Association between modified youth healthy eating index and nutritional status among Iranian children in Zabol city: a cross-sectional study

Association between modified youth healthy eating index and nutritional status among Iranian children in Zabol city: a cross-sectional study

Study subjects

In the present cross-sectional study, 580 school children aged 7–12 years were recruited from May to September 2021 by a multi-stage cluster sampling method as a representative sample of children in the urban areas of Zabol, Sistan and Baluchestan Province in the southeast of Iran. At first, schools were selected as clusters, and then school classes were considered as strata. Afterward, the children were randomly chosen from the list of student records of each class.

The sample size of the study was calculated based on information obtained from the study by Shahraki et al15. By considering a confidence interval of 95% (z), a degree of precision of 3% (d), and a prevalence of stunting of 16% (p), it was calculated that 574 subjects needed to be included in the study. Estimating a nonresponse rate of 5%, 602 children were invited to participate in this study. The inclusion criteria were being in the age range of 7 to 12 years and the willingness of child parents to participate in the study. The exclusion criteria included taking any medications, being on a specific diet, and having any hereditary disorders or chronic diseases. After excluding those with implausible energy intakes of lower than 500 kcal/day and higher than 4000 kcal/day (12 boys, 10 girls), 580 children remained for the analyses.

Demographic data and anthropometric measurements

General characteristics of children and their parents including age and sex, parent’s educational level, parent’s occupation, household size, and number of children in the household were obtained through face-to-face interviews with the child’s mother by two trained research assistants using a questionnaire.

The weight of participants was measured without shoes in light clothing using a Beurer digital weighing scale (Beurer BF66, Germany). Also, height was measured in a standing position without shoes by mounting tape to the nearest 0.1 cm precision. Body mass index (BMI) was calculated as weight (kg) divided by squared height (m2). The weighing scale was calibrated to zero before taking every measurement. To minimize the subjective error, all measurements were done by the same person.

Assessment of dietary intake

Dietary intake was evaluated using a semi-quantitative food frequency questionnaire (FFQ) with 168 food items, which was designed and validated specifically for the Iranian population14. The good validity and reliability of the FFQ in terms of assessing the nutrient and food consumption of Iranian children has been reported previously16. The FFQ also evaluated eating behaviors relevant to the diet quality of children, including the use of sugar-sweetened beverages, sweet snacks, salty snacks, and the frequency of eating fast foods.

The trained research assistants administered all the questionnaires by interviewing the children and their mothers. The mothers were asked about the consumption of a given serving of each food item by children during the previous year on a daily (e.g. bread), weekly (e.g. rice, milk), or monthly (e.g. fish) basis. The research assistants guided the child’s mothers on the estimation of food quantities, using a set of calibrated household measurements (e.g. cups, glasses, bowls, plates, spoons, ladles). Portion sizes of consumed foods were then converted to the gram, using household measures. Food intakes were then converted to energy and other nutrients using the Nutritionist-IV (N4) software program (version 7.0; N-Squared Computing, Salem, OR, USA)17,18, modified for Iranian foods. Almost all foods eaten by the subjects could be coded. When a particular ethnic food was not in the database of N4, it was coded as a similar item.

Assessment of adherence to the modified youth healthy eating index

Adherence of the participants to the healthy eating guidelines was assessed using the MYHEI scoring system. Briefly, MYHEI consisted of 10 components including whole grains, fruits, vegetables, dairy, meat ratio, sugar-sweetened beverages, butter and margarine, sweet snacks, salty snacks, and fast foods. In the MYHEI scoring system, higher consumption of the five components (whole grains, fruits, vegetables, dairy, and meat ratio) and avoidance or lower consumption of the remaining five components (sugar-sweetened beverages, butter and margarine, sweet snacks, salty snacks, and fast foods) indicate a healthier diet. Each component is scored 0 (for lack of adherence) to 10 (for full adherence), with intermediate scores calculated to indicate the degree of adherence to dietary recommendations. All the component scores are summed to obtain a total MYHEI score, which ranges from 0 to 100, with a higher score indicating a healthier diet. The criteria for scoring each component are summarized in Table 1.

Table 1 Components and scoring criteria of Modified Youth Healthy Eating Index.

Assessment of nutritional outcomes

In this study, underweight, stunting, and wasting as nutritional outcomes were investigated in the participants. Nutritional outcomes of children were evaluated by calculating weight-for-age (WAZ), height-for-age (HAZ), and BMI-for-age (BAZ) Z scores according to the World Health Organization (WHO) growth standards 2007 for 5–19 years (WHO 2007). The Z scores for these nutritional indicators were calculated using the WHO Anthro Plus software program (version 1.0.4)19. Underweight, stunting, and wasting among children were considered as WAZ, HAZ, and BAZ less than 2 standard deviations (Z score < -2SD) below the median of the reference population (growth references, WHO 2007), respectively19.

Statistical analysis

Data were analyzed using IBM SPSS version 25 (IBM Corp., Armonk, NY, USA). Participants were classified based on cut-points of MYHEI in quartiles categories as follows: 1st, < 47.5; 2nd, 47.5 to < 54.5; 3rd, 54.5 to < 64.4; 4th, ≥ 64.4. The Kolmogorov–Smirnov test was applied to determine the normality of the data. The results are presented as mean ± standard deviation for quantitative data with normal distribution; while for qualitative data, frequency (percent) was used. Noticeable variations in anthropometric and general characteristics across quartile groups of MYHEI were assessed by the ANOVA with Tukey’s post hoc test. To identify considerable differences, the Pearson chi-square (χ2) test was employed across quartile groups of MYHEI for qualitative data.

Age-, sex- and energy-adjusted intakes of nutrients and food groups were compared across the MYHEI categories using analysis of covariance (ANCOVA), with Bonferroni correction. The Kruskal–Wallis test was used to compare numerical variables with non-normal distribution. The association of MYHEI component scores and nutritional outcomes among participants were also investigated by ANCOVA, after adjusting for age, sex, and energy intake. To explore the relationship between MYHEI and the probability of underweight, stunting, and wasting, multivariate logistic regression was used in crude and adjusted models. In the adjusted model, important factors including age (years), sex (boy/girl), and energy intake (kcal/day) were controlled. In all multivariate models, the fourth quartile (Q4) of the MYHEI was considered as a reference. The Mantel–Haenszel extension test was used to evaluate the overall trend of increasing quartile categories of MYHEI associated with an increasing prevalence of nutritional outcomes. The findings of logistic regression are described as adjusted odds ratios (ORs) with 95% confidence intervals (CIs). A p-value < 0.05 was defined as significant.

Ethics approval and consent to participate

All the methods and procedures carried out in this study were by the guidelines of the Declaration of Helsinki and approved by the Ethics Committee of Zabol University of Medical Sciences (Ethics code: IR.ZBMU.REC.1401.006). Before the beginning of the study, children’s parents were fully informed about the objectives and protocol of the study. Parents and guardians provided informed written consent for their children participating in the study. Parents were informed that they could revoke the participation agreement at any time.