Obesity prevention in children and adolescents

Childhood and adolescent obesity has been increasing in most middle- and high-income countries, and, as with adult obesity, this has been driven by increasingly obesogenic environments, especially the food environment. This constitutes a “market failure,” signaling the need for government interventions with policies, programs, and social marketing. Population prevention strategies are critical, and children and adolescents should be the priority populations. Food marketing to children is a central policy issue for governments to address, and comprehensive regulations are needed to provide substantive protection for children. Community-based intervention programs show some real promise in reducing childhood obesity, but the 2 big challenges ahead are to ensure that there is substantial ongoing funding so that the community capacity to promote healthy weights can be scaled up to a national level and to ensure that policies are in place to support these efforts. The social and cultural shifts that support healthy eating and physical activity occur differentially, and special efforts are needed to reduce the socioeconomic gradients associated with childhood obesity. A positive public health approach encompassing environmental, regulatory, sociocultural, and educational strategies offer the best chance of reducing obesity without increasing disordered eating patterns.

Prioritizing policy interventions to improve diets? Will it work, can it happen, will it do harm?

Policies from non-health sectors have considerable impacts on the food environment and in turn on population nutrition. Health impact assessment (HIA) methods have been developed to identify the potential health effects of non-health policies; however, they are underused both within and outside the health sector. HIA and other assessment methods and tools can be used more extensively in health promotion to assist with the identification of the best policy options to pursue to improve and protect health. A participatory process is presented in this paper which combines HIAs with feasibility and effectiveness assessments. The intention is to enable health promoters to more accurately identify which policy change options would be most likely to improve diets, considering both impact and likelihood of implementation. The process was successfully used in Fiji and Tonga and provided a more systematic way of understanding which policy interventions showed the most promise.

A cluster randomized controlled trial of a telephone-based parent intervention to increase preschoolers’ fruit and vegetable consumption

Background: Inadequate fruit and vegetable consumption is associated with increased chronic disease risk and represents a considerable global health burden. Despite evidence that dietary habits track from early childhood, there are few published trials of interventions attempting to increase preschoolers’ fruit and vegetable consumption.

Objective: The Healthy Habits trial aimed to assess the efficacy of a telephone-based intervention for parents to increase the fruit and vegetable consumption in their 3–5-y-old children.

Design: A cluster randomized controlled trial was conducted involving 394 parents of children aged 3–5 y recruited through local preschools. Parents allocated to the intervention received printed resources plus four 30-min telephone calls targeting aspects of the home food environment associated with children's fruit and vegetable consumption. Parents allocated to the control group received generic printed nutrition information. Children's fruit and vegetable consumption was assessed by using the Fruit and Vegetable Subscale of the Children's Dietary Questionnaire, which was administered via telephone interview at baseline and 2 and 6 mo later.

Results: Analysis of all available data showed that children's fruit and vegetable scores were significantly higher in the intervention group than in the control group at 2 mo (P < 0.001) and at 6 mo (P = 0.021). Sensitivity analysis using baseline observation carried forward showed an intervention effect at 2 mo (P = 0.008) but not at 6 mo (P = 0.069).

Conclusions: Telephone-delivered parent interventions may be an effective way of increasing children's fruit and vegetable consumption in the short term. Further investigation to determine whether the intervention effect is maintained in the longer term is recommended.

Does the choice of neighbourhood supermarket access measure influence associations with individual-level fruit and vegetable consumption? A case study from Glasgow

Background
Previous studies have provided mixed evidence with regards to associations between food store access and dietary outcomes. This study examines the most commonly applied measures of locational access to assess whether associations between supermarket access and fruit and vegetable consumption are affected by the choice of access measure and scale.

Method
Supermarket location data from Glasgow, UK (n = 119), and fruit and vegetable intake data from the 'Health and Well-Being' Survey (n = 1041) were used to compare various measures of locational access. These exposure variables included proximity estimates (with different points-of-origin used to vary levels of aggregation) and density measures using three approaches (Euclidean and road network buffers and Kernel density estimation) at distances ranging from 0.4 km to 5 km. Further analysis was conducted to assess the impact of using smaller buffer sizes for individuals who did not own a car. Associations between these multiple access measures and fruit and vegetable consumption were estimated using linear regression models.

Results
Levels of spatial aggregation did not impact on the proximity estimates. Counts of supermarkets within Euclidean buffers were associated with fruit and vegetable consumption at 1 km, 2 km and 3 km, and for our road network buffers at 2 km, 3 km, and 4 km. Kernel density estimates provided the strongest associations and were significant at a distance of 2 km, 3 km, 4 km and 5 km. Presence of a supermarket within 0.4 km of road network distance from where people lived was positively associated with fruit consumption amongst those without a car (coef. 0.657; s.e. 0.247; p0.008).

Conclusions
The associations between locational access to supermarkets and individual-level dietary behaviour are sensitive to the method by which the food environment variable is captured. Care needs to be taken to ensure robust and conceptually appropriate measures of access are used and these should be grounded in a clear a priori reasoning.

Does the availability of snack foods in supermarkets vary internationally?

Background
Cross-country differences in dietary behaviours and obesity rates have been previously reported. Consumption of energy-dense snack foods and soft drinks are implicated as contributing to weight gain, however little is known about how the availability of these items within supermarkets varies internationally. This study assessed variations in the display of snack foods and soft drinks within a sample of supermarkets across eight countries.

Methods
Within-store audits were used to evaluate and compare the availability of potato chips (crisps), chocolate, confectionery and soft drinks. Displays measured included shelf length and the proportion of checkouts and end-of-aisle displays containing these products. Audits were conducted in a convenience sample of 170 supermarkets across eight developed nations (Australia, Canada, Denmark, Netherlands, New Zealand, Sweden, United Kingdom (UK), and United States of America (US)).

Results
The mean total aisle length of snack foods (adjusted for store size) was greatest in supermarkets from the UK (56.4 m) and lowest in New Zealand (21.7 m). When assessed by individual item, the greatest aisle length devoted to chips, chocolate and confectionery was found in UK supermarkets while the greatest aisle length dedicated to soft drinks was in Australian supermarkets. Only stores from the Netherlands (41%) had less than 70% of checkouts featuring displays of snack foods or soft drinks.

Conclusion
Whilst between-country variations were observed, overall results indicate high levels of snack food and soft drinks displays within supermarkets across the eight countries. Exposure to snack foods is largely unavoidable within supermarkets, increasing the likelihood of purchases and particularly those made impulsively.

Acculturation and obesity among migrant populations in high income countries - a systematic review

Background:
There is evidence to suggest that immigrant populations from low or medium-income countries to high income countries show a significant change in obesogenic behaviors in the host society, and that these changes are associated with acculturation. However, the results of studies vary depending on how acculturation is measured. The objective of this study is to systematically review the evidence on the relationship between acculturation - as measured with a standardized acculturation scale - and overweight/obesity among adult migrants from low/middle countries to high income countries.

Methods:

Exploring influences on eating behaviours of adolescents experiencing socioeconomic disadvantage

Dr Stephens' thesis utilised a novel approach to examine eating habits of socioeconomically disadvantaged adolescents and to identify factors supportive of healthy eating. Several potential targets and strategies were identified that could be considered when designing interventions, particularly the role of parents and the home food environment.

Nutritional psychiatry research: an emerging discipline and its intersection with global urbanization, environmental challenges and the evolutionary mismatch

In 21st-century public health, rapid urbanization and mental health disorders are a growing global concern. The relationship between diet, brain function and the risk of mental disorders has been the subject of intense research in recent years. In this review, we examine some of the potential socioeconomic and environmental challenges detracting from the traditional dietary patterns that might otherwise support positive mental health. In the context of urban expansion, climate change, cultural and technological changes and the global industrialization and ultraprocessing of food, findings related to nutrition and mental health are connected to some of the most pressing issues of our time. The research is also of relevance to matters of biophysiological anthropology. We explore some aspects of a potential evolutionary mismatch between our ancestral past (Paleolithic, Neolithic) and the contemporary nutritional environment. Changes related to dietary acid load, advanced glycation end products and microbiota (via dietary choices and cooking practices) may be of relevance to depression, anxiety and other mental disorders. In particular, the results of emerging studies demonstrate the importance of prenatal and early childhood dietary practices within the developmental origins of health and disease concept. There is still much work to be done before these population studies and their mirrored advances in bench research can provide translation to clinical medicine and public health policy. However, the clear message is that in the midst of a looming global epidemic, we ignore nutrition at our peril.

Individual, social, and environmental correlates of healthy and unhealthy eating

Few studies use comprehensive ecological approaches considering multilevel factors to understand correlates of healthy (and unhealthy) dietary intake. The aim of this study was to examine the association between individual, social, and environmental factors on composite measures of healthy and unhealthy dietary intake in adults.

Nutrition promotion approaches preferred by Australian adolescents attending schools in disadvantaged neighbourhoods: a qualitative study

BACKGROUND: Links between socioeconomic disadvantage and unhealthy eating behaviours among adolescents are well established. Little is known about strategies that might support healthy eating among this target group. This study aimed to identify potential strategies and preferred dissemination methods that could be employed in nutrition promotion initiatives focussed on improving eating behaviours among socioeconomically disadvantaged adolescents. METHODS: Semi-structured interviews were conducted in 2011 among 22 adolescents (12-15 years) recruited from secondary schools in disadvantaged neighbourhoods in Victoria, Australia. RESULTS: Strategies suggested by adolescents to support healthy eating included increasing awareness about healthy eating; greater cooking involvement; greater parental and peer support; frequent family meal participation; greater parental and peer role-modelling of healthy eating; increased availability of healthy foods and decreased availability of unhealthy foods in homes and schools. Adolescents preferred electronic media, adolescent-specific recipe books, and school-based methods for distributing nutrition promotion messages and strategies. CONCLUSIONS: A number of suggested strategies and methods identified in the present investigation have been employed with success in previous nutrition promotion interventions targeting socioeconomically disadvantaged adolescents. The present study also contributes novel insights into potential strategies and methods that could be employed in initiatives aiming to improve eating behaviours in this vulnerable group, and particularly highlights the importance of incorporating strategies involving parents and modifying the home food environment.

The use of kernel density estimation to examine associations between neighborhood destination intensity and walking and physical activity

BACKGROUND: Local destinations have previously been shown to be associated with higher levels of both physical activity and walking, but little is known about how the distribution of destinations is related to activity. Kernel density estimation is a spatial analysis technique that accounts for the location of features relative to each other. Using kernel density estimation, this study sought to investigate whether individuals who live near destinations (shops and service facilities) that are more intensely distributed rather than dispersed: 1) have higher odds of being sufficiently active; 2) engage in more frequent walking for transport and recreation. METHODS: The sample consisted of 2349 residents of 50 urban areas in metropolitan Melbourne, Australia. Destinations within these areas were geocoded and kernel density estimates of destination intensity were created using kernels of 400m (meters), 800m and 1200m. Using multilevel logistic regression, the association between destination intensity (classified in quintiles Q1(least)-Q5(most)) and likelihood of: 1) being sufficiently active (compared to insufficiently active); 2) walking≥4/week (at least 4 times per week, compared to walking less), was estimated in models that were adjusted for potential confounders. RESULTS: For all kernel distances, there was a significantly greater likelihood of walking≥4/week, among respondents living in areas of greatest destinations intensity compared to areas with least destination intensity: 400m (Q4 OR 1.41 95%CI 1.02-1.96; Q5 OR 1.49 95%CI 1.06-2.09), 800m (Q4 OR 1.55, 95%CI 1.09-2.21; Q5, OR 1.71, 95%CI 1.18-2.48) and 1200m (Q4, OR 1.7, 95%CI 1.18-2.45; Q5, OR 1.86 95%CI 1.28-2.71). There was also evidence of associations between destination intensity and sufficient physical activity, however these associations were markedly attenuated when walking was included in the models. CONCLUSIONS: This study, conducted within urban Melbourne, found that those who lived in areas of greater destination intensity walked more frequently, and showed higher odds of being sufficiently physically active-an effect that was largely explained by levels of walking. The results suggest that increasing the intensity of destinations in areas where they are more dispersed; and or planning neighborhoods with greater destination intensity, may increase residents' likelihood of being sufficiently active for health.

Change of school in early adolescence and adverse obesity-related dietary behavior: a longitudinal cohort study, Victoria, Australia, 2013-2014

INTRODUCTION: Environments that facilitate energy-dense, nutrient-poor diets are associated with childhood obesity. We examined the effect of a change of school environment on the prevalence of obesity and related dietary behavior in early adolescence. METHODS: Fifteen schools in Victoria, Australia, were recruited at random from the bottom 2 strata of a 5-level socioeconomic scale. In 9 schools, students in grade 6 primary school transitioned to different schools for grade 7 secondary school, whereas in 6 schools, students remained in the same school from grade 6 to grade 7. Time 1 measures were collected from students (N = 245) in grade 6 (aged 11-13 y). Time 2 data were collected from 243 (99%) of the original cohort in grade 7. Data collected were dietary recall self-reported by students via questionnaire, measured height and weight of students, and aspects of the school food environment via school staff survey. Comparative and mixed model regression analyses were conducted. RESULTS: Of 243 students, 63% (n = 152) changed schools from time 1 to time 2, with no significant difference in weight status. Students who changed schools reported an increase in purchases of after-school snack food, greater sweetened beverage intake, fewer fruit-and-vegetable classroom breaks, and less encouragement for healthy eating compared with students who remained in the same school. School staff surveys showed that more primary than secondary schools had written healthy canteen policies and fewer days of canteen or food services operation. CONCLUSION: A change of school environment has negative effects on children's obesity-related dietary behavior. Consistent policy is needed across school types to support healthy eating in school environments.

A review of the relationship between socioeconomic position and the early-life predictors of obesity

A range of important early-life predictors of later obesity have been identified. Children of lower socioeconomic position (SEP) have a steeper weight gain trajectory from birth with a strong socioeconomic gradient in child and adult obesity prevalence. An assessment of the association between SEP and the early-life predictors of obesity has been lacking. The review involved a two-stage process: Part 1, using previously published systematic reviews, we developed a list of the potentially modifiable determinants of obesity observable in the pre-natal, peri-natal or post-natal (pre-school) periods; and part 2, conducting a literature review of evidence for socioeconomic patterning in the determinants identified in part 1. Strong evidence was found for an inverse relationship between SEP and (1) pre-natal risk factors (pre-pregnancy maternal body mass index (BMI), diabetes and pre-pregnancy diet), (2) antenatal/peri natal risk factors (smoking during pregnancy and low birth weight) and (3) early-life nutrition (including breastfeeding initiation and duration, early introduction of solids, maternal and infant diet quality, and some aspects of the home food environment), and television viewing in young children. Less strong evidence (because of a lack of studies for some factors) was found for paternal BMI, maternal weight gain during pregnancy, child sleep duration, high birth weight and lack of physical activity in young children. A strong socioeconomic gradient exists for the majority of the early-life predictors of obesity suggesting that the die is cast very early in life (even pre-conception). Lifestyle interventions targeting disadvantaged women at or before child-bearing age may therefore be particularly important in reducing inequality. Given the likely challenges of reaching this target population, it may be that during pregnancy and their child's early years are more feasible windows for engagement.

Mexico: A new heavy weight in a global world

In the last three decades, obesity has been gaining recognition as a serious public health problem in Mexico. This epidemic developed insidiously in a country that was still focused on chronic under-nutrition in the population. During that same period, macro-economic reforms projected Mexico into the global economic arena. Foreign investments, trade in goods and services, and technological transfers were promoted through participation in numerous trade agreements between Mexico and other countries. The North American Trade Agreement (NAFTA), signed in 1994, promised an integrated market between the three North American countries: Canada, the United States, and Mexico. Although these trade policies were likely to have effects on the available food supply in Mexico, this association has not been elucidated. In this case study, we examine how these trade liberalization policies may have influenced the food supply in Mexico.^ Information on the trade of food commodities between the United States and Mexico and the nature of foreign investment in Mexico was compiled using public data available through American, Mexican, and other international published reports for 1986 through 2011. After the implementation of NAFTA, an increase in trade and investments was observed between Mexico and its two North American partners, but most of the trade increase occurred between the US and Mexico. Since the liberalization of trade policies between these counties, exports of fruit and vegetables into the U.S. from Mexico have increased, while exports of cereals, fats, vegetable oils, meat, dairy products and processed foods from the U.S. into Mexico have increased. During this same time period, there has been an increase in the foreign direct investment in the food industry in Mexico, as well as changes in the types and amounts of dietary energy available on a population level. Specifically, between 1990 to 2006, the dietary energy supply per person has increased 6.1% available animal protein has increased 35.8%, and available fat has increased 18.9%.^ Thus, this case study suggests that the recent changes in food-related industries through foreign direct investment and market liberalization may be likely contributors to the obesogenic food environment in Mexico. Although this initial case study provides interesting data, whether trade liberalization policies should be considered hazardous for health as a distal determinant of the obesity epidemic needs to be further examined using a more stringent study design or further follow up of the US Mexico trade data.^