There is increasing evidence that events early in life may 'programme' later body composition (BC) and health outcomes. The aim of the work presented in this thesis was to test the following hypotheses: (l) birthweight and growth in infancy programme specific components of BC in later life and therefore have differential effects on health outcomes (2) infant BC is differentially related to later BC, and is potentially involved in the programming process. These hypotheses were investigated in 2 cohorts (1) prospective follow-up during adolescence of subjects who had BC measurements during infancy (by stable isotope) as part of nutrition intervention studies (2) healthy children who participated in a BC reference study, with retrospective collection of early growth records. The main outcome was BC assessed by the four-component model. Secondary outcomes were cardiovascular risk factors (blood pressure, lipid profiles, and insulin resistance markers). 308 subjects aged 4.22-20.36 years were studied. Birthweight (regarded as a proxy for prenatal growth) was positively related to later height in both sexes, and positively associated with fat free mass (FFM) in boys. In contrast, postnatal growth during the first 6 months of life positively influenced later fat mass (FM) and central fat distribution, with a weaker effect on FFM. Whilst FM showed a consistent association with most cardiovascular risk factors except HDL-C, FFM showed a strong negative association with HDL-C, independent of FM and central fat distribution. In a smaller group (n=41), BC at 12 weeks of age showed no significant association with adolescent BC but SF during very early postnatal life (3 and 6 weeks) was related to later FFM and central fat distribution. Infant nutrition affected infant body composition, but I was unable to detect effects on later BC. Conclusion: I found differential effects of growth during different periods on later BC, measured using the 'gold standard' four-component model. The mechanism by which early growth 'programs' later BC possibly involves both prenatal and postnatal nutrition and warrants further investigation, since it could be useful in terms of designing effective early intervention to reduce obesity prevalence in childhood and adolescence. BC during adolescence has a differential impact on cardiovascular risk factors. Therefore, separate measurements of FM, FFM, and central fat distribution may offer more insight into the impact of body composition programming on health outcomes.

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Children's fruit and vegetable intake is well below recommended levels on average, but explanations for the wide variation in consumption remain elusive. This thesis investigates the determinants of children's food preferences and eating habits with the aim of informing the development of effective interventions to promote healthier diets. Study 1 examined the developmental patterning of food preferences from age four to 16 in a large cross-sectional survey. Vegetables were widely disliked at all ages with little evidence of developmental improvement, but children rated fruit unexpectedly highly. Study 2 investigated the relative contribution of parental behaviours and children's own traits to fruit and vegetable consumption in a large sample of preschool children. The strongest predictors of children's intake were parental intake and the child's food neophobia. Two studies further investigated the relationship with neophobia. In Study 3A, neophobia was significantly negatively correlated with intake of fruit, vegetables and protein, but not with intake of starchy, dairy, or fatty/sugary foods. These findings were based on parental reports of children's intake, but they were replicated in Study 3B which assessed food intake directly in a school setting. Study 4 investigated the relative contribution of genes and environment to phenotypic variation in neophobia in a large cohort of 9-11 year-old twins. Heritability estimates for neophobia were high but nevertheless over a quarter of the variance was accounted for by shared environmental factors, pointing to the importance of the home setting. Study 5 was a RCT of an exposure-based intervention aimed at increasing children's acceptance of vegetables. Intake was measured in taste tests and showed significantly greater increases in the intervention group than either of the control conditions. Finally, Study 6 tested the effectiveness of the intervention in a low-income population obtaining similar results. The implications and potential applications of these findings are discussed.

The South Asian population is the largest minority ethnic . group in the UK. Their diet and food habits depend on their geographical origin, but they can change after migration due to acculturation. It has been observed that South Asians have a higher risk of diet related diseases than white Caucasians. Another observation is that diet during childhood affects health outcomes in adulthood. The main aim of this thesis is to develop and validate dietary assessment methods adapted to South Asian children aged 4-11 years living in the UK and to test the hypothesis that their diets and food habits are influenced by both their original and adopted cultures. Food portion photographs were developed and tested. Following this, detailed dietary information was collected from mothers of South Asian children aged 4-11 years through completion of a food habit questionnaire (n=190) and three multiple pass 24-hour recalls (n=150, total 450 interviews). A verage portion sizes of commonly consumed foods were calculated. The results showed that South Asian Food Portion Photographic Atlas can be used to improve the accuracy of portion estimation of South Asian mothers. South Asian children tended to consume mainstream foods as part of their breakfast, snacks and lunch, while more traditional foods were eaten as part of their afternoon snack and dinner. Some significant differences were found in median portion sizes by ethnicity, religion, gender and age group. The energy intake was close to the UK's EAR, whereas most of the vitamins and minerals obtained exceeded the UK's RNIs. Furthermore, they had a significantly lower intake of vitamin D when compared with WHO recommendations. It is recommended that longitudinal studies are undertaken in order to establish ethnic-specific requirements for this group.

The aim of the present PhD was to assess how the glycaemic potency of breakfast affects cognitive function (CF) in adolescent children; using CF tests which have previously been shown to be sensitive to variations in circulating blood glucose (BG) levels; and timing the CF tests appropriately to the physiological properties of the breakfast under study. Three studies were conducted in order to test this; a cross-sectional study in children (A), a clinical study in young adults (B), and an intervention study in children (C). (A): Sixty children aged 11-14 years were selected on the basis of being regular breakfast caters. Their breakfast on the morning of the study was recorded. They were then categorized into four groups according to the glycacmic index (GI) and glycaemic load (GL) of the breakfast; low GI - high GL, high GI - high GL, low GI - low GL and high GI - low GL above or below the median for GI=60.6 and GL=27.5. Consumption of a low GI - high GL breakfast was associated with better performance on a majority of the tests 90-120 minutes later, suggesting a possible role for the glycacmic potency in CF. (B): In order to test meals that were different in their GI and GL in an intervention setting, we would have to ensure that the meals selected differed in their glycaemic and insulinacmic responses The meals were based on what the children reported eating in the cross-sectional study. Therefore, the aim of the clinical study was to measure the postprandial glycaemic and insulinaemic responses of breakfast meals differing in their GI and GL over a period of three hours after the ingestion of the meals( every 15 min during the first hour, and then ever 30 min); to measure cortisol levels over the same period; and to investigate the validity of the methods for calculating GI and GL. Ten young adults (5 males, 5 females) took part. The breakfast meals were administered in a cross-over design, and differed in their GI and GL: a low GI - high GL (1), a high - GI high GL (2a) of similar GL to (1), a high GI - high GL (2b) of similar energy and macronutrient composition to (1), a low GI - low GL (3) and a high GI - low GL (4). Insulin and glucose responses differed significantly between the high and the low GL meals, while the picture is less clear for the high and low GI meals. The iAUC (incremental area under the curve) at 120 min was predicted in a linear fashion by the calculated GL. There were no differences with regard to cortisol responses. (C): The four breakfast meals( 1,2b, 3,4) were administered in 74 children. The children were matched based on gender, form, age, height and BMI. Each child and their match were randomly assigned to the low or the high GL breakfast. Within each GL group, children were given high or low GI breakfasts. Mood, salivary cortisol (SC) and BG levels were measured The low GI - high GL meal was associated with improved mood and satiating effects. When taking mood, BG and SC levels into account, the low GI meals predicted better performance on a verbal fluency task, and the high GI meals on vigilance tasks. The assumption that could be made is that the GI effects are domain specific: a low GI meal, and as a result of that lower BG levels, could result in lower activation of the HPA-axis (hypothalamic pituitary adrenal) under demanding situations (lower SC levels and feeling less `nervous'), and therefore better declarative memory performance. Conversely, a high GI meal, and as a result of that higher BG levels, could result in stronger activation of the HPA-axis under demanding situations (higher SC levels and feeling more 'nervous'), and therefore better vigilance.

Objective: Poor dietary habits in the first years have been associated with overweight, obesity and health consequences in later life. Young children, particularly in the years before going to school, depend on their caregivers to make healthy food choices on their behalf. Little is known about caregiver experiences, attitudes and perceptions about the feeding of toddlers and preschool children (l-5y) in Switzerland. This research aims to provide, for the first time, an understanding of the lived experience of these caregivers from the French-speaking region of Switzerland. Methods: In-depth, in-home interviews (n=17) were conducted with 19 male and female caregivers (16 = female, 3 = male, age range = 20-46y, low to high income). The model, “Food Choice Process over the Life Course”, was used as a theoretical framework. The interviews explored experiences, attitudes and perceptions about the provision of foods and beverages to children (l-5y). Interview transcripts underwent a thematic analysis and key themes were developed from the data. Results: Two over-arching themes were identified: “Managing” and “Rules and Routines”. Rules about foods and beverages to be encouraged/limited were widespread, along with finishing, or not, the entire meal. Eating in-between meals was routine at 10 o’clock and 4 o’clock. Participants struggled to explain how they portioned foods but offered volume-estimates of beverages consumed. Participants also held specific beliefs about some beverages. Childhood memories and health-professional advice were given as common origins of rules and beliefs. Managing time and budget for food purchases determined the nature of foods and beverages bought, and the types of meals prepared. Home-cooked food was considered superior to ready-meals, and cooking skills helped to save time. There was good agreement between the findings of this study and the theoretical framework. Conclusions and Implications: Rules and routines helped to standardise feeding, minimise cognitive effort and encourage healthy eating behaviours. Snacking routines appeared linked to cultural classifications. Rules and routines provide an insight into the caregiver feeding-styles and practices in Switzerland. Cooking skills helped overcome time constraints, and appeared to encourage the preparation of vegetables. The opportunities for further research, and the education of Swiss caregivers, and healthcare professionals, are discussed.

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