New Vitamin D Evidence New Vitamin D Evidence
National Office of Dietary Supplements
A new evidence report on vitamin D and bone health reviews the current scientific evidence and identifies its strengths and weaknesses. This report will be a valuable resource for an upcoming National Institutes of Health conference September 5-6 that will examine a range of scientific perspectives related to vitamin D and bone health across the lifecycle.
“This independent, systematic review is timely because there are mixed messages and recommendations to consumers regarding the benefits and harms of vitamin D intake” said NIH Office of Dietary Supplements (ODS) Director, Paul M. Coates, Ph.D. He added, “The evidence report in combination with the conference presentations and discussions, newly available methodological tools, and newer information on the vitamin D status of the US population will provide an invaluable and very timely update for the research and public health communities of what we know and what we need to know for this key nutrient.”
Researchers have long known that vitamin D had an impact on bone health but there is uncertainty about how much vitamin D is needed to achieve optimal bone health and whether there are differences in the relationship of vitamin D status to bone health across age and life stage groups. This report highlights the fact that the largest amount of evidence for bone health benefits is in postmenopausal women and older men (the majority over 60 years of age) taking vitamin D supplements. This report also confirms that vitamin D from ultraviolet-B (sunlight) exposure, fortified foods, or dietary supplements are all effective in raising the level of circulating vitamin D. Of concern, there were only sparse data on other subgroups cited as being at high risk for the consequences of low vitamin D, such as dark-skinned individuals and pregnant and lactating women.
The report found it difficult to define specific blood levels of markers for vitamin D status that indicate optimal levels for bone health. One reason for this is that current methods, which measure serum-25-hydroxy vitamin D as the marker for vitamin D status, yield highly inconsistent results. As part of its broader vitamin D initiative, ODS is working with laboratory testing facilities to standardize the quantification of vitamin D status.
The report investigators were not able to separate the impact of vitamin D from that of calcium, as most trials studied the effect of vitamin D plus calcium. The combination of vitamin D3 (daily dose 700 to 800 IU) and calcium (daily dose 500 to1200 mg) decreased the risk of falls, fractures and bone loss in the elderly (ages ranged from 62 to 85 years). The current recommended intake is 400 IU/day for people 51-70 years of age, and 600 IU/day for people over 70 years of age. Based on the combined data of two trials, the decreased risk of fractures was seen primarily in the subgroup of elderly women (average age 85 years) living in nursing homes.
Vitamin D intake above current recommended levels was not reported to be associated with an increased risk of harms. However, most trials using higher doses of vitamin D were not adequately designed to assess potential harms.
“The vitamin D and bone health evidence report provides valuable insights because it is based on an independent and rigorous examination of the totality of evidence across all age groups and during pregnancy and lactation,” said Agency for Healthcare Research and Quality (AHRQ) Director Carolyn Clancy, M.D. “It Is important that health care decisions are made using a review of all available evidence and not solely on the results of individual study reports.”
This report will serve as the framework for a conference, Vitamin D and Health in the 21st Century: An Update, September 5-6, 2007 on the NIH campus. Although the conference is free of charge and open to the public, attendees are requested to register at http://vitamindandhealth.od.nih.gov, where additional conference materials are available. Speakers will present the salient points of emerging research since the 2003 NIH Vitamin D conference, including the AHRQ evidence report, Effectiveness and Safety of Vitamin D in Relation to Bone Health. The goals of the conference are to evaluate the efficacy and safety of vitamin D, identify gaps in knowledge on the efficacy and safety of vitamin D, inform NIH and other Federal agencies on vitamin D and health research priorities, and to disseminate the conference findings to the broad scientific nutrition community