The review, published in The Cochrane Library, concludes that supplementation with vitamin D does not improve bone density in the general population of children, but may have benefits for those with very low vitamin D status.
"Vitamin D supplementation had no statistically significant effects on bone density at any site in healthy children. There was, however, some indication that children who had low levels of vitamin D in their blood might benefit from supplementation," said study leader Dr Tania Winzenberg, of the Menzies Research Institute, Tasmania.
Fragile bones
Osteoporosis is characterised by low bone mass and deterioration of bone tissues, leading to high bone fragility and an increased risk of fracture.
Low bone mineral density is a major risk factor for osteoporosis. Previous studies have suggested that up to 90 per cent of bone mass is built during childhood, and increasing bone mass in childhood is seen as a potential way to reduce the impact of osteoporosis
“It is estimated that a 10 per cent increase in peak bone mass reduces the risk of an osteoporotic fracture in adult life by 50 per cent,” stated the researchers.
Vitamin D is known to improve calcium deposition in bones, and previous research has suggested children with vitamin D deficiency have reduced bone density.
“By measuring bone density, you can assess how well an intervention such as vitamin D supplementation improves bone health,” said Dr Winzenberg.
The new Cochrane review assessed the results of six high quality trails looking at vitamin D supplementation and bone density in children, investigating
No effect
The authors reported vitamin D supplementation to have no statistically significant effects on, hip bone, forearm, or whole body bone mineral density. However, a small but statistically insignificant trend was found lumbar spine bone mineral density.
Researchers also found “a trend towards a larger effect with low vitamin D for total body bone mineral concentration”, indicating that low vitamin D status trails reported significant effects on total body bone density and lumbar spine bone density from vitamin D supplementation.
Talking to NutraIngredients, Dr Winzenberg outlined two key findings to take from the review. “Firstly, there is reasonable evidence that giving vitamin D supplements to a general population does very little in terms of bone density.”
“But secondly, if we look at a specific group like deficient children, then the indications are that groups with lower status could see some benefits. But as it stands, the evidence is not good enough to make firm conclusions.”
Further work
Commenting independently on the review, Dr. Ailsa Welch, from the University of East Anglia told NutraIngredients.com that the effects of vitamin D hinge on the baseline status: “If your status is already adequate, then the authors found no effect. But there needs to be more work done to determine the effects in low status children.”
Welch added that she believed the research was “very useful”, and said that the work “points to the need for further research in children.”
Andrew Shao, Ph.D, Senior Vice President of Scientific & Regulatory Affairs for the Council for Responsible Nutrition (CRN) highlighted that the authors “had very little data to work with, because there are very few studies in children.”
“Right from the start the researchers are restricted in terms of participants – there just aren’t enough studies in children to give a conclusive answer on the subject,” added Shao.
Shao also pointed out the “many other health benefits associated with vitamin D”, and stated that the findings of any study on vitamin D “should not overlook the fact that a lot of people – including children – have inadequate vitamin D status, or are fully deficient.”
Dr Winzenberg confirmed that the evidence is “pretty strong […]to suggest that research with deficient children is a promising area,” but added that “there is no suggestion that supplementing the entire population would be a good idea.”
Source: Cochrane Database of Systematic Reviews
Issue 10, Article Number: CD006944, doi: 10.1002/14651858.CD006944.pub2.
“Vitamin D supplementation for improving bone mineral density in children”
Authors: T.M. Winzenberg, S. Powell, K.A. Shaw, G. Jones