The Relationship between the Source of Protein Intake and Obesity Risk in Children

THE RELATIONSHIP BETWEEN THE SOURCE OF PROTEIN INTAKE AND OBESITY RISK IN CHILDREN by Grace Stuhrman Background: Previous research has reported a relationship between high protein intake (>15% of energy) during early childhood and an increased risk of obesity later in life. However, few studies have investigated this relationship during middle childhood to early adolescence or examined the effects of different sources of protein. Objective: The aim of this study was to investigate the relationship between the source of protein intake (animal vs. plant) and body mass index (BMI) in children between the ages 6-14 years. Participants/setting: 285 healthy 6-14 year old (male n=154) Caucasian and African American (n=171) children from Pittsburgh, Pennsylvania completed a food frequency questionnaire. Main outcome measures: Median protein intake (grams) by total, animal, and plant protein and BMI-for-age classification. Statistical analysis: The Kruskal-Wallis test was used to evaluate differences in median protein intake (grams) by weight classification (normal weight [BMI 5 th %ile to <85 th %ile], overweight [BMI 85 th %tile to <95 th %tile], obese [BMI >95 th %tile]). Correlation statistics were also conducted to examine the relationship between protein intake and BMI. Results: The population used in the data analysis included 285 children/early adolescents (median age 9.8  2.1 years; 53% boys; 40% Caucasian). Data from 11 children were excluded due to outliers or missing data. Girls had a significantly higher BMI than boys (20.1 vs. 18.2 kg/m 2 , respectively; P=<0.001). The majority (62%) of participants had a normal BMI while 20% of participants were overweight and 18% of participants were obese. No difference in the source of protein intake was observed by gender. However, median protein intake differed significantly by weight classification for total protein and for animal and plant protein (P=<0.05). Reported total protein intake was adequate for all children. Calorie intake was sufficient in children who were of normal weight or overweight but was below the requirement for age in those who were obese. The percent of total protein calories but not animal or plant protein differed by BMI weight classification (normal, 15.3%; overweight and obese, 14.6%; P=<0.01). Correlation statistics showed no association between the amount of total protein or animal or plant protein intake and BMI. Conclusions: We observed a significant curvilinear versus linear trend in total protein and animal and plant protein intake by weight classification in middle-aged children that may be due to under-reporting in overweight and obese children. Total percent protein intake was significantly higher in children of normal weight. Future longitudinal studies using multiple measures of body fatness should be conducted to determine the relationship between protein intake and BMI during middle childhood to early