Early life protein intake: food sources, correlates, and tracking across the first 5 years of life

Background: High consumption of protein has been associated with accelerated growth and adiposity in early childhood. Objective: To describe intake, food sources, correlates, and tracking of protein in young children. Design: Secondary analysis of Melbourne Infant Feeding Activity and Nutrition Trial (InFANT). Dietary data were collected using three 24-hour dietary recalls at ages 9 and 18 months as well as 3.5 and 5 years. Participants/setting: First-time mothers and their child (n=542) participated in an 18-month intervention to prevent childhood obesity and the cohort was followed-up with no intervention when children were aged 3.5 and 5 years. Main outcome measures: Protein intake, food sources, correlates, and tracking of protein. Statistical analyses performed: Child and maternal correlates of protein intake were identified using linear regression and tracking of protein intake was examined using Pearson correlations of residualized protein scores between time points. Results: Mean protein (grams per day) intake was 29.7±11.0, 46.3±11.5, 54.2±13.8, and 60.0±14.8 at 9 and 18 months and 3.5 and 5 years, respectively. Protein intakes at all ages were two to three times greater than age-appropriate Australian recommendations. The primary source of protein at 9 months was breast/formula milk. At later ages, the principal sources were milk/milk products, breads/cereals, and meat/meat products. Earlier breastfeeding cessation, earlier introduction of solids, high dairy milk consumption (≥500 mL), and high maternal education were significant predictors of high protein intake at various times (P < 0.05). Slight tracking was found for protein intakes at 9 months, 18 months, and 5 years (r=0.16 to 0.21; P < 0.01). Conclusions: This study provides unique insights into food sources and correlates of young children's high protein intakes, and confirms that early protein intakes track slightly up to age 5 years. These finding have potential to inform nutrition interventions and strategies to address high protein intakes and protein-related obesity risk.