|Nutrition Evidence Library|
Skinner JD, Bounds W, Carruth BR, Ziegler P. Longitudinal calcium intake is negatively related to children's body fat indexes. J Am Diet Assoc. 2003 Dec;103(12):1626-31.
PubMed ID: 14647089
Cohort study (longitudinal, prospective)
B - Click here for explanation of classification scheme.
Research Design and Implementation Rating:
POSITIVE: See Research Design and Implementation Criteria Checklist below.
This study examines
8-year-old children of mothers who chose to have a dual-energy x-ray absoptiometry (DEXA) scans for themselves and their children. Children and mothers were a subset of a larger longitudinal study.
Mother’s pregnancy excluded her from DEXA scan administration.
Description of Study Protocol:
Children were followed from ages 2 months to 8 years with in-home interviews collected at 20 data collection points. Mothers were given 24-hour recall and 2 days of food records for each child and for themselves. Mothers estimated the daily time their child spent in sedentary activities (TV/video viewing, playing computer games, listening to audiotapes, non-active games/activities).
Correlation statistics (Pearson r) calculated among variables BMI, %BF, and kg BF at 8 years, between DEXA measurements at 6 and 8 years, and between mother/child pairs for %BF and kg BF.
PROC RSQUARE and stepwise regression used to predict children's calcium intake.
Data Collection Summary:
Timing of MeasurementsChildren were followed from ages 2 months to 8 years with in-home interviews collected at 20 data collection points.
%BF and g BF
Breast feeding duration, age of introduction to cereal, child’s mean, dietary variety score from ages 3.5 to 7 years, sedentary activity time of the child, number of foods the child liked from a list of 196 commonly eaten foods as reported by mothers, the number of foods liked by mothers (same food list), whether the mother perceived the child as a picky eater, child’s carbonated beverage intake at 8 years, child’s intake of beverages other than milk, 100% juices, carbonated drinks and water at age 8 years, mothers calcium intake, child’s previous milk intake (age 2 to 7 years).
Potential Independent Variables
Mother's % BF or g BF; mother's BMI; father's BMI; child's gender; child's weighted sedentary activity hours/day; child's daily longitudinal dietary intakes for calcium, energy, protein, carbohydrate, fat, saturated fat, polyunsaturated fat, and monounsaturated fat
Description of Actual Data Sample:
Initial N: 70 child/mother pairs
Attrition (final N): 52 child/mother pairs (25 boys, 27 girls)
Age: 8 years old
SES: Middle and upperclass
Summary of Results:
Mean age of children 8.1±0.1 years. Mean age of mothers 38.0±3.6 years.
Percent body fat increased by 4.8% in boys and 5.4% in girls. Body fat indexes were significantly correlated between mothers and daughters (r-0.58; p=0.002(%BF); r=0.59, p=0.001(g BF))
Percentages of energy were about 14%, 32%, 56% from protein, fat, and carbohydrate and did not differ significantly by gender. Boys’ diets average approximately 175 kcal more per day and approximately 100 mg more calcium compared with girls’ intakes.
Differences in intake between genders were only significantly at age 5 years. Boys’ mean intakes met the adequate intake (AI) amount at each time, girls’ intakes were slightly less than 800 mg/day at 2 of 6 of the interview times from ages 4 to 8 years. Correlations tracking boys’ calcium intakes over time were significant for 4 of the 10 comparisons between interview times whereas girls’ calcium intakes were significantly correlated for 9 of the 10 comparisons.
Best model predicting children’s calcium intake included 3 variables:
Children averages 2.9±1.7 hours per day in sedentary activities (range was 0.8 to 8.8 hours per day).
Dietary calcium and polyunsaturated fat were negatively related to children’s body fat. Positive predictors of body fat were total fat, saturated fat, sedentary activity, female gender, mothers’ percent body fat, fathers BMI. Longitudinal dietary calcium explained 4.5% to 9.0% o the variability in body fat among these children.
Saturated fat, monounsaturated fat, protein, and carbohydrates were examined but not found to be significantly associated with children's body fat.
The similarities of the children’s mean calcium intakes over time and the significant correlations among age periods highlight the importance of establishing food habits early in a child’s life. The negative relationship between dietary calcium and body fat (4.5% to 9.0% of the variance) indicates that the children could reduce their body fat by 0.4% if they increased their calcium intake with one 8-oz serving of a non-fat milk or yogurt. This study also supports the role of physical activity in controlling childhood obesity. Children averaged more than 20 hours per week in sedentary activity, which is especially significant considering that most of the interviews over 7 years were conducted in June, July, and August, when school was not in session.
Copyright American Dietetic Association (ADA).