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Appendicular bone mass in children with a high prevalence of low dietary calcium intakes
1Department of Paediatrics, University of the Witwatersrand, Johannesburg, South Africa.
Insights
Low dietary calcium intake negatively impacts bone density in rural South African children. This study found lower bone mineral density and apparent density in children with calcium deficiency and elevated alkaline phosphatase (ALP).
Area of Science:
- Pediatric Nutrition
- Bone Health Research
- South African Public Health
Background:
- Previous studies identified dietary calcium deficiency in rural South African black children.
- Bone mass assessment is crucial for understanding long-term skeletal health in pediatric populations.
Purpose of the Study:
- To determine appendicular bone mass in children with documented dietary calcium deficiency.
- To compare bone mass with a control group of children without calcium deficiency.
- To identify factors influencing bone mass, including biochemical markers and anthropometrics.
Main Methods:
- A random sample of 306 boys and 345 girls (ages 1-20) from a rural South African community were studied.
- Bone mineral density (BMD), bone mineral apparent density (BMAD), and bone width (BW) of the distal radius were measured.
- Serum calcium and alkaline phosphatase (ALP) levels were assessed and correlated with bone measurements.
Main Results:
- Children with dietary calcium deficiency exhibited significantly lower BMD and BMAD, and greater BW compared to controls, after adjusting for age, weight, and height.
- Hypocalcemia (low serum calcium) and elevated ALP were prevalent in the study group.
- Serum calcium positively correlated with bone mineral content (BMC) and BMD, while ALP showed a negative correlation.
Conclusions:
- Low dietary calcium intake appears detrimental to appendicular bone density in rural black children.
- Biochemical markers like serum calcium and ALP are significant predictors of bone mass.
- Long-term implications of these findings on skeletal health require further investigation.
Abstract:
We have previously documented evidence of dietary calcium deficiency in black children living in a rural community in the eastern part of South Africa. The present study determined the bone mass of the distal one-third of the radius in a random sample of children living in the same community and compared their bone mass measurements with those of black children living in a similar rural community but without evidence of dietary calcium deficiency. Further, factors (weight, height, serum corrected total calcium, phosphorus, and alkaline phosphatase [ALP]) that might influence appendicular bone mass were assessed and correlated with the bone mass measurements. A random sample of 306 boys and 345 girls between the ages of 1 and 20 years were included in the study. Hypocalcemia was found in 6.5% of the boys and 5% of the girls, while elevated ALP values were recorded in 20 and 26% of the boys and girls, respectively. After adjusting for differences in age, weight, and height, bone mineral density (BMD) and bone mineral apparent density (BMAD) were significantly lower and bone width (BW) greater in study than control children. In a stepwise regression analysis, weight and/or height accounted for the majority of the observed variance in BMC, BW, and BMD; however, a significant effect of serum calcium (positively) and ALP (negatively) on BMC and BMD was also found. In boys, but not girls, serum ALP also had a positive effect on BW.BMAD was negatively correlated to ALP and positively correlated to serum calcium in both boys and girls. Those children with hypocalcemia or elevated ALP levels had significantly lower BMC, BMD, and BMAD and a trend toward greater BW than children with normal biochemistry. The findings suggest that low dietary calcium intake may have a detrimental effect on appendicular bone density in rural black children. Whether or not these effects are disadvantageous in the long-term is not known.