Use of dietary indexes among children in developed countries

Three-year change in diet quality and associated changes in BMI among schoolchildren living in socio-economically disadvantaged neighbourhoods

Findings from research that has assessed the influence of dietary factors on child obesity have been equivocal. In the present study, we aimed to test the hypothesis that a positive change in diet quality is associated with favourable changes in BMI z-scores (zBMI) in schoolchildren from low socio-economic backgrounds and to examine whether this effect is modified by BMI category at baseline. The present study utilised data from a subsample (n 216) of the Resilience for Eating and Activity Despite Inequality study, a longitudinal cohort study with data collected in 2007-8 (T1) and 2010-11 (T2) in socio-economically disadvantaged women and children (5-12 years at T1). Dietary data were collected using a FFQ and diet quality index (DQI) scores derived at both time points. The objective measures of weight, height and physical activity (accelerometers) were included. The other variables were reported in the questionnaires. We examined the association between change in DQI and change in zBMI, using linear regression analyses adjusted for physical activity, screen sedentary behaviour and maternal education level both in the whole sample and in the sample stratified by overweight status at baseline. After accounting for potential covariates, change in diet quality was found to be inversely associated with change in zBMI only in children who were overweight at baseline (P= 0.035), thus supporting the hypothesis that improvement in diet quality is associated with a concurrent improvement in zBMI among already overweight children, but not among those with a normal BMI status. The identification of modifiable behaviours such as diet quality that affect zBMI longitudinally is valuable to inform future weight gain prevention interventions in vulnerable groups.

Systematic review of diet quality indices and their associations with health-related outcomes in children and adolescents

BACKGROUND

Diet quality indices add an important dimension to dietary assessment. The aim of this systematic review was to: (i) identify and describe the attributes and applications of diet quality indices developed for use or used in paediatric populations; (ii) describe associations between these diet quality indices and health-related variables in paediatric populations; and (iii) identify factors that are associated with diet quality in paediatric populations worldwide.

METHODS

Studies were identified by searching electronic databases for relevant papers from 1980 to October 2013 using keywords. Inclusion criteria were original studies that utilised a quantitative measure of diet quality in children and adolescents aged 0-18 years.

RESULTS

One hundred and nineteen studies met the inclusion criteria, from which 80 different diet quality indices were identified. The majority of studies had >1000 participants and were of acceptable quality. Of the 56 studies that investigated health-related outcomes, weight status was the most researched. Europe produced the most number of diet quality indices (n = 27 indices). Of the 119 studies, seven intervention studies were identified. Paediatric diet quality indices were found to be associated with environmental, behavioural and maternal factors.

CONCLUSIONS

The use of diet quality indices in paediatric populations is a rapidly expanding area of research in diverse populations internationally. In economically disadvantaged countries, diet quality indices may be predictive of child growth. However, prospective cohort, intervention and validation studies are required to draw stronger conclusions concerning risk of future disease in paediatric populations in general.

A health promotion intervention can affect diet quality in early childhood

Initiatives to promote children's nutrition and prevent childhood obesity are vital. Dietary patterns are a useful way to characterize whole diets, though no previous early childhood health promotion trial to our knowledge has assessed intervention impact using this approach. This research aimed to assess the effect of a healthy eating and physical activity intervention on young children's dietary patterns. The Melbourne Infant Feeding Activity and Nutrition Trial Program was a health promotion, cluster-randomized controlled trial involving 542 families. Child diets were assessed by multiple 24-h recalls postintervention at ~18 mo of age. An Obesity Protective Dietary Index (OPDI) was created and dietary patterns were also assessed by principal components analysis (PCA). These outcomes were used to compare intervention and control participants to test the effectiveness of the intervention. Children in the intervention arm scored higher (15.6 ± 5.9) than those in the control arm (14.5 ± 6.7) for the OPDI (scores out of 30, P = 0.01). Three dietary patterns were identified by PCA; however, the scores did not substantially differ between the intervention and control arms. In conclusion, this paper presents novel results in both the evaluation of an early childhood health promotion intervention and the assessment of child dietary patterns. The results highlight the capacity for such an initiative to improve child diets and the need for further research in this area.

Monitoring and benchmarking population diet quality globally: a step-wise approach

INFORMAS (International Network for Food and Obesity/non-communicable diseases Research, Monitoring and Action Support) aims to monitor and benchmark the healthiness of food environments globally. In order to assess the impact of food environments on population diets, it is necessary to monitor population diet quality between countries and over time. This paper reviews existing data sources suitable for monitoring population diet quality, and assesses their strengths and limitations. A step-wise framework is then proposed for monitoring population diet quality. Food balance sheets (FBaS), household budget and expenditure surveys (HBES) and food intake surveys are all suitable methods for assessing population diet quality. In the proposed 'minimal' approach, national trends of food and energy availability can be explored using FBaS. In the 'expanded' and 'optimal' approaches, the dietary share of ultra-processed products is measured as an indicator of energy-dense, nutrient-poor diets using HBES and food intake surveys, respectively. In addition, it is proposed that pre-defined diet quality indices are used to score diets, and some of those have been designed for application within all three monitoring approaches. However, in order to enhance the value of global efforts to monitor diet quality, data collection methods and diet quality indicators need further development work.

Development and validation of a food-based diet quality index for New Zealand adolescents

Background

As there is no population-specific, simple food-based diet index suitable for examination of diet quality in New Zealand (NZ) adolescents, there is a need to develop such a tool. Therefore, this study aimed to develop an adolescent-specific diet quality index based on dietary information sourced from a Food Questionnaire (FQ) and examine its validity relative to a four-day estimated food record (4DFR) obtained from a group of adolescents aged 14 to 18 years.

Methods

A diet quality index for NZ adolescents (NZDQI-A) was developed based on ‘Adequacy’ and ‘Variety’ of five food groups reflecting the New Zealand Food and Nutrition Guidelines for Healthy Adolescents. The NZDQI-A was scored from zero to 100, with a higher score reflecting a better diet quality. Forty-one adolescents (16 males, 25 females, aged 14–18 years) each completed the FQ and a 4DFR. The test-retest reliability of the FQ-derived NZDQI-A scores over a two-week period and the relative validity of the scores compared to the 4DFR were estimated using Pearson’s correlations. Construct validity was examined by comparing NZDQI-A scores against nutrient intakes obtained from the 4DFR.

Results

The NZDQI-A derived from the FQ showed good reliability (r = 0.65) and reasonable agreement with 4DFR in ranking participants by scores (r = 0.39). More than half of the participants were classified into the same thirds of scores while 10% were misclassified into the opposite thirds by the two methods. Higher NZDQI-A scores were also associated with lower total fat and saturated fat intakes and higher iron intakes.

Conclusions

Higher NZDQI-A scores were associated with more desirable fat and iron intakes. The scores derived from either FQ or 4DFR were comparable and reproducible when repeated within two weeks. The NZDQI-A is relatively valid and reliable in ranking diet quality in adolescents at a group level even in a small sample size. Further studies are required to test the predictive validity of this food-based diet index in larger samples.

Dietary and lifestyle quality indices with/without physical activity and markers of insulin resistance in European adolescents: the HELENA study

Emerging data indicate that higher levels of insulin resistance (IR) are common among children and adolescents and are related to cardiometabolic risk; therefore, IR requires consideration early in life. In addition, there is a lack of conclusive evidence regarding the role of dietary nutrients on IR. The Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) was conducted in European adolescents aged 12·5–17·5 years. A total of 637 participants with valid homeostasis model assessment (HOMA) index data and who completed at least a 2 d 24 h dietary recall were included in the study (60% of the total HELENA-CSS sample). There were two dietary indices calculated, with the only difference between them being the inclusion or not of physical activity (PA). Markers of IR such as HOMA and the quantitative insulin sensitivity check index (QUICKI) were calculated. Pubertal status, BMI and cardiorespiratory fitness (CRF) were measured as potential confounders. The dietary index including PA was inversely associated with HOMA and directly with the QUICKI in females, but not in males, after adjusting for pubertal status, centre, BMI and CRF. In conclusion, the present study indicates that considering PA as part of the dietary index is of relevance as the resulted index is inversely related to IR independently of potential confounders including CRF. Overall, these findings suggest that intervention studies aimed at preventing IR in young people should focus on increasing the quality of the diet and also on including an optimal PA level in healthy adolescents.

Evaluation of methodologies for assessing the overall diet: dietary quality scores and dietary pattern analysis

This paper aims to describe different approaches for studying the overall diet with advantages and limitations. Studies of the overall diet have emerged because the relationship between dietary intake and health is very complex with all kinds of interactions. These cannot be captured well by studying single dietary components. Three main approaches to study the overall diet can be distinguished. The first method is researcher-defined scores or indices of diet quality. These are usually based on guidelines for a healthy diet or on diets known to be healthy. The second approach, using principal component or cluster analysis, is driven by the underlying dietary data. In principal component analysis, scales are derived based on the underlying relationships between food groups, whereas in cluster analysis, subgroups of the population are created with people that cluster together based on their dietary intake. A third approach includes methods that are driven by a combination of biological pathways and the underlying dietary data. Reduced rank regression defines linear combinations of food intakes that maximally explain nutrient intakes or intermediate markers of disease. Decision tree analysis identifies subgroups of a population whose members share dietary characteristics that influence (intermediate markers of) disease. It is concluded that all approaches have advantages and limitations and essentially answer different questions. The third approach is still more in an exploration phase, but seems to have great potential with complementary value. More insight into the utility of conducting studies on the overall diet can be gained if more attention is given to methodological issues.

Change in the family food environment is associated with positive dietary change in children

Background

The family food environment is an important influence in the development of children’s dietary habits. Research suggests that influences of current dietary behaviour and behaviour change may differ. The aims of this paper were to: (1) investigate the association between the food environment at baseline and change in children’s saturated fat intake; and (2) to explore whether a change in the food environment was associated with a change in children’s saturated fat intake.

Method

Secondary analysis of a 12 week cluster randomised controlled trial in 133 4-13 year old children. Families were randomly allocated to parental education regarding changing to reduced-fat dairy foods or a comparison non-dietary behaviour. The interventions were family focused. Parents received education from a dietitian in 3x30minute sessions to facilitate behaviour change. Parents completed a comprehensive questionnaire capturing three domains of the food environment – Parent knowledge and attitudes; shaping practices; and behaviours and role modelling. Children’s dietary intake was assessed via multiple 24-hour recalls at baseline and week 12. Changes in the family food environment and primary outcome (saturated fat) were calculated. Hierarchical linear regression models were performed to explore the association between baseline and change in food environment constructs and change in saturated fat intake. Standardised Beta are presented (p<0.05).

Results

After adjustments for child and family demographics, higher levels of perceived food availability (β=-0.2) at baseline was associated with greater reduction in saturated fat intake, where as higher perceived responsibility (β=0.2), restriction (β=0.3) and pressure to eat (β=0.3) were associated with lesser change in saturated fat. An increase in nutrition knowledge (β=-0.2), perceived responsibility (β=-0.3) and restriction (β=-0.3) from baseline to week 12 were associated with greater reduction in saturated fat intake.

Conclusions

The present study was one of the first to quantify changes in the family food environment, and identify a number of factors which were associated with a positive dietary change. Because interventions focus on behaviour change, the findings may provide specific targets for intervention strategies in the future.

Trial registration

Australia New Zealand Clinical Trials Registry ACTRN12609000453280.