Formative evaluation of the dietary assessment component of Children's and Adolescents' Nutrition Assessment and Advice on the Web (CANAA-W).

BACKGROUND: The increased availability of computers and the efficiency and user-acceptability of computer-assisted questioning have increased the attractiveness of computer-administered querying for large-scale population nutrition research during the last decade. The Young Adolescents' Nutrition Assessment on Computer (YANA-C), a computer-based 24-h dietary recall, was originally developed to collect dietary data among Belgian-Flemish adolescents. A web-based version was created to collect parentally reported dietary data of preschoolers, called Young Children's Nutrition Assessment on the Web (YCNA-W), which has been improved and adapted for use in young adolescents: Children and Adolescents' Nutrition Assessment and Advice on the Web (CANAA-W). The present study describes recent developments and the formative evaluation of the dietary assessment component. METHODS: A feasibility questionnaire was completed by 131 children [mean (SD) age: 11.3 (0.7) years] and 53 parents. Eight focus groups were held with children (n = 65) and three with parents (n = 17). RESULTS: Children (C) and parents (P) found the instrument clear (C: 97%; P: 94%), comprehensible (C: 92%; P: 100%), attractive (C: 84%; P: 85%), fun (C: 93%; P: 83%) and easy to complete (C: 91%; P: 83%). There was ample explanation (C: 95%; P: 94%); the pictures were clear (C: 97%; P: 96%); and most respondents found the food items easy to find (C: 71%, P: 85%). The results helped to refine the lay out and structure of the instrument and the list of food items included. CONCLUSIONS: Children and parents were enthusiastic. The major challenge will be to convince parents who are less interested in dietary intake and less computer literate to participate in this type of study. Children in this age group (11-12 years) should complete the instrument with assistance from an adult.

Correlates of energy balance-related behaviours in preschool children: a systematic review.

Childhood overweight is a multifactorial health problem influenced by several factors. The interaction of behaviours such as physical activity, sedentary behaviour and eating behaviour determines whether or not a positive energy balance or weight gain is experienced. Knowing the correlates of these behaviours in 4- to 6-year-old children is of major interest for intervention development. According to the systematic literature search, attending a rural preschool was positively associated with physical activity. Gender, age and socioeconomic status were not associated with physical activity, while an indeterminate result was found for ethnicity. Gender and ethnicity were not associated with sedentary behaviour and indeterminate results were found for age and socioeconomic status. Preschoolers were more physically active as well as sedentary on weekdays. Watching television was associated with a higher consumption of snacks and sweet beverages. Strategies aiming to influence energy balance-related behaviours in preschoolers should target both boys and girls and all ethnic groups from low as well as high social status. During the week, there should be a focus on decreasing sedentary behaviour and in the weekend on increasing physical activity. Focusing on television viewing and the consumption of snacks and sweet beverages could/should also be a strategy.

The HELENA online food frequency questionnaire: reproducibility and comparison with four 24-h recalls in Belgian-Flemish adolescents.

OBJECTIVES: To investigate the reproducibility of the HELENA Food Frequency Questionnaire (FFQ) developed as a basis for an online tailored intervention and to compare the FFQ with four computerized 24-h recalls. SUBJECTS/METHODS: A convenience sample of 48 Belgian-Flemish adolescents completed four computerized 24-h recalls, the FFQ and a retest 1-2 weeks later. Correlations, the Wilcoxon's signed rank test and Bland and Altman's plots were used to compare the intakes of 22 food groups, energy (kcal), fibre (g, g/1000 kcal), vitamin C (mg, mg/1000 kcal), calcium (mg, mg/1000 kcal), iron (mg, mg/1000 kcal) and fat (g, % from total energy). RESULTS: Reproducibility correlations were good (0.46-0.90). De-attenuated correlations between both methods were high (> or =0.51) for all nutrients and nutrient densities, except for fibre (g), vitamin C (mg) and percent energy from fat (respectively 0.23, 0.40 and 0.30). On a food group level correlations were significant (r(unadjusted)>0.3) for most (17/22) food groups. No systematic differences were found between test and retest; comparison with the recalls resulted in a significantly higher intake of bread, breakfast cereals, other snacks, vegetables, potatoes, coffee and tea, alcoholic beverages, energy, and most nutrients. No significant difference was found for calcium, whereas an underestimation was found for nutrient density of calcium and fat. CONCLUSIONS: The overestimation in seven food groups, resulting in an overestimation of energy, fibre, iron and vitamin C, and underestimation of percentage energy from fat, needs to be considered when the estimated intakes are used for tailored feedback.

Comparison of a food frequency questionnaire with an online dietary assessment tool for assessing preschool children's dietary intake.

BACKGROUND: It is important to assess the dietary habits of children as they progress from early childhood to adolescence. However, there are few validated tools available to assess the diet of this group of children. The present study aimed to investigate the relative validity of a food frequency questionnaire (FFQ) developed for use in a biennial longitudinal study. METHODS: The parents of 216 Belgian-Flemish preschool children completed a FFQ (including questions on 77 food groups) and an online dietary assessment tool for three nonconsecutive days on their child's diet. Intakes of energy, macronutrients, fibre, calcium and 20 food groups recorded by both methods were compared using Spearman's correlations, Wilcoxon's signed rank test and Bland and Altman analyses. RESULTS: At the group level, good agreement was found for energy, fat and protein intake, an overestimation was found for carbohydrates (5.6%) and fibre (13.3%), and an underestimation was found for calcium (9%). For the food groups, overestimation as well as underestimation and good agreement were found, although overestimation was most common. Good agreement was found in ranking the children's fruit (r = 0.53), beverages (r = 0.58-0.76), soup (r = 0.51), breakfast cereals (r = 0.55) and calcium (r = 0.59) intake according to both methods. CONCLUSION: The results obtained revealed that the FFQ was a useful alternative for estimating energy and macronutrient intake at a group level; however, when used to estimate fibre and calcium intake, respectively, over- and underestimation need to be considered. The short reference period (3 days) may have compromised agreement in ranking and agreement at the individual level.

[A longitudinal study on dietary habits and the primary socialization of these habits in young children]. / Een longitudinale studie rond voedingsgewoontes en de primaire socialisatie van voedingsgewoontes bij jonge kinderen.

The Family Influences on Food Intake study (FIFI), is a longitudinal study on dietary habits of young children and the primary socialization of these habits during childhood and during the transition into adolescence. Special attention is paid to the development, validation and feasibility of instruments measuring as well dependent as independent variables useful for large scale surveys. Parents of preschool children from the first year (+/-3 years of age) of 56 school departments were asked to complete a self-administered questionnaire biennially. Data of 862 children was available for the first measurement (2008). A web based dietary record tool was developed to investigate the relative validity of the Food Frequency Questionnaire (FFQ) used in the study. Two hundred and seventeen parents completed the online tool for three non-consecutive days. The feasibility of the online data collection is investigated and the reported intake is compared with the FFQ estimates. Associations between nutritional knowledge and attitudes of the children's mothers and dietary patterns of the children (FFQ) are investigated as well as relations between parent and child characteristics and fruit and vegetable intake. Additionally, 70 teachers completed a questionnaire on their attitudes towards the school food policy. The teachers' responses are compared with responses of parents from a previous study. Finally, the feasibility of an animated web based fruit and vegetables preferences tool, to be used in the follow up surveys, has been investigated in 4-6 years old (n=139 for fruit and n=135 for vegetables). The findings are summarized in the present paper.

The contribution of club participation to adolescent health: evidence from six countries.

BACKGROUND: Social networks have been recognised as an important factor for enhancing the health of people and communities. Bridging social capital, characterised by numerous and varied weak ties, exemplifies a particular type of network that can help people reach their goals and improve their health. This study seeks to contribute to the evidence base on the use of positive social networks for young people's health by exploring the importance of club participation in predicting the health and health-related behaviours of 15-year-old girls and boys across Europe and North America. METHODS: Data are derived from a 2005-6 World Health Organization collaborative study, to establish the relationships between different types of club and a range of health outcomes (self-perceived health, wellbeing and symptoms) and health-related behaviours (smoking, drinking). Multi-level logistic regression was used to assess the independent effects of club participation by controlling for gender and socioeconomic position. Data were compared across six countries. RESULTS: All the considered outcomes, both in terms of perceived health and wellbeing and health behaviours were associated with participation in formal associations. The associations are in the expected direction (participation corresponding to better health) except for some particular association types. CONCLUSIONS: Participation in formal associations seems supportive for good health and health behaviours in adolescence, and should be promoted in this age group.

Socioeconomic position, macroeconomic environment and overweight among adolescents in 35 countries.

OBJECTIVE: It is important to understand levels and social inequalities in childhood overweight within and between countries. This study examined prevalence and social inequality in adolescent overweight in 35 countries, and associations with macroeconomic factors. DESIGN: International cross-sectional survey in national samples of schools. SUBJECTS: A total of 11-, 13- and 15-year-olds from 35 countries in Europe and North America in 2001-2002 (N=162 305). MEASUREMENTS: The main outcome measure was overweight based on self-reported height and weight (body mass index cut-points corresponding to body mass index of 25 kg/m(2) at the age of 18 years). Measures included family and school affluence (within countries), and average country income and economic inequality (between countries). RESULTS: There were large variations in adolescent overweight, from 3.5% in Lithuanian girls to 31.7% in boys from Malta. Prevalence of overweight was higher among children from less affluent families in 21 of 24 Western and 5 of 10 Central European countries. However, children from more affluent families were at higher risk of overweight in Croatia, Estonia and Latvia. In Poland, Lithuania, Macedonia and Finland, girls from less affluent families were more overweight whereas the opposite was found for boys. Average country income was associated with prevalence and inequality in overweight when considering all countries together. However, economic inequality as measured by the Gini coefficient was differentially associated with prevalence and socioeconomic inequality in overweight among the 23-high income and 10-middle income countries, with a positive relationship among the high income countries and a negative association among the middle income countries. CONCLUSION: The direction and magnitude of social inequality in adolescent overweight shows large international variation, with negative social gradients in most countries, but positive social gradients, especially for boys, in some Central European countries. Macroeconomic factors are associated with the heterogeneity in prevalence and social inequality of adolescent overweight.

Associations of overweight and of weight dissatisfaction among Palestinian adolescents: findings from the national study of Palestinian schoolchildren (HBSC-WBG2004).

BACKGROUND: Overweight and obesity as well as weight dissatisfaction have been increasing in prevalence worldwide. Body weight dissatisfaction and fear of fatness are potential contributors to disordered eating. The present study aimed to investigate the prevalence of self-reported overweight and weight dissatisfaction along with associations with socio-demographic characteristics, body image, health complaints, risk behaviours, physical activity and television viewing in adolescents in Palestine. METHODS: The 2003/04 Palestinian Health Behaviour in School-aged Children (HBSC) is a cross-sectional survey of 17,817 adolescents from 405 randomly selected schools. Students from a representative sample of grades 6, 8, 10 and 12 (aged 12-18 years) self-completed a modified version of the international World Health Organization collaborative Health Behaviour in School-aged Children (HBSC-2002) questionnaire. RESULTS: Although 16.5% of the adolescents were overweight, almost twice that number (32.1%) were dissatisfied with their weight (i.e. dieting or perceiving a need to diet). Of those adolescents, two-thirds were not actually overweight (56.4% boys; 73.5% girls). One-fifth of the total number of adolescents (16.0% boys; 24.0% girls) were not overweight but were dissatisfied with their weight. Boys reporting overweight or weight dissatisfaction were more likely to have mothers with higher education or to be from more affluent families. Among both genders, but especially among girls, weight dissatisfaction was positively associated with most of the outcome variables (body image, health complaints, risk behaviours, and television viewing) regardless of weight status, whereas weight status was associated with only a few of the outcome variables. CONCLUSIONS: Weight dissatisfaction, independent of weight status, is associated with body image, health complaints, risk behaviours and television viewing, and represents a potential health risk factor for adolescents. Preventive interventions should focus not only on weight status, but also on body weight dissatisfaction.

Socioeconomic questionnaire and clinical assessment in the HELENA Cross-Sectional Study: methodology.

RATIONALE: Environmental factors such as dietary habits, breastfeeding, socioeconomic conditions and educational factors are strong influences on nutritional and puberty status, physical activity, food choices and their interactions. Several diseases of adulthood seem to be linked to, or to originate from, lifestyle in childhood and adolescence. OBJECTIVE: The aims of this study are to describe birth parameters and socioeconomic factors and to assess clinical status in adolescents aged 13-16 years from 10 European countries participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Cross-Sectional Study (CSS). METHODOLOGY: A self-report questionnaire on the socioeconomic status, a parental questionnaire concerning neonatal period and also a case report form (CRF), in which clinical items during clinical examination (such as medical history, treatments, anthropometry, Tanner staging, blood pressure, heart rate) were assessed. To develop these documents, first a list of items was established, a search of existing documents was performed and the advice of local and international experts was taken. All documents (questionnaires and an operations manual) were discussed in plenary HELENA meetings; a final version of these documents was fixed, and the process of translation and back translation was performed. RESULTS: The questionnaires and CRF were tested for validation in all 10 participant cities; 208 adolescents were enrolled during the pilot study. All items that caused problems or questions in one or more participating centers or were completed by < 85% of the adolescents were reviewed before the beginning of the HELENA-CSS. CONCLUSION: These final questionnaires and CRF will contribute to better understanding of the inequalities in nutrition, behavior and health in the European adolescent population. The experience and process should be useful for other multicenter studies.

Development and evaluation of a self-administered computerized 24-h dietary recall method for adolescents in Europe.

OBJECTIVE: To describe the development of a European computerized 24-h dietary recall method for adolescents, and to investigate the feasibility of self-administration (self report) by comparison with administration by a dietician (interview). METHODS: Two hundred and thirty-six adolescents (mean age 14.6 years (s.d.=1.7)) of eight European cities completed the 24-h recall (Young Adolescents Nutrition Assessment on Computer (YANA-C)) twice (once by self-report and once by interview). RESULTS: A small but significant underestimate in energy (61 (s.e.=31) kcal) and fat (4.2 (s.e.=1.7) g) intake was found in the self-reports in comparison with the interviews; no significant differences were found for the intake of carbohydrates, proteins, fibre, calcium, iron and ascorbic acid. Spearman's correlations were highly significant for all nutrients and energy ranging between 0.86 and 0.91. Agreement in categorizing the respondents as consumers and non-consumers for the 29 food groups was high (kappa statistics >or=0.73). Percentage omissions were on average 3.7%; percentage intrusions: 2.0%. Spearman's correlations between both modes were high for all food groups, for the total sample (>or=0.76) as well as for the consumers only (>or=0.72). Analysing the consumer only, on an average 54% of the consumed amounts were exactly the same; nevertheless, only for one group 'rice and pasta' a significant difference in consumption was found. CONCLUSION: Adaptation, translation and standardization of YANA-C make it possible to assess the dietary intake of adolescents in a broad international context. In general, good agreement between the administration modes was found, the latter offering significant potential for large-scale surveys where the amount of resources to gather data is limited.

Food and nutrient intake, nutritional knowledge and diet-related attitudes in European adolescents.

BACKGROUND AND OBJECTIVE: To provide an overview of methods used to assess food and nutrient intake, nutritional knowledge and diet-related attitudes in the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS), with selected results from the feasibility study. MATERIAL AND METHODS: To assess food intake in 13- to 16-year-old adolescents, a previously developed computer-assisted and self-administered 24-h recall was adapted for international use. Food consumption data were linked to national food composition databases to calculate energy and nutrient intakes. To assess nutritional knowledge in pupils not having any special (trained) education concerning 'nutrition', a 23-item validated multiple choice questionnaire was adapted. To assess eating attitudes, behaviour and/or putative problems with body weight in adolescents, a validated inventory covering 60 questions or statements was adapted for the study. In a feasibility study, instruments, data collection and processing were tested in one school class in each of the 10 participating European cities. RESULTS AND CONCLUSIONS: The feasibility study provided plausible results, quite consistent between countries. Against this background and for the first time, standardized and uniform methodology was made available for the main study to assess and characterize dietary intake, nutritional knowledge and eating attitudes.

A feasibility study of using a diet optimization approach in a web-based computer-tailoring intervention for adolescents.

OBJECTIVE: Adolescents are an interesting but neglected target group in obesity prevention. We assessed the feasibility of using a diet optimization approach for computer-tailored nutrition interventions for adolescents. METHOD: Development of an optimization model based on the public health approach to diet optimization. On the basis of food frequency questionnaires (FFQ) of 48 adolescents (14-17 years) optimized diets were calculated. RESULTS: The optimization calculations for all cases resulted in individual advice. On a total of 137 items included in the FFQ, the individualized advice included changes in a minimum of 36 and a maximum of 88 items (mean: 61 items), recommendations for changes in the food items ranged from less than 1 g day(-1) up to 1660 g day(-1). In almost all cases a higher intake of fruit and vegetables was recommended; some unexpected advice was also generated (for example, to decrease the consumption of brown bread and to increase the consumption of pizza). The strengths and weaknesses of the optimized diets are discussed. CONCLUSION: Using the optimization approach is a step forward in nutrition tailoring interventions but the model used in the present feasibility study still needs to be refined.

Smoking in young people with asthma.

BACKGROUND: Modern guidelines for the management of asthma state that asthmatic patients should be strongly advised not to smoke. However, it remains unclear to what extend young people with asthma actually behave like this. This study compares the prevalence of daily smoking between 15-year adolescents with diagnosed asthma and without asthma, and evaluates to what extent risk factors for smoking play a comparable role in the smoking behaviour of these two groups. METHODS: The study is part of the 2001-2002 international HBSC study. Besides questions about health behaviour, individual and social resources, a set of asthma questions were included in six countries. RESULTS: Adolescents with diagnosed asthma are more likely to be daily smokers than non-asthmatic adolescents. In asthmatic and non-asthmatic adolescents, similar associations with risk factors are found for daily smoking (drunkenness, cannabis use, low life satisfaction, spending evenings with friends, having smoking parents and peers). Diagnosed asthmatics are more prone to score high on these factors than non-asthmatics. CONCLUSIONS: Smoking in adolescents with asthma is a public health problem. Smoking prevention efforts directed towards young people should pay attention to young people with asthma and the curative sector should increase their efforts to motivate asthmatic adolescents not to smoke.

Food habits and physical activity patterns among Palestinian adolescents: findings from the national study of Palestinian schoolchildren (HBSC-WBG2004).

OBJECTIVE: To describe the food habits and physical (in)activity patterns and to investigate the relationship with sociodemographic factors among Palestinian adolescents. DESIGN AND SUBJECTS: The Palestinian Health Behaviour in School-aged Children (HBSC) is a cross-sectional survey of grades 6, 8, 10 and 12. Students completed a modified version of the international HBSC questionnaire. A total of 8885 students were included in this analysis; 53% were from the West Bank and 47% from the Gaza Strip. RESULTS: Adolescents in the West Bank consume more fruit, meat, chicken, sweets and soft drinks, but less vegetables than adolescents in Gaza (P<0.01). Girls reported more daily consumption of fruit, vegetables and sweets than boys (P<0.001), and less consumption of soft drinks, milk, meat and chicken (P<0.01). Boys were physically more active than girls (P<0.01), whereas girls reported doing more homework (P<0.001). Both boys and girls reported less physical activity with increasing age (P<0.001). Consumption of fruit and milk was positively associated with both parents' education, while consumption of meat, chicken and soft drinks was positively associated with mother's education only. Having breakfast on schooldays was positively associated with the father's education. Physical activity and television viewing were associated with the mother's education (P<0.01). The parents' level of education had no effect on vegetable consumption and dieting status. CONCLUSION: This study indicated that there are problems with Palestinian adolescents' eating, dieting and physical activity. Regional, gender and parental socio-economic status differences should be taken into account in developing interventions. More detailed studies are needed with more elaborate instruments about food habits and physical activity of adolescents.

Asthma and wheezing symptoms in young people in six Western countries.

BACKGROUND: Asthma diagnosed in children shows wide geographical variations. Large scale surveys identify children with diagnosed asthma, but neglect the group of youngsters with multiple asthmatic complaints. METHODS: A short validated asthma questionnaire was included in six national surveys of the Health Behaviour in School-Aged Children Study. Prevalence rates are presented by country, gender and age. Gender and age differences are analysed using binary and multinomial logistic regressions controlling for age and smoking. RESULTS: Large country differences are observed in the prevalence rates of diagnosed asthma (8.6%-20.9% in boys, 6.9%-18.5% in girls) and young people with "asthma-like symptoms" (9.6%-20.2% in boys, 9.2%-23.1% in girls). When controlling for age and smoking, significant gender differences are observed (more diagnosed asthma in boys, more asthmatic symptoms in girls). Age differences were observed in adolescents with "asthma-like symptoms", but not in diagnosed asthma. CONCLUSIONS: Using a short asthma questionnaire, large differences in diagnosed asthma and wheezing symptoms are observed between the countries. A considerable group of youngsters with "asthma-like symptoms" is detected in all countries, and may be an unrecognised risk group in health promotion.

Comparison of overweight and obesity prevalence in school-aged youth from 34 countries and their relationships with physical activity and dietary patterns.

The purposes of this systematic review were to present and compare recent estimates of the prevalence of overweight and obesity in school-aged youth from 34 countries and to examine associations between overweight and selected dietary and physical activity patterns. Data consisted of a cross-sectional survey of 137 593 youth (10-16 years) from the 34 (primarily European) participating countries of the 2001-2002 Health Behaviour in School-Aged Children Study. The prevalence of overweight and obesity was determined based on self-reported height and weight and the international child body mass index standards. Logistic regression was employed to examine associations between overweight status with selected dietary and physical activity patterns. The two countries with the highest prevalence of overweight (pre-obese + obese) and obese youth were Malta (25.4% and 7.9%) and the United States (25.1% and 6.8%) while the two countries with the lowest prevalence were Lithuania (5.1% and 0.4%) and Latvia (5.9% and 0.5%). Overweight and obesity prevalence was particularly high in countries located in North America, Great Britain, and south-western Europe. Within most countries physical activity levels were lower and television viewing times were higher in overweight compared to normal weight youth. In 91% of the countries examined, the frequency of sweets intake was lower in overweight than normal weight youth. Overweight status was not associated with the intake of fruits, vegetables, and soft drinks or time spent on the computer. In conclusion, the adolescent obesity epidemic is a global issue. Increasing physical activity participation and decreasing television viewing should be the focus of strategies aimed at preventing and treating overweight and obesity in youth.

Young adolescents' nutrition assessment on computer (YANA-C).

OBJECTIVE: To assess the relative validity and acceptability of the computerised 24-h recall 'Young Adolescent's Nutrition Assessment on Computer (YANA-C)'. DESIGN: Food and nutrient intakes assessed with YANA-C were compared with food records (study 1) and 24-h dietary recall interviews (study 2). MAIN OUTCOME MEASURES: Intakes of food groups (fruit, fruit juice, vegetables, potatoes, bread, cereals, milk, cheese, other milk products, soft drinks, diet soft drinks, sugar/sweets, pastry/cookies, savoury snacks, butter/sauces, eggs, fish, meat) and nutrients (energy, carbohydrates, protein, fat, fiber, calcium, vitamin C and iron). SUBJECTS AND SETTING: A total of 237 pupils (11-14 y) from two primary and four secondary schools (study 1: n = 136; study 2: n = 101) in Belgium-Flanders. RESULTS: YANA-C proved to agree well with both standard methods in categorizing subjects in consumers and nonconsumers (kappa(study 1) = 0.48-0.92; kappa(study 2) = 0.38-0.90). Spearman's correlations for energy and nutrient intakes ranged between 0.44 and 0.79 for study 1 and between 0.44 and 0.86 for study 2. Nutrient and energy intakes were in general (excluding calcium) significantly higher in YANA-C in comparison with the food record, but not in comparison with the interview (only fiber). Statistics used to investigate whether YANA-C agreed with the other methods in ranking portions/amounts in consumers only were fair to moderate for most of the food groups (weighted kappa study 1 = 0.11-0.55; study 2 = 0.04-0.73); amounts in consumers only, were significantly lower in YANA-C against both standards for cereals; amounts were significantly higher in YANA-C against the food record for milk, soft drinks, sugar/sweets and savoury snacks and against the interview for potatoes. Only a few pupils evaluated the program negatively. CONCLUSION: YANA-C is a promising method to collect detailed dietary information from young adolescents with relatively low staff resources, useful in many nutrition research applications.

School food policy at primary and secondary schools in Belgium-Flanders: does it influence young people's food habits?

OBJECTIVE: To describe the availability of food items at primary and secondary schools in Belgium-Flanders and to examine the influence of school food policy (availability of food items, school food rules, nutrition education programmes) and aggregated school socioeconomical status (AGG SES) on the consumption of fruit, soft drinks, crisps and sweets, using multilevel modelling. DESIGN, SETTING AND SUBJECTS: In spring 2002, 360 schools were invited to participate in the Health Behaviour in School-aged Children survey. In January 2003, the same schools were asked to complete a short school policy questionnaire. Pupils of 197 schools participated in the pupil survey (n=16560); 247 school principals completed the school questionnaire; for 157 schools data were available for both (n=12 360). RESULTS: Mineral water, fruit juice, chocolate milk, and soup were available in most schools. Whole fat milk was available in most primary schools; soft drinks, diet soft drinks and biscuits were available in most secondary schools. Fruit was available in 14% of primary and 26% of secondary schools. Assessment of the variation in the outcome variables revealed no significant between-school variation in primary schools, but considerable variation between secondary schools in the consumption of soft drinks, sweets and crisps (but not fruit). School characteristics explaining some of this school variance independent of pupil level characteristics were: for soft drinks: availability at the school, rules regarding the consumption of sweets and AGG SES; for sweets: AGG SES; and for crisps: rules regarding the consumption of savoury snacks and AGG SES. CONCLUSION: The results indicate that school food policy can have an impact on adolescents' food habits.

Longitudinal comparison of virus load parameters and CD8 T-cell suppressive capacity in two SIVcpz-infected chimpanzees.

In a longitudinal study we address the hypothesis that resis tance to disease progression in lentivirus-infected chimpanzees is related to potent non-cytotoxic suppression of virus replication. In a long-term follow-up, the viral suppressive capacity in two simian immunodeficiency virus (SIV)cpz-infected chimpanzees was correlated with two polymerase chain reaction (PCR)- and two culture-based virus load measurements. In both animals, quantitative virus isolation (QVI) tended to decline slowly, whereas in vitro virus suppression was sustained or increased over time. In general, plasma virus loads in SIVcpz-infected animals were maintained for extended periods of time. Based on current assays that measure virus suppressive capacity in peripheral blood, it was not possible to conclude that virus suppression played a major role in the maintenance of the disease-free state in lentivirus-infected chimpanzees.