Co-author of the study, Professor Leslie Cleland, Clinical Professor at the Department of Medicine, University of Adelaide, says high rates of vitamin D deficiency among aged care residents are well documented.
Lack of exposure to sunlight and the usual shortcomings of diet as the sole source of vitamin D are likely contributing factors.
Prof Cleland suggests a policy-based approach, subject to medical consent, replacing individual supplementation with a supplement given to all residents every three months — a cheap and quick method of improving residents' vitamin D status.
During a six-month controlled trial, one group of aged care residents were given a high-dose vitamin D supplement once every three months, mixed in with water, juice or milk.
At the beginning of the study, 95% of residents had blood levels of vitamin D below the desirable range. By the end, all treated residents had reached recommended levels.
In no resident did vitamin D reach toxic levels, and the cost of the supplement — bought in bulk and prepared by the Royal Adelaide Hospital — was just $4 per resident per year. The cost of the nearest equivalent retail product is about $50 per annum.
"[The supplement] is inexpensive enough for aged care facilities to be willing to meet the cost, making the program potentially cost-neutral for health service authorities," says Prof Cleland.
In addition, nurses were able to accommodate the quarterly dosing readily into their normal work patterns.
Prof Cleland says the study confirms that the supplement is a practical, safe, effective and inexpensive way to meet the vitamin D requirements of aged care residents.