Effect of calcium and vitamin D on growth, rickets and Kashin-Beck disease in 0- to 5-year-old children in a rural area of central Tibet.

Objective To evaluate the effect of calcium (15 mmol/day) and vitamin D (625 µg/month) as single supplement or in combination versus no supplement on growth clinical signs of rickets and Kashin-Beck disease (KBD) and dental health. Methods Prospective controlled trial involving children aged 0-5 years living in 4 groups of villages in a KBD-endemic rural area of Central Tibet who received either calcium and/or vitamin D or no supplement. The cohort was followed over 3 years. Primary outcome was the impact of the different supplementation regimes on KBD rickets and growth; secondary outcomes were impact on urinary levels of calcium and phosphorus biomarkers of bone and cartilage turnover and dental health. Results No difference was observed between the 4 groups with regard to anthropometric data rickets KBD urinary levels of Croslaps® and Cartilaps®. Weight for height or age mid-upper arm circumference and skin fold thickness decreased in the 4 groups. Height for age increased and the prevalence of KBD fell in the four groups. Dental health was better in the group receiving calcium and vitamin D. Urinary calcium levels increased after 3 years of follow-up in all groups; the group receiving vitamin D had a higher increase (p-value: 0044). The same global increase was observed for urinary phosphorus levels; the group receiving calcium had a higher increase (p-value: 001). Conclusions Calcium and vitamin D failed to improve growth and bone metabolism of children living in a KBD-endemic rural area. Calcium and vitamin D supplementation improved dental health.