ORIGINAL COMMUNICATION Reliability of a Dietary Questionnaire on Food Habits, Eating Behaviour and Nutritional Knowledge of Adolescents

ORIGINAL COMMUNICATION Reliability of a dietary questionnaire on food habits, eating behaviour and nutritional knowledge of adolescents

G Turconi1*, M Celsa1, C Rezzani2, G Biino2, MA Sartirana1 and C Roggi1

1Department of Applied Health Sciences – Section of Human Nutrition, University of Pavia, Italy; and 2Department of Applied Health Sciences – Section of Statistics, University of Pavia, Italy

Objective: To develop a dietary questionnaire on food habits, eating behaviour and nutrition knowledge of adolescents and to examine its reliability. Design: A cross-sectional baseline survey. The questionnaire was self-administered to study participants twice with 7 days between each administration. Setting: A school community in Pavia, Italy. Subjects: A group of students (n ¼ 72, aged 14–17 y, both sexes) studying in a secondary school in the second year of the course were invited to compile a dietary questionnaire during school time. Informed written consent was obtained from each subject and their parents. Subjects were initially recruited for a nutrition intervention; recruitment was opportunistic and school based. Statistical analyses: Reliability was assessed using the Cronbach’s alpha and the Pearson correlation coefficients. Results: Cronbach’s alpha ranges from a minimum of 0.55 to a maximum of 0.75, indicating that only two sections have a poor internal consistency. The Pearson correlation coefficients range from a minimum of 0.78 to a maximum of 0.88, indicating a very good temporal stability of the questionnaire. All the Pearson correlation coefficients are statistically significant with Po0.01. Conclusions: The present questionnaire has the potential to measure the effects of nutrition interventions on adolescents because of its stability in making comparisons over time. The instruments is low in cost and easy to administer and analyse; moreover, it could be modified appropriately to fit the needs of other populations as well. European Journal of Clinical Nutrition (2003) 57, 753–763. doi:10.1038/sj.ejcn.1601607

Keywords: dietary questionnaire; food habits; eating behaviour; reliability; adolescents

Introduction quate lifestyle and nutrition and health education has been Collecting epidemiological dietary data represents an recognized in improving good health (Gracey et al, 1996; indirect although fundamental tool in nutritional surveil- Povey et al, 1998; Sorensen et al, 1998; Larkey et al, 1999; lance of population. The link between unhealthy diet, Anesbury et al, 2000). Planning an incisive nutrition sedentary lifestyle and chronic-degenerative diseases such intervention on a given sample of population requires as cardiovascular disorders, diabetes and cancer is increas- identification of its nutritional problems and primary needs. ingly well documented (Keys, 1986; WHO, 1990; Ulbricht & Traditional dietary assessment method measure both short- Southgate, 1991; Muller et al, 1999; Liu et al, 2001). term dietary intake, such as 24-h recall and food records, and Moreover, the relation between healthy food habits, ade- long-term dietary intake, such as food frequency questionnaires and dietary histories (Bingham, 1987, 1995). Although largely used in the last 50–60 y (Bingham, 1995), *Correspondence: G Turconi, Department of Applied Health Science-Section of Human Nutrition, University of Pavia, these methods present some characteristics that limit their Via Bassi, 21, I-2700 Pavia, Italy. use in dietary survey (Kristall et al, 1990; Bingham, 1995; Guarantors: G Turconi and M Celsa. Birkett & Boulet, 1995; Yaroch et al, 2000); most of them are Contributors: G Turconi and M Celsa: project of the study and not always appropriate because of cost, response burden, bias development of the questionnaire. G Biino and C Rezzani: study of validity and reliability. MA Sartirana: collaboration in development and need of highly trained staff for administration (Yaroch of the questionnaire and administration of it. C Roggi: supervisor. et al, 2000). Reliability of a dietary questionnaire G Turconi et al 754 The methods in nutritional epidemiological survey most Individual character and personality are decisively formed commonly used in the last years are the semi-quantitative during adolescence. Young people begin to assume respon- food frequency questionnaires. In fact, they are brief, sibility for their own food habits, health-related attitudes inexpensive, easy to administer and less burdensome when and behaviours (Coates et al, 1982), and their growing compared with the other traditional methods for assessing independence is often associated with unconventional dietary intake (Yaroch et al, 2000). eating patterns (Truswell & Darton-Hill, 1981). Although Nevertheless, the above-mentioned questionnaires are eating behaviour during adolescence may be transitory in designed to measure dietary intake of energy and nutrients some individuals, health behaviour shows tracking through and do not investigate other aspects of nutrition, such as adolescence (Kelder et al, 1994). If habits acquired in food habits and eating behaviour, both relating to nutrition adolescence persist into adult life, behaviour developed in itself and food safety. All these aspects are very important in young people may have important long-term consequences a nutritional surveillance programme. on health. In the last 10 years, other questionnaires have been Therefore, knowledge about food habits and eating developed aimed at investigating some of the above-men- behaviour of adolescents turns out to be very important for tioned aspects and structured with scores and scale scores planning educational nutrition programme in the promo- (Kristall et al, 1990; Falconer et al, 1993; Williams et al, 1993; tion of good health and well-being in adult life. Greene et al, 1994; Birkett & Boulet, 1995; Vandongen et al, The aim of the present study is to develop dietary 1995; Johansson et al, 1997; Sapp & Jensen, 1997; Par- questionnaire on food habits, eating behaviour, lifestyle, menter & Wardle, 1999; Hu et al, 1999; Yaroch et al, 2000). It food safety and nutritional knowledge for adolescents and to is well documented that each questionnaire must be tested test its reliability. in order to measure reliability prior to use in large-scale studies. Reliability is the scale ability of measuring something in Methods reproducible fashion. An instrument is reliable if individual Questionnaire measurements taken on different occasions, or made by In order to make sure that the selected items are representa- different observers, or by parallel tests, produce the same tive of all topics being measured, some items were taken result. Reliability is usually quoted as a ratio of the variability from existing questionnaires while others were obtained between individuals to the total variability in the scores; in from the literature (Gracey et al, 1996; Povey et al, 1998). other words, reliability is a measure of the proportion of the Using pool of 127 items generated by a group of expert variability in scores caused by the differences between nutritionists, one review was carried out by a panel of five individuals. Reliability is commonly expressed as a number dieticians to select the best in terms of clarity of the between 0 and 1, with 0 indicating no reliability and 1 questions and interpretability. This process reduced the indicating perfect reliability. number of items to 99. A total of 10 students aged 14–17 y There are two main approaches to reliability measures: were then invited to complete the questionnaire to identify internal consistency, which represents the extent to which ambiguity or lack of clarity in the items. The students were the scale items are highly intercorrelated, and temporal then quizzed on their comprehension of the significance of stability (test–retest reliability); a measure is considered the items. reliable if it gives the same result over and over again, The questionnaire was self-administered and divided into assuming that what we are measuring is not changing. In nine main sections. The first section (Section A) contained test–retest reliability, the questionnaire is administered to information on personal data collected by means of seven the study participants on two occasions and the scores are questions; the other sections contained 99 items overall correlated to yield a coefficient of stability. relating to various topics as shown below. The last nutrition questionnaires cited above have limita- Section BFFrequency of Food Consumption: It contains 28 tions because they cover only a limited area of nutrition questions aimed at investigating daily frequency of con- knowledge (Towler & Shepherd, 1990; Steenhuis et al, 1996; sumption of typical foods and beverages such as bread, pasta, Resnicow et al, 1997) or were not subjected to rigorous cereal products, fruit and vegetables, milk, tea, coffee and validation (Andersson et al, 1988) or were designed for use weekly consumption of other foods such as meat and meat with adults and might not be suitable for use with an products, fish, eggs, cheese, legumes, etc. Alcoholic drinks adolescent sample (Resnicow et al, 1997; Sapp & Jensen, had also been investigated. 1997). Construct validity in McDougall’s questionnaires Section CFFood Habits: It consists of 14 questions. This (1998) had not been assessed and the test–retest reliability section was designed to investigate the food habits of the had been measured administering the questionnaire on two adolescents in particular related to breakfast contents, different occasions separated by just 1 day; therefore, number of meals a day, daily consumption of fruit and although reliability was found to be high it is not possible vegetables as well as of both soft and alcoholic beverages. to know whether the measure would be stable over a longer In this section, some questions already investigated in period of time. section B are asked again aimed at evaluating if numbers of

European Journal of Clinical Nutrition Reliability of a dietary questionnaire G Turconi et al 755 portions consumed by the students satisfy the ones recom- healthiest behaviour in hygiene practices. The total score of mended. this section was 32. Eight of the questions had the following response The questionnaire was self-administered at different times categories: always, often, sometimes, never; the other six twice over a 2-week period. Administration was performed have instead four response categories structured in different during school lesson times under the supervision of a ways. dietician and of the teacher who were always ready to The score assigned to each response rages from 1 to 4, with answer any of the students’ questions. the maximum score assigned to the healthiest one and the minimum score to the least healthy one. The total score of this section was 56. Subjects F Section D Physical Activity and Lifestyle: It contains six The questionnaire was self-administered to a sample of questions aimed at investigating lifestyle and physical students studying in four sections of the second year in a activity levels. All responses are structured in different ways secondary school in Pavia, Italy. A total of 78 students were according to each question, each score raging from 1 to 4, invited to complete the questionnaire. Selected subjects were with the maximum score assigned to the healthiest habit. initially recruited for a nutrition intervention. In all, 72 The total score of the present section was 24. students completed the questionnaires during the first F Section E Healthy and Unhealthy Diet and Food: It consists administration; the 72 adolescents ranged in age form 14 of five questions aimed at investigating the students’ beliefs to 17 y (mean7standard deviation [s.d.] ¼ 15.170.3 years), about healthy and unhealthy diet and food. Each question 59 females and 13 males. Of these 68 subjects completed the had four different responses, with the score ranging from 1 questionnaire during the second administration 1 week later. to 4. The total score of the section was 20. School selection and recruitment of the subjects were F Section F Self-Efficacy: It contains eight questions with opportunistic, based on the fact that the teachers, recently three response categories: yes ¼ 3, no ¼ 1, I don’t know ¼ 2. involved in a nutrition education programme held in the This section aimed at estimating how each student is able to school, were interested in participating in the study. All the assume attitudes and behaviours that can improve his health students were informed of the study’s objectives. Informed status related to nutrition. The total score was 24. written consent was obtained from each subject and their F Section G Barriers to Change: Consisting of nine questions parents. with two response categories: yes ¼ 1, no ¼ 2; the questions aimed at investigating which difficulties, if present, the student has in modifying his eating habits in order to improve them. A score of 2 was assigned to the major barrier Statistical analyses Reliability study is conducted following classical test theory towards change; in this way greater barriers to change were principles. As a measure of internal consistency Cronbach’s related to higher scores. The total score of this section was 18. alpha was computed, while we computed Pearson correlation coefficient as a measure of temporal stability. Section HFNutrition Knowledge: It contains eleven ques- According to classical test theory, we computed Cronba- tions, each with four response categories structured in different ways. This section focused on a few nutritional ch’s alpha and Pearson correlation coefficient of each section aspects, investigating the level of knowledge that the total score, with the exception of section B. Aim of section B is to describe frequency of food consumption; this section is students have in this area. The response categories are four and the true response of each question received a score of 1 not a scale in the very sense of the term and thus there is no and 0 for the other response. The total score of this section total score. Therefore, we cannot compute Cronbach’s alpha and Pearson correlation coefficient of the total score, but we was 11. evaluate temporal stability of each item of section B. The Section IFFood Safety Knowledge: It contains ten questions, each with four response categories structured in different Statistical Package for the Social Sciences (SPSS version 10, 2000) was used. ways: this section focused on students’ knowledge level regarding food safety. The score was 1 for the true response to each question and 0 for the other response. The total score of this section was 10. Results Section JFFood Safety and Behaviour in Hygiene Practices:It Reliability contains eight questions, seven of which present the Table 1 reports the measures of internal consistency, following response categories: always, often, sometimes, Cronbach’s alpha and the stability measures, Pearson never; the last one (J6) had four different responses correlation coefficients for each of the eight sections structured in different ways. This section aimed at investi- computed between the two administration total scores. gating each student’s behaviour in hygiene practices related Cronbach’s alpha ranges from a minimum of 0.55 (section to food safety and its problems on health. The score ranging G) to a maximum of 0.75 (section C), indicating that the from 1 to 4, with the maximum score assigned to the sections with a poor internal consistency are sections G, H

European Journal of Clinical Nutrition Reliability of a dietary questionnaire G Turconi et al 756 Table 1 Internal and test–retest reliability (n=68) Table 2 Test-retest reliability for section B (n=68)

Sections Internal reliability Test–retest Items Test–retest (Cronbach’s a) reliability a reliability a

CFFood habits 0.75 0.88 B1 0.87 DFPhysical activity and lifestyle 0.71 0.88 B2 0.90 EFHealthy and unhealthy diet 0.59 0.78 B3 0.86 and food B4 0.53 FFSelf-efficacy 0.73 0.81 B5 0.45 GFBarriers to change 0.55 0.79 B6 0.52 HFNutrition knowledge 0.56 0.80 B7 0.84 IFFood safety knowledge 0.57 0.80 B8 0.82 JFFood safety and behaviour 0.69 0.80 B9 0.73 in hygiene practices B10 0.57 B11 0.74 a B12 0.55 Pearson correlation coefficients computed between the two administration B13 0.68 total scores=Po0.01. B14 0.56 B15 0.59 B16 0.45 and I. Section E has Cronbach’s alpha equal to 0.59 B17 0.63 indicating a nearly sufficient score. B18 0.84 Pearson correlation was used to assess test–retest reliability B19 0.70 B20 0.69 on the scores of the 68 students who completed the B21 0.87 questionnaire twice. As shown in Table 1, the reliability for B22 0.79 each of the sections is very high: Pearson correlation B23 0.90 coefficients range from a minimum of 0.78 to a maximum B24 0.90 B25 0.83 of 0.88, indicating a very good temporal stability of the B26 0.83 questionnaire. All Pearson correlation coefficients are statis- B27 0.65 tically significant with Po0.01. B28 0.66 Table 2 reports Pearson correlation coefficients for items of section B. aPearson correlation coefficients computed between the two administration Pearson correlation coefficients of section B items range Po0.01. from a minimum of 0.45 to a maximum of 0.90, indicating a good temporal stability of the section B items. All Pearson correlation coefficients are statistically significant with explanation regarding section G, the total score resulted Po0.01. skewed towards lowest scores, meaning that the major part of our students responded in a similar way; this could be Discussion partly because of the fact that our sample was quite In studies such as nutrition education programmes aimed at homogeneous. Section E low Cronbach’s alpha could be improving food habits and behaviour, the use of traditional explained by the scarce number of items forming the scale. dietary assessment methods such as 24-h recalls, dietary In fact, it has been shown that Cronbach’s alpha increases histories and dietary records is not suitable. Different with increasing items number (Hattie, 1985). Low Cronba- nutritional questionnaires may be desirable in order to assess ch’s alpha in sections H and I could be explained by the efficacy of the intervention. items variability; in other words, items of sections H and I The objective of the present study was to assess reliability cover all the aspects of nutrition and food safety knowledge. of a dietary questionnaire on food habits, eating behaviour Nutrition knowledge and food safety knowledge are very and nutritional knowledge of adolescents. Evidence for complex constructs, and they are made of different domains; reliability, measured as temporal stability, of the question- therefore, items of sections H and I are quite heterogeneous naire was indicated by the good Pearson correlation and this may lead to a low Cronbach’s coefficient. coefficients obtained for each section. For reliability in- As regards test–retest reliability of section B, the correla- tended as internal consistency, the sections on food habits tion coefficients are all statistically significant but some (C), physical activity and lifestyle (D), self-efficacy (F), and coefficients are lower than 0.50 indicating a moderate food safety and behaviour in hygiene practices (J) showed a correlation (Table 2). These low coefficients are referred to respectable reliability. Section E on healthy and unhealthy items about the consumption of several foods (item B5, dietary habits and food had a nearly acceptable reliability, item B6); these items may result to be confusing for the while section barriers to change (G), nutrition knowledge (H) reader and this fact may lower the correlation coefficients. In and food safety knowledge (I) showed an unacceptable order to bypass this problem, it is possible to put up an item reliability (Cronbach’s alpha o0.60) (DeVellis, 1991). An for each kind of food. We prefer to retain the current version

European Journal of Clinical Nutrition Reliability of a dietary questionnaire G Turconi et al 757 of the questionnaire in order to avoid a too long and tedious a nutrition education programme. We believe that the instrument. In our opinion, the low coefficient of item B12 present questionnaire (see Appendix 1) can measure the can be explained by the fact that in our country there is a low effects of nutrition interventions on adolescents given its consumption of eggs; therefore, the reader can have some stability in making comparisons over time. The instrument difficulties in quantifying eggs consumption. has low costs and is easy to administer and analyse. The results show that section G should be retested on a Moreover, it could be modified appropriately to fit the needs larger number of students and it would be necessary to of other populations as well. include new items in section E to increase the reliability of the section itself. 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If no, how many times do you & 1–2 cardiovascular health in 10- to 12-years-old children. Prevent. Med. eat fruit and vegetables during & 3–4 24, 9–22. 1 week? & more than 4 WHO (1990): Diet, Nutrition and the Prevention of Chronic Diseases. & 1 time in 10–15 days WHO Technical Report Series 797, Geneva: WHO. & never

European Journal of Clinical Nutrition Reliability of a dietary questionnaire G Turconi et al 759 B10. How many times do you eat & 1–2 B21. Do you drink wine? & yes meat in 1 week? & 3–4 & no & 1 time every day B22. If yes, how many times do you & 1–2 & 2 times every day drink wine in 1 week? & 3–4 & 1 time in 10–15 days & 1 time in 10–15 days & never & every day B11. How many times do you eat & 1–2 B23. Do you drink beer? & yes fish in 1 week? & 3–4 & no & more than 4 B24. If yes, how many times do you & 1–2 & 1 time in 10–15 days drink beer in 1 week? & 3–4 & never & 1 time in 10–15 days B12. How many times do you eat & 1–2 & every day eggs in 1 week? & 3–4 B25. Do you drink aperitifs and & yes & more than 4 alcoholic drinks? & no & 1 time in 10–15 days B26. If yes, how many times do you & 1–2 & never drink aperitifs and alcoholic & 3–4 B13. How many times do you eat & 1–2 drinks in 1 week? & 1 time in 10–15 days cheese in 1 week? & 3–4 & every day & more than 4 B27. Do you drink whisky, gin, & yes & 1 time in 10–15 days cognac and vodka? & no & never B28. If yes, how many times do you & 1–2 B14. How many times do you eat & 1–2 drink whisky, gin, cognac and & 3–4 ham, salami and sausages in 1 & 3–4 vodka in 1 week? & 1 time in 10–15 days week? & more than 4 & every day & 1 time in 10–15 days & never B15. How many times do you eat & 1–2 Section C. Food Habits legumes in 1 week? & 3–4 & more than 4 C1. Do you eat breakfast? & always & 1 time in 10–15 days & often & never & sometimes B16. How many times do you eat & 1–2 & never sweets and cakes in 1 week? & 3–4 C2. Which beverage do you & milk/milk and & 1 time every day consume at breakfast? coffee/cappuccino/ & more than 1 time yogurt daily & fruit juice & 1 time in 10–15 days & tea/coffee & never & chocolate B17. How many times do you eat & 1–2 C3. At breakfast you eat: & biscuits/cakes/ fried potatoes in 1 week? & 3–4 crackers/breakfast & 1 time every day cereals/bread & 2 times every day & fruit & 1 time in 10–15 days & sausages and cheese & never & pizza/focaccia/toast B18. How times do you eat in a & 1–2 C4. Do you eat at least 2 portions & always fast-food in 1 week? & more than 2 times (200 g) of fruit every day? & often & 1 time in 10–15 days & sometimes & never & never B19. How many times do you eat in & 1–2 C5. Do you eat at least 2 portions & always a pizzeria in 1 week? & more than 2 times (200 g) of vegetables every & often & 1 time in 10–15 days day? & sometimes & never & never B20. How many times do you drink & 1–2 C6. Do you usually eat a cake or & always in a pub in 1 week & more than 2 times a dessert at meals? & often & 1 time in 10–15 days & sometimes & never & never

European Journal of Clinical Nutrition Reliability of a dietary questionnaire G Turconi et al 760 C7. Do you usually drink wine or & always D3. What do you prefer to do & walking beer at meals? & often during free time? & watching TV/listening & sometimes to music/using the & never computer/reading a C8. Do you usually eat breakfast, & always book lunch and dinner every day? & often & practicing a sport & sometimes & shopping & never D4. How many hours do you & 1–2 h a day C9. Your diet: spend on the computer or & 3–4 h a day & is different every day watching TV? & 5–6 h a day & is different only sometimes during a week & more than 6 h a day & is different only during the weekend days D5. The physical activity that & are tiring & is very monotonous you practice at school: & are boring C10. Your diet is based mainly on: & stimulates you to & high protein content foods (meat, fish, eggs, practice sports even out of cheese, dried legumes) school & high fat content foods (sausages, focacce, fried & make you feel well potatoes, cakes with butter and cream) D6. Your lifestyle is: & very sedentary & high carbohydrate content foods (bread, pasta, & sedentary rice, potatoes, biscuits) & moderately active & different foods every day & very active C11. Your snacks are based mainly on: & fruit/fruit juice/fruit and milk shakes/yogurt & biscuits/crackers/bread/stick bread Section E. Healthy and Unhealthy Dietary Habits & fried potatoes/pop corn/krapfen/peanuts/soft and Food drinks E1. According to you, which is a healthy diet? & sweets/chocolate/ice cream/cakes & a diet rich in different foods C12. Which beverages do you usually drink & foods rich in protein (meat, fish, eggs, cheese, between meals? dried legumes) & mineral water & a diet without any fats & soft drinks (cola, orange, soda, iced tea, tonic & eating fish very often water, etc.) E2. According to you, which is the healthiest eating & wine/beer behaviour? & fruit/fruit juice/fruit and milk shakes & drinking two glasses of milk/eating two cups of C13. Do you drink at least one glass & always yogurt every day of milk or do you eat at least & often & preferring cooked vegetables to uncooked one cup of yogurt every day? & sometimes vegetables & never & eating always cheese instead of meat C14. Do you drink at least 1–1.5 l of & always & when you eat snacks, preferring fruit/fruit juice/ & mineral water every day? often biscuits and crackers & sometimes E3. According to you, which is a healthy food? & never & a food rich in protein & a food rich in calories & a microbiologically tested food & a food without preservatives and additives Section D. Physical Activity and Lifestyle E4. According to you, which is the healthiest food? & washed vegetables ready to eat D1. Do you usually practice a & always during the entire & a canned food physical activity? year & a food very rich in dressing & only in some seasons & a fried food & sometimes E5. According to you, which is the healthiest cooking & never method? D2. How many hours do you & 1–2 h in a week & cooking on a grill/in boiled water practice it? & 3–4 h in a week & frying/braising & more than 4 h in a week & cooking in the oven without fats & no hour & cooking in a pan with fats

European Journal of Clinical Nutrition Reliability of a dietary questionnaire G Turconi et al 761 Section F. Self-efficacy Section H. Nutrition Knowledge

F1. Do you think you are able to & yes H1. Which different foods & meat choose anything by yourself? & no contain carbohydrates? & butter & I don’t know & bread F2. Do you think you are able to & yes & cheese & use advice aimed at improving no H2. Which different foods do & wholemeal bread & your well-being? I don’t know not contain dietary fibre? & beans F3. Do you think you are able to & yes & white bread & modify your diet if needed? no & meat & I don’t know H3. Which different foods are & hamburger with & F4. Do you think you are able to yes less rich in fat? mayonnaise & no loose or to gain weight if & grilled meat & I don’t know needed? & focaccia F5. Do you think you are able to & yes & sandwich with use nutrition advice aimed at & no salami improving your dietary & I don’t know H4. Which different foods are & dry legumes habits? richer in protein? & dover sole F6. Do you think you are able to & yes & spaghetti with use nutrition advice aimed at & no tomato sauce improving your health status? & I don’t know & F7. Do you think you are able to & yes apple & practice a constant physical & no H5. Which different foods are bread & potatoes activity in order to improve & I don’t know richer in calories? & fruit salad your well-being? & F8. Do you think you are able to & yes tiramisu´ & practice a constant physical & no H6. Which different substances protein & activity in order to improve & I don’t know contain more energy? carbohydrates & your physical aspect? fat & alcohol H7. What are the functions of vitamins and minerals? Section G. Barriers to Change & to put on muscular tissue & to lose body fat & G1. Do you have some influence on & yes to catalyse biochemical cooking food at home? & no reactions in the body G2. Do you know which foods must be & yes & to provide energy restricted to reduce dietary intake & no H8. According to you, what is ‘a of fats and cholesterol? balanced diet’? G3. Do you know which foods must be & yes & a diet rich in protein restricted to reduce dietary intake of & no & a diet poor in fat sugar? & a diet without G4. Do you know which foods must be eaten & yes carbohydrates to increase dietary intake of fibre? & no & a diet containing all G5. Do you know which benefits you could & yes nutrients in proper quantities gain by eating a healthy diet? & no H9. According to you, what is G6. Do you know how to improve your diet? & yes ‘daily energy expenditure’? & no & energy consumed in the G7. Do you know how much you must eat & yes whole day to satisfy your energy requirement? & no & energy consumed during G8. Do you know how important it is not & yes sleep to be influenced by your friends in & no & energy consumed only for choosing your food? physical activity G9. Do you think that your family would & yes & energy consumed for support your efforts in improving your & no maintaining body food habits? temperature at 371C H10. What are ‘biological foods’?

European Journal of Clinical Nutrition Reliability of a dietary questionnaire G Turconi et al 762 & foods grown without any & use of the same utensils for use of chemical fertilizer cooked and raw foods & foods grown in greenhouse & washing one’s hands after & foods without additive and having handling raw foods and preservatives before handling cooked foods & foods grown in a ground far & using different surfaces for from the highway cooked and raw foods H11. What are ‘transgenic foods’? & keeping cooked and raw foods & foods imported from separated foreign countries I.6. How can you transmit Salmonella? & foods in which different & by coughing on the food fragments of DNA have been & by touching foods without included having washed one’s hands & foods without potentially & by sneezing on the food pathogenus germs & by smoking while preparing the & foods without toxic food substances I.7. Which is the optimum temperature for bacterial growth? & from 01Cto+41C & from +41C to +601C Section I. Knowledge on Food Safety & beyond 601C & under À51C I.1. A food intoxication is: I.8. Do cold temperatures kill & an infection caused by lack of pathogenic germs which may be vitamins present in foods? & a disease caused by the & rarely consumption of foods & no, on the contrary it facilitates contaminated by pathogenic growth germs & no, it inhibits growth & a disease caused by an excessive & yes, always consumption of food I.9. Does heat kill germs? & yes, always & a disease caused by & no, never assumption of a chemical toxin & yes, above 401C I.2. Which of the following are caused & yes, above 601C by food intoxication? I.10. Which of the following diseases & hepatitis A & vomit, diarrhoea, fever can be transmitted by ingestion & AIDS & only vomit and diarrhoea of contaminated foods? & pneumonia & it depends on the type of & the flu causative germ & fever, sore throat and cough I.3. Which of the following are most responsible for food intoxication? Section J. Food Safety and Behaviour in & inadequate preservation Hygene Practices & contamination of food prior to cooking J.1. When you buy packaged food, do & always & manipulation of cooked food you check the expiry date? & often immediately prior to consumption & sometimes & inadequate washing of plates & never and silver ware J.2. Do you read the instruction for & always & I.4. Which of the following foods are & eggs and cream use and for preservation written often & mostly implicated in the onset of & vegetables on the packaged foods? sometimes & food intoxication? & frozen meat never & biscuits J.3. Do you wash your hands before & always & I.5. Which of the following behaviours eating and before touching foods? often & can cause cross-contamination of sometimes & foods? never

European Journal of Clinical Nutrition Reliability of a dietary questionnaire G Turconi et al 763 J.4. Do you usually wash fruit that & always J.7. If the butcher touches ham with & always must not be peeled before & often his hands, do you eat it? & often eating it? & sometimes & sometimes & never & never J.5. After drinking a glass of milk, do & always J.8. Do you eat canape´ lying out for a & always you usually put the milk in the & often long time at the bar? & often fridge? & sometimes & sometimes & never & never J.6. If you realize you have left the milk out of the fridge during the night, what do you do? & you throw it away & you tell your mother to throw it away & you put it in the fridge again & you drink it

European Journal of Clinical Nutrition