The results of the randomized, multiple-dose study, published in the Journal of the American Geriatrics Society, did not show a dose-dependent dose, but at the highest dose (800 mg) only 20 per cent of the group suffered falls, compared to 44 per cent in the placebo group.
"Ensuring that nursing home residents are receiving adequate daily supplemental vitamin D may reduce the number of falls in elderly nursing home residents and could potentially reduce the risk of fracture in this high-risk group," wrote lead author Kerry Broe from the Institute of Aging and Boston-based Hebrew SeniorLife.
Falls among the elderly individuals occur frequently and lead to substantial morbidity and mortality, but although research has already shown use of vitamin D supplements to reduce the risk, not all trials confirm these benefits.
The new study recruited 124 nursing home residents (average age 89, average serum vitamin D level 19.5 nanograms per millilitre) and randomly assigned them to receive one of five interventions – placebo, 200, 400, 600, or 800 International Units (IU) of vitamin D2 – for five months.
The researchers report that, at the end of the study, 44 per cent of the placebo group had experienced falls, compared to 58, 60, and 60 per cent of the people taking the 200, 400, 600 IU doses, respectively. Of the group taking the high dose (800 IU) vitamin D supplement, only 20 per cent of the participants fell.
"Past studies have shown that vitamin D could help prevent falls in seniors, and may be due to a possible strengthening effect the vitamin has on the musculoskeletal system. Until now, we didn't know what dosage amount would be effective," said Broe and Kiel.
"No 'dose response' trend of lower risk of falls with greater supplement dose was observed in this study," wrote the authors. "The only observed effects were in the group receiving 800 IU."
"For the 17 participants in the group taking 800 IU with valid measures, the mean follow-up [serum vitamin D] concentration of 29.95 ng/mL was well within the recommended optimal range, and none had serum measures below 20 ng/mL," they said.
"Attaining serum concentrations within the recommended optimal range may have positive benefits on muscle function as well as bone health in this elderly nursing home population, and this may be the reason why significant reductions in falling were found only in the group taking 800 IU," wrote Broe.
The researchers said that generalisation of the results to the wider population is limited since the sample population size was small, all the participants were Caucasian, and were, on average, healthier than many nursing home residents.
Further research is needed, they said, to extend understanding on the role of vitamin D on falls in the elderly, as well as the potential of the more potent vitamin D3 to further reduce falls.
Vitamin D refers to two biologically inactive precursors – D3, also known as cholecalciferol, and D2, also known as ergocalciferol. The former is produced in the skin on exposure to UVB radiation (290 to 320 nm) and can also be consumed from oily fish. The latter is derived from plants and only enters the body via the diet.
Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D, the non-active 'storage' form, and 1,25-dihydroxyvitamin D, the biologically active form that is tightly controlled by the body.
Source: Journal of the American Geriatrics Society
February 2007, Volume 55, Pages 234-239
"A higher dose of vitamin D reduces the risk of falls in nursing home residents: a randomized, multiple-dose study"
Authors: K.E. Broe, T.C. Chen, J. Weinberg, H.A. Bischoff-Ferrari, M.F. Holick, D.P. Kiel
