Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

    Records 1 - 20 / 215

    • help
    • print

      Print search results

    • export

      Export search results

    • alert
      We will mail you new results for this query: q=Kleef
    Check title to add to marked list
    Exploring the effects of a healthy school lunch on cognitive performance in Dutch primary school children within the Healthy School Lunch project
    Dijkstra, Coosje ; Haar, Sandra van der; Bergen, Geertje van; Kleef, Ellen van; Vingerhoeds, Monique - \ 2020
    Wageningen : Wageningen Food & Biobased Research (Wageningen Food & Biobased Research report 2041) - ISBN 9789463953832 - 17
    The ‘Healthy School Lunch’ project (PPS Een gezonde schoollunch - TKI AF-16098) aimed to study the feasibility and impact of offering a healthy school lunch in Dutch primary schools. In the first phase of the project we studied the support for a healthy school lunch among a wide range of stakeholders and we explored what they thought a healthy school lunch should look like. The next phase aimed to study the effects of a healthy school lunch on dietary intake and cognitive performance. In order to investigate the effects of providing a healthy school lunch on the dietary intake of children during lunch, a longitudinal intervention study with three schools was designed, where a healthy school lunch was offered for six months. Due to various financial and methodological reasons that were not fully considered when starting this project, it was not possible to combine the dietary intake and cognition study in the school lunch intervention. Instead, we explored the possibilities and requirements to perform a solid experimental cross-over study on the effects of a healthy school lunch on cognitive performance within the Healthy School Lunch Project. This process is described in the current report. We started with a review of the literature on the effects of a healthy school lunch on cognitive performance of children. Studies on the immediate and transient effects of a healthy school lunch versus skipping lunch showed, on a variety of cognitive measures, small and inconsistent effects on alertness and working memory of children. Studies on the long-term effects of a healthy school lunch versus habitual lunch showed small improvements in concentration and language processing ability of children. Given the restriction that long term effects of a school lunch on cognitive performance could not be examined within the scope of this project, the focus shifted to understanding immediate effects. A well-designed study to capture immediate effects of a healthy school lunch on cognitive performance of children within our project would require a strictly controlled cross-over design in a school setting. The intervention should consist of an ad libitum buffet-style healthy school lunch, compared with a control condition in which children eat ad libitum from a provided lunch comparable to the common relatively unhealthy packed school lunch of Dutch children. Finding an adequate measure for cognitive performance is hampered by the great variation of previously used measures across studies. These ranged from relatively indirect measures of concentration and disengagement to standardized computerized tests assessing specific cognitive domains such as alertness and higher-level executive functions. Hence, a comprehensive battery of tests would be advisable to explore various potential effects. Power calculations would be needed to determine the sample size of such a study, but it is clear that large numbers of children would be needed, given the small expected effects and methodological challenges. As more than one participating school would be needed, multilevel statistical models would be required to handle grouped and individual children’s data. More research on the effects of a healthy school lunch on cognition in primary school children would be very useful. However, a well-designed study that would provide convincing evidence of the effects of a healthy school lunch on cognitive performance in primary school children, would require a high cost set-up that places a very high burden on both the children and the schools. Therefore, we decided that it is not realistic to perform this study within the Healthy School Lunch project. In this report we would like to share our findings, considerations and recommendations to researchers of future studies on the effect of healthy school lunches on cognitive performance in children.
    The impact of providing a healthy school lunch at Dutch primary schools on dietary intake and appreciation
    Rongen, Frédérique C. ; Vingerhoeds, M.H. ; Dijkstra, C. ; Kleef, E. van; Seidell, Jacob C. - \ 2019
    The impact of providing a healthy school lunch at Dutch primary schools on dietary intake and appreciation
    Rongen, Frédérique ; Vingerhoeds, M.H. ; Dijkstra, S.C. ; Kleef, E. van; Ummels, Meeke ; Seidell, J.C. - \ 2019
    - 1 p.
    Transitioning to a healthy school lunch at primary schools in the Netherlands: which school lunch concepts have most support from children and parents?
    Rongen, Frédérique ; Dijkstra, Coosje ; Kleef, E. van; Seidell, Jacob C. ; Vingerhoeds, M.H. - \ 2019
    The impact of providing a healthy school lunch at Dutch primary schools on dietary intake and appreciation
    Rongen, Frédérique ; Vingerhoeds, M.H. ; Kleef, E. van; Ummels, Meeke ; Dijkstra, Coosje ; Seidell, Jacob C. - \ 2019
    The impact of providing a healthy school lunch at Dutch primary schools on dietary intake and appreciation
    Rongen, Frédérique ; Vingerhoeds, Monique ; Dijkstra, Coosje ; Kleef, Ellen van; Ummels, Meeke ; Seidell, Jacob C. - \ 2019
    De Gezonde schoollunch – voorlopige resultaten
    Vingerhoeds, Monique ; Dijkstra, Coosje ; Kleef, Ellen van; Rongen, Frédérique ; Ummels, Meeke ; Seidell, Jacob C. - \ 2019
    Preferences of Dutch parents for a school lunch program on primary schools and their willingness to pay
    Dijkstra, Coosje ; Rongen, Frédérique ; Vingerhoeds, Monique ; Seidell, Jacob C. ; Kleef, Ellen van - \ 2019
    The impact of providing a healthy school lunch at Dutch primary schools on dietary intake and appreciation
    Rongen, Frédérique ; Vingerhoeds, Monique ; Dijkstra, Coosje ; Kleef, Ellen van; Seidell, Jacob C. - \ 2019
    Served portion sizes affect later food intake through social consumption norms
    Raghoebar, Sanne ; Haynes, Ashleigh ; Robinson, Eric ; Kleef, Ellen van; Vet, Emely de - \ 2019
    Nutrients 11 (2019)12. - ISSN 2072-6643
    Food environment - Food intake - Personal norms - Portion size - Portion size normality - Social norms

    Portion sizes of commercially available foods have increased, and there is evidence that exposure to portion sizes recalibrates what is perceived as ‘normal’ and subsequently, how much food is selected and consumed. The present study aims to explore the role of social (descriptive and injunctive) and personal portion size norms in this effect. Across two experiments, participants were either visually exposed to (Study 1, N = 329) or actually served (Study 2, N = 132) a smaller or larger than normal food portion. After 24 h, participants reported their intended consumption (Study 1) or served themselves and consumed (Study 2) a portion of that food and reported perceived portion size norms. In Study 1, visual exposure to portion size did not significantly affect intended consumption and perceived portion size norms. In Study 2, participants consumed a smaller portion of food when they were served a smaller rather than a larger portion the previous day, which was mediated by perceived descriptive and injunctive social (but not personal) portion size norms. Results suggest that being served (but not mere visual exposure to) smaller (relative to larger) portions changes perceived social norms about portion size and this may reduce future consumption of that food.

    What’s for lunch? The content and quality of lunches consumed by Dutch primary schoolchildren and the differences between lunches consumed at home and at school
    Rongen, Frédérique C. ; Kleef, E. van; Sanjaya, S. ; Vingerhoeds, M.H. ; Buurma-Rethans, E. ; Bogaard, C. van den; Rossum, Caroline van; Seidell, Jacob C. ; Dijkstra, Coosje - \ 2019
    BMC Public Health 19 (2019). - ISSN 1471-2458
    Background: Lunch is an important part of a healthy diet, which is essential for the development, growth and academic performance of school-aged children. Currently there is an increasing number of Dutch primary schoolchildren who are transitioning from eating lunch at home to school. There is limited knowledge about the current quality of the lunches consumed by primary schoolchildren in the Netherlands and whether there are any differences between lunches consumed at home or at school. To investigate differences in content and quality of lunches consumed by Dutch primary schoolchildren at home and at school. Methods: Cross-sectional study among 363 Dutch primary schoolchildren aged 4–12 years based on the first two years of the 2012–2016 Dutch National Food Consumption Survey. Demographic characteristics were obtained through a questionnaire. Diet was assessed with two non-consecutive 24-h dietary recalls. Quality of lunches was assessed on their nutritional quality whether they fitted the nutritional guidelines. ‘Nonparametric tests were used to examine the content and quality of the lunches between place of consumption and parental educational position. Results: The most consumed lunch products among primary schoolchildren were bread, dairy products and sugar-sweetened beverages. Fruit and vegetable consumption was very low. Consumption of milk and other dairy products was higher among children who eat lunch at home than children who eat lunch at school (p < 0.01). Consumption of sugar-sweetened beverages was higher among children who eat lunch at school than children who eat lunch at home (p < 0.01), and at school a higher proportion of the drinks did not fit within the Dutch dietary recommendations (p < 0.01). Conclusions: The current content of the lunches consumed by Dutch primary schoolchildren leaves room for improvement, especially regarding fruit and vegetables. The statistically significantly higher consumption of sugar-sweetened beverages and lower consumption of milk and dairy products at school vs. home is worrisome, as currently more children in the Netherlands are transitioning to having lunch at school.
    Moving towards a healthier assortment in secondary and vocational school food environments: Perspectives of Dutch students and school food policy professionals
    Kleef, Ellen van; Meeuwsen, Tanja ; Rigterink, Jetteke ; Trijp, Hans Van - \ 2019
    British Food Journal 121 (2019)9. - ISSN 0007-070X - p. 2052 - 2066.
    Adolescents - Consumer Attitudes - Government policy - Healthy food environment - Intervention acceptability - School canteen

    Purpose: In many countries, schools move toward healthier canteen assortments by limiting the supply of unhealthy foods. The question arises whether this gives any undesirable side effects with students (e.g. compensation in purchases from school to outside retailers, reactance) and how to handle these so that operating school canteens remains financially viable. The purpose of this paper is to identify perspectives toward healthy school food assortments held by vocational education students and professionals within secondary and vocational schools with responsibility for school food policy (e.g. school canteen workers, teachers, school directors) in the Netherlands. Design/methodology/approach: Four focus groups were conducted with students at a vocational school (n=25 in total). A semi-structured interview guide was used to conduct discussions. The interview guide also included three school canteen scenario’s (A: 100 percent healthy food, B: 50 percent healthy/50 percent unhealthy foods and C: 100 percent unhealthy food) and a set of nine intervention strategies. A brief survey included questions on the same three scenario’s and nine intervention strategies. A web-based survey was conducted among 68 professionals responsible for school food policy and included their evaluation of the same canteen scenarios and interventions. Survey data were analyzed using descriptive statistics and content analysis. Content analysis was done on the qualitative data. Findings: School food professionals were highly supportive of Scenario A (100 percent healthy food), as this formed a better fit with their policies and was believed to stronger encourage healthy eating. They did worry about financial feasibility given lower affordability and student reluctance to accept the assortment. Students were less in favor of Scenario A. Students discussed getting value for money and remaining freedom to make unhealthy choices. The authors discuss implications for policy makers who aim to implement measures to improve young people’s eating habits. Originality/value: This study contributes to the literature on creating healthier school food environments. This study uniquely examines a healthier school canteen from a viability perspective, including the views of students as primary customers. Given the need to progressively increase the number of foods complying to dietary guidelines in canteen assortments, this study provides insights into how and why assortment changes best can be implemented.

    Changing the behaviour of children living in Dutch disadvantaged neighbourhoods to improve breakfast quality: Comparing the efficacy of three school-based strategies
    Zeinstra, Gertrude G. ; Vingerhoeds, Monique H. ; Vrijhof, Milou ; Mourik, Sanne van; Houtzager, Romy N. ; Kleef, Ellen van - \ 2019
    Appetite 137 (2019). - ISSN 0195-6663 - p. 163 - 173.
    Breakfast - Children - Disadvantaged communities - Education - Role models - Tailored feedback

    Children's breakfast habits are suboptimal. A novel school-based education programme was developed and tested with the aim of improving children's attitude, knowledge and breakfast quality. A pre- and post-test design was used with four conditions: group-based education, role modelling, tailored feedback with goal setting, and a combination of these three delivery modes. Two hundred eighty children from disadvantaged communities (9.3 ± 0.8 years) participated in three lessons at school over a two-month period. Children's attitude, knowledge and breakfast behaviour were evaluated by a pre- and post-questionnaire completed by the children. A follow-up measure was executed at 24 weeks. The data were analysed by repeated measures ANOVA. At baseline, 90% of the children ate breakfast on the measurement day; 60–76% of the children ate breakfast daily. Between pre- and post-test, a significant time effect was found for children's attitude, self-efficacy, knowledge and behaviour (all p < 0.05). Children in the feedback condition improved most favourably: correct classification of breakfast products increased by 10 products (out of 44) and breakfast quality score improved by 25 points (on a 100-point scale). The feedback condition also resulted in positive changes in the home setting. The follow-up test showed a decline in children's knowledge and their breakfast quality across conditions. To conclude, this study showed that a three-lesson school programme based on individual feedback and goal setting is most effective for changing knowledge on breakfasting and self-reported breakfast quality among children aged 8–10 years living in disadvantaged neighbourhoods. To maintain effectiveness, longer-term programmes embedded in the school curriculum are needed to enhance breakfast quality. Future research should explore the optimal duration and intensity of such programmes and should incorporate the topic of suitable portion sizes.

    What’s for lunch: content and preferences of Dutch primary school children
    Rongen, Frédérique ; Kleef, E. van; Vingerhoeds, M.H. ; Seidell, Jacob C. ; Dijkstra, Coosje - \ 2018
    Een verzorgde lunch op de basisschool: wat kost dat en wat mag dat volgens ouders kosten?
    Dijkstra, S.C. ; Rongen, Frédérique C. ; Kleef, Ellen Van; Seidell, Jaap C. ; Vingerhoeds, Monique H. - \ 2018
    Tijdschrift voor Gezondheidswetenschappen 96 (2018)6. - ISSN 1388-7491 - p. 234 - 237.
    Kinderen in de basisschoolleeftijd eten te weinig groente, fruit en volkorenproducten. Melk en yoghurt worden steeds vaker vervangen door alternatieven met veel suiker [1]. Dit zien we ook terug in de lunchtrommels op
    basisscholen: er zijn grote verschillen in de samenstelling en kwaliteit van broodtrommels tussen kinderen op school en tussen scholen onderling [2–4]. De invoering van het continurooster op steedsmeer basisscholen maakt de introductie van een verzorgde schoollunch mogelijk. Er zijn echter nog veel vragen over een verzorgde schoollunch in Nederland. Een daarvan is: wat
    is de voorkeur van ouders? En daaraan gekoppeld de vragen: wat kost dat en wat zijn ouders bereid ervoor te betalen? Dit artikel geeft een beeld van de voorkeuren van ouders met betrekking tot een verzorgde schoollunch
    en de kosten ervan, en van de betalingsbereidheid van ouders.
    Commanding to “Nudge” via the Proportionality Principle? : A Study on Diets in EU Food Law
    Purnhagen, K. ; Kleef, E. van - \ 2018
    In: Regulating and Managing Food Safety in the EU / Bremmers, Harry, Purnhagen, Kai, Springer (Economic Analysis of Law in European Legal Scholarship ) - ISBN 9783319770437 - p. 151 - 167.
    This chapter assesses whether nudging techniques can be argued to be a less restrictive but equally effective way to regulate diets in EU law, when contrasted to classical information-related or content-related regulation. It has been argued that nudging techniques, due to their freedom-preserving nature, might influence the proportionality test in such a way that authorities need to give preference to nudging techniques over content-related or information regulation. We will illustrate on the example of EU food law how behavioural sciences have first altered the EU food law’s goal from the mere provision of safety to also steering behaviour towards healthier diets. In line with this development, the regulatory toolbox advanced beyond the traditional dichotomy of content-related vs. information-related regulation, eventually adding nudging as a third way to regulate. Drawing on previous works of legal scholars we will then present the hypothesis that nudging techniques, according to their choice preserving nature on the one hand and steering character on the other, may be less restrictive but equally effective when contrasted with information-related or content-related regulation. With reference to recent CJEU case law that such a claim would better be backed up by scientific evidence, we will evaluate several nudging studies in the area of food that test the effectiveness of this approach. We will illustrate that, while nudging indeed has a choice-preserving nature and therefore might be less restrictive, it may also be classified under certain circumstances equally effective to information-related regulation. The EU judiciary has introduced an interpretation of the proportionality principle which requires a general preference for information-related rules. The evidence presented, however, may call for a different interpretation of the proportionality principle in some cases to the end that it may require policy makers in the EU to primarily use nudges instead of information-related regulation.
    Promoting healthy choices from vending machines : Effectiveness and consumer evaluations of four types of interventions
    Bos, Colin ; Lans, Ivo A. van der; Kleef, Ellen van; Trijp, Hans C.M. van - \ 2018
    Food Policy 79 (2018). - ISSN 0306-9192 - p. 247 - 255.
    Acceptance - Choice evaluation - Effectiveness - Food choice - Intervention intrusiveness - Vending machine

    Vending machines often provide relatively energy-dense snack foods and beverages at a wide variety of points-of-purchase. Vending-machine interventions that stimulate low-calorie choices can therefore play a role in improving the healthfulness of the food environment landscape. The aim of this study is to examine the effects of four vending-machine interventions, varying in level of intrusiveness, on consumers’ choices, consumers’ acceptance of such interventions, and consumers’ evaluations of the choice they made. In a between-subjects design experiment (N = 206), respondents were asked to purchase a snack and a beverage from a vending machine. In addition to a no-intervention condition, four types of incrementally intrusive interventions were implemented: calorie labelling, increasing accessibility of low-calorie choices, increasing prices of high-calorie choices, and restricting availability of high-calorie choices. A post-choice questionnaire included items concerning intervention acceptance, and assortment and choice evaluations. Compared to the no-intervention condition, the most intrusive intervention (i.e. restricting availability of high-calorie choices) led to more low-calorie choices (39% vs. 78%), while less intrusive interventions (i.e. calorie labelling, increasing accessibility of low-calorie choices, and increasing prices of high-calorie choices) did not. Intervention acceptance and choice evaluations were equally high across the four intervention types. Overall, the results suggest that restricting high-calorie options is a promising route to stimulate healthier choices from vending machines. As such, the present study provides intervention opportunities in the combat against obesity for governments and their potential allies, such as food manufacturers and the food service industry.

    Methodological Challenges of Research in Nudging
    Kleef, E. van; Trijp, J.C.M. van - \ 2018
    In: Methods in Consumer Research / Ares, Gaston, Varela, Paula, Woodhead Publishing - ISBN 9780081020890 - p. 329 - 349.
    Complex societal issues, related to health and sustainability, provide major challenges to scientists, business managers, and policy makers alike. Despite their diversity, these issues have in common that effective solutions to public health (e.g., reducing prevalence of overweight and obesity) and environmental degradation (e.g., reducing pollution and household level waste), as well as social inequality issues (e.g., working conditions of primary producers in developing and emerging countries) critically depend on initiatives of companies but certainly, and probably even more so, on behavioral change on the part of end consumers. Mobilizing commitment of and actual demand from end consumers, in the end, is the “oil in the machinery” needed to move markets into a more healthful and sustainable direction (Van Trijp & Fischer, 2010). Unfortunately, despite societal urgency, there is not a strong track record to build on regarding the success of previous efforts to change consumer behavior “for the better.” Notwithstanding considerable policy attention, such approaches have not been particularly successful, as for example exemplified by the fact that no country in the world has been able to reverse the obesity epidemic (Roberto et al., 2015).
    The effect of a default-based nudge on the choice of whole wheat bread
    Kleef, Ellen van; Seijdell, Karen ; Vingerhoeds, Monique H. ; Wijk, René A. de; Trijp, Hans C.M. van - \ 2018
    Appetite 121 (2018). - ISSN 0195-6663 - p. 179 - 185.
    Behavioural economics - Default effect - Food choice behaviour - Intervention - Nudging - Whole wheat bread
    Consumer choices are often influenced by the default option presented. This study examines the effect of whole wheat bread as a default option in a sandwich choice situation. Whole wheat bread consists of 100% whole grain and is healthier than other bread types that are commonly consumed, such as brown or white bread. A pilot survey (N = 291) examined the strength of combinations of toppings and bread type as carrier to select stimuli for the main study. In the main experimental study consisting of a two (bread type) by two (topping type) between-subjects design, participants (N = 226) were given a free sandwich at a university stand with either a relatively unhealthy deep-fried snack (croquette) or a healthy topping. About half of the participants were offered a whole wheat bun unless they asked for white bun, and the other half were offered a white bun unless they asked for a whole wheat bun. Regardless of the topping, the results show that when the whole wheat bun was the default option, 108 out of 115 participants (94%) decided to stick with this default option. When the default of bread offered was white, 89 out of 111 participants (80%) similarly chose to stick with this default. Across conditions, participants felt equally free to make a choice. The attractiveness of and willingness to pay for the sandwich were not affected by default type of bread. This study demonstrated a strong default effect of bread type. This clearly shows the benefit of steering consumers towards a healthier bread choice, by offering healthier default bread at various locations such as restaurants, schools and work place canteens.
    A tomato with your coffee?
    Witkamp, R.F. ; Kleef, E. van; Zeinstra, G.G. - \ 2017
    Check title to add to marked list
    << previous | next >>

    Show 20 50 100 records per page

     
    Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.