Milk Intake, Height and BMI in Preschool Children
Milk Intake, Height and BMI in Preschool Children
We analysed data from 10 700 ECLS-B participants. Of these, 8950 at the 4-year evaluation and 7000 at the 5-year evaluation had complete data on our variables of interest. Among participants with anthropometric measures, only 12 children were missing data regarding the amount of milk consumed daily at 4 years. Participant characteristics are shown by milk consumption in Table 1. There was a low rate of non-milk consumption (2.6% of boys and 2.1% of girls). Non-milk drinkers appeared to be different from milk drinkers in that, as compared with milk drinkers, non-drinkers were more likely to consume ≥1 servings of SSBs daily (adjusted OR 1.55, CI 1.06 to 2.27, p<0.05). Among milk-drinking children, the majority drank two or three servings of milk per day (53%). There was no correlation between the type and the amount of milk consumed (data not shown). There was a high degree of overweight (16.3%) and obesity (16.0%) in this preschool age group. Compared with higher SES quintiles, there was both a higher percentage of children drinking low amounts of milk (<1 serving daily) and a high amount of milk (≥4 servings daily) in lower SES quintiles.
Linear Regression. On cross-sectional analysis, there was a positive association between the number of servings daily at 4 years and the BMI z-score at 4 years; this association persisted following adjustment for potential confounding variables (p<0.05, Table 2). A similar but stronger association was seen between the amount of milk consumed and height-for-age z-score (p<0.001). Because higher body weight status can be associated with advanced maturation (and thus taller stature), we also assessed weight-for-height z-scores, and these were also positively associated with milk consumption (p<0.05). In each of these analyses we adjusted for sex, race/ethnicity, SES and milk type, which were all related to our outcomes.
Adjusted means. The regression models described previously were used to generate mean z-scores of BMI, height and weight-for-height by number of daily milk servings, adjusted for sex, SES, race/ethnicity and type of milk consumed (figure 1A–C). At 4 years old, children drinking ≥4 servings of milk daily were significantly taller than those drinking one serving daily (p<0.01).
(Enlarge Image)
Figure 1.
Milk consumption and anthropomorphic measures. Adjusted mean z-scores for body mass index (BMI), height and weight-for-height based among milk drinkers based on milk consumption at 4 years of age, as measured at age 4 years (A–C) and 5 years (D–F). All data are adjusted for sex, race/ethnicity, socioeconomic status and milk type. Arrows indicate linear regression results from the same model, assessing for linear relationships between milk amount and the same z-score outcome. Linear regression: *p<0.05; ***p<0.001. Adjusted mean values: compared WITH drinkers of 1 serving daily: p<0.05, p<0.01, p<0.001; compared with drinkers of <1 serving: p<0.01; p<0.001.
Logistic Regression. When compared with other milk drinkers, children at age 4 years who drank higher volumes of milk (three or more servings daily, above the AAP recommendation) had a higher odds of overweight/obesity (p<0.05) but not obesity (Table 3).
In evaluating for longitudinal relationships between milk consumption at 4 years on anthropometric measures at 5 years using linear regression, only the relationship between milk consumption and height-for-age z-score persisted (p<0.001) (Table 2). In assessing adjusted mean z-scores at age 5 years (figure 1D–F), children drinking 2, 3 and ≥4 servings were taller than those drinking one or less than one serving daily (p<0.05).
There were no associations of milk consumption with changes in z-scores of BMI, height or weight-for-height between 4 and 5 years (data not shown).
Results
Demographics
We analysed data from 10 700 ECLS-B participants. Of these, 8950 at the 4-year evaluation and 7000 at the 5-year evaluation had complete data on our variables of interest. Among participants with anthropometric measures, only 12 children were missing data regarding the amount of milk consumed daily at 4 years. Participant characteristics are shown by milk consumption in Table 1. There was a low rate of non-milk consumption (2.6% of boys and 2.1% of girls). Non-milk drinkers appeared to be different from milk drinkers in that, as compared with milk drinkers, non-drinkers were more likely to consume ≥1 servings of SSBs daily (adjusted OR 1.55, CI 1.06 to 2.27, p<0.05). Among milk-drinking children, the majority drank two or three servings of milk per day (53%). There was no correlation between the type and the amount of milk consumed (data not shown). There was a high degree of overweight (16.3%) and obesity (16.0%) in this preschool age group. Compared with higher SES quintiles, there was both a higher percentage of children drinking low amounts of milk (<1 serving daily) and a high amount of milk (≥4 servings daily) in lower SES quintiles.
Cross-sectional Associations of Milk Consumption With Height and Weight at 4 Years
Linear Regression. On cross-sectional analysis, there was a positive association between the number of servings daily at 4 years and the BMI z-score at 4 years; this association persisted following adjustment for potential confounding variables (p<0.05, Table 2). A similar but stronger association was seen between the amount of milk consumed and height-for-age z-score (p<0.001). Because higher body weight status can be associated with advanced maturation (and thus taller stature), we also assessed weight-for-height z-scores, and these were also positively associated with milk consumption (p<0.05). In each of these analyses we adjusted for sex, race/ethnicity, SES and milk type, which were all related to our outcomes.
Adjusted means. The regression models described previously were used to generate mean z-scores of BMI, height and weight-for-height by number of daily milk servings, adjusted for sex, SES, race/ethnicity and type of milk consumed (figure 1A–C). At 4 years old, children drinking ≥4 servings of milk daily were significantly taller than those drinking one serving daily (p<0.01).
(Enlarge Image)
Figure 1.
Milk consumption and anthropomorphic measures. Adjusted mean z-scores for body mass index (BMI), height and weight-for-height based among milk drinkers based on milk consumption at 4 years of age, as measured at age 4 years (A–C) and 5 years (D–F). All data are adjusted for sex, race/ethnicity, socioeconomic status and milk type. Arrows indicate linear regression results from the same model, assessing for linear relationships between milk amount and the same z-score outcome. Linear regression: *p<0.05; ***p<0.001. Adjusted mean values: compared WITH drinkers of 1 serving daily: p<0.05, p<0.01, p<0.001; compared with drinkers of <1 serving: p<0.01; p<0.001.
Logistic Regression. When compared with other milk drinkers, children at age 4 years who drank higher volumes of milk (three or more servings daily, above the AAP recommendation) had a higher odds of overweight/obesity (p<0.05) but not obesity (Table 3).
Longitudinal Associations of Milk Consumption on Height at 4 Years and Weight at 5 Years
In evaluating for longitudinal relationships between milk consumption at 4 years on anthropometric measures at 5 years using linear regression, only the relationship between milk consumption and height-for-age z-score persisted (p<0.001) (Table 2). In assessing adjusted mean z-scores at age 5 years (figure 1D–F), children drinking 2, 3 and ≥4 servings were taller than those drinking one or less than one serving daily (p<0.05).
There were no associations of milk consumption with changes in z-scores of BMI, height or weight-for-height between 4 and 5 years (data not shown).