, and a reduced and attenuated glucose supply. Under unrestricted feeding conditions, dietary fibres promoting satiation (alginate) and satiety (resistant starch) did not reduce long-term food intake and total body weight gain, yet, colon empty weight was increased and carcass growth was reduced. This implies that changes in body composition and intestinal weight or content, rather than body weight and body mass index (BMI) alone may be relevant to fully acknowledge the effects of fibres to aid in maintaining or promoting healthy body weight in humans.

Digestion of dietary fat : gastrointestinal behaviour of emulsions and human physiological responses
Helbig, A. - \ 2013
University. Promotor(en): Harry Gruppen; Rob Hamer, co-promotor(en): Erika Silletti. - S.l. : s.n. - ISBN 9789461735607 - 166
voedingsvet - spijsvertering - vetemulsies - spijsverteringskanaal - darmfysiologie - verzadigdheid - dietary fat - digestion - fat emulsions - digestive tract - intestinal physiology - satiety

Two in vitromodels were used to understand emulsion behavior and the subsequent formation of free fatty acids (FFA), monoglycerides (MG) and diglycerides (DG). Emulsions stabilized by whey protein isolate (WPI) or gum arabic (GA), varying in droplet size, were digested under intestinal conditions. Concentrations of FFA, MG and DG, assessed by gas chromatography, decreased with increasing droplet size. FFA release from gum arabic-stabilized emulsions was higher compared to WPI-stabilized emulsions showing an influence of the interface. Next, lipolysis of protein stabilized emulsions (i.e. WPI or lysozyme) and the influence of flocculation at the isoelectric point (pI) were investigated in a dynamic gastrointestinal model. The stomach properties including gradual acidification caused WPI-stabilized emulsions to cream during transition through the pI of the protein. This resulted in delayed intestinal lipolysis compared to the lysozyme-stabilized emulsion. Thus, since gastric passage affects emulsion behavior and intestinal lipolysis, the gastric passage should be part of digestion models. Next, in a human study emulsion behavior and resulting lipolytic products were related to the release of satiety hormones, satiety perception and ad libitumintake. Also, gallbladder volume and oral processing were studied. A delayed entry into the duodenum and lipolysis for the un-homogenized sample resulted in lower CCK, delayed GLP-1/PYY responses and barely gallbladder contraction compared to the homogenized emulsion. No difference was found between treatments on ghrelin, only the perception 'desire to eat´ was elevated for homogenized emulsions. Oral processing induced prolonged gallbladder contraction, but had no additive effect on other measures. A homogenous system as such is possibly not effective to induce pronounced satiety perceptions compared to phase separated or creamed systems using the same emulsifier. Moreover, the release of gastrointestinal hormones cannot directly be related to the satiating effect of food.

Towards global experimental design using Bayesian networks : case studies on modeling sensory satiation
Phan, V.A. - \ 2013
University. Promotor(en): Tiny van Boekel; U. Garczarek, co-promotor(en): Matthijs Dekker. - [S.l.] : s.n. - ISBN 9789461735379 - 156
sensorische evaluatie - verzadigdheid - bayesiaanse theorie - proefopzet - wiskundige modellen - modelleren - sensory evaluation - satiety - bayesian theory - experimental design - mathematical models - modeling

Food science problems are complex. Scientists may be able to capture more of the complexity of an investigated theme if they were able to integrate related studies. Unfortunately, individual studies are usually not designed to allow such integration, and the common statistical methods cannot be used for analyzing integrated data. The modeling technique of Bayesian networks has gained popularity in many fields of application due to its ability to deal with complexity, but has emerged only recently in food science. This thesis used data from experiments on sensory satiation as case studies. The objective was to explore the use of Bayesian networks to combine raw data of independently performed but related experiments to build a quantitative model of sensory satiation.
Methods
This thesis started with introducing the theoretical background of Bayesian networks to food science. The available data from various independent experiments on sensory satiation were then examined for their potential to be combined. Finally, the outcomes obtained using Bayesian networks on a single dataset were compared with the published outcomes of the respective study, in which classical statistical procedures were used to analyze the data.
Results
Two hurdles were identified when combining the data of related studies that were performed independently and without the intention of combining their data. The first hurdle was a lack of essential information for reliable estimations of parameters of the combined model network. This information could be obtained by deriving it from existing information in the individual studies or by performing extra experiments; these practices are, however, not always possible. The second hurdle was a possible conflict in causal relationships underlying the individual experimental designs, which can cause misleading analyses of the combined dataset. This was the case for some experiments that involved the control of secondary explanatory variables. As such, an approach termed as Global Experimental Design was proposed in this thesis as a solution to overcome these hurdles. This approach emphasizes the building of an overall network prior to designing individual studies.
In comparison to using the classical statistical procedures, more information can be extracted using Bayesian networks. This technique could make use of the domain knowledge in a transparent manner as well as empirical data with missing values.
Conclusions
It is possible to combine raw data from related studies for a meaningful analysis if effort is made in the phase of experimental design. The approach of Global Experimental Design outlines this phase with the building of an overall network. By using Bayesian networks as a tool for exploratory analysis, scientists are able to gain more insights into a research domain.

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