CRN and NPA: Faulty vitamin D meta-analysis only looks at half of the supplement equation

WASHINGTON — Two associations representing the dietary supplement industry issued separate statements in response to what they characterized as a faulty meta-analysis, “Effects of Vitamin D Supplements on Bone Mineral Density: A Systematic Review and Meta-Analysis,” published last week in The Lancet.

"Most healthy adults do not need vitamin D supplements," concluded study leader Ian Reid from the University of Auckland in New Zealand. "Our data suggest that the targeting of low-dose vitamin D supplements only to individuals who are likely to be deficient could free-up substantial resources that could be better used elsewhere in health care."

Reid and colleagues from the University of Auckland conducted a systematic review and meta-analysis of all randomized trials examining the effects of vitamin D supplementation on bone mineral density in healthy adults up to July 2012.

"This systematic review provides very little evidence of an overall benefit of vitamin D supplementation on bone density," Reid wrote. "Continuing widespread use of vitamin D for osteoporosis prevention in community-dwelling adults without specific risk factors for vitamin D deficiency seems to be inappropriate."

But Reid and fellow researchers may have only looked at half of the supplement equation, the associations noted. “The scientific literature supports that vitamin D is necessary for calcium absorption and bone density, and therefore the two nutrients work in combination to provide a protective effect for helping to prevent osteoporosis," stated Duffy MacKay, VP scientific and regulatory affairs for the Council for Responsible Nutrition. "One of the serious limitations of this meta-analysis was the lack of consideration of studies that looked at how vitamin D and calcium work together. For populations that are most vulnerable to vitamin D deficiencies and insufficiencies — especially older adults — getting vitamin D from food alone is particularly challenging, and so supplementation may be warranted."

"The beneficial effect of vitamin D and calcium is due to the fact they work in tandem, and examining the outcomes of just vitamin D caused the researchers to start with a weak premise," added Cara Welch, SVP scientific and regulatory affairs for the Natural Products Association. "In fact, the Food and Drug Administration has an approved health claim for vitamin D and calcium regarding osteoporosis."