Calcium absorption and vitamin D status in school age children

Increasing serum 25‐hydroxyvitamin D (25‐D) in adults may enhance calcium absorption (Ca‐Abs). There are few similar pediatric data. We evaluated the relationship between 25‐D and Ca‐Abs by pooling data from 439 Ca‐Abs measurements over a 15 yr period at our center in 251 healthy children 4.9 to 16.7 yrs of age. Serum 25‐D ranged from 28 to 197 nmol/L (Mean 85 nmol/L). Ca‐Abs was correlated to 25‐D in the whole population, r = 0.16, p = 0.001. This relationship was closer in the 197 studies in early puberty (Tanner 2 or 3), r = 0.35, p < 0.001. We found no close relationship between Ca‐Abs and 25‐D in the 206 studies in which 25‐D was <80 nmol/L (r= 0.08, p = 0.24), including the 113 studies conducted in early puberty (r = 0.002, p = 0.98). In early puberty, Ca‐Abs was 111 ± 21 mg/d (SEM) greater in studies in which 25‐D was >80 nmol/L compared to those in which it was <80 nmol/L. This difference was not seen in prepubertal (Tanner 1) or postpubertal (Tanner 4 or 5) subjects. Improving vitamin D status may have limited effects on Ca‐Abs in healthy children except when 25‐D >80 nmol/L is achieved during early puberty.