Development of the HELIUS Food Frequency Questionnaires: Ethnic-Speciﬁc Questionnaires to Assess the Diet of a Multiethnic Population in the Netherlands

ORIGINAL ARTICLE Development of the HELIUS food frequency questionnaires: ethnic-speciﬁc questionnaires to assess the diet of a multiethnic population in The Netherlands

MH Beukers1,2, LH Dekker1, EJ de Boer2, CWM Perenboom3, S Meijboom3, M Nicolaou1, JHM de Vries3 and HAM Brants2

OBJECTIVES: Ethnic minorities are often not included in studies of diet and health because of a lack of validated instruments to assess their habitual diets. Given the increased ethnic diversity in many high-income countries, insight into the diets of ethnic minorities is needed for the development of nutritional policies and interventions. In this paper, we describe the development of ethnic-specific food frequency questionnaires (FFQs) to study the diets of Surinamese (African and South Asian), Turkish, Moroccan and ethnic Dutch residents of The Netherlands. METHODS: An existing Dutch FFQ was adapted and formed the basis for three new FFQs. Information on food intake was obtained from single 24 h recalls. Food items were selected according to their percentage contribution to and variance in absolute nutrient intake of the respective ethnic groups. A nutrient database for each FFQ was constructed, consisting of data from the Dutch Food Composition table; data on ethnic foods were based on new chemical analyses and available international data. RESULTS: We developed four ethnic-specific FFQs using a standardised approach that included ~ 200 food items each and that covered more than 90% of the intake of the main nutrients of interest. CONCLUSIONS: The developed FFQs will enable standardised and comparable assessment of the diet of five different ethnic groups and provide insight into the role of diet in differences in health between ethnic groups. The methodology described in this paper and the choices made during the development phase may be useful in developing similar FFQs in other settings. European Journal of Clinical Nutrition (2015) 69, 579–584; doi:10.1038/ejcn.2014.180; published online 17 September 2014

INTRODUCTION not require highly trained interviewers and may be self- Assessing habitual dietary intake is one of the greatest challenges in administered in the participant’s preferred language. A problem dietary research, especially in ethnic minority groups. To date, is that FFQs should be adapted to the food habits of the target ethnic minorities have been underrepresented in studies on diet population, which may hamper comparability of collected intake and disease. Issues such as language, culture and the relatively low data between different populations. fi socioeconomic status of ethnic minorities have formed barriers for We aimed to develop comparable ethnic-speci c FFQs to assess fi their inclusion in research. Furthermore, differences in dietary the habitual dietary intake of ve ethnic groups living in The habits, a lack of food composition data on ethnic foods1 as well as a Netherlands: Moroccan, Turkish, South Asian-origin Surinamese, lack of validated dietary assessment tools further complicate the African-origin Surinamese and ethnic Dutch. These FFQs are 1,2 intended to enable research into the role of diet in ethnic collection of accurate and representative dietary intake data. differences in chronic disease risk, with a focus on cardiovascular European populations have become increasingly ethnically disease. diverse. In The Netherlands, the predominant ethnic minority groups, that is, African-origin Surinamese, South Asian Surina- mese, Turkish and Moroccans, form ~ 23% of the population in MATERIALS AND METHODS Amsterdam.3 Diet is an important modifiable risk factor for chronic 4 Basis for the FFQs disease including cardiovascular disease. In The Netherlands, the We adapted an existing validated 183-item semiquantitative FFQ prevalence of cardiovascular disease risk factors is higher among developed for the ethnic Dutch group.11 This questionnaire was adjusted 5–9 ethnic minorities than in the ethnic Dutch population. The role to reflect the foods usually consumed by the different ethnic groups. A of dietary patterns in these differences is unclear. Therefore, it is single FFQ for the two Surinamese groups, African origin and South Asian, important to include these groups in monitoring surveys and in was developed because of similarities in commonly eaten foods.12 studies on diet and health to guide the development of public Nutrients and food groups that have been recognised to have a role in health strategies to promote healthy diets and reduce health chronic disease risk were the focus of the developed FFQs. In addition, we aimed to measure the intake of nutrients that have previously been inequalities. identified as potentially inadequate by the ethnic minority groups.13,14 Food frequency questionnaires (FFQs) are an acceptable Table 1 provides an overview of the nutrients and food groups prioritised 10 method for assessing usual dietary intake. FFQs can provide in each of the newly developed FFQs; the original, Dutch, FFQ was adapted data on habitual dietary intake, while their administration does to measure the same nutrients and food groups.

1Department of Public Health, Academic Medical Centre, Amsterdam, The Netherlands; 2Centre for Nutrition, Prevention and Health Services, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands and 3Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands. Correspondence: Dr M Nicolaou, Academic Medical Centre, University of Amsterdam, PO Box 22660, 1100 Amsterdam, The Netherlands. E-mail: [email protected] Received 21 June 2013; revised 30 June 2014; accepted 18 July 2014; published online 17 September 2014 Food frequency questionnaires for ethnic minorities MH Beukers et al 580 2. Comparable food groups were included in each of the ethnic-specific Table 1. Nutrients and food groups prioritised in the four FFQs to maximise their comparability. Thus, food items were considered fi ethnic-speci c FFQs for selection if they were included in one of the other FFQs. When this was not feasible, highly specific food items—for example, antroewa, a Nutrients Food groups Surinamese vegetable—were included as a single food. Other reasons for inclusion of food items were an increasing trend in consumption in Total energy intake Fruits and vegetables recent years, based on the DNFCS 2007–2010 (Dutch National Food Macronutrients Milk and dairy Consumption Survey)18—for example, breakfast drinks, as well as face Mono- and disaccharides Meat Polysaccharides Poultry validity, as detailed in the paragraph pretesting FFQs (see below). Finally, Dietary fibre Fish to account for the consumption of foods not included in the FFQ, an open question was included at the end of the questionnaire. Food items added Animal protein Soya and other meat substitutes fi Vegetable protein Nuts and seeds by respondents in this open eld are individually evaluated by the Total fat researchers and, where appropriate, are included in an existing Fatty acid clusters questionnaire item. (saturated, monounsaturated, polyunsaturated and trans-fatty Layout of the FFQs acids) The questionnaire layout was based on the existing Dutch FFQ. Where Alcohol possible, food items are asked together based on the order that they are Micronutrients usually consumed during the day; thus, the questionnaire begins with Calcium foods commonly consumed at breakfast. Ethnic-specific food habits were Iron (haem and non-haem) also accounted for in ordering the questions; for example, in the Turkish Vitamin A FFQ, foods related to breakfast also include questions about sliced raw Vitamin B2 vegetables and olives, which are consumed as part of a traditional Turkish Folate breakfast. In addition, foods consumed at a particular meal are ordered so Vitamin B2 that less commonly used foods are mentioned before more common Vitamin C items. For example, a question on different types of crackers precedes the Vitamin D question on bread rolls and croissants, which in turn comes before the question on sliced bread. In this way, we hope to minimise the chance of Abbreviation: FFQ, food frequency questionnaire. overreporting, as participants are forced to think about all bread products before the question about sliced bread, which they presumably eat more frequently, is asked. Respondents were asked to report the frequency of The food items for the ethnic-specific FFQs were selected on the basis of consumption over the last 4 weeks in 10 categories, followed by the usual single 24 h recalls. Data originated from the LASER study, including quantity eaten on a consumption day, based on standardised units, Moroccan and Turkish participants,15 the SUNSET study, which included household measures or colour photos. For many food items participants — African-origin and South Asian Surinamese participants,12 and a study were asked to specify the types of foods usually eaten for example, among Moroccan and Turkish women in The Netherlands.16 These studies orange juice or other fruit juice and/or the preparation methods used, for were conducted between 1998 and 2005 and included, in total, 154 example, boiled or fried. Box 1 illustrates the layout of questions, using Moroccan, 275 Turkish and 109 Surinamese adults. soup as an example. The differences in the types of soup eaten per ethnic group are also illustrated here. The language used in all FFQs is Dutch. The Turkish and Moroccan FFQs Selection of food items were also translated into Turkish and Arabic–Moroccan, respectively. The selection of food items to be included in each of the ethnic-specific FFQs was based on two criteria: (1) the percentage of contribution of that Pretesting of the FFQs food item to absolute nutrient intake and its percentage contribution to the variance in absolute nutrient intake and (2) comparability with the The newly developed FFQs were tested to supplement information on FFQs for other ethnic groups. food items. Several methods were applied to identify potential problems: 1. Foods were selected on their percentage contribution to and variance (1) expert judgement by 13 dieticians of the specific ethnic origins; (2) 30 19,20 in absolute nutrient intake of the specific ethnic group based on the plus-minus interviews conducted with participants; (3) 9 focus groups methodology described by Molag et al.17 The single foods reported in consisting of 6–12 participants of the same ethnic origin; and (4) cognitive the 24-h recalls were arranged into food groups at different levels. The 24 interviews among 7 Moroccan participants. food groups in the Dutch Food Composition Table were regarded as level 0, Dieticians from the respective ethnic groups evaluated the FFQs for face the highest level of aggregation. However, the food groups on this level are validity, specifically to check for missing ethnic-specific food items, too broad to be questioned as a food item in an FFQ. Therefore, these 24 inaccurate portion sizes, incorrect spelling or incorrect description of food groups were further subdivided into three hierarchical levels of foods. Plus-minus interviews were conducted with potential participants aggregation. The grouping was based on similarity in the types of food and from each ethnic group to identify areas of the FFQs that required nutrient composition and represented increased detail in the specification of improvement. This method requires participants to add a plus or a minus food groups—for example: level 0, milk products; level 1, yoghurt; level 2, in the margin of the questionnaire while filling it out. A plus indicates a natural yoghurt; and level 3, low-fat natural yoghurt. The reported foods in well-understood question, whereas a minus indicates a difficult or unclear the 24-h dietary recalls were classified in the food groups at all hierarchical question. Consequently, the interviewer probes for information from the levels.17 Consumption in grams/per day of each food group at levels 1, 2 and participant on the basis of the pluses or minuses they note. In the focus 3 and the contribution of these food groups to absolute nutrient intake were groups, similar issues were covered. In addition, two different options for calculated. At each level, the food groups were ranked according to their specifying the types of foods consumed were tested, one using the grid percentage contribution to the absolute intake of the individual nutrients of format, in which four answer categories ‘never’ until ‘always’ were interest. The set of foods that yielded at least 80% of intake was determined included, and one in which the participants could indicate which foods at each level and selected for inclusion in the FFQ. This procedure was they ‘usually’ ate. Finally, cognitive interviews were conducted using the – repeated for each of the selected nutrients. As suggested, we also ‘think aloud’ method.21 23 The latter was applied in testing questions from performed calculations based on variance of nutrient intake within each the Moroccan FFQ, as it was expected that this group would best represent ethnic group; these calculations revealed no additional food groups to those the potential difficulties in filling out the questionnaire. We obtained already selected for percentage contribution.17 information on design and comprehension of the questions, portion sizes, To minimise the FFQ length, food items were grouped at the highest food products, frequency of intake, order of food groups and possible hierarchical level. However, we chose to split these groups further composed meals. if the variation in nutrient content of the different food items within one Once the FFQs were fully adapted, the original Dutch FFQ underwent a group was too large or if there were differences in consumption units or final language check for comprehensibility; this was used as the basis for how food items are consumed. the formulation of the other FFQs.

Box 1 Questionnaire layout and illustration of differences in questions between the three ethnic-speciﬁc FFQs—question about soup

All: In the past 4 weeks, how often did you eat soup (homemade, ready-made, cup-a-soup and soup based on bouillon)? Please note: plain bouillon does not count.

Not in the past 4 weeks 1 day per 2–3 days 1 day per 2 days per 3 days per 4 days per 5 days per 6 days per 7 days per 4 weeks per 4 weeks week week week week week week week

□ □□□□□□□□□ ↓ go to …

How many bowls of soup have you mostly eaten on a day that you ate soup?

Less than ½ ½ 1 1½ 2 2½ 3 4 5 6 More than 6

□ □□□□□□□□□□

Dutch:What types of soup you usually eat? (You can check multiple answers) & Soup with legumes, such as pea soup, brown bean soup and lentil soup & Other soups Moroccan:What types of soup you usually eat? (You can check multiple answers) & Soup with legumes, such as lentil soup, harira, pea soup and brown bean soup & Other soups Turkish:What types of soup you usually eat? (You can check multiple answers) & Soup with legumes, such as mercimek (lentil soup), pea soup and brown bean soup & Other soups Surinamese:What types of soup you usually eat? (You can check multiple answers) & Soup with legumes, such as karhi, lentil soup, pea soup and brown bean soup & Soup with root vegetables, such as bravoe, okra soup, cassava soup, bananas griti, tajersoep or soups with tomtom or napi & Peanut soup (peanut bravoe) & Other soups

Nutrient database overview of the main differences in the foods specified between A nutrient database for each FFQ was constructed on the basis of data in the FFQs. For example, in the Surinamese FFQ, we included the Dutch Food Composition Table 2011.24 For ethnic-specific products, questions relating to the intake of roti (a flat bread usually eaten the database was supplemented with international food composition data, as part of a meal), but as this food is not commonly consumed by information from food packaging and data from recipe calculations. Six the other ethnic groups it was not included in the other FFQs; commonly consumed Turkish foods were chemically analysed: two types chocolate milk was included in the Dutch and Surinamese FFQs of yoghurt, cow cheese, goat cheese, Turkish pizza and Turkish brown but not in the Turkish and Moroccan FFQs. There are also bread. Multiple samples of each food were mixed for analysis; these fi samples were based on brand and different sale locations. differences in the speci cation of food items; Box 1 illustrates this with an example of differences in the question about soup. Overall, the FFQs cover 490% of the absolute intake of each of Conversion into nutrients the nutrients that are of interest in this study. Table 3 shows the Each food item in the questionnaire was linked with one or more foods minimum contribution to absolute nutrient intake and the from the food composition table. For food items consisting of more than a minimum proportion of between-person variance explained by single food, we calculated the nutrient values by weighting the individual the selected food items in the various ethnic-specific FFQs for foods according to their frequency of consumption (as percentage consumption days). Data from the DNFCS18 were used where appropriate, each of these nutrients. These calculations were not made for the but, when the contribution of the individual foods to the food item Dutch FFQ, as it was based on an existing questionnaire that was differed from that in the general Dutch population, weighting was based developed using similar methodology. With regard to absolute on the ethnic-specific 24-h recall data. intake, the nutrients with the highest contribution are alcohol Foods contributing o2.5% to the amount of intake of the food item (100% in all FFQs), haem iron and animal protein. The lowest were not included in the composition of the food item, as it was decided contribution is 90.3% for polysaccharides in the Turkish FFQ, that at this level of consumption those food items would have little impact 92.9% for non-haem iron in the Surinamese FFQ and 93.8% for fi on the overall nutrient intake. In the case of forti ed food products, this polysaccharides in the Moroccan FFQ. However, the actual limit was set at 1%, as these products are likely to have a greater impact on contribution to absolute intake is likely to be somewhat higher nutrient intake. The choice to use the cutoffs of 2.5 and 1% was subjective. The composite portion size for each food item was also based on a than that shown in this table because of the contribution of foods – weighted average of the portion sizes of the individual foods, using the that are not mentioned separately but are part of mixed dishes same weight factors as for the nutrient values. for example, flour is an ingredient in bread or cakes. With regard SAS version 9.2 (SAS Institute Inc., Cary, NC, USA) was used for all to their contribution to explaining the between-person variation, calculations. the nutrients with the highest contribution percentage explained are alcohol and haem iron (100%), the lowest is 81.6% for vitamin A in the Moroccan FFQ, 89.5% for polysaccharides in the Turkish RESULTS FFQ and 92.5% for fibre in the Surinamese FFQ. The lower values FFQ development for vitamin A in the Moroccan FFQ and for polysaccharides in the The ethnic-specific FFQs range from 189 (Moroccan) to 238 Turkish FFQ are due to carrot juice (rarely consumed) and flour (Dutch) food items. Differences in the number of items are due to (frequently consumed in 24-h recalls but included in mixed food inclusion of ethnic-specific food items. Table 2 presents an items like bread and cake in FFQs), respectively.

Table 2. Overview of the main differences in food items included in the four ethnic-speciﬁc FFQs

Ethnic Dutch Surinamese Turkish Moroccan

Total number of items 238 228 209 189 per FFQ Items common to Gingerbread Gingerbread Turkish/Moroccan bread Turkish/Moroccan bread some of the FFQs Chocolate milk Chocolate milk Olive oil to dip bread Olive oil to dip bread Salty biscuits or cheese Salty biscuits or cheese Olives Olives biscuits/cheese sticks biscuits/cheese sticks Cordial/Syrup diluted with Cordial/Syrup diluted with water water Items that are unique, Pancakes Roti (flat bread) Börek andpogaca Couscous per FFQ (pastry-based savouries) Applesauce Pom (mixed dish with chicken Ayran (a yoghurt drink) Rghaif/lemsemmen and root vegetables) (Moroccan pancakes) Gravy Other tubers: pomtajer, cassava, Bulgur Beghrir (Moroccan sweet yam, cooking banana donut) Cream in warm dish, e.g., Coconut milk/cream Sarma and Dolma (filled sour cream grape leaves) Nuts and seeds in warm dish Soya sauce Yogurt sauce Salad based on mayonnaise, Avocado Leblebi (dried chickpeas, e.g., Russian salad eaten as a snack) Small toast with cheese, fish, Hindu sweets, e.g., barfi, gullab Sunflower seeds (eaten as pate, salad, etc. jamun a snack) Cheese as an in-between Fried banana meal snack Sausage as an in-between meal snack Abbreviation: FFQ, food frequency questionnaire.

Testing phase relatively small studies that conducted single 24 h recalls. Results from the testing phase indicated that participants did not Although the use of single 24 h recalls for this purpose is not always comprehend questions in the FFQ. Common problems unusual, most studies have tended to include larger groups, from 25 26;27, included the use of unfamiliar terminology and long phrases. 200 to 500 participants to 4800. In the literature, one other Participants also had difficulties describing portion sizes for items study was found that used single 24 h recalls from small numbers 27 such as couscous and Turkish or Moroccan bread. Input from of participants to adapt an existing questionnaire. However, dieticians and the focus groups gave additional insight into the most studies have compensated for small numbers by using 28–30 suitability of portion sizes and missing food items. multiple 24 h dietary recalls and food records. In this study, In testing the two types of questions used to establish the foods we compensated for small numbers by extensively testing the eaten within composite food item questions, the grid format was questionnaire for completeness and comprehension. However, it perceived as more difficult by most participants. remains necessary to regularly collect detailed dietary data of These findings led to refinement, including addition of these ethnic groups using an open-ended method such as descriptions of food items, rephrasing long sentences, adaptation multiple 24 h recalls. Ideally, the ethnic groups would be included of portion size ranges, extra colour photos and dropping the grid in sufficient numbers in national food consumption surveys, which format in favour of multiple answer questions (Box 1). would provide insight into food consumption patterns and allow Issues detected by the dieticians, like missing ethnic-specific updates of the newly developed FFQs. FFQ data are useful in food items, were discussed by the researchers. The decision to add ranking individuals on the basis of their dietary intake and are missing items was made on the basis of the evaluation that the therefore suitable for epidemiological research of the link specific food was important in the diet of the group in question. between diet and health. However, the closed nature of the data limits its utility as a tool for establishing trends in the food consumption of populations. This is important for the develop- DISCUSSION ment of strategies to deal with dietary inadequacies or excesses. Using the standardised methodology previously described by 17 Molag et al., we developed three ethnic-specific FFQs and Selection of food items fi adapted an existing Dutch FFQ to assess the habitual diet of ve There are several methods to select food items from existing food ethnic groups. The FFQs consist of 185–238 food items and cover 10 4 consumption data. We selected food items on the basis of their 90% of the intake of the nutrients of interest. This discussion percentage contribution to and variances in absolute nutrient focuses on a number of challenges that were faced during the intake in a population. Food items can also be selected on the process of development. basis of variance while taking covariance between nutrient intakes of food items into account, using forward regression. Because of Food consumption data underlying the FFQs the small numbers of participants in our underlying data, the data The development of FFQs usually relies on up-to-date food set was less suitable for selection based on regression analysis. In consumption data from the populations for which the ques- addition, the availability of just a single 24-h dietary recall per tionnaire is intended. The baseline food consumption data used to participant meant that calculations of variances were unlikely to develop the FFQs described in this paper originated from be optimal. Nonetheless, analyses were performed on variances,

Table 3. Percent contribution of the FFQs to the % absolute intake of nutrients of interest and to explaining the between-person variation in the intake of these nutrients

Contribution to absolute intake of nutrients (%) Contribution to percentage of between-person variation explained (%)

Nutrient Surinamese FFQ Moroccan FFQ Turkish FFQ Surinamese FFQ Moroccan FFQ Turkish FFQ

Total energy intake 97.8 96.2 95.1 99.6 96.9 94.6 Mono- and disaccharides 96.7 95.5 96.6 97.0 95.2 97.9 Polysaccharides 97.4 93.8 90.3 98.3 95.7 89.5 Dietary fibre 94.8 96.7 94.5 92.5 98.8 95.5 Animal protein 99.2 99.2 99.1 99.9 99.9 99.8 Vegetable protein 96.6 94.6 91.9 99.2 96.8 92.0 Total fat 99.2 98.3 98.1 99.9 98.5 99.1 Saturated fatty acids 98.3 97.2 97.7 99.7 97.0 98.7 Mono-unsaturated fatty acids 98.8 98.6 98.5 99.9 99.1 98.8 Poly-unsaturated fatty acids 99.2 99.0 98.5 100 99.9 99.6 Trans fatty acids 97.8 97.0 98.4 99.9 97.8 99.6 Alcohol 100 100 100 100 100 100 Calcium 96.7 97.3 96.8 97.7 98.9 97.4 Iron haem 99.8 100 99.9 100 100 100 Iron non-haem 92.9 95.2 93.4 96.4 98.3 95.8 Vitamin A 98.2 94.4 96.5 99.9 81.6 99.9 Vitamin B2 97.4 97.2 95.3 99.0 98.3 94.3 Folate 97.3 97.5 94.9 99.6 99.3 97.7 Vitamin B12 99.2 99.1 98.9 100 99.9 100 Vitamin C 98.5 97.9 96.6 99.9 98.8 99.2 Vitamin D 99.0 98.9 97.0 99.9 99.9 95.9 Abbreviation: FFQ, food frequency questionnaire. but this did not lead to the selection of additional food items for not have a question about ‘tajine’, a Moroccan dish consisting of the FFQs. This may be explained by the fact that selection meat, potatoes and vegetables, but in the questions about meat, according to the contribution of absolute intake was performed vegetables and potatoes participants are reminded to include the for a large number of nutrients (van Lemmen, paper submitted for amounts of these individual items that are eaten in tajine and publication). other mixed dishes. This method was chosen as it was expected To confirm the suitability of the chosen food items in the that the large variation in ingredients used in such mixed dishes Surinamese questionnaire, the available 24-h recall data (2003) would complicate the use of standard recipes. A possible were supplemented with data from a more recent study at the consequence of this choice may be that participants have municipal health service of The Hague (2007).31 The latter data problems reporting frequencies and quantities of ingredients that consisted of 3-day food records of 82 South Asian Surinamese are eaten as part of a mixed dish. This issue was addressed during women. Food items that were not selected from the 24-h recall the testing phase; it was found that asking mixed dishes in this data but were eaten regularly according to the food records were way did not pose a problem. added to the Surinamese FFQ. Unfortunately, there were no such data available to enable a similar process in the development of Inclusion of fortified products the Turkish and Moroccan questionnaires. To allow for the Fortified products that were eaten in the DNFCS 2007–2010 and reporting of foods not included in the FFQ, an open question contributed 1% or more to the consumption of composite food relating to this was included at the end of the questionnaire. items were included in the weighting. The most frequently consumed fortified products were dairy products, margarines and Comparability FFQs nonalcoholic beverages. Assessing the intake of fortified products The underlying aim in developing the ethnic-specific FFQs is to with an FFQ is difficult: the nutritive value of fortified products conduct research into ethnic differences in the association varies as fortification level differs between brands and between between diet and health. A simple approach would be to apply products within one brand; people often do not know whether a single FFQ in all ethnic groups. However, this option would they consume fortified products. We therefore chose not to either result in a very long questionnaire or in a compromise of its specify these items in the FFQs. As a result, the intake of fortified face validity. Therefore, we chose to develop separate FFQs per products will reflect intake at the group level and not at the ethnic group and strived to make them as similar as possible to individual level. Furthermore, as the DNFCS data are based on the each other by applying rigorous methodology in their develop- general Dutch population, the population level intake may not ment and testing. The resulting four questionnaires have the same apply to the ethnic minority groups. This further underscores the layout and consist of similar, comparable food items. However, need for including ethnic minorities in future national food differences are inevitable because of differences in the diet of the consumption studies. groups studied. Future perspective Questions relating to mixed dishes The FFQs described in this paper were primarily designed for the One of the difficulties encountered when developing the FFQs HELIUS-Dietary Patterns study.32,33 In this study, data will be was in deciding how to deal with mixed dishes. We chose not to gathered on the habitual intake of participants of ethnic Dutch, name specific mixed dishes but to ask participants about their African Surinamese, South Asian Surinamese, Turkish and Mor- intake of individual food components. For instance, the FFQ does occan origin, aiming for ~ 1000 participants per ethnic group. The

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