Determinants of bone mineral density in healthy term-born children at age 6 months and 3 years

Background & aims

The first 6 months of life are a critical window for adiposity programming, which could potentially also be true for bone mineral density (BMD) development. It is, however, currently unknown which determinants associate with BMD during early childhood. Our objective was to assess which determinants associate with BMD at 6 months and 3 years of age, with focus on growth during the first 6 months of life and macronutrient intake.

Methods

In 428 healthy term-born infants, aged 6 months and 3 years, we measured anthropometrics, BMD total body less head (BMD_TBLH) and body composition by Dual-energy X-ray absorptiometry (DXA), and collected feeding characteristics by questionnaires. At age 3 months, macronutrient intake was measured in formula-fed and exclusively breastfed infants using a Human Milk Analyzer. At age 3 years, feeding diaries were analyzed regarding macronutrients and vitamin D intake. Associations of BMD_TBLH standard deviation score (SDS) with child characteristics, growth and macronutrient intake were investigated with regression analyses.

Results

Reference values for BMD_TBLH at age 6 months were constructed. Weight SDS, lean body mass (LBM) and fat mass (FM) associated positively with BMD_TBLH SDS at age 6 months. The same variables associated positively with BMD_TBLH SDS at age 3 years, with also length SDS. Protein intake at age 3 months associated positively with BMD_TBLH SDS at age 6 months, and fat intake at 3 years inversely with BMD_TBLH SDS at 3 years.

Conclusion

Lean body mass is the most important determinant of BMD_TBLH SDS at age 6 months and 3 years. Higher protein intake at age 3 months and lower fat intake at age 3 years associate with higher BMD_TBLH SDS.