- Ingrid Torjesen
- London, UK
Vitamin D supplementation does not prevent fractures or falls, or have any clinically meaningful effects on bone mineral density, a large meta-analysis has found.1 The authors concluded there “is little justification to use vitamin D supplements to maintain or improve musculoskeletal health,” as is currently recommended by Public Health England (PHE).
In July 2016, PHE issued guidance that the general population should consider taking a daily supplement containing 10 mg of vitamin D during the autumn and winter as people may not get enough of the vitamin through sunlight on the skin and diet.2
This recommendation coincided with the publication of a report by the Scientific Advisory Committee on Nutrition that concluded that everyone over the age of one year should consume 10 mg of vitamin D daily.3
The findings of the new meta-analysis, published in Lancet Diabetes and Endocrinology, now question the benefits of taking vitamin D supplements.
The authors reviewed 81 randomised controlled trials (n=53 537 participants) assessing the health effects of vitamin D supplementation published before 26 February 2018.
Pooled analyses showed that vitamin D supplementation had no effect on total fracture (36 trials; n=44 790; relative risk (RR) 1.00; 95% confidence interval (CI), 0.93 to 1.07), hip fracture (20 trials; n=36 655; RR 1.11; 95% CI, 0.97 to 1.26), or falls (37 trials; n=34 144; RR 0.97; 95% CI, 0.93 to 1.02).
Vitamin D supplementation made no clinically relevant difference to bone mineral density at any site (range −0.16% to 0.76% over 1 to 5 years).
Results were similar in randomised controlled trials of high dose versus low dose vitamin D and in subgroup analyses of randomised controlled trials using doses greater than 800 IU per day.
The authors concluded, “Vitamin D supplementation did not have meaningful effects on fracture, falls, or bone mineral density, and future trials are unlikely to alter these conclusions. Therefore, there is little justification for the use of vitamin D supplements to maintain or improve musculoskeletal health, and clinical guidelines should reflect these findings.”
They considered the only exception was vitamin D supplementation for the prevention or treatment of rickets and osteomalacia, which can occur after a prolonged lack of exposure to sunshine that leads to 25-(OH)D concentrations lower than 25 nmol/L.
“More than half of the trials reported a mean baseline 25-(OH)D concentration of less than 50 nmol/L, a cut-off often considered to indicate vitamin D insufficiency,” the study authors said, but they conceded that trials of populations with low baseline 25-(OH)D levels might produce different results, and that only four trials, involving a total of 831 participants, had baseline levels less than 25 nmol/L.
Commenting on the findings, Adrian Martineau, clinical professor of respiratory infection and immunity at Queen Mary University of London said PHE’s recommendations “are designed specifically to elevate vitamin D levels out of the deficient range” of <25 nmol/L. “Achieving this target in the whole UK population would save lives by preventing the most extreme manifestations of vitamin D deficiency (seizures and heart failure in infants), which occur every year in the UK,” he said. “The findings of the new paper do not provide any reason to revisit or reconsider this sound advice.”
While the meta-analysis included all available trials of vitamin D, these trials included too few participants, used an insufficient dose of vitamin D, and had an insufficient duration of treatment, said Robert Clarke, professor of epidemiology and public health, University of Oxford. “It is too soon to suggest making changes to health recommendations on vitamin D for bone health based on this study,” he said. “We should wait until the results of the five ongoing trials of vitamin D, involving a total of 57 000 adults, that will be available in the next year or so.”