Bone mineral density in Nigerian children after discontinuation of calcium supplementation.

BACKGROUND

Nigerian toddlers with low dietary calcium intakes increased forearm bone mineral density (BMD) after 18 months of calcium supplementation compared with placebo. However, it is not known if this bone mineral accretion is sustained after calcium supplement withdrawal. We therefore investigated the influence of prior calcium supplementation on forearm BMD 12 months after withdrawal of the supplement.

METHODS

Nigerian toddlers aged 12-18 months from three urban communities were enrolled in a controlled trial of calcium supplementation. Two communities received daily calcium supplements, one as calcium carbonate (400mg), and the other as ground fish (529±109 mg), for a duration of 18 months, and all three communities received vitamin A (2500 IU daily) as placebo. Forearm BMD was measured 5 times during 18 months of calcium supplementation and at 12 months after supplement withdrawal.

RESULTS

Of 647 children enrolled, 390 completed the trial of calcium supplementation and 261 of these returned for the final follow-up 12 months after discontinuation of supplementation. During the 18 months of supplementation, an adjusted model demonstrated that the increase in both distal and proximal forearm BMD over time was significantly greater in the calcium supplemented groups than in the placebo group (P<0.04). However, after supplement withdrawal, the increase in BMD over time was largely attenuated and only remained significant at the proximal forearm in the ground fish group (P=0.03).

CONCLUSION

The benefit of calcium supplementation on forearm BMD in young Nigerian children is not sustained after supplement withdrawal.