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A serum 25-hydroxyvitamin D level below 50 nmol/l has been associated with increased body sway and a level below 30 nmol/l with decreased muscle strength.
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....Changes in gait, difficulties in rising from a chair, inability to ascend stairs and diffuse muscle pain are the main clinical symptoms in osteomalacic myopathy......
....Vitamin D supplementation in vitamin D-deficient, elderly people improved muscle strength, walking distance, and functional ability and resulted in a reduction in falls and non-vertebral fractures......calcium and vitamin D supplementation significantly improves body sway and lower extremity strength, reducing the risk of falls.
Vitamin D and muscle function
Institute of Clinical Osteology Gustav Pommer and Clinic Der Fuirstenhof, Bad Pyrmont, Germany. iko_pyrmont@t-online.de
The aim of this review is to summarize current knowledge on the relation between vitamin D and muscle function. Molecular mechanisms of vitamin D action on muscle tissue have been known for many years and include genomic and non-genomic effects. Genomic effects are initiated by binding of 1,25-dihydroxyvitamin D3 (1,25(OH)2D) to its nuclear receptor, which results in changes in gene transcription of messenger RNA and subsequent protein synthesis. Non-genomic effects of vitamin D are rapid and mediated through a membrane-bound vitamin D receptor (VDR). Genetic variations in the VDR and the importance of VDR polymorphisms in the development of osteoporosis are still a matter of controversy and debate. Most recently, VDR polymorphisms have been described to affect muscle function. The skin has an enormous capacity for vitamin D production and supplies the body with 80-100% of its requirements of vitamin D. Age, latitude, time of day, season of the year and pigmentation can dramatically affect the production of vitamin D in the skin. Hypovitaminosis D is a common feature in elderly people living in northern latitudes and skin coverage has been established as an important factor leading to vitamin D deficiency. A serum 25-hydroxyvitamin D level below 50 nmol/l has been associated with increased body sway and a level below 30 nmol/l with decreased muscle strength. Changes in gait, difficulties in rising from a chair, inability to ascend stairs and diffuse muscle pain are the main clinical symptoms in osteomalacic myopathy. Calcium and vitamin D supplements together might improve neuromuscular function in elderly persons who are deficient in calcium and vitamin D. Thus 800 IU of cholecalciferol in combination with mg of elemental calcium reduces hip fractures and other non-vertebral fractures and should generally be recommended in individuals who are deficient in calcium and vitamin D. Given the strong interdependency of vitamin D deficiency, low serum calcium and high levels of parathyroid hormone, however, it is difficult to identify exact mechanisms of action.
[Effect of vitamin D on muscle strength and relevance in regard to osteoporosis prevention]
Z Rheumatol. 2003 Dec;62(6):518-21.
Department of Medicine, Harvard Medical School, The Robert B. Brigham Arthritis and Musculoskeletal Clinical Research Center, Boston, MA 02115, USA. hbischof@hsph.harvard.edu
A successful prevention strategy for fractures in the elderly should not be limited to an improvement in bone mineral density. Equally important is the prevention of falls. Thus, 90% of fractures in the elderly are associated with a fall and 30% of all ambulatory, and 50% of institutionalized elderly age 65 years and older fall at least once a year. Fall incidence increases 10% per decade thereafter. According to recent studies, vitamin D and calcium supplementation may be a promising treatment strategy targeting both bone mineral density, as well as muscle strength and the risk of falling. The protective effect of vitamin D on fractures has been attributed to the established moderate benefit of vitamin D on bone mineral density. However, an alternative explanation might be that vitamin D affects factors directly related to muscle strength, thus, reducing fracture risk through improved function and fall prevention, in addition to its benefits on calcium homeostasis.
Addressing the musculoskeletal components of fracture risk with calcium and vitamin D: a review of the evidence
Calcif Tissue Int. 2006 May;78(5):257-70. Epub 2006 Apr 21
Leuven University Center for Metabolic Bone Diseases and Division of Geriatric Medicine, Katholieke Universiteit Leuven, Leuven, Belgium. steven.boonen@uz.kuleuven.ac.be
Osteoporotic fractures are an extremely common and serious health problem in the elderly. This article presents the rationale for calcium and vitamin D supplementation in the prevention and treatment of osteoporotic fractures and reviews the literature evidence on the efficacy of this strategy. Two musculoskeletal risk factors are implicated in osteoporotic fractures in the elderly: the loss of bone mass due to secondary hyperparathyroidism and the increased propensity to falls. Calcium and vitamin D reverse secondary hyperparathyroidism with resultant beneficial effects on bone mineral density (BMD). Additionally, calcium and vitamin D supplementation significantly improves body sway and lower extremity strength, reducing the risk of falls. The effects of combined calcium and vitamin D on parathyroid function and BMD provide a strong rationale for the use of this therapy in the prevention and treatment of osteoporosis and osteoporotic fractures. There is general agreement that, in patients with documented osteoporosis, calcium and vitamin D supplementation should be an integral component of the management strategy, along with antiresorptive or anabolic treatment. Frail elderly individuals constitute another major target population for calcium and vitamin D because evidence from randomized studies in institutionalized elderly subjects demonstrates that these supplements reduce osteoporotic fracture risk, particularly in the presence of dietary deficiencies. However, the results of trials in community-dwelling subjects have been equivocal. Within the primary-care setting, further research is required to establish appropriate target subgroups for calcium and vitamin D supplementation; overall, the data are consistent with a benefit individuals with insufficient calcium and/or vitamin D, although patients with documented osteoporosis will derive further benefit in terms of fracture prevention from the addition of an antiresorptive agent.
Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis
Tang BM, Eslick GD, Nowson C, Smith C, Bensoussan A.
Centre for Complementary Medicine Research, University of Western Sydney, New South Wales, Australia. benjamin@clubsalsa.com.au
BACKGROUND: Whether calcium supplementation can reduce osteoporotic fractures is uncertain. We did a meta-analysis to include all the randomised trials in which calcium, or calcium in combination with vitamin D, was used to prevent fracture and osteoporotic bone loss. METHODS: We identified 29 randomised trials (n=63 897) using electronic databases, supplemented by a hand-search of reference lists, review articles, and conference abstracts. All randomised trials that recruited people aged 50 years or older were eligible. The main outcomes were fractures of all types and percentage change of bone-mineral density from baseline. Data were pooled by use of a random-effect model. FINDINGS: In trials that reported fracture as an outcome (17 trials, n=52 625), treatment was associated with a 12% risk reduction in fractures of all types (risk ratio 0.88, 95% CI 0.83-0.95; p=0.0004). In trials that reported bone-mineral density as an outcome (23 trials, n=41 419), the treatment was associated with a reduced rate of bone loss of 0.54% (0.35-0.73; p<0.0001) at the hip and 1.19% (0.76-1.61%; p<0.0001) in the spine. The fracture risk reduction was significantly greater (24%) in trials in which the compliance rate was high (p<0.0001). The treatment effect was better with calcium doses of 1200 mg or more than with doses less than 1200 mg (0.80 vs 0.94; p=0.006), and with vitamin D doses of 800 IU or more than with doses less than 800 IU (0.84 vs 0.87; p=0.03). INTERPRETATION: Evidence supports the use of calcium, or calcium in combination with vitamin D supplementation, in the preventive treatment of osteoporosis in people aged 50 years or older. For best therapeutic effect, we recommend minimum doses of 1200 mg of calcium, and 800 IU of vitamin D (for combined calcium plus vitamin D supplementation).
Vitamin D deficiency, muscle function, and falls in elderly people.
Am J Clin Nutr. 2002 Apr;75(4):611-5.Click here to read
Department of Geriatric Medicine, University Medical Center, Utrecht, Netherlands. h.c.j.p.janssen@azu.nl
An inadequate serum vitamin D status is commonly seen in elderly people as the result of various risk factors interacting in this population. Apart from the well-known effects on bone metabolism, this condition is also associated with muscle weakness, predominantly of the proximal muscle groups. Muscle weakness below a certain threshold affects functional ability and mobility, which puts an elderly person at increased risk of falling and fractures. Therefore, we wanted to determine the rationale behind vitamin D supplementation in elderly people to preserve and possibly improve muscle strength and subsequently functional ability. From experimental studies it was found that vitamin D metabolites directly influence muscle cell maturation and functioning through a vitamin D receptor. Vitamin D supplementation in vitamin D-deficient, elderly people improved muscle strength, walking distance, and functional ability and resulted in a reduction in falls and non-vertebral fractures.In healthy elderly people, muscle strength declined with age and was not prevented by vitamin D supplementation. In contrast,severe comorbidity might affect muscle strength in such a way that restoration of a good vitamin D status has a limited effect on functional ability. Additional research is needed to further clarify to what extent vitamin D supplementation can preserve muscle strength and prevent falls and fractures in elderly people.
[Role of vitamin D in the neuro-muscular function]
Arq Bras Endocrinol Metabol. 2005 Aug;49(4):495-502. Epub 2005 Oct 19
Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP.
Through its action in the kidney, intestines, bone and parathyroid glands vitamin D is a major regulator of calcium homeostasis and for the development of a healthy skeleton. Moreover, receptors for this hormone are present in almost all body tissues and other actions which are not related to the mineral metabolism have been imputed to it. In the skeletal muscle cell, vitamin D acts through the classic mechanism of binding to a nuclear receptor and also by binding to a membrane receptor, carrying out actions that involve calcium transport, protein synthesis and kinetics of muscle contraction. Clinically, vitamin D deficiency, which is very common among the elderly, including the ones in our country, has been related to an increase in the incidence of falls, as well as the reduction of muscle strength and deterioration of body sway, evaluated by the oscillation of the body in the erect position. On the other hand, it has been demonstrated that supplementation of calcium associated to vitamin D in deficient elderly contributes to the improvement of these aspects of the neuro-muscular function. In this review, the mechanisms involved in the association between vitamin D and neuro-muscular function will be discussed, as well as the supplementation of vitamin D and calcium to prevent non-vertebral osteoporotic fractures under the perspective of the neuro-muscular effects.
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