Pharmacology & Pharmacy, 2012, 3, 453-457
http://dx.doi.org/10.4236/pp.2012.34061 Published Online October 2012 (http://www.SciRP.org/journal/pp)
Vitamin D and Number of Falls in a Long-Term Care
Robert B. Raffa1*, Frank Breve2, Robert Taylor Jr.3, Joseph V. Pergolizzi Jr.4,5,6
1Temple University School of Pharmacy, Philadelphia, USA; 2Mid Atlantic Pharma Tech Consultants, LLC, Ventnor City, USA;
3NEMA Research Inc., Naples, USA; 4Temple University School of Medicine, Temple University, Philadelphia, USA; 5School of
Medicine, The Johns Hopkins University, Baltimore, USA; 6School of Medicine, Georgetown University, Washington USA.
Received June 27th, 2012; revised July 28th, 2012; accepted August 10th, 2012
Falls represent a significant contribution to the morbidity and mortality of the elderly population. Because vitamin D is
important in bone physiology, the use of vitamin D to restore deficient bone and ameliorate the effects of bone fractures
due to falls has become a common practice in recent years. Following introduction of widespread use, reports began to
emerge that vitamin D not only aided in repair of fall-induced bone fractures, but that it also reduced the occurrence of
falls. Vitamin D now has become a routine intervention as a fall-prevention measure. Early analyses found evidence of
prevention efficacy (reduced falls), but recent analyses are more equivocal. We retrospectively examined the records of
350 patients in a long-term care facility in which vitamin D administration and the number of falls were recorded as part
of a comprehensive database of care. We found a dramatic rise in vitamin D use over the period covered (2006-2011)
and a corresponding dramatic decrease in the number of falls. However, the number of falls continued to decline after
2008, despite a plateau in number of patients on vitamin D, particularly females. It appears that other factors contribute
to the overall decline.
Keywords: Falls; Bone Fracture; Vitamin D; Long-Term Care Facility
Already by 1987 strategies to address the morbidity and
mortality associated with falls in the elderly and others in
which osteoporosis is common (such as postmenopausal
women) advocated optimization of calcium absorption, a
process in which vitamin D plays an important role .
Vitamin D also aids in bone growth and bone remodeling
by osteoblasts and osteoclasts (for review, see ). The
two major forms of the several forms of vitamin D are
the secosteroids vitamin D2 (ergocalciferol, a derivative
of ergosterol) and vitamin D3 (cholecalciferol, produced
by UV irradiation of its precursor 7-dehydrocholesterol).
As used here, vitamin D (without a subscript) refers to D2,
D3, or both. The active form of vitamin D, calcitriol,
binds to the VDR (vitamin D receptor), which acts as a
transcription factor that modulates the gene expression of
transport factors including TRPV6 (a transient receptor
potential cation channel) and calbindin (calcium-binding
protein), which are involved in the absorption of calcium
from the intestine . An insufficient amount of vitamin
D (calcium) leads to osteoporosis and bone brittleness
that predisposes the individual to bone fractures during
falls . Since few foods contain significant amounts of
vitamin D, the diet is not usually a major source (unless
fortified with the vitamin). Thus an exposure to sunshine,
which promotes endogenous synthesis of vitamin D from
cholesterol , is important. Situations that tend to limit
exposure to the sun, increase the likelihood that vitamin
D levels can drop below optimal levels .
An increasing incidence of fall-related bone fractures,
in particular of the hip, has been associated with the age-
ing population . Since vitamin D is believed to have
only minimal toxicity, even at very large doses , vita-
min D supplementation—usually with concomitant cal-
cium—has become a common guideline recommendation
and practice (e.g., [9-18]). Reports support beneficial
effects of vitamin D supplementation. As an example, a
meta-analysis of double-blinded randomized controlled
trials examined the efficacy of supplemental vitamin D
alone or with calcium in preventing falls in older popula-
tions . Based on the trials that met the inclusion cri-
teria, falls were not significantly reduced (p > 0.05) in
those who received a low dose of supplemental vitamin
D (200 - 600 IU/day), but those who received a high dose
(700 - 1000 IU/day) had significantly reduced risk of fall
Copyright © 2012 SciRes. PP
Vitamin D and Number of Falls in a Long-Term Care Facility
(p < 0.05) of 19%. In a retrospective review of nine
studies that included vitamin D (800 IU) and calcium
(1200 IU) supplementation in nursing home residents, a
population that falls more than 10-times more frequently
than their age-matched community-dwelling counterparts,
supplementation improved bone mineral density and re-
duced fracture risk  (the topic is reviewed in ).
Similar positive findings were reported by others for
older adults  and female stroke survivors in institu-
tional settings . Doses even greater than 700 - 1000
IU have been suggested for individuals with more severe
vitamin D deficiency and those who are overweight .
However, a 15-year literature overview  points out
that the literature is not universal in showing a beneficial
effect. Some studies have failed to show any significant
effect and alternative explanations have been offered. In
light of this, we examined the records of a long-term care
facility that had detailed records of falls and vitamin D
supplementation over the period 2006-2011.
2. Materials and Methods
2.1. Description of Facility
The facility selected for data source is a county-owned,
not-for-profit, 300-bed long-term care facility located in
southern NJ with a 99% average census rate comprised
of six nursing units, including a rehabilitation unit. The
rehabilitation unit has a high admission turnover rate,
which effectively brings the average monthly facility
census rate to 350 residents.
2.2. Data Sources
All data were collected from the facility’s fully inte-
grated EMR (electronic medical records) computerized
system, MEDITECH™ (Westwood, MA) and compiled
from the computer-generated reports of residents who
received vitamin D and documented fall incident during
the six- year period starting January 1, 2006 and ending
December 31, 2011.
2.3. Data Extraction
The relevant computer records were examined and each
resident’s age, sex, and vitamin D usage was recorded.
The number of documented falls during each of the same
years was obtained. All data were de-identified and are in
compliance with the Health Insurance Portability and
Accountability Act (HIPAA) requirements. The protocol
was submitted to the Institutional Review Board (IRB)
In the first year for which there were complete records of
both vitamin D supplementation and falls, 2006, the total
number of residents receiving some form of a vitamin D
supplement was 35, of which 33, were female (35 - 101
y.o.) and only 2 were males (58 - 79 y.o.). This number
represents 10% of the total population and corresponds to
a year in which a number of reviews were published on
the use of vitamin D supplements for prevention of falls
(e.g., [17,26-30]). The most common supplement regi-
men consisted of a 500 mg tablet of vitamin D given b.i.d.
with calcium. Other regimens involved vitamin D 1000
or 2000 IU or calcitriol 0.25, 0.5, 1.0 or 2.0 g daily,
t.i.d., q.d., or on alternate days. The total number of falls
during 2006 was 681, that is, almost 2 falls per resident.
The number of residents on vitamin D supplements
grew significantly in 2007 to 66 (52 females, 40 - 97 y.o.;
14 males, 73 - 92 y.o.) and 2008 to 92 (75 females).
During this time the total number of falls fell to 641
(about 6%) and 628 (about 8%), respectively.
The number of females receiving a calcium + vitamin
D supplementation regimen essentially plateaued in 2008
(75; 38 - 103 y.o.), 2009 (77; 38 - 96 y.o.), 2010 (75; 23 -
101 y.o.), and 2011 (77; 24 - 97 y.o.). The number of
males on supplementation grew modestly up till 2010:
2008 (17; 48 - 91 y.o.), 2009 (20; 56 - 93 y.o.), 2010 (26;
49 - 92 y.o.), 2011 (24; 39 - 92 y.o.).
Despite the plateau in total number of residents on vi-
tamin D supplementation (reaching about 30% in 2011),
the number of falls continued to decline to 484 (less than
1.5 per resident) in 2011 (Figure 1).
Each year, about a third of adults in the US who are over
65 y.o. will experience a fall [31-33]. Those over 80 y.o.
2006 2007 2008 2009 2010 2011
Number of Falls
Number on Vit D (per 350)
Number of falls (per 350)
Figure 1. Relationship between number residents in a long-
term care facility and number of falls during the years
Copyright © 2012 SciRes. PP
Vitamin D and Number of Falls in a Long-Term Care Facility 455
have a risk almost 50% . Some common risk factors
include osteoporosis, lack of physical activity, impaired
vision, sedative-producing medications, and fall-related
hazards; thus females are at greater risk than males and
those in long-term care facilities are at greater risk than
those in community settings . The consequences are
both medical (injury) and psychological (distress). Bone
fractures (mainly of hip or head) are the most common
injuries, leading to hospitalization, disability, admission
to nursing homes or long-term care facilities, increase in
healthcare costs , and even early death . About
25% of those who experience a hip fracture need some
extended nursing care; about half of those hospitalized
are discharged to nursing homes rather than to their own
home . Approximately 95,000 deaths of older adults
each year in the US are attributed to falls and about one
fourth of those who experience a hip fracture die within
six months . Thus, any intervention that strengthens
bone, enhances recovery, or better still, prevents falls, is
highly desirable and needed.
Several systematic reviews and meta-analyses have
reported that supplementation with vitamin D, and usually
also calcium, decreases the number of falls in susceptible
populations. The potential beneficial effects of such
supplementation on the healing of bone fractures that
result from falls seem straight- forward because of the
important roles that calcium plays in bone health and
healing and that vitamin D plays in calcium absorption.
Several studies have reported positive results (reviewed
in ). In one large study , in which over 3000
women (mean age 84 y.o.) living in facilities for the
elderly were randomized to receive either daily vitamin
D (800 IU + calcium (1.2 g) or placebo, decreased risk of
hip fracture was found, which was sustained at a 3-year
follow-up . In another large randomized study  of
more than 9000 community-dwelling elderly, vitamin D
(800 IU) + calcium (1000 mg) reduced fracture risk in
women, but there was no benefit in men (an observation
noted in more than one such study). There is less evi-
dence for efficacy of vitamin D alone (without calcium). A
low dose of vitamin D (400 IU) daily increased bone
density, but there was no reduction in fractures .
Higher doses, such as oral 100,000 IU every four months
 or annual intramuscular injection of 150,000 -
300,000  resulted in reductions in fracture risk.
The perception of lack of serious toxic consequence of
vitamin D supplementation fosters its use even in
absence of definitive proof of therapeutic efficacy in a
particular application. The estimated tolerable daily
intake of vitamin D is 4000 IU for those more than 9 y.o.
(including pregnant or lactating women) . The intake
of more than 50,000 IU (1250 g) over several months
can produce overt toxicity. The main symptoms of
vitamin D overdose are those of hypercalcemia (≥40,000
IU daily) .
An ability of vitamin D with or without calcium to
prevent falls, not just to prevent or heal fractures, is
seemingly less obvious. One putative mechanism is that
fractures lead to, rather than result from, falls. The
present study examined the existing records of a long-
term care facility for a correlation between vitamin D
supplementation and the number of falls. The data were
blinded in the sense that all of the recording of the in-
formation was not intended for research purposes and
was collected by a number of different individuals, each
unaware of the eventual use. The data reveal a very large
increase in the use of vitamin D supplementation, always
with calcium, starting in 2006 (about 10% of the residents)
and continuing in 2007, and 2008 (more than 25% of
residents). During these same years the number of falls
progressively declined, seemingly providing strong sup-
port of a beneficial effect of vitamin D (or at least of a
combination of vitamin D + calcium) in preventing falls.
However, the number of falls continued to decline during
2009, 2010, and 2011 despite the fact that the number
(percentage) of the female residents given vitamin D
supplementation plateaued in the period 2008-2011 and
there was only a small increase in the total number
(females + males). This suggests that the vitamin D
(+calcium) supplementation might not have been cau-
sative, but only incidental, to decline in number of falls.
Data regarding the occurrence or the consequence of any
fractures that resulted from these falls, which is the most
likely beneficial effect of vitamin D + calcium supple-
mentation, is not available. Another possible explanation
for continued decline in number of falls is that the resi-
dents might have been transitioned to medications that
had less propensity to cause falls.
In the present retrospective review of the computer records
of a 350-residential (majority female) long-term care
facility, vitamin D (most commonly 500 mg b.i.d.) +
calcium supplementation was closely correlated with a
decreased number of falls during the period 2006-2008,
consistent with studies that report a beneficial effect of
vitamin D on prevention of falls. However, the continued
decline in number of falls during the period 2009-2011,
despite lack of a significant increase in the number of
residents receiving supplementation, raises doubts about
the assignment of causation.
The most effective intervention to prevent falls is a
multifactorial assessment and management program that
includes a vitamin D supplementation regimen with or
without calcium [44,48-50], particularly in institutional-
ized elderly women who are the most likely to have vi-
tamin D deficiency and secondary hyperparathyroidism
Copyright © 2012 SciRes. PP
Vitamin D and Number of Falls in a Long-Term Care Facility
 F. Heidrich and R. S. Thompson, “Osteoporosis Preven-
tion: Strategies Applicable for General Population Groups,”
Journal of Family Practice, Vol. 25, No. 1, 1987, pp. 33-
 E. Laird, M. Ward, E. McSorley, J. J. Strain and J. Wall-
ace, “Vitamin D and Bone Health: Potential Mechanisms,”
Nutrients, Vol. 2, No. 7, 2010, pp. 693-724.
 R. Bouillon, S. Van Cromphaut and G. Carmeliet, “Intes-
tinal Calcium Absorption: Molecular Vitamin D Medi-
ated Mechanisms,” Journal of Cellular Biochemistry, Vol.
88, No. 2, 2003, pp. 332-339. doi:10.1002/jcb.10360
 P. Lips and N. M. van Schoor, “The Effect of Vitamin D
on Bone and Osteoporosis,” Best Practice and Research
Clinical Endocrinology & Metabolism, Vol. 25, No. 4,
2011, pp. 585-591. doi:10.1016/j.beem.2011.05.002
 O. Engelsen, “The Relationship between Ultraviolet Ra-
diation Exposure and Vitamin D Status,” Nutrients, Vol.
2, No. 5, 2010, pp. 482-495. doi:10.3390/nu2050482
 B. A. Gilchrest, “Sun Exposure and Vitamin D Sufficiency,”
American Journal of Clinical Nutrition, Vol. 88, No. 2,
2008, pp. 570S-577S.
 M. D’Imporzano, F. M. Liuni and U. Tarantino, “Acetabu-
lar Fragility Fractures in Elderly Patients,” Aging Clinical
and Experimental Research, Vol. 23, Suppl. 2, 2011, pp.
 D. W. Stephenson and A. N. Peiris, “The Lack of Vitamin
D Toxicity with Megadose of Daily Ergocalciferol (D2)
Therapy: A Case Report and Literature Review,” South-
ern Medical Journal, Vol. 102, No. 7, 2009, pp. 765-768.
 J. J. Body, P. Bergmann, S. Boonen, Y. Boutsen, O. Bru-
yere, J. P. Devogelaer, S. Goemaere, N. Hollevoet, J. M.
Kaufman, K. Milisen, S. Rozenberg and J. Y. Reginster,
“Non-Pharmacological Management of Osteoporosis: A
Consensus of the Belgian Bone Club,” Osteoporos Inter-
national, Vol. 22, No. 11, 2011, pp. 2769-2788.
 T. P. Ip, J. Leung and A. W. Kung, “Management of Os-
teoporosis in Patients Hospitalized for Hip Fractures,” Os-
teoporosis International, Vol. 21, No. 4, 2010, pp. 605-
 P. Geusens, “Strategies for Treatment to Prevent Fragility
Fractures in Postmenopausal Women,” Best Practice and
Research in Clinical Rheumatology, Vol. 23, No. 6, 2009,
pp. 727-740. doi:10.1016/j.berh.2009.09.001
 M. G. Sweet, J. M. Sweet, M. P. Jeremiah and S. S. Ga-
lazka, “Diagnosis and Treatment of Osteoporosis,” Amer-
ican Family Physician, Vol. 79, No. 3, 2009, pp. 193-200.
 D. L. Schneider, “Management of Osteoporosis in Geri-
atric Populations,” Current Osteoporosis Reports, Vol. 6,
No. 3, 2008, pp. 100-107. doi:10.1007/s11914-008-0018-4
 C. Roux, H. A. Bischoff-Ferrari, S. E. Papapoulos, A. E.
de Papp, J. A. West and R. Bouillon, “New Insights into
the Role of Vitamin D and Calcium in Osteoporosis
Management: An Expert Roundtable Discussion,” Cur-
rent Medical Research and Opinion, Vol. 24, No. 5, 2008,
pp. 1363-1370. doi:10.1185/030079908X301857
 J. T. Lin and J. M. Lane, “Nonpharmacologic Manage-
ment of Osteoporosis to Minimize Fracture Risk,” Nature
Clinical Practice Rheumatology, Vol. 4, No. 1, 2008, pp.
 S. L. Kates, O. S. Kates and D. A. Mendelson, “Advan-
ces in the Medical Management of Osteoporosis,” Injury,
Vol. 38, Suppl. 3, 2007, pp. S17-S23.
 J. P. Levine, “Pharmacologic and Nonpharmacologic
Management of Osteoporosis,” Clinical Cornerstone, Vol.
8, No. 1, 2006, pp. 40-53.
 S. L. Follin and L. B. Hansen, “Current Approaches to the
Prevention and Treatment of Postmenopausal Osteoporo-
sis,” American Journal of Health System Pharmacists,
Vol. 60, No. 9, 2003, pp. 883-901.
 H. A. Bischoff-Ferrari, B. Dawson-Hughes, H. B. Stae-
helin, J. E. Orav, A. E. Stuck, R. Theiler, J. B. Wong, A.
Egli, D. P. Kiel and J. Henschkowski, “Fall Prevention
with Supplemental and Active Forms of Vitamin D: A
Meta-Analysis of Randomised Controlled Trials,” British
Medical Journal, Vol. 339, 2009, p. b3692.
 S. Parikh, J. Avorn and D. H. Solomon, “Pharmacologi-
cal Management of Osteoporosis in Nursing Home Popu-
lations: A Systematic Review,” Journal of the American
Geriatrics Society, Vol. 57, No. 2, 2009, pp. 327-334.
 C. Becker and K. Rapp, “Fall Prevention in Nursing
Homes,” Clinical in Geriatric Medicine, Vol. 26, No. 4,
2010, pp. 693-704. doi:10.1016/j.cger.2010.07.004
 R. R. Kalyani, B. Stein, R. Valiyil, R. Manno, J. W.
Maynard and D. C. Crews, “Vitamin D Treatment for the
Prevention of Falls in Older Adults: Systematic Review
and Meta-Analysis,” Journal of the American Geriatrics
Society, Vol. 58, No. 7, 2010, pp. 1299-1310.
 F. Batchelor, K. Hill, S. Mackintosh and C. Said, “What
Works in Falls Prevention after Stroke? A Systematic
Review and Meta-Analysis,” Stroke, Vol. 41, No. 8, 2010,
pp. 1715-1722. doi:10.1161/STROKEAHA.109.570390
 H. Bischoff-Ferrari, “Vitamin D: What Is an Adequate
Vitamin D Level and How Much Supplementation Is
Necessary?” Best Practice and Research Clinical Rheu-
matology, Vol. 23, No. 6, 2009, pp. 789-795.
 C. Annweiler, M. Montero-Odasso, A. M. Schott, G.
Berrut, B. Fantino and O. Beauchet, “Fall Prevention and
Vitamin D in the Elderly: An Overview of the Key Role
of the Non-Bone Effects,” Journal of Neuroengineering
and Rehabilitation, Vol. 7, No. 1, 2010, p. 50.
 E. M. Lewiecki and S. L. Silverman, “Redefining Osteo-
porosis Treatment: Who to Treat and How Long to Treat,”
Arquivos Brasileiros de Endocrinologia & Metabologia,
Vol. 50, No. 4, 2006, pp. 694-704.
 C. G. Swift, “The Role of Medical Assessment and Inter-
vention in the Prevention of Falls,” Age and Ageing, Vol.
Copyright © 2012 SciRes. PP
Vitamin D and Number of Falls in a Long-Term Care Facility
Copyright © 2012 SciRes. PP
35, Suppl. 2, 2006, pp. ii65-ii68.
 K. F. Mauck and B. L. Clarke, “Diagnosis, Screening, Pre-
vention, and Treatment of Osteoporosis,” Mayo Clinic
Proceedings, Vol. 81, No. 5, 2006, pp. 662-672.
 M. Gass and B. Dawson-Hughes, “Preventing Osteoporo-
sis-Related Fractures: An Overview,” American Journal
of Medici ne, Vol. 119, No. 4, 2006, pp. S3-S11.
 E. S. Siris, “Patients with Hip Fracture: What Can Be Im-
proved?” Bone, Vol. 38, No. 2, 2006, pp. 8-12.
 J. M. Hausdorff, D. A. Rios and H. K. Edelberg, “Gait
Variability and Fall Risk in Community-Living Older
Adults a 1-Year Prospective Study,” Archives of Physi-
cal Medicine and Rehabilitation, Vol. 82, No. 8, 2001, pp.
 M. E. Tinetti, M. Speechley and S. F. Ginter, “Risk Fac-
tors for Falls among Elderly Persons Living in the Com-
munity,” New England Journal of Medicine, Vol. 319, No.
26, 1988, pp. 1701-1707.
 J. T. Chang, S. C. Morton, L. Z. Rubenstein, W. A. Mo-
jica, M. Maglione, M. J. Suttorp, E. A. Roth and P. G.
Shekelle, “Interventions for the Prevention of Falls in
Older Adults: Systematic Review and Meta-Analysis of
Randomised Clinical Trials,” British Medical Journal,
Vol. 328, No. 7441, 2004, p. 680.
 A. J. Blake, K. Morgan, M. J. Bendall, H. Dallosso, S. B.
Ebrahim, T. H. Arie, P. H. Fentem and E. J. Bassey,
“Falls by Elderly People at Home: Prevalence and Asso-
ciated Factors,” Age and Ageing, Vol. 17, No. 6, 1988, pp.
 P. C. Walker, A. Alrawi, J. F. Mitchell, R. E. Regal and U.
Khanderia, “Medication Use as a Risk Factor for Falls
among Hospitalized Elderly Patients,” American Journal
of Health System Pharmacists, Vol. 62, No. 23, 2005, pp.
 B. H. Alexander, F. P. Rivara and M. E. Wolf, “The Cost
and Frequency of Hospitalization for Fall-Related Injuries
in Older Adults,” American Journal of Public Health, Vol.
82, No. 7, 1992, pp. 1020-1023.
 J. E. Dunn, S. E. Furner and T. P. Miles, “Do Falls Pre-
dict Institutionalization in Older Persons? An analysis of
Data from the Longitudinal Study of Aging,” Journal of
Aging Health, Vol. 5, No. 2, 1993, pp. 194-207.
 C. Casteel, C. Peek-Asa, C. Lacsamana, L. Vazquez and J.
F. Kraus, “Evaluation of a Falls Prevention Program for
Independent Elderly,” American Journal of Health Be-
havior, Vol. 28, Suppl. 1, 2004, pp. S51-S60.
 R. M. Francis, “Calcium, Vitamin D and Involutional Os-
teoporosis,” Current Opinion in Clinical Nutrition and
Metabolic Care, Vol. 9, No. 1, 2006, pp. 13-17.
 M. C. Chapuy, M. E. Arlot, F. Duboeuf, J. Brun, B. Crou-
zet, S. Arnaud, P. D. Delmas and P. J. Meunier, “Vitamin
D3 and Calcium to Prevent Hip Fractures in the Elderly
Women,” New England Journal of Medicine, Vol. 327,
No. 23, 1992, pp. 1637-1642.
 M. C. Chapuy, M. E. Arlot, P. D. Delmas and P. J. Me-
unier, “Effect of Calcium and Cholecalciferol Treatment
for Three Years on Hip Fractures in Elderly Women,”
British Medical Journal, Vol. 308, No. 6936, 1994, pp.
 B. Dawson-Hughes, S. S. Harris, E. A. Krall and G. E.
Dallal, “Effect of Calcium and Vitamin D Supplementa-
tion on Bone Density in Men and Women 65 Years of
Age or Older,” New England Journal of Medicine, Vol.
337, No. 10, 1997, pp. 670-676.
 P. Lips, W. C. Graafmans, M. E. Ooms, P. D. Bezemer
and L. M. Bouter, “Vitamin D Supplementation and Fra-
cture Incidence in Elderly Persons: A Randomized, Pla-
cebo-Controlled Clinical Trial,” Annals of Internal Medi-
cine, Vol. 124, No. 4, 1996, pp. 400-406.
 A. Avenell, W. J. Gillespie, L. D. Gillespie and D. O’Con-
nell, “Vitamin D and Vitamin D Analogues for Prevent-
ing Fractures Associated with Involutional and Post-Meno-
pausal Osteoporosis,” Cochrane Database of Systematic
Reviews, No. 2, 2009, Article No. CD000227.
 R. J. Heikinheimo, J. A. Inkovaara, E. J. Harju, M. V.
Haavisto, R. H. Kaarela, J. M. Kataja, A. M. Kokko, L. A.
Kolho and S. A. Rajala, “Annual Injection of Vitamin D
and Fractures of Aged Bones,” Calcified Tissue Interna-
tional, Vol. 51, No. 2, 1992, pp. 105-110.
 A. C. Ross, J. E. Manson, S. A. Abrams, J. F. Aloia, P. M.
Brannon, S. K. Clinton, R. A. Durazo-Arvizu, J. C. Gal-
lagher, R. L. Gallo, G. Jones, C. S. Kovacs, S. T. Mayne,
C. J. Rosen and S. A. Shapses, “The 2011 Report on Die-
tary Reference Intakes for Calcium and Vitamin D from
the Institute of Medicine: What Clinicians Need to Know,”
Journal of Clinical Endocrinology and Metabolism, Vol.
96, No. 1, 2011, pp. 53-58. doi:10.1210/jc.2010-2704
 R. Vieth, “Vitamin D Supplementation, 25-Hydroxyvita-
min D Concentrations, and Safety,” American Journal of
Clinical Nutrition, Vol. 69, No. 5, 1999, pp. 842-856.
 L. D. Gillespie, M. C. Robertson, W. J. Gillespie, S. E.
Lamb, S. Gates, R. G. Cumming and B. H. Rowe, “Inter-
ventions for Preventing Falls in Older People Living in
the Community,” Cochrane Database of Systematic Re-
views, 2009, Article No. CD007146.
 I. D. Cameron, G. R. Murray, L. D. Gillespie, M. C.
Robertson, K. D. Hill, R. G. Cumming and N. Kerse, “In-
terventions for Preventing Falls in Older People in Nurs-
ing Care Facilities and Hospitals,” Cochrane Database
of Systematic Reviews, No. 1, 2010, Article No. CD005465.
 C. A. Nowson, “Prevention of Fractures in Older People
with Calcium and Vitamin D,” Nutrients, Vol. 2, No. 9,
2010, pp. 975-984. doi:10.3390/nu2090975