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LONDON — Vitamin D supplements do not increase bone strength or prevent bone fractures in children with the vitamin deficiency, claims a major clinical trial of over 8,000 kids.
Around one-third of children have at least one fracture before the age of 18. This is a major global health issue, as childhood fractures can lead to life years of disability and/or poor quality of life.
The findings, published in The Lancet Diabetes & Endocrinology, challenges widely held perceptions relating to the effects of vitamin D on bone health.
"The absence of any effect of sustained, generous vitamin D supplementation on fracture risk or bone strength in vitamin D deficient children is striking," said Dr Ganmaa Davaasambuu, Associate Professor at the Harvard T.H. Chan School of Public Health.
“In adults, vitamin D supplementation works best for fracture prevention when calcium is given at the same time -- so the fact that we did not offer calcium alongside vitamin D to trial participants may explain the null findings from this study,” Davaasambuu added.
Researchers from Queen Mary University of London and the Harvard T.H. Chan School of Public Health conducted the trial on children from Mongolia -- a setting with a particularly high fracture burden and where vitamin D deficiency is highly prevalent.
Over the course of three years, 8,851 schoolchildren aged 6-13 living in Mongolia received a weekly oral dose of vitamin D supplementation.
About 95.5 per cent of participants had vitamin D deficiency at baseline, and study supplements were highly effective in boosting vitamin D levels into the normal range.
However, they had no effect on fracture risk or on bone strength, measured in a subset of 1,438 participants using quantitative ultrasound.
The findings are likely to prompt scientists, doctors and public health specialists to re-consider the effects of vitamin D supplements on bone health.