Do cardiometabolic risk factors mediate the relationship between body composition and bone mineral content in South Indian children aged 5 to 16 years?

Background/objective: The complex interplay between adiposity, bone health and cardiometabolic risk (CMR) factors is unclear in Indian children. We aimed to investigate the mediating role of number of CMR factors on the relationship between fat % and bone mineral content (BMC) % in South Indian children aged 5-16 years.

Subjects and methods: Healthy children (n = 317), from India, underwent anthropometric, blood biochemistry, blood pressure, along with body composition and BMC assessments using Dual-energy X-ray absorptiometry. Based on the number of CMR factors, children were categorised into three groups: 0, 1 and ≥ 2. Analysis of variance was used to compare the parameters between the CMR groups and mediation analysis was performed to examine if the number of CMR factors mediated the relationship between fat % and BMC %.

Results: The prevalence of 0, 1 and ≥ 2 CMR factors was 42.3%, 33.9% and 23.9% respectively; mean BMC % was lowest in ≥ 2 CMR group. In the whole group, BMC % had significant negative correlation with fat % (r = -0.68, p < 0.0001) and positive correlation with lean % (r = 0.64, p < 0.0001). Adjusted for age and sex, results suggested significant mediating effect of number of CMR factors on the relationship between fat % and BMC % (Average Causal Mediation Effects =-0.002, bootstrapped 95% CI: -0.0039, -0.0001, p < 0.01), but losing significance when adjusted for co-variates.

Conclusion: Number of CMR factors mediates the relationship between fat % and BMC % in Indian children. Further studies are needed to confirm these findings, understand mechanisms and plan appropriate strategies.