High dose vitamin D supplementation did not improve functional status in the elderly

1. Based on this randomized controlled trial, administering high monthly doses of vitamin D compared to lower doses did not improve functional status of older adults who had recently suffered a fall.

2. While high dose supplementation of vitamin D increased the surrogate marker (higher serum vitamin D levels), it did not confer improvement in lower extremity function, and in fact was associated with greater numbers of falls.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Vitamin D deficiency has been associated with decreased lower extremity muscle strength and decreased overall function in the elderly. There have been numerous studies evaluating outcomes with vitamin D supplementation, but these have produced mixed results. This randomized controlled trial was conducted to examine the relationship between high dose monthly vitamin D supplementation (either by itself or in combination with calcifediol, a more potent liver metabolite of vitamin D) in the elderly and their functional status. The results of the study showed administering high monthly doses of vitamin D (60 000 IU D3 or 24 000 IU D3 plus 300 mg calcifediol) compared to lower doses (24 000 IU D3) did not lead to any improved functional status in older adults who had recently had a fall. Additionally, the two groups that received higher doses of vitamin D had a greater proportion of participants who suffered from a fall compared to the lower dose group.

The study had a good study design and the population selected could adequately represent older adults, though the Swiss population may not be exactly similar to the US population. Also, while the study was adequately powered to ascertain differences, the study groups were relatively small. Lastly, the bolus dosing may have been the cause of adverse effects, compared to daily dosing (as the current guidelines recommend).

Click to read the study, published today in JAMA Internal Medicine

Relevant Reading: A pooled analysis of vitamin D dose requirements for fracture prevention.

In-Depth [randomized controlled trial]: The study population consisted of 200 adults in Zurich, Switzerland over age 70 years who had suffered a low-trauma fall in the prior twelve months. The study period was over one year (2009–2011). The three study groups were divided based on monthly treatments of the following: low-dose control group that received 24 000 IU vitamin D3 (equivalent to the current recommendation of 800 IU/day), group that received 60 000 IU vitamin D3, and group that received 24 000 IU vitamin D3 plus 300 mg calcifediol. The primary endpoint was difference in lower extremity function, as determined by the Short Physical Performance Battery (SPPB), which consisted of walking speed, successive chair stands, and a balance test. Also included in the outcome was the proportion of participants who achieved a 25-hydroxyvitamin D level of greater than or equal to 30 ng/mL. The secondary outcome was falls amongst the participants.

At the end of the study period, the levels of 25-hydroxyvitamin D increased in the following fashion: by 11.7 ng/mL in the 24 000 IU group, by 19.2 ng/mL in the 60 000 IU group, and by 25.8 ng/mL in the 24 000 IU plus calcifediol group. However, there was no difference in the SPPB score at the end of the year between the three groups. Percentage of fallers in the control 24 000 IU group was significantly lower (47.9%; 95%CI 35.8–60.3%) compared to the 60 000 IU group (66.9%; 95%CI 54.4–77.9%) and the 24 000 IU plus calcifediol group (66.1%; 95%CI 53.5–76.8%).

Image: PD

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