Associations of protein intake in early childhood with body composition, height, and insulin-like growth factor I in mid-childhood and early adolescence

Abstract

Background: Early protein intake may program later body composition and height growth, perhaps mediated by insulin-like growth factor I (IGF-I). In infancy, higher protein intake is consistently associated with higher IGF-I concentrations and more rapid growth, but associations of protein intake after infancy with later growth and IGF-I are less clear.

Objectives: Our objective was to examine associations of protein intake in early childhood (median 3.2 y) with height, IGF-I, and measures of adiposity and lean mass in mid-childhood (median 7.7 y) and early adolescence (median 13.0 y), and with changes in these outcomes over time. We hypothesized that early childhood protein intake programs later growth.

Methods: We studied 1165 children in the Boston-area Project Viva cohort. Mothers reported children's diet using food-frequency questionnaires. We stratified by child sex and examined associations of early childhood protein intake with mid-childhood and early adolescent BMI z score, skinfold thicknesses, dual-energy X-ray absorptiometry (DXA) fat mass, DXA lean mass, height z score, and IGF-I concentration. We adjusted linear regression models for race/ethnicity, family sociodemographics, parental and birth anthropometrics, breastfeeding status, physical activity, and fast food intake.

Results: Mean protein intake in early childhood was 58.3 g/d. There were no associations of protein intake in early childhood with any of the mid-childhood outcomes. Among boys, however, each 10-g increase in early childhood total protein intake was associated with several markers of early adolescent size, namely BMI z score (0.12 higher; 95% CI: 0.01, 0.23), DXA lean mass index (1.34% higher; 95% CI: -0.07%, 2.78%), and circulating IGF-I (5.67% higher; 95% CI: 0.30%, 11.3%). There were no associations with fat mass and no associations with any adolescent outcomes among girls.

Conclusions: Early childhood protein intake may contribute to programming lean mass and IGF-I around the time of puberty in boys, but not to adiposity development. This study was registered at clinicaltrials.gov as NCT02820402.

Keywords: IGF-I; Project Viva; body composition; cohort; early childhood protein intake; height growth.

FIGURE 1

Flow of participant involvement in Project Viva from recruitment through the mid-teen visit. Flow from recruitment through mid-childhood reprinted from Oken et al., Cohort Profile: Project Viva, International Journal of Epidemiology, 2015;44(1):37–48 by permission of Oxford University Press.

FIGURE 2

Associations of total, animal, and plant protein intake in early childhood with BMI z score (A), height z score (B), DXA lean mass index (kg/m²) (C), and IGF-I (ng/mL) (D) in early adolescence among Project Viva boys and girls. Points are βs (BMI z score and height z score) or percentage differences (DXA lean mass index and IGF-I), with 95% CIs represented by error bars. Results were generated from multivariable linear regression models adjusted for child race/ethnicity, child age at outcome measurement (except z score outcomes), child age at diet assessment, household income, maternal education, breastfeeding status at 6 mo, and: 1) maternal and paternal BMI, birth weight for gestational age z score, fast food intake, and physical activity (BMI z score); 2) fast food intake and physical activity (DXA lean mass index); or 3) maternal and paternal height and birth length (height z score and IGF-I). Protein intake is adjusted for total energy intake and body weight at the time of diet assessment. n = 963 for analyses of BMI z score, height z score, and DXA lean mass index; n = 717 for analyses of IGF-I. DXA, dual-energy X-ray absorptiometry; IGF-I, insulin-like growth factor I.