A new study involving nearly 9,000 children deficient in Vitamin D found that supplementing children’s diets with Vitamin D had very little impact on the strength of a child’s bones or the number of fractures they had.

The findings, which the researchers describe as ‘striking’, are published in the Lancet Diabetes & Endocrinology and will likely have implications for policymakers and healthcare workers.

Childhood fractures are a major global health issue, with approximately a third of all children fracturing a bone before the age of 18. Early bone fractures can lead to lifelong disability and subsequent poor quality of life. Vitamin D is thought to promote bone mineralisation and thus aid in preventing bone fractures; however, no previous clinical trials have tested whether Vitamin D supplements can prevent breaks.

Researchers from the Queen Mary University of London and the Harvard T.H. Chan School of Public Health identified a population of children in Mongolia where young people have both high levels of Vitamin D deficiency and an increased incidence of bone fractures.

Working with research partners in Mongolia, 8,851 school children aged six to 13 were given weekly Vitamin D supplements for three years, making this the largest randomised controlled trial of vitamin D supplementation ever conducted in children.

Using ultrasound measurements, the researchers were able to get quantitative results of bone strength and fracture risk in a subset of 1,438 children. They found that supplementation had little effect on the rate of fractures or bone strength. The supplementation was, however, highly efficient at reducing Vitamin D deficiency in all children.

Dr Ganmaa Davaasambuu, associate professor at the Harvard T.H. Chan School of Public Health, said: ‘The absence of any effect of sustained, generous vitamin D supplementation on fracture risk or bone strength in vitamin D deficient children is striking. 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.’

The researchers cautioned that the findings should not be applied to children diagnosed with rickets.

Professor Adrian Martineau, from Queen Mary University, added: ‘It is also important to note that children who were found to have rickets during screening for the trial were excluded from participation, as it would not have been ethical to offer them placebo. Thus, our findings only have relevance for children with low vitamin D status who have not developed bone complications. The importance of adequate vitamin D intake for prevention of rickets should not be ignored, and UK government guidance recommending a daily intake of 400 IU vitamin D remains important and should still be followed.’

It is hoped the trial will prompt scientists, doctors and public health specialists to re-consider the effects of vitamin D supplements on bone health.

This article was first published by our sister title Nursing in Practice