Meta-Analysis Queries Widespread Vitamin D Supplementation

11 Oct 2013 --- Taking vitamin D supplements does not improve bone mineral density at the total hip, spine, forearm, or in the body as a whole, a large meta-analysis involving more than 4,000 healthy adults published in The Lancet has found. With close to half of adults aged 50 and older using vitamin D supplements, the authors conclude that continuing widespread use of these supplements to prevent osteoporosis in healthy adults is needless.

"Most healthy adults do not need vitamin D supplements", explains study leader Professor 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 healthcare."

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

Analysis of data from 23 studies involving 4082 healthy adults (average age 59 years) did not identify any effects for people who took vitamin D for an average period of 2 years, apart from a small but statistically significant increase in bone density (0.8%) at the femoral neck. According to the authors, such a localised effect is unlikely to be clinically significant.

The authors conclude, "This systematic review provides very little evidence of an overall benefit of vitamin D supplementation on bone density…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."

Writing in a linked Comment, Clifford J Rosen from the Maine Medical Research Institute in the USA discusses how our recent understanding of vitamin D lends support to these findings, confirming that, "Supplementation to prevent osteoporosis in healthy adults is not warranted. However, maintenance of vitamin D stores in the elderly combined with sufficient dietary calcium intake (800–1200 mg per day) remains an effective approach for prevention of hip fractures."

In response to the study, Duffy MacKay, N.D., vice president, scientific and regulatory affairs, at the Council for Responsible Nutrition (CRN) said: “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. 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. We have concerns that the author’s broad-based advice will do nothing but cause potentially dire consequences if people, particularly those at-risk for fracture, fail to obtain the recommended daily intake of vitamin D.

We feel just as strongly that this meta-analysis not discourage healthy people from taking vitamin D for all the possible benefits. Beyond osteoporosis and bone health, vitamin D provides extensive benefits in other areas. The body of scientific literature, including new and emerging research, shows vitamin D plays an important role in cardiovascular health, immune health and diabetes; therefore, it is vital that doctors and other healthcare practitioners continue to test vitamin D levels. Because vitamin D is not easily obtained from food, and obtaining it through sunlight carries cancer risks, replenishing through supplementation is a safe and appropriate way to get vitamin D.

The Institute of Medicine recommends dietary intake for adults of 600-800 IU of vitamin D and 1000-1300 mg of calcium daily, and the 2010 Dietary Guidelines for Americans identifies supplements containing combinations of certain nutrients such as calcium and vitamin D as useful in postmenopausal women who have low levels of these nutrients in their diets to reduce the risk of osteoporosis. In addition, the Food and Drug Administration has an approved health claim for calcium, vitamin D and osteoporosis.

Osteoporosis-related fractures in the U.S. cost an estimated $14 billion in 2012. They also place tremendous financial, mental and physical burdens on the individual. A new economic report from Frost and Sullivan found that over $12 billion in cumulative osteoporosis-attributed cost savings is potentially realizable, between 2013 and 2020, if U.S. women over the age of 55 diagnosed with osteoporosis were to use calcium and vitamin D dietary supplements at what the report identified as preventive intake levels. The daily cost per person in the targeted population to supplement would be $.16—not ‘expensive’ compared to the costs one, or the overall system, would incur if appropriate levels of vitamin D were not met. Supplementation is smart prevention.