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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    Global status and conservation potential of reef sharks
    MacNeil, Aaron ; Chapman, Demian D. ; Heupel, Michelle ; Simpfendorfer, Colin A. ; Heithaus, Michael ; Meekan, Mark ; Harvey, Euan ; Goetze, Jordan ; Kiszka, Jeremy ; Bond, Mark E. ; Currey-Randall, Leanne M. ; Speed, Conrad W. ; Sherman, Samantha ; Rees, Matthew J. ; Udyawer, Vinay ; Flowers, Kathryn I. ; Clementi, Gina ; Valentin-Albanese, Jasmine ; Gorham, Taylor ; Adam, Shiham ; Khadeeja, Ali ; Pina-Amargós, Fabián ; Angulo-Valdés, Jorge A. ; Asher, Jacob ; García Barcia, Laura ; Beaufort, Océane ; Benjamin, Cecilie ; Bernard, Anthony T.F. ; Berumen, Michael L. ; Bierwagen, Stacy ; Bonnema, Erika ; Bown, Rosalind M.K. ; Bradley, Darcey ; Brooks, Edd ; Brown, Jed ; Buddo, Dayne ; Burke, Patrick ; Cáceres, Camila ; Cardeñosa, Diego ; Carrier, Jeffrey C. ; Caselle, Jennifer E. ; Charloo, Venkatesh ; Claverie, Thomas ; Clua, Eric ; Cochran, Jesse E.M. ; Cook, Neil ; Cramp, Jessica ; D’Alberto, Brooke ; Graaf, Martin de; Dornhege, Mareike ; Estep, Andy ; Fanovich, Lanya ; Farabough, Naomi F. ; Fernando, Daniel ; Flam, Anna L. ; Floros, Camilla ; Fourqurean, Virginia ; Garla, Ricardo ; Gastrich, Kirk ; George, Lachlan ; Graham, Rory ; Guttridge, Tristan ; Hardenstine, Royale S. ; Heck, Stephen ; Henderson, Aaron C. ; Hertler, Heidi ; Hueter, Robert ; Johnson, Mohini ; Jupiter, Stacy ; Kasana, Devanshi ; Kessel, Steven T. ; Kiilu, Benedict ; Kirata, Taratu ; Kuguru, Baraka ; Kyne, Fabian ; Langlois, Tim ; Lédée, Elodie J.I. ; Lindfield, Steve ; Luna-Acosta, Andrea ; Maggs, Jade ; Manjaji-Matsumoto, Mabel ; Marshall, Andrea ; Matich, Philip ; McCombs, Erin ; McLean, Dianne ; Meggs, Llewelyn ; Moore, Stephen ; Mukherji, Sushmita ; Murray, Ryan ; Kaimuddin, Muslimin ; Newman, Stephen J. ; Nogués, Josep ; Obota, Clay ; O’Shea, Owen ; Osuka, Kennedy ; Papastamatiou, Yannis P. ; Perera, Nishan ; Peterson, Bradley ; Ponzo, Alessandro ; Prasetyo, Andhika ; Quamar, Sjamsul ; Quinlan, Jessica ; Ruiz-Abierno, Alexei ; Sala, Enric ; Samoilys, Melita ; Schärer-Umpierre, Michelle ; Schlaff, Audrey ; Simpson, Nikola ; Smith, Adam N.H. ; Sparks, Lauren ; Tanna, Akshay ; Torres, Rubén ; Travers, Michael J. ; Zinnicq Bergmann, Maurits van; Vigliola, Laurent ; Ward, Juney ; Watts, Alexandra M. ; Wen, Colin ; Whitman, Elizabeth ; Wirsing, Aaron J. ; Wothke, Aljoscha ; Zarza-Gonzâlez, Esteban ; Cinner, Joshua E. - \ 2020
    Nature 583 (2020). - ISSN 0028-0836 - p. 801 - 806.

    Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status1,2. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats3. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally. Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs. Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population. However, opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks. These results reveal several policy pathways for the restoration and management of reef shark populations, from direct top-down management of fishing to indirect improvement of governance conditions. Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries.

    The effect of replacing sucrose with L-arabinose in drinks and cereal foods on blood glucose and plasma insulin responses in healthy adults
    Pol, Korrie ; Graaf, Kees de; Diepeveen-de Bruin, Marlies ; Balvers, Michiel ; Mars, Monica - \ 2020
    Journal of Functional Foods 73 (2020). - ISSN 1756-4646
    Food matrix - Functionality - Glycaemic response - Insulin response - L-arabinose - Sucrose

    Glycaemic control is important in metabolic diseases such as diabetes and impaired glucose tolerance. L-arabinose inhibits the hydrolysis of sucrose into glucose and fructose. So far little is known about its functionality in different food matrices. We assessed the effect of replacing sucrose with L-arabinose in drinks and in cereal foods on blood glucose and insulin in healthy adults. Glucose and insulin responses were reduced when sucrose was replaced by L-arabinose in drinks. Replacement of sucrose in cereal foods did not affect glucose responses, however it reduced the insulin peak. L-arabinose without sucrose in a drink did not affect glucose responses. Therefore, replacing sucrose with L-arabinose is potentially a good strategy to lower glycaemic and insulin responses. However, the effects depend on the food matrix and the nutritional composition of the food. More research is warranted on the functionality of L-arabinose in different food matrices and in other populations.

    Effects of distraction on taste-related neural processing : a cross-sectional fMRI study
    Duif, Iris ; Wegman, Joost ; Mars, Monica M. ; Graaf, Cees De; Smeets, Paul A.M. ; Aarts, Esther - \ 2020
    American Journal of Clinical Nutrition 111 (2020)5. - ISSN 0002-9165 - p. 950 - 961.
    attention - consumption - distraction - fMRI - insula - orbitofrontal cortex - taste

    Background: In the current obesogenic environment we often eat while electronic devices, such as smart phones, computers, or the television, distract us. Such "distracted eating"is associated with increased food intake and overweight. However, the underlying neurocognitive mechanisms of this phenomenon are unknown. Objective: Our aim was to elucidate these mechanisms by investigating whether distraction attenuates processing in the primary and secondary taste cortices, located in the insula and orbitofrontal cortex (OFC), respectively. Methods: Forty-one healthy, normal-weight participants received fixed amounts of higher-And lower-sweetness isocaloric chocolate milk while performing a high-or low-distracting detection task during fMRI in 2 test sessions. Subsequently, we measured ad libitum food intake. Results: As expected, a primary taste cortex region in the right insula responded more to the sweeter drink (P < 0.001, uncorrected). Distraction did not affect this insular sweetness response across the group, but did weaken sweetness-related connectivity of this region to a secondary taste region in the right OFC (P-family-wise error, cluster, small-volume corrected = 0.020). Moreover, individual differences in distraction-related attenuation of taste activation in the insula predicted increased subsequent ad libitum food intake after distraction (r = 0.36). Conclusions: These results reveal a mechanism explaining how distraction during consumption attenuates neural taste processing. Moreover, our study shows that such distraction-induced decreases in neural taste processing contribute to individual differences in the susceptibility for overeating. Thus, being mindful about the taste of food during consumption could perhaps be part of successful prevention and treatment of overweight and obesity, which should be further tested in these target groups. This study was preregistered at the Open Science Framework as

    Tackling drought on high sandy ground
    Graaf, Myrjam de - \ 2020
    Outcome prediction of head and neck squamous cell carcinoma by MRI radiomic signatures
    Mes, Steven W. ; Velden, Floris H.P. van; Peltenburg, Boris ; Peeters, Carel F.W. ; Beest, Dennis E. te; Wiel, Mark A. van de; Mekke, Joost ; Mulder, Doriene C. ; Martens, Roland M. ; Castelijns, Jonas A. ; Pameijer, Frank A. ; Bree, Remco de; Boellaard, Ronald ; Leemans, C.R. ; Brakenhoff, Ruud H. ; Graaf, Pim de - \ 2020
    European Radiology (2020). - ISSN 0938-7994
    Factor analysis - Head and neck neoplasms - Magnetic resonance imaging - Prognosis

    Objectives: Head and neck squamous cell carcinoma (HNSCC) shows a remarkable heterogeneity between tumors, which may be captured by a variety of quantitative features extracted from diagnostic images, termed radiomics. The aim of this study was to develop and validate MRI-based radiomic prognostic models in oral and oropharyngeal cancer. Materials and Methods: Native T1-weighted images of four independent, retrospective (2005–2013), patient cohorts (n = 102, n = 76, n = 89, and n = 56) were used to delineate primary tumors, and to extract 545 quantitative features from. Subsequently, redundancy filtering and factor analysis were performed to handle collinearity in the data. Next, radiomic prognostic models were trained and validated to predict overall survival (OS) and relapse-free survival (RFS). Radiomic features were compared to and combined with prognostic models based on standard clinical parameters. Performance was assessed by integrated area under the curve (iAUC). Results: In oral cancer, the radiomic model showed an iAUC of 0.69 (OS) and 0.70 (RFS) in the validation cohort, whereas the iAUC in the oropharyngeal cancer validation cohort was 0.71 (OS) and 0.74 (RFS). By integration of radiomic and clinical variables, the most accurate models were defined (iAUC oral cavity, 0.72 (OS) and 0.74 (RFS); iAUC oropharynx, 0.81 (OS) and 0.78 (RFS)), and these combined models outperformed prognostic models based on standard clinical variables only (p < 0.001). Conclusions: MRI radiomics is feasible in HNSCC despite the known variability in MRI vendors and acquisition protocols, and radiomic features added information to prognostic models based on clinical parameters. Key Points: • MRI radiomics can predict overall survival and relapse-free survival in oral and HPV-negative oropharyngeal cancer. • MRI radiomics provides additional prognostic information to known clinical variables, with the best performance of the combined models. • Variation in MRI vendors and acquisition protocols did not influence performance of radiomic prognostic models.

    How oro-sensory exposure and eating rate affect satiation and associated endocrine responses-a randomized trial
    Lasschuijt, Marlou ; Mars, Monica ; Graaf, Cees de; Smeets, Paul A.M. - \ 2020
    American Journal of Clinical Nutrition 111 (2020)6. - ISSN 0002-9165 - p. 1137 - 1149.
    cephalic phase - eating behavior - eating rate - ghrelin - human - insulin - oro-sensory exposure - pancreatic polypeptide - satiation

    BACKGROUND: Longer oral processing decreases food intake. This can be attributed to greater oro-sensory exposure (OSE) and a lower eating rate (ER). How these factors contribute to food intake, and the underlying physiological mechanisms, remain unclear. OBJECTIVES: We aimed to determine the independent and simultaneous effects of OSE and ER on satiation and associated endocrine responses. METHODS: Forty participants in study 1 [mean ± SD age: 24 ± 4 y; BMI (in kg/m2): 22 ± 2] and 20 in study 2 (mean ± SD age: 23 ± 3 y; BMI: 23 ± 2) participated in a 2 × 2 randomized trial. In both studies, participants ate chocolate custard with added caramel sauce (low OSE) or caramel fudge (high OSE) and with short (fast ER) or long breaks (slow ER) in between bites, until fullness. In study 2, endocrine responses were measured during the meal. RESULTS: In study 1, participants ate (mean ± SEM) 42 ± 15 g less in the slow- than in the fast-ER condition, only within the high-OSE condition (P = 0.04). In study 2, participants ate 66 ± 21 g less in the high- than in the low-OSE condition and there were no intake differences between slow and fast ER (P = 0.35). Eight minutes after starting to eat, insulin concentrations increased by 42%-65% in all treatments compared with the control. At the end of the meal, insulin concentrations were 81% higher in the high-OSE, slow-ER than in the low-OSE, fast-ER condition (P = 0.049). Pancreatic polypeptide (PP) increased by 62%, 5 min after meal onset in the low-OSE, fast-ER condition (P = 0.005). Ghrelin concentrations did not change. CONCLUSIONS: Greater OSE increases insulin responsiveness. In contrast, PP responses are stronger when OSE is reduced and ER is fast. Insulin and PP responses may mediate the independent effects of OSE and ER on food intake. These may be beneficial eating strategies, particularly for type 2 diabetic patients, to control food intake and maintain glucose homeostasis.This trial was registered at as NL6544.

    Resting energy expenditure in cystic fibrosis patients decreases after lung transplantation, which improves applicability of prediction equations for energy requirement
    Hollander-Kraaijeveld, F.M. ; Lanen, A.S. van; Roos, N.M. de; Graaf, E.A. van de; Heijerman, H.G.M. - \ 2020
    Journal of Cystic Fibrosis (2020). - ISSN 1569-1993
    REE and REE/kg FFM significantly decrease after lung transplantation in CF patients. Prediction equations for energy requirement are inaccurate until a year after LTx. Measuring REE by indirect calorimetry is advised in CF patients before and until one year after LTx. Pre-LTx, energy requirements are at least 20% higher than predicted with common energy requirement equations.
    Sensory Evaluation of E-Liquid Flavors by Smelling and Vaping Yields Similar Results
    Krüsemann, Erna J.Z. ; Wenng, Franziska M. ; Pennings, Jeroen L.A. ; Graaf, Kees de; Talhout, Reinskje ; Boesveldt, Sanne - \ 2020
    Nicotine & Tobacco Research 22 (2020)5. - ISSN 1462-2203 - p. 798 - 805.

    INTRODUCTION: Sensory research on e-liquid flavors can be performed by means of smelling and vaping. However, data comparing smelling versus vaping e-liquid flavors are lacking. This study aims to investigate if smelling could be an alternative to vaping experiments by determining the correlation for hedonic flavor assessment between orthonasal smelling and vaping of e-liquids, for smokers and nonsmokers. METHODS: Twenty-four young adult smokers (mean age 24.8 ± 9.3) and 24 nonsmokers (mean age 24.9 ± 7.7) smelled and vaped 25 e-liquids in various flavors. Participants rated liking, intensity, familiarity, and irritation on a 100-mm Visual Analog Scale. Pearson correlations within and between smelling and vaping were calculated. Differences between user groups were calculated using t tests. RESULTS: Correlation coefficients between smelling and vaping based on mean group ratings were 0.84 for liking, 0.82 for intensity, 0.84 for familiarity, and 0.73 for irritation. Means of the within-subjects correlation coefficients were, respectively, 0.51, 0.37, 0.47, and 0.25. Correlations between smelling and vaping varied across individuals (ranging from -0.27 to 0.87) and flavors (-0.33 to 0.81). Correlations and mean liking ratings did not differ between smokers and nonsmokers. CONCLUSIONS: The strong group-level correlations between orthonasal smelling and vaping e-liquid flavors justify the use of smelling instead of vaping in future research. For example, smelling could be used to investigate differences in e-liquid flavor liking between (potential) user groups such as nicotine-naïve adolescents. The more modest within-subject correlations and variation across individuals and flavors merit caution in using smelling instead of vaping in other types of experiments. IMPLICATIONS: This study supports the use of orthonasal smelling (instead of vaping) e-liquids to measure hedonic flavor perception in some studies where vaping would be inappropriate or not feasible. Examples of research situations where smelling e-liquids may be sufficient are (1) investigating nicotine-naïve individuals (ie, nonusers), (2) investigating individuals under legal age for e-cigarette use (ie, youth and adolescents), (3) investigating brain responses to exposure of e-liquid flavors using functional magnetic resonance imaging or electroencephalogram, and (4) comparing hedonic flavor assessment between adolescent nonusers and current smokers to provide support for future regulations on e-liquid flavors.

    Foraging minds in modern environments : High-calorie and savory-taste biases in human food spatial memory
    Vries, Rachelle de; Vet, Emely de; Graaf, Kees de; Boesveldt, Sanne - \ 2020
    Appetite 152 (2020). - ISSN 0195-6663
    Cognitive bias - Eating behavior - Food spatial memory - Olfaction - Optimal foraging theory - Vision

    Human memory may show sensitivity to content that carried fitness-relevance throughout evolutionary history. We investigated whether biases in human food spatial memory exist and influence the eating behavior of individuals within the modern food environment. In two lab studies with distinct samples of 88 participants, individuals had to re-locate foods on a map in a computer-based spatial memory task using visual (Study 1) or olfactory (Study 2) cues that signaled sweet and savory high- and low-calorie foods. Individuals consistently displayed an enhanced memory for locations of high-calorie and savory-tasting foods – regardless of hedonic evaluations, personal experiences with foods, or the time taken to encode food locations. However, we did not find any clear effects of the high-calorie or savory-taste bias in food spatial memory on eating behavior. Findings highlight that content matters deeply for the faculty of human food spatial memory and indicate an implicit cognitive system presumably attuned to ancestral priorities of optimal foraging.

    Smelling our appetite? The influence of food odors on congruent appetite, food preferences and intake
    Morquecho-Campos, Paulina ; Graaf, Kees de; Boesveldt, Sanne - \ 2020
    Food Quality and Preference 85 (2020). - ISSN 0950-3293
    Congruency - Eating behavior - Explicit exposure - Macronutrients - Olfaction - Sensory-specific appetite

    We are surrounded by sensory food cues, such as odors, that may trigger (un)conscious decisions and even lead to (over)eating, it is therefore crucial to better understand the effect of food odors on behavioral responses. Food odor exposure has been shown to enhance appetite for food products with similar properties: sensory-specific appetite. This suggests that based on previous encounters with foods, we have learned to detect the nutritional content of foods, through our sense of smell. We investigated the influence of aware exposure of macronutrient-related odors on various measures of eating behavior, in a cross-over intervention study. Thirty two normal-weight healthy and unrestrained Dutch females took part in five test sessions. On each test session, they were exposed to one of five conditions (active smelling of clearly noticeable odors representing food high in carbohydrates, protein, and fat, low in calories, and a no-odor condition for 3-min) and assessed on specific appetite, food preferences and intake. Odor exposure increased congruent appetite after protein-related odor exposure. Similarly, protein-related odor exposure influenced the liking for protein foods and the preference ranking for savory products. However, food intake was not affected by smelling congruent food odors. Together this indicates that exposure to (aware) food odors may mostly influence appetite, but does not impact subsequent food intake. Moreover, appetite seems to be triggered by taste qualities rather than macronutrient information of the food, as signaled by olfactory cues. Future studies should investigate the role of awareness in more detail, to fully understand how odors might be used to steer people towards healthier food choices.

    Healthy is (not) tasty? Implicit and explicit associations between food healthiness and tastiness in primary school-aged children and parents with a lower socioeconomic position
    Heijden, Amy van der; Molder, Hedwig te; Graaf, Cees de; Jager, Gerry - \ 2020
    Food Quality and Preference 84 (2020). - ISSN 0950-3293
    Explicit associations - Food healthiness - Food tastiness - Implicit associations - Lower socioeconomic position - Primary school-aged children

    Many people implicitly (automatically) believe that unhealthy foods are tastier than healthy foods, even when they explicitly (deliberately) report that they don't. It is unclear whether this ‘unhealthy = tasty intuition’ is already present in childhood. Children from families with a lower socioeconomic position (SEP) consume poorer diets than children from families with a higher SEP. Paradoxically, populations with a lower SEP are underrepresented in research and least reached by lifestyle interventions. This study explored implicit and explicit associations between healthiness, tastiness and liking of foods in primary school-aged children and parents with a lower SEP. These associations and an estimate of dietary intake were assessed with implicit association tests and paper-and-pencil questionnaires, developed and adapted specifically for this target group. Participants were recruited at Dutch food banks. Results of 37 parent-child dyads indicated that children and parents implicitly associated healthy foods and tastiness more strongly with each other than healthy foods and not tasty (D = −0.19, p =.03 and D = −0.46, p <.001, respectively). Explicitly, parents showed similar results, while children rated pictures of unhealthy foods as tastier than pictures of healthy foods. Following the discrepancy between our hypotheses, results, and more unhealthy eating habits that often prevail in families with a lower SEP, potential explanations are discussed. We address the possibility that an internalised social norm was exposed, rather than an intrinsic belief. We propose that this research calls for in-depth qualitative research on food-related preferences and norms in the everyday life of low SEP families.

    Ultra-Processing or Oral Processing? A Role for Energy Density and Eating Rate in Moderating Energy Intake from Processed Foods
    Forde, Ciarán G. ; Mars, Monica ; Graaf, Kees De - \ 2020
    Current Developments in Nutrition 4 (2020)3. - ISSN 2475-2991
    eating rate - energy density - energy intake rate - food texture - metabolic disease - obesity - ultra-processed foods - unprocessed foods

    Background: Recent observational data and a controlled in-patient crossover feeding trial show that consumption of "ultra-processed foods" (UPFs), as defined by the NOVA classification system, is associated with higher energy intake, adiposity, and at a population level, higher prevalence of obesity. A drawback of the NOVA classification is the lack of evidence supporting a causal mechanism for why UPFs lead to overconsumption of energy. In a recent study by Hall the energy intake rate in the UPF condition (48 kcal/min) was >50% higher than in the unprocessed condition (31 kcal/min). Extensive empirical evidence has shown the impact that higher energy density has on increasing ad libitum energy intake and body weight. A significant body of research has shown that consuming foods at higher eating rates is related to higher energy intake and a higher prevalence of obesity. Energy density can be combined with eating rate to create a measure of energy intake rate (kcal/min), providing an index of a food's potential to promote increased energy intake. Objective: The current paper compared the association between measured energy intake rate and level of processing as defined by the NOVA classification. Methods: Data were pooled from 5 published studies that measured energy intake rates across a total sample of 327 foods. Results: We show that going from unprocessed, to processed, to UPFs that the average energy intake rate increases from 35.5 ± 4.4, to 53.7 ± 4.3, to 69.4 ± 3.1 kcal/min (P < 0.05). However, within each processing category there is wide variability in the energy intake rate. Conclusions: We conclude that reported relations between UPF consumption and obesity should account for differences in energy intake rates when comparing unprocessed and ultra-processed diets. Future research requires well-controlled human feeding trials to establish the causal mechanisms for why certain UPFs can promote higher energy intake.

    A feeling of full-filment : Sensory and physiological processes involved in satiation
    Lasschuijt, Marlou - \ 2020
    Wageningen University. Promotor(en): K. de Graaf, co-promotor(en): P.A.M. Smeets; M. Mars. - Wageningen : Wageningen University - ISBN 9789463952484 - 251

    Satiation is a process that occurs during eating and involves inhibitory signals at a sensory, hormonal, digestive and cognitive level. The taste and texture of food influence this process. Harder foods with an intense taste are more satiating, i.e. we need to eat less of these foods to feel full, compared to softer foods with lower taste intensity. Oro-sensory exposure (OSE), the in-mouth taste perception of food, thus plays an important role in satiation and influences meal size. However, how oro-sensory signals affect satiation is not fully understood. Therefore, the main aim of this thesis was to better understand the role of sensory signals in the physiological processes underlying satiation. To study this we investigated the effect of OSE (duration and intensity) and eating rate on food intake, associated (cephalic) endocrine responses and brain reactivity. 

    We started by investigating the independent contributions of oral processing duration and taste intensity and their combined effect on satiation (chapter 2). This was done by manipulating texture and sweet taste intensity of model foods (2x2 study design, soft and hard vs. sweet and high sweet). Hard textured model foods decreased food intake through increased OSE duration, whereas sweetness intensity did not affect intake.

    To better understand the physiology underlying the effects of oro-sensory exposure on satiation we studied the effect of texture and sweetness intensity on endocrine cephalic phase responses (chapter 3). Cephalic phase responses are neurally mediated anticipatory and conditioned responses to food cues and are considered the first phase of digestion. Insulin, pancreatic polypeptide and ghrelin responses were measured while participants modified sham fed (chew and spit) the same model foods as used in chapter 2. We expected a cephalic peak increase in these hormones 5-15 min after food exposure. However, we did not find a typical cephalic phase peak response for any of the hormones. Insulin levels tended to be higher 5 min after starting to chew but this increase could not be not be attributed to the texture or taste manipulations. In addition, we found that pancreatic polypeptide was more responsive to sweetness. Ghrelin concentrations were higher when chewing the hard texture compared to the soft texture model foods.

    Based on the results from chapter 2 and 3 we hypothesized that part of the mechanism behind the oro-sensory exposure duration effect on satiation might be eating rate. When the duration of oro-sensory exposure is increased, eating rate is slowed down. Previous studies have shown that a reduced eating rate also leads to a decrease in food intake. Additionally, we hypothesized that part of the reason why we did not find typical cephalic responses in chapter 2 was because the model foods scored ‘neutral’ on liking, whereas palatability may be important to trigger a cephalic response. We therefore investigated the effect of OSE duration and eating rate on food intake (palatable chocolate custard) and associated endocrine responses (chapter 4). Two studies were set up. In both studies subjects ate until fullness of chocolate custard with and without fudge pieces (low or high oro-sensory exposure) at two different eating rates (slow or fast eating rate). In study 1 participants received a small portion and in study 2 a larger portion. Additionally, blood samples were collected during the meal in study 2. We found that a reduced eating rate (ER) (only in the high oro-sensory exposure condition) (study 1) and increased oro-sensory exposure (study 2) decreased food intake but that this was dependent on the portion size. Eight minutes after starting to eat, insulin concentrations increased for all treatments compared to control. At the end of the meal insulin concentrations were higher in the high OSE, slow ER compared to the low OSE, fast ER condition. Pancreatic polypeptide increased at 5 min after meal onset in the low OSE, fast ER condition. There were no changes in ghrelin concentration. Greater OSE thus increases insulin responsiveness. In contrast, PP responses are stronger when OSE is reduced and ER is fast. Prandial Insulin and PP responses may mediate the independent effects of OSE and ER on food intake.

    To determine whether typical cephalic phase responses were specific to certain food cues or  sub-populations we quantified outcomes of existing literature on cephalic insulin and pancreatic polypeptide responses in a systematic review (chapter 5). In addition, we aimed to quantify the hypotheses made by previous qualitative cephalic phase reviews that cephalic responses allow for larger meal sizes, induce satiation earlier on in the meal and improve postprandial glucose homeostasis. A cephalic phase insulin and pancreatic polypeptide increase was observed in about half of all included treatments. About one fifth of the treatments induced a significant increase from baseline. The size of the cephalic insulin increase relative to spontaneous fluctuations was small and there was substantial variation in magnitude and onset time of cephalic insulin and pancreatic polypeptide responses between food cues and individuals. Based on this we concluded that cephalic phase insulin responses are small compared to spontaneous fluctuations. Although cephalic pancreatic polypeptide responses are of a larger magnitude, both show substantial variation in magnitude and onset time. Based on the current evidence, we refute the hypotheses that CPRs improve satiation and glucose homeostasis in daily life

    Finally, to determine how OSE or taste signals are processed in the brain to affect satiation we performed an fMRI study in which we measured neural reactivity to chocolate milk in the brain(stem) over the course of satiation (chapter 6). Additionally we measured gastric volume such that we could identify regions that respond solely to taste, independent of gastric distention. We found that taste activation in the parabrachial nuclei (PBN) in the brain stem, and bilateral (anterior) insula, amygdala and putamen gradually decreased as satiation increased, in line with the decrease in affective value of the chocolate milk stimuli. When subjects were hungry and completely satiated this effect could completely be explained by gastric filling, whereas this was not the case when subjects felt half full.  Responses of these brain regions are thus modulated by gastric volume and sensory satiation seems especially important early in the meal when not completely satiated.

    To conclude, we confirmed that increased OSE can decrease food intake. Insulin, PP and ghrelin cephalic phase responses do not mediate the oro-sensory exposure effect on satiation. Instead, we hypothesize that the underlying mechanisms are 1) a direct effect of oro-sensory exposure on satiation through sensory satiation and 2) an indirect effect of increased oro-sensory exposure duration which also slows down ingestion rate. This allows more time for stomach distention signals, hormone secretion, and early uptake of nutrients which are processed by the brain and induce satiation.

    Geoquímica microbiana del lago ácido y salino de la corta de la mina Brunita (La Unión, SE España)
    Sánchez-España, Javier ; Yusta, Iñaki ; Ilin, Andrey ; Graaf, Charlotte van der; Sánchez-Andrea, Irene - \ 2020
    Mine Water and the Environment (2020). - ISSN 1025-9112 - 21 p.
    Acidic mine pit lakes - Bacterial sulfate reduction - Metal pollution - Natural attenuation

    We present the first study of a unique acidic lake formed in the Brunita open pit (La Unión mines, Cartagena, SE Spain). This pit lake exhibits chemical characteristics typical of AMD, such as low pH (pH 2.2–5.0) and high iron content (500–6400 mg/L total Fe). It also has some of the highest sulfate concentrations reported to date in pit lakes (26,000–38,400 mg/L SO42-) and transition metals like Mn (up to 2000 mg/L), Zn (500 mg/L), or Cu (250 mg/L). In addition, we found abnormally high concentrations of salt-forming ions (e.g. 5500 mg/L Mg, 750–1300 mg/L Cl, and 300–630 mg/L Na). The resulting high salinity (58‰) at the bottom creates a meromictic lake despite the lake’s low relative depth (9%), with an anoxic, reducing monimolimnion isolated from the oxygenated mixolimnion. In the monimolimnion, we observed decreased metal concentrations (e.g. Cu, Zn, Cd, Cr, Pb, Th). We hypothesize that these metals are being removed by interaction with biogenic H2S and subsequent precipitation as metal sulfides. Scanning electron microscopy shows sub-micron, spherical particles of ZnS in close association with cocci and rod-like bacteria. Analysis of the microbial community composition through 16S rRNA gene amplicon sequencing revealed different genera of sulfate-reducing bacteria (SRB) in the monimolimnion, including Desulfobacca, Desulfomonile, Desulfurispora, and Desulfosporosinus. Their apparent ability to reduce sulfate and selectively precipitate potentially toxic metals, and their resistance to this lake’s extreme geochemical conditions, makes these bacteria of great interest for biotechnological applications (e.g. bioremediation and biomining).

    Relating oral physiology and anatomy of consumers varying in age, gender and ethnicity to food oral processing behavior
    Ketel, Eva C. ; Wijk, Rene A. de; Graaf, Cees de; Stieger, Markus - \ 2020
    Physiology and Behavior 215 (2020). - ISSN 0031-9384
    Age - Ethnicity - Gender - Oral anatomy - Oral physiology - Oral processing behavior

    The aim of this study was to link parameters describing oral physiology and anatomy of consumers varying in age, gender and ethnicity to food oral processing behavior. Three groups of healthy consumers were compared: Dutch, Caucasian adults (18–30 yrs, n =32), Chinese, Asian adults (18–30 yrs, n =32) and Dutch, Caucasian older adults (65–85 yrs, n =32). Mastication performance, salivary flow rate (stimulated and unstimulated) and dental status were quantified to characterize oral physiology. Volume of oral cavity, tongue dimensions, facial anthropometry, height and weight were quantified to characterize anatomy. Oral processing behavior of three solid foods (carrot, cheese and sausage) was quantified by video recordings and eating rate (g/s), average consumption time (s), chews per bite (-) and average bite size (g) were determined. Dutch, Caucasian older adults had smaller volume of oral cavity, lower number of teeth and larger head width compared to Dutch, Caucasian adults. Chinese, Asian adults showed significantly higher mastication performance and larger head width compared to Dutch, Caucasian consumers, while dental status did not significantly differ between groups. Males had significantly larger volumes of oral cavity and larger head height and width compared to females. Dutch, Caucasian adults had a shorter average consumption time (s), less chews per bite and consumed the three foods with higher eating rate (g/s) compared to Dutch, Caucasian older adults. Chinese, Asian adults had a significantly longer average consumption time (s), more chews per bite, smaller average bite size (g) and lower eating rate (g/s) compared to Dutch, Caucasian adults. Twenty-one significant relationships were found between oral physiological and anatomical parameters and oral processing behavior. Body weight resulted in the largest β-values, indicating to be the anatomical parameter of largest influence on oral processing behavior. We conclude that only few oral physiological and anatomical parameters related with food oral processing behavior. We suggest that other factors, including cultural factors contribute to variation in food oral processing behavior between different consumer groups more than saliva flow, volume of oral cavity, mastication performance and dental status.

    The nutritious drink: a specialized nutrient supplement for adults and adults living with HIV in Malawi
    Rodas-Moya, Santiago - \ 2020
    Wageningen University. Promotor(en): K. de Graaf, co-promotor(en): S. de Pee. - Wageningen : Wageningen University - ISBN 9789463952200 - 183


    Undernutrition is a major problem in the world, affecting vulnerable population groups such as people living with HIV (PLHIV). Ready-to-use-therapeutic-foods or corn-soy-blends [e.g., Super Cereal (SC)] are often used to treat undernutrition among PLHIV. However, their acceptability and compliant use are not optimal. 


    To develop a culturally appropriate food nutrient supplement with sensory properties tailored to the preference, primarily of PLHIV, and potentially of adults from the general population, leading to more optimal micronutrient intake.


    We conducted two qualitative studies based on Grounded Theory. In-depth interviews with a triangulation of participants and an iterative approach to data collection were used to investigate the factors influencing preferences for food and nutrient supplements among PLHIV. Based on the results of the qualitative research, we developed eight samples of a nutritious drink.

    Next, we studied the olfactory and gustatory (chemosensory) function of PLHIV to assess whether they suffer from chemosensory losses that could explain possible differences in preferences for the eight samples of the nutritious drink. We used the Sniffin’ Sticks and Taste Strips to assess the olfactory and gustatory function of 100 PLHIV and 100 healthy adults for comparison.

    Subsequently, 100 PLHIV and 98 healthy adults evaluated the nutritious drink samples. We used hedonic scales for assessing liking, and CATA (check-all-that-apply) questions to develop a sensory characterization of the nutritious drink samples. Penalty analysis was conducted to identify the drivers of liking and disliking of the samples for subsequent product optimization.

    Our last study assessed the acceptability and ad libitum intake of the nutritious drink, RUTF, and SC. Fifty-four PLHIV evaluated the products, monadically on three consecutive days. The three food nutrient supplements were served in isocaloric portions of 1000 kcal each. Participants were instructed to consume the products ad libitum. The participants were also asked to rate their liking and wanting for each product. Time of consumption (ad libitum), the number of bites used to consume the products were also measured, and the eating rate was calculated.


    The findings from the qualitative studies indicated that PLHIV preferred a thick beverage slightly sweet and sour as a nutrient supplement. Maheu, a maize-based drink of sweet and sour flavor and a thick, gritty consistency was utilized as a benchmark for the development of the nutritious drink samples for Malawi. The results from the study on olfactory and gustatory function, suggest that PLHIV suffer from olfactory loss. However, their gustatory function was normal.

    The findings from the study using CATA questions showed clear and significant differences in the acceptability of the samples, but no significant differences in preferences between PLHIV and healthy adults. The sensory characterization of the samples made by the two groups was also similar. A preference toward sweet, somewhat sour, thick samples with a soft texture and a milky flavor was identified.

    The results from the ad libitum intake study showed a significantly higher intake of the nutritious drink (356 g) compared to RUTF (107 g) and SC-porridge (312 g). The average intake of eight essential micronutrients as a percentage of target quantities was 58 % from the nutritious drink, 33 % from RUTF, and 20 % from SC. The average caloric intake from the nutritious drink, RUTF, and SC was 507, 581, and 339 kcal, respectively.


    The combination of qualitative research and advanced techniques from sensory science allowed us to identify a product of high acceptability and to identify directions for tailoring the sensory properties of the product to the preference of the potential consumers. A more substantial weight of food and larger quantities of micronutrients were ingested from the nutritious drink compared to RUTF and SC. The nutritious drink also had a much higher eating rate compared to the semisolid supplements. These findings suggest that nutrient-dense food supplements in liquid form may be more effective than semisolid products (e.g., RUTF and SC) in treating undernutrition among PLHIV and other adults. Future research should focus on testing the efficacy of the nutritious drink in the treatment of undernutrition in comparison to RUTF and SC.

    Food preferences and intake in a population of Dutch individuals with self-reported smell loss: An online survey
    Postma, E.M. ; Graaf, C. De; Boesveldt, S. - \ 2020
    Food Quality and Preference 79 (2020). - ISSN 0950-3293
    Anosmia - Dietary intake - Eating behavior - Hyposmia - Macronutrients - Smell loss

    Olfaction plays a major role in food intake regulation. Losing the sense of smell might therefore affect eating behavior. This study investigated food preferences and intake in individuals suffering from self-reported smell loss with an online survey. Members of the Dutch Anosmia Foundation (DAF) performed the Macronutrient and Taste Preference Ranking Task (n = 71) to measure preference for foods high in fat, carbohydrates or protein and low energy foods, and for sweet and savory tastes. To assess dietary intake, adherence to the Dutch Dietary Guidelines for consumption of vegetables, fruit, fiber, fish, saturated fat, trans fatty acids, salt and alcohol was measured (n = 105). Results of the DAF participants were compared to local cohort groups. Both the control and DAF participants showed the lowest preference for carbohydrate-rich foods and highest preference for low-energy foods. Participants suffering from congenital smell loss showed an aberrant pattern, with a higher preference for fat. The total adherence score to the Dutch Dietary Guidelines was similar for the control and DAF group, but adherence scores for fiber, trans fatty acids and alcohol were lower in DAF participants. Overall, no major significant differences in food preferences and intake were found for participants who lost their sense of smell during life. Participants suffering from congenital smell loss did show changes in food preferences, suggesting they are potentially more taste-oriented during eating. Together these results show the importance of tailored advice on dietary intake for this patient group.

    Exploring in vitro gastric digestion of whey protein by time-domain nuclear magnetic resonance and magnetic resonance imaging
    Deng, Ruoxuan ; Janssen, Anja E.M. ; Vergeldt, Frank J. ; As, Henk Van; Graaf, Cees de; Mars, Monica ; Smeets, Paul A.M. - \ 2020
    Food Hydrocolloids 99 (2020). - ISSN 0268-005X
    Gastric digestion - Gel - In vitro - MRI - Time-domain NMR - Whey protein

    Gastric digestion is crucial for protein breakdown. Although it has been widely studied with in vitro models, verification in vivo remains a big challenge. Magnetic resonance imaging (MRI) has the potential to bridge this gap. Our objective was to use the transverse relaxation time (T2) and rate (R2 = T2 −1) to monitor hydrolysis of protein-rich food during in vitro gastric digestion. Whey protein solution and heat-induced hydrogels were digested by means of simulated gastric fluid (SGF). Free amino groups (–NH2 groups) and protein concentration in the supernatant were measured. T2 and R2 of the digestion mixture were determined by time-domain nuclear magnetic resonance (TD-NMR) and MRI. Subsequently, relative amplitudes (TD-NMR) for different T2 values and T2 distribution (MRI) were determined. For the solution, protein concentration and T2 did not change during digestion. For the gels, water in supernatant and gel phase could be discriminated on the basis of their T2 values. During digestion, R2 of supernatant correlated positively with protein (–NH2 groups) concentration in SGF. Also, the decrease in relative amplitude of gel fraction correlated linearly with the increase of supernatant protein concentration. MRI T2-mapping showed similar associations between R2 of supernatant and protein (–NH2 groups) concentration. In conclusion, T2-measurements by TD-NMR and MRI can be used to monitor in vitro gastric digestion of whey protein gels; TD-NMR measurements contributed to interpreting the MRI data. Thus, MRI has high potential for monitoring in vivo gastric digestion and this should be further pursued.

    Non-fasting bioelectrical impedance analysis in cystic fibrosis: Implications for clinical practice and research
    Hollander-Kraaijeveld, F.M. ; Lindeman, Y. ; Roos, N.M. de; Burghard, M. ; Graaf, E.A. van de; Heijerman, H.G.M. - \ 2020
    Journal of Cystic Fibrosis 19 (2020)1. - ISSN 1569-1993 - p. 153 - 158.
    Anthropometry - Body composition - Cystic fibrosis - FEV1%pred - Non-fasting - Single frequency bioelectrical impedance analysis

    Background: Nutritional status affects pulmonary function in cystic fibrosis (CF) patients and can be monitored by using bioelectrical impedance analysis (BIA). BIA measurements are commonly performed in the fasting state, which is burdensome for patients. We investigated whether fasting is necessary for clinical practice and research. Methods: Fat free mass (FFM) and fat mass (FM) were determined in adult CF patients (n = 84) by whole body single frequency BIA (Bodystat 500) in a fasting and non-fasting state. Fasting and non-fasting BIA outcomes were compared with Bland-Altman plots. Pulmonary function was expressed as Forced Expiratory Volume at 1 s percentage predicted (FEV1%pred). Comparability of the associations between fasting and non-fasting body composition measurements with FEV1%pred was assessed by multiple linear regression. Results: Fasting FFM, its index (FFMI), and phase angle were significantly lower than non-fasting estimates (−0.23 kg, p = 0.006, −0.07 kg/m2, p = 0.002, −0.10°, p = 0.000, respectively). Fasting FM and its index (FMI) were significantly higher than non-fasting estimates (0.22 kg, p = 0.008) 0.32%, p = 0.005, and 0.07 kg/m2, (p = 0.005). Differences between fasting and non-fasting FFM and FM were <1 kg in 86% of the patients. FFMI percentile estimates remained similar in 83% of the patients when measured after nutritional intake. Fasting and non-fasting FFMI showed similar associations with FEV1%pred (β: 4.3%, 95% CL: 0.98, 7.70 and β: 4.6%, 95% CI: 1.22, 8.00, respectively). Conclusion: Differences between fasting and non-fasting FFM and FM were not clinically relevant, and associations with pulmonary function remained similar. Therefore, BIA measurements can be performed in a non-fasting state.

    Indoor-visteelt verhoogt rendement
    Boedijn, Alexander ; Graaf, Marcel van de - \ 2019
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