Vitamin D supplements do not improve bone density, study finds
Authors recommend clinical guidelines on vitamin D supplements should be changed
Vitamin D supplements have long been recommended for older people to treat or prevent osteoporosis.
Taking Vitamin D supplements does not prevent fractures, falls or improve bone mineral density a study has found.
The study is the largest meta-analysis to date and includes data from 81 randomised controlled trials published in The Lancet Diabetes and Endocrinology journal.
Vitamin D supplements have long been recommended for older people to treat or prevent osteoporosis, with some early evidence suggesting benefits for bone health.
However, recent large-scale reviews have reported no effect of vitamin D supplementation on bone mineral density, falls or fractures.
The authors say that clinical guidelines that continue to recommend vitamin D supplementation for bone health should be changed to reflect the best available evidence.
The study also found there were no differences in the effects of higher versus lower doses of vitamin D.
The authors conclude there is little justification to use vitamin D supplements to maintain or improve musculoskeletal health.
But the vitamin can help in the prevention of rare conditions such as rickets and osteomalacia in high risk groups, which can occur due to vitamin D deficiency after a prolonged lack of exposure to sunshine.
The authors said since the last major review of evidence in 2014, more than 30 randomised controlled trials on vitamin D and bone health have been published, nearly doubling the evidence base available.
Lead author Dr Mark J Bolland of the University of Auckland, New Zealand said their meta-analysis finds that vitamin D does not prevent fractures, falls or improve bone mineral density, whether at high or low dose.
“Clinical guidelines should be changed to reflect these findings. On the strength of existing evidence, we believe there is little justification for more trials of vitamin D supplements looking at musculoskeletal outcomes,” he said.
In the study, the authors pooled data from 81 randomised controlled trials. There was no clinically meaningful effect of vitamin D supplementation on total fracture, hip fracture, or falls.
There was reliable evidence that vitamin D does not reduce total fractures, hip fractures, or falls by 15 per cent,a clinically meaningful threshold.
Even when lower thresholds were assessed, there was still reliable evidence that vitamin D does not reduce falls by 7.5 per cent and total fractures by 5 per cent.
In secondary analyses looking at bone density, there were small differences for lumbar spine, femoral neck, and for total body, but none of these were clinically relevant.
The authors noted that the data was collected differently for falls in different trials, which might affect the study findings.
While the authors rated all trials for risk of bias, there were limitations in some of the trials.
Additionally, they noted that smaller trials of shorter duration tended to find stronger effects of vitamin D compared to larger trials of longer duration.
Study author J Chris Gallagher of Creighton University Medical Centre, said many patients and doctors have been persuaded by various studies and social media “that vitamin D is a cure-all”.
“This thinking is reminiscent of the fervour that supported the widespread use of vitamin A, vitamin C, and vitamin E years ago, and all of those vitamin trials later proved to be clinically negative,” said Mr Gallagher.
He said future studies may show what the extra-skeletal benefits of vitamin D are.
“Within three years, we might have that answer because there are approximately 100,000 participants currently enrolled in randomised, placebo-controlled trials of vitamin D supplementation. I look forward to those studies giving us the last word on vitamin D,”he said.