Vitamin D only strengthens bone in those with significant vit D deficiency
The results of the study - carried out by researchers at the University of Auckland, New Zealand, and Harvard Medical School, Boston, MA - were announced today by Professor Ian R. Reid at ECTS 2017, the 44th European Calcified Tissue Society Congress being held in Salzburg, Austria.
Professor Reid said: "We know that severe vitamin D deficiency causes osteomalacia, yet trials in the community have not consistently shown that vitamin D supplements improve older adults' bone density or reduce the risk of fracture. So we set out to determine whether a higher dose of vitamin D influences bone density or whether benefit is dependent on the level of vitamin D already present in the individual.
"The study was part of a bigger trial among community-resident adults aged 50-84 years and followed 418 participants for two years, who were randomized to receive, monthly, either high oral doses of vitamin D or a placebo. We were looking at changes over time to bone density in their lower spines, primarily, and in other commonly tested sites on the body.
the findings represent a significant step towards defining vitamin D deficiency for bone health in older adults
Professor Ian R. Reid
"We were also testing thresholds in the levels of vitamin D already present in the participants and found that that level was significant when it came to the effect of the vitamin D treatment. There was a certain threshold (of 30 nmol 25-hydroxyvitamin D per litre) where, for those above the threshold, there was no real change in bone density for those receiving the treatment, compared to those receiving the placebo, while for those at or below the threshold, the change in bone density was around 2%.
Professor Reid concluded: "It was clear to us that future trials of vitamin D supplements in older adults should focus on those who have baseline vitamin D levels equal to or below 30 nmol per litre and that the findings represent a significant step towards defining vitamin D deficiency for bone health in older adults."
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Notes for editors
About the study
It is a sub-study of ViDA (the Vitamin D Assessment Study), a randomised control trial which recruited community-resident adults aged 50-84 years. 452 entered the sub-study and 418 completed 2 years. Participants were randomized to receive oral vitamin D3 in an initial dose of 200,000 IU, followed by monthly doses of 100,000 IU, or placebo, for 2 years. The primary endpoint was change in lumbar spine BMD, with other BMD sites as secondary endpoints. Exploratory analyses to identify thresholds of baseline 25-hydroxyvitamin D for vitamin D effects on BMD were pre-specified.
Intention-to-treat analyses showed no significant treatment effect in the lumbar spine (between-groups difference 0.6%) or total body but BMD loss at both hip sites was significantly attenuated over 2 years by about Â½%. There was a significant interaction between baseline 25-hydroxyvitamin D and treatment effect (P=0.04). In participants with baseline 25-hydroxyvitamin D ≤30 nmol/L (n=46), there were between-groups BMD changes at the spine and femoral sites of ~2%, significant in the spine and femoral neck. When baseline 25-hydroxyvitamin D levels were >30 nmol/L, between-groups BMD differences were ~Â½% and significant only at the total hip.
The study concluded that the primary analysis does not demonstrate a clinically important benefit to BMD from untargeted vitamin D supplementation of older community-dwelling adults, but exploratory analyses suggest meaningful benefit in those with baseline 25-hydroxyvitamin D ≤30 nmol/L, suggesting that any future trials should focus on this group. These findings represent a significant step towards a trial-based definition of vitamin D deficiency for bone health in older adults.
ECTS 2017 is the 44th European Calcified Tissue Society Congress, held from 13 to 16 May 2017 in the Austrian city of Salzburg.
ECTS serves as a forum for researchers and clinicians working in the musculoskeletal field to join forces, discover and discuss the latest advances and controversies in research and in the daily care of patients.
The European Calcified Tissue Society (ECTS) is the major organisation in Europe for researchers and clinicians working in the field of calcified tissues and related fields. ECTS acts as a forum for the dissemination of high quality research through its annual meeting, the European Symposium on Calcified Tissues, and through training courses and workshops.
Calcified tissues are central to a healthy skeleton and to bone disorders - such as osteoporosis, back pain and fractures - that make life a misery for countless people. Children can inherit some forms of bone diseases causing bone pain, shortness and deformed limbs.
For further information please contact
Roberta Mugnai, ECTS executive director
Tel: + 32 476 520 716
ECTS 2017: http://ects2017.org
Event hashtag: #ECTS2017 http://bit.ly/ECTS17-vitD
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