Vitamin D2 is an analog of cholecalciferol that has
a much shorter biological half life and is not
equilivalent unit for unit in practical activity.

This should be another reason to look
for vitamin D3 in your vitamin supplement or
as the form to be used if fortification rather
than D2.

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Osteoporos Int. 2007 Jun;18(6):811-8.
Epub 2007 Feb 15.

Preventing fractures among older people living in institutional care:
a pragmatic randomised double blind placebo controlled
trial of vitamin D supplementation.

Lyons RA, Johansen A, Brophy S, Newcombe RG, Phillips CJ, Lervy B,
Evans R,
Wareham K, Stone MD.

School of Medicine, University of Wales Swansea, Singleton Park, SA2
8PP,
Swansea, UK. r.a.lyons@swansea.ac.uk

INTRODUCTION:
Osteoporotic fractures in older people are a major and
increasing public health problem. We examined the effect
of vitamin D supplementation on fracture rate in people
living in sheltered accommodation.

METHODS:
In a pragmatic double blind randomised controlled trial
of 3 years duration, we examined 3,440 people
(2,624 women and 816 men) living in residential or care
home. We used four-monthly oral supplementation using
100,000 IU vitamin D(2) (ergocalciferol). As a main
outcome measure, we used the incidence of first
fracture using an intention to treat analysis.
This was a multicentre study in 314 care homes or
sheltered accommodation complexes in South Wales, UK.

RESULTS:
The vitamin D and placebo groups had similar baseline
characteristics. In intention-to-treat analysis,
205 first fractures occurred in the intervention
group during a total of 2,846 person years of follow-up
(7 fractures per 100 people per year of follow-up),
with 218 first fractures in the control group over
2,860 person years of follow-up. The hazard ratio
of 0.95 (95% confidence interval 0.79-1.15) for intervention
compared to control was not statistically
significant.

CONCLUSION:
Supplementation with four-monthly 100,000 IU of oral
vitamin D(2) is not sufficient to affect fracture incidence
among older people living in institutional care.

PMID: 17473911