Vitamin D supplementation is unlikely to offer any health benefits
Supplementation with vitamin D does not prevent heart attack, stroke, cancer, or bone fractures and is therefore unlikely to offer any health benefits, according to a meta-analysis published in The Lancet today (24 January 2014). Furthermore, data from future trials are unlikely to change these conclusions, say the researchers.
The team, from the University of Auckland, New Zealand, performed a traditional meta-analysis followed by a trial sequential analysis of 40 existing randomised controlled trials. They found that supplementation with vitamin D or vitamin D with calcium does not reduce instances of myocardial infarction, ischaemic heart disease, stroke or cerebrovascular disease, or cancer by 15 per cent or more in participants living in the community.
Vitamin D with calcium did reduce the incidence of hip fractures in two trials involving elderly nursing home residents. In a comment accompanying the study, Karl Michaëlsson, of the Department of Surgical Sciences, Uppsala University, Sweden, attributed this to the fact that elderly nursing home residents probably have “lower serum concentrations of 25-hydroxyvitamin D [vitamin D] combined with a low calcium intake”.
However, it was uncertain whether vitamin D alone increased hip fracture incidence or had no effect. Overall, the authors concluded that vitamin D, with or without calcium, did not decrease total fracture or hip fracture by 15 per cent or more in participants living in the community.
The researchers also say that there was uncertainty as to whether vitamin D, with or without calcium, reduces the risk of death, using a risk reduction threshold of 5 per cent.
The trial sequential analysis indicated that findings from future studies with a similar design to those examined, or that differ only by dose of vitamin D, are unlikely to alter the results of the meta-analysis.
Professor Michaëlsson suggested: “Without stringent indications—ie, supplementing those without true insufficiency—there is a legitimate fear that vitamin D supplementation might actually cause net harm.”
Citation: The Pharmaceutical Journal DOI: 10.1211/PJ.2014.11133309
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