Bone mineral contents and plasma osteocalcin concentrations of Gambian children 12 and 24 mo after the withdrawal of a calcium supplement.
BACKGROUND
Our randomized, placebo-controlled supplementation study of 160 rural Gambian children aged 8.3-11.9 y showed that an increase in calcium intake of 714 mg/d for 12 mo resulted in a 5% increase in forearm bone mineral acquisition and a 22% decrease in plasma osteocalcin concentration, a bone formation marker, but had no effect on height or bone dimensions.


OBJECTIVE
We investigated whether these results were sustained after supplement withdrawal.


METHODS
All participants were followed up 12 (FU1) and 24 (FU2) mo after supplementation ended. Bone mineral content (BMC), bone mineral density (BMD), and BMC adjusted for bone width, body weight, and height (size-adjusted BMC) were measured at the midshaft and distal radius. Plasma osteocalcin concentration was measured at FU1.


RESULTS
At follow-up, the calcium group had greater bone mineral status than did the placebo group at the midshaft radius (mean difference +/- SE), FU1: BMC (4.7 +/- 1.6%; P = 0.004), BMD (5.1 +/- 1.1%; P </= 0.0001), size-adjusted BMC (5.0 +/- 1.1%; P </= 0.0001); FU2: BMC (3.8 +/- 1.6%; P = 0.02), BMD (2.7 +/- 1.3%; P = 0.04), size-adjusted BMC (2.5 +/- 1.3%; P = 0.06). Similar differentials were observed at the distal radius but were not significant. No significant differences in plasma osteocalcin concentrations (FU1: -0.5 +/- 6.5%; P = 0.9) were observed between groups.


CONCLUSIONS
Although some of the effects of calcium supplementation were still evident at follow-up, further studies are required to determine whether short-term increases in calcium intake have lasting benefits for Gambian children.
MRC Keneba, The Gambia. bakjd@hotmail.com
Bakary
B
Dibba
Ann
A
Prentice
Mustapha
M
Ceesay
Michael
M
Mendy
Sainabou
S
Darboe
Dorothy M
DM
Stirling
Tim J
TJ
Cole
Elizabeth M E
EM
Poskitt
D001827:Body Height; D001835:Body Weight; D015519:Bone Density; D002136:Calcium, Dietary / Q000008:administration & dosage*; D002648:Child; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D005714:Gambia; D006801:Humans; D008297:Male; D008572:Menarche; D015675:Osteocalcin / Q000097:blood*; D010919:Placebos; D011627:Puberty; D011884:Radius; D012424:Rural Population
D002136:Calcium, Dietary; D010919:Placebos; D015675:Osteocalcin