Effects of a short-term vitamin D and calcium supplementation on body sway and secondary hyperparathyroidism in elderly women

A critical analysis of the (near) legendary status of vitamin D

Labels such as food constituent, nutrient and supplement do not convey a sense of being essential. Yet these rather mundane descriptors, even if correct, belie the true significance of vitamin D. Long believed to be merely a functioning cofactor akin to vitamin C, deficiency of this secosteroid hormone is clearly associated with morbid complications of calcium and bone mineral metabolism, and because the hormonal effects are mediated by nuclear receptors that regulate the expression of many subordinate genes, the vitamin's pleiotropic mode of action can influence numerous metabolic pathways and, possibly, a number of different diseases. Although the vitamin is under intensive investigation, much still remains unknown, even in bone health, as the identity of osteoporosis susceptibility genes remains uncertain. This article focuses on various aspects of the basic science and molecular biology of the vitamin D endocrine system. The primary goal is to critically examine the evidence supporting its role in bone metabolism, diabetes and cancer.

Fracture risk and prevention: a multidimensional approach

Although physical therapists commonly manage neuromusculoskeletal disorders and injuries, their scope of practice also includes prevention and wellness. In particular, this perspective article proposes that physical therapists are well positioned to address the client's skeletal health by incorporating fracture prevention into clinical practice with all adults. Fracture prevention consists primarily of maximizing bone strength and preventing falls. Both of these initiatives require an evidence-based, multidimensional approach that customizes interventions based on an individual's medical history, risk factors, and personal goals. The purposes of this perspective article are: (1) to review the role of exercise and nutrition in bone health and disease; (2) to introduce the use of the Fracture Risk Assessment Tool (FRAX®) into physical therapist practice; (3) to review the causes and prevention of falls; and (4) to propose a role for the physical therapist in promotion of bone health for all adult clients, ideally to help prevent fractures and their potentially devastating sequelae.

Is vitamin D a determinant of muscle mass and strength?

There remains little consensus on the link between vitamin levels and muscle mass or strength. We therefore investigated the association of serum 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)(2) D), and parathyroid hormone (PTH) levels with skeletal muscle mass and strength. We studied 311 men (mean age, 56 years; range, 23-91 years) and 356 women (mean age, 57 years; range, 21-97 years) representing an age-stratified, random sample of community adults. Multivariate linear regression models were used to examine the association of skeletal muscle mass (by total body dual-energy X-ray absorptiometry) and strength (handgrip force and isometric knee extension moment) with each of 25(OH)D, 1,25(OH)(2) D, and PTH quartiles, adjusted for age, physical activity, fat mass, and season. We found no consistent association between 25(OH)D or PTH and any of our measurements of muscle mass or strength, in either men or women. However, in subjects younger than 65 years, there was a statistically significant association between low 1,25(OH)(2) D levels and low skeletal mass in both men and women and low isometric knee extension moment in women, after adjustment for potential confounders. Modestly low 25(OH)D or high PTH levels may not contribute significantly to sarcopenia or muscle weakness in community adults. The link between low 25(OH)D and increased fall risk reported by others may be due to factors that affect neuromuscular function rather than muscle strength. The association between low 1,25(OH)(2) D and low skeletal mass and low knee extension moment, particularly in younger people, needs further exploration.

Effects of alfacalcidol on circulating cytokines and growth factors in rat skeletal muscle

Supra-physiological levels of vitamin D induce skeletal muscle atrophy, which may be particularly detrimental in already sarcopaenic elderly. Neither the cause nor whether the atrophy is fibre type specific are known. To obtain supraphysiological levels of circulating vitamin D (1,25(OH)(2)D(3)) 27.5-month-old female Fischer(344) × Brown Norway F1 rats were orally treated for 6 weeks with vehicle or the vitamin D analogue alfacalcidol. Alfacalcidol treatment induced a 22% decrease in body mass and 17% muscle atrophy. Fibre atrophy was restricted to type IIb fibres in the low-oxidative part of the gastrocnemius medialis only (-22%; P < 0.05). There was a concomitant 1.6-fold increase in mRNA expression of the ubiquitin ligase MuRF-1 (P < 0.001), whereas those of insulin-like growth factor 1 and myostatin were not affected. Circulating IL-6 was unaltered, but leptin and adiponectin were decreased (-39%) and increased (64%), respectively. The treated rats also exhibited a reduced food intake. In conclusion, supraphysiological levels of circulating 1,25(OH)(2)D(3) cause preferential atrophy of type IIb fibres, which is associated with an increased expression of MuRF-1 without evidence of systemic inflammation. The atrophy and loss of body mass in the presence of supra-physiological levels of vitamin D are primarily due to a reduced food intake.

Serum 25-hydroxyvitamin D and muscle atrophy in the elderly

The objective of this review is to consider the mechanisms by which vitamin D affects muscle and the evidence that vitamin D status is important for muscle performance and fall prevention in older adults. Vitamin D receptors have been identified in human skeletal-muscle cells. Activation of these receptors by 1,25-dihydroxyvitamin D is involved in the action of vitamin D on the myocyte. Several studies have examined the effect of supplemental vitamin D on muscle strength, balance and falls. Among those examining muscle strength, results have been either positive for vitamin D or null. A recent meta-analysis of seventeen such trials revealed no significant effect of vitamin D overall, but a significant improvement in strength was observed in the trials in which the mean starting level of 25-hydroxyvitamin D was 25 nmol/l or below. Evidence for an effect of vitamin D on balance, measured as sway, is less abundant but more consistently positive. Many trials have evaluated the effect of supplemental vitamin D on falls. Overall, there is about a 20% lower risk of falling with supplementation. One meta-analysis considered the vitamin D dose administered and concluded that doses up through 15 μg (600 IU) were ineffective and doses of 17·5–25 μg/d (700–1000 IU/d) significantly lowered fall risk. The minimal 25-hydroxyvitamin D level needed for benefit was 60 nmol/l.

How much vitamin D do we need for skeletal health?

BACKGROUND

Vitamin D is critical for musculoskeletal health and has been implicated in the risk of extraskeletal diseases, including cancer, cardiovascular diseases, and autoimmune diseases, as well as overall mortality. Although numerous studies deal and have dealt with vitamin D deficiency and its consequences, experts cannot agree on the right 25-hydroxyvitamin D levels. This survey aims to shed light on the ongoing vitamin D controversy from different angles.

QUESTIONS/PURPOSES

We discuss the minimum threshold for the 25-hydroxyvitamin D level to guarantee optimal health, why vitamin is D critical to musculoskeletal and extraskeletal functions, and new evidence for the success of prevention measures such as food fortification.

METHODS

We searched PubMed, Google Scholar, and reference lists of articles using several keywords. The most recent search was in February 2011.

RESULTS

While the use of parathyroid hormone as a surrogate measure did not lead to a consensus concerning the required 25-hydroxyvitamin D serum level, the combined analysis of bone mineralization and vitamin D status has established minimum levels of more than 75 nmol/L (30 ng/mL) to guarantee at least skeletal health. An effective measure to approach this status is food fortification, which has been demonstrated by countries such as Canada, the United States, and Finland.

CONCLUSIONS

Given the health economic implications of failure to maintain a balanced vitamin D status, action is recommended to integrate current scientific knowledge on vitamin D into physicians' treatment of patients and governmental policies on food fortification.

Cardiorespiratory fitness, adiposity, and serum 25-dihydroxyvitamin D levels in women: the Cooper Center Longitudinal Study

PURPOSE

We examined the cross-sectional associations among cardiorespiratory fitness (CRF), different measures of adiposity, and serum vitamin D levels in women.

METHODS

Between 2007 and 2010, 1320 women completed a health examination. Measures included body mass index (BMI), waist circumference (WC), waist/hip ratio, percent body fat, CRF based on a maximal treadmill exercise test, and measurement of serum vitamin D. Participants were classified by CRF as unfit (lowest 20%) and fit (remaining 80%) based on age, as well as by clinical cutoff points for adiposity measures, and by categories of serum vitamin D. We examined trends of CRF and adiposity exposures across serum vitamin D categories. We calculated odds ratios (OR) of serum vitamin D insufficiency or deficiency across levels of adiposity exposures before and after adjustment for CRF.

RESULTS

We observed a significant positive trend for CRF across incremental serum vitamin D categories (p<0.001). When compared to ORs for normal weight women, ORs for serum vitamin D insufficiency or deficiency were significantly higher for overweight women within each adiposity exposure (p<0.05). When grouped into categories of fit and unfit (upper 80% and lower 20% of CRF distribution, respectively), serum vitamin D was significantly lower in unfit than in fit women within each stratum of WC and waist/hip ratio and within the normal weight BMI stratum.

CONCLUSIONS

Serum vitamin D levels are positively associated with CRF and negatively associated with different measures of adiposity in women. Higher CRF attenuates the relationship between adiposity level and serum vitamin D. Future prospective studies are warranted.

The role of falls in fracture prediction

Close to 75% of hip and non-hip fractures occur among seniors age 65 years and older. Notably, the primary risk factor for a hip fracture is a fall, and over 90% of all fractures occur after a fall. Thus, critical for the understanding and prevention of fractures at later age is their close relationship with muscle weakness and falling. In fact, antiresorptive treatment alone may not reduce fractures among individuals 80 years and older in the presence of nonskeletal risk factors for fractures despite an improvement in bone metabolism. This article will review the epidemiology of falls, and their importance in regard to fracture risk. Finally, fall prevention strategies and how these translate into fracture reduction are evaluated based on data from randomized controlled trials.

Vitamin D supplementation versus combined calcium and vitamin D in older female patients - an observational study

BACKGROUND

In most developed countries overt vitamin D deficiency, characterized by rickets or osteomalacia, is now uncommon. However, subclinical vitamin D insufficiency is extremely common and may contribute to the development of skeletal and non-skeletal problems. Standard practice involves supplementation with a combination of vitamin D and calcium although the benefit of adding calcium to vitamin D supplements has not been fully established and may reduce adherence due to its bulky and chalky consistency.

PURPOSE OF STUDY

To compare the effects of vitamin D alone versus vitamin D/calcium supplements on vitamin D levels, bone profile and parathyroid hormone level.

POPULATION

Older (> 65 years) female patients living in the community and long term care institutions.

INTERVENTIONS

Either 800 iu of vitamin D3 or a composite supplement of 800 iu vitamin D3 and 1000 mg calcium were given to patients in an open-labelled observational study. Serum 25-hydroxy-vitamin D, parathyroid hormone, calcium, phosphate and alkaline phosphatase levels were assessed at baseline and after 3 months of treatment.

RESULTS

Serum 25-hydroxy-vitamin D levels rose from baseline levels of 25 ± 16 to 79 ± 16 in those treated with vitamin D alone and from 35 ± 24 nmol/L to 70 ± 24 nmol/L in those treated with vitamin D and calcium. Serum PTH levels fell by similar amounts in both groups. In both community dwellers and institutionalised patients, those treated with vitamin D alone were at least as likely to achieve normalisation of serum vitamin D levels as those on combined calcium/vitamin D treatment.

CONCLUSION

Vitamin D alone appears as effective as combined calcium/vitamin D treatment in restoring serum vitamin D levels in older community dwelling and institutionalised patients. A prospective randomised trial would help confirm these findings.

Vitamin D status and its seasonal variability in healthy young adults in an Asian Indian urban population

OBJECTIVE

To assess the vitamin D status and its seasonal variability in healthy young adults in Chandigarh, a city in northern India.

METHODS

The history was elicited and examination was performed pertaining to metabolic bone disease in 329 young adults (18 to 25 years of age) at the end of summer and 237 subjects from the same cohort at the end of winter. The calcium profile, 25-hydroxyvitamin D [25(OH)D], and intact parathyroid hormone were measured during both the seasons.

RESULTS

Among the young adults in this study cohort, 25(OH)D sufficiency (≥ 30 ng/mL) was found in 72.5% in summer and in 50.7% in winter. A significantly higher number of men were 25(OH)D sufficient in comparison with women in summer (P = .001). The mean (standard deviation) serum 25(OH)D levels were significantly higher at the end of summer-52.9 (33.7) ng/mL-in comparison with that at the end of winter-31.8 (21.1) ng/mL; P<.001. The intact parathyroid hormone levels were significantly lower in the 25(OH)D-sufficient group (P = .001) and began to increase at 25(OH)D levels below 25 ng/mL. The serum 25(OH)D levels correlated positively with the duration of exposure to sunlight during summer (r = 0.111; P = .05) and also the calcium intake during summer (r = 0.129; P = .03).

CONCLUSION

Vitamin D sufficiency may be a reality with a combination of young skin, optimal and effective exposure to sunlight, and adequate calcium intake.

The effects of vitamin D on skeletal muscle function and cellular signaling

It is thought that every cell in the body expresses the vitamin D receptor, and therefore vitamin D may play a role in health and homeostasis of every organ system, including skeletal muscle. Human, animal, and cell culture studies have collectively shown that vitamin D affects muscle strength and function. Vitamin D functions in a plethora of cellular processes in skeletal muscle including calcium homeostasis, cell proliferation, cell differentiation, fiber size, prevention of fatty degeneration, protection against insulin resistance and arachidonic acid mobilization. These processes appear to be mediated by several signaling pathways affected by vitamin D. This review aims to explore the effects of vitamin D on skeletal muscle in each model system and to delineate potential cell signaling pathways affected by vitamin D.

Reporting of complex interventions in clinical trials: development of a taxonomy to classify and describe fall-prevention interventions

BACKGROUND

Interventions for preventing falls in older people often involve several components, multidisciplinary teams, and implementation in a variety of settings. We have developed a classification system (taxonomy) to describe interventions used to prevent falls in older people, with the aim of improving the design and reporting of clinical trials of fall-prevention interventions, and synthesis of evidence from these trials.

METHODS

Thirty three international experts in falls prevention and health services research participated in a series of meetings to develop consensus. Robust techniques were used including literature reviews, expert presentations, and structured consensus workshops moderated by experienced facilitators. The taxonomy was refined using an international test panel of five health care practitioners. We assessed the chance corrected agreement of the final version by comparing taxonomy completion for 10 randomly selected published papers describing a variety of fall-prevention interventions.

RESULTS

The taxonomy consists of four domains, summarized as the "Approach", "Base", "Components" and "Descriptors" of an intervention. Sub-domains include; where participants are identified; the theoretical approach of the intervention; clinical targeting criteria; details on assessments; descriptions of the nature and intensity of interventions. Chance corrected agreement of the final version of the taxonomy was good to excellent for all items. Further independent evaluation of the taxonomy is required.

CONCLUSIONS

The taxonomy is a useful instrument for characterizing a broad range of interventions used in falls prevention. Investigators are encouraged to use the taxonomy to report their interventions.

Current and future pharmacologic treatment of sarcopenia

Sarcopenia is a complex multifactorial condition that can by treated with multimodal approaches. No pharmacologic agent to prevent or treat sarcopenia has been as efficacious as exercise (mainly resistance training) in combination with nutritional intervention (adequate protein and energy intake). However, performing resistance training sessions and following nutritional advice can be challenging, especially for frail, sarcopenic, elderly patients, and results remain only partial. Therefore, new pharmacologic agents may substantially reduce the functional decline in older people. This article reviews the new pharmacologic agents currently being assessed for treating sarcopenia.

Effect of vitamin D nutritional status on muscle function and strength in healthy women aged over sixty-five years

BACKGROUND

Vitamin D insufficiency is common in elderly adults, and leads to secondary hyperparathyroidism, bone loss, muscle weakness, and osteoporotic fractures.

OBJECTIVE

To evaluate the relation between vitamin D nutritional status and muscle function and muscle strength in women aged over 65 years.

METHODS

Fifty-four postmenopausal women from Buenos Aires (latitude 34° S), average age (X±DS) 71±4, were included in the study. Determinations of serum calcium, phosphate, 25 hydroxyvitamin D (25OHD), intact parathormone (iPTH) and calciuria / creatininuria ratio in 24-hour urine samples were performed. Muscle function was assessed by means of walking-speed test, standing balance, and sit-to-stand tests. Lower extremity muscle strength was determined using a manual dynamometer.

RESULTS

25OHD levels ≥20 ng/ml were found to be associated with better lower extremity muscle function and strength. Forty- six % of participants had 25OHD levels ≥20 ng/ml. Women with 25OHD levels ≥20 ng/ml scored higher on the muscle function tests (11.2±0.9 vs.10.0±2.1; p<0.003) and had stronger knee extensor (13.4±2.7 vs.11.6±2.5 Kg.; p<0.03) and hip abductor (8.3±2.7 vs. 7.3±3.1 Kg; p<0.04) muscles; strength of their hip flexors tended to be higher but did not reach significantly different values (17.0±3.3 vs. 15.4±2.8 Kg.; 0.1>p>0.05). Negative correlation was observed between iPTH and muscle function (r= -0.436; p<0.02).

CONCLUSION

25OHD levels ≥20 ng/ml are needed for a better muscle function and strength. Assessing vitamin D nutritional status in adults aged ≥ 65 years would allow correcting hypovitaminosis D and improve muscle function and strength.

The 6-minute walk is associated with frailty and predicts mortality in older adults with heart failure

Heart failure (HF) may contribute to the development of functional decline and frailty in older adults. Sixty HF patients with an ejection fraction ≤ 40% evaluated in 2004 and 2005 were reevaluated in 2008. Six-minute walk distance (6MW), frailty score, and biomarkers (25-hydroxyvitamin D, C-reactive protein, and interleukin-6 [IL-6]) were measured. Participants were categorized at baseline and follow-up into 3 groups: nonfrail/normal endurance (NF/NE), nonfrail/low endurance (NF/LE) and frail/low endurance (F/LE). Survival time was assessed according to frailty/endurance status and associated predictors of mortality. Forty-three men, 17 women (mean age, 78 ± 12 years) were contacted. At follow-up, 20 had died, 20 participated, and 20 did not participate. There were no changes in frailty/endurance status over time (McNemar;P=.19). Deaths occurred in 18% of NF/NE, 45% of NF/LE, and 60% of F/LE persons. The NF/NE group had greater survival rates than the NF/LE (  P=.032) and F/LE (  P=.014) groups. The 6MW and frailty score were independently predictive of mortality, with hazard ratios of 0.82 (95% confidence interval, 0.72-0.94) and 1.64 (95% confidence interval, 1.19-2.26), respectively, as was New York Heart Association class and IL-6. Backward stepwise Cox regression revealed that 6MW and frailty each were associated with mortality (P=.005) and highly correlated. Physical function is an important predictor of mortality in older adults with HF. The 6MW may be useful as a measure of frailty.

Preventing falls and fractures in long-term care

The prevalence of falls and associated injuries increases with age and dependency. The highest occurs among individuals living in long-term care institutions. Preventing falls results in reduced physical and psychological morbidity as well as having cost-saving implications. This review explores both uni- and multifactorial approaches to reducing fall rates and risk in individuals in long-term care, as well as highlighting the differences in this group from community-dwelling individuals.

The Role of Vitamin D in Human Health: A Paradigm Shift

Vitamin D deficiency is pandemic, spanning many continents and including all ages, genders and racial/ethnic groups. Currently, world-wide attention is focused on the importance of vitamin D in optimizing health and preventing disease. This focus is largely the result of the scientific discovery that vitamin D receptors are present in nearly every tissue and cell in the body and that adequate vitamin D status is essential for optimal functioning of these tissues and cells. An impressive body of research has accumulated over the past two decades providing new information about the role of vitamin D in prevention of a broad range of diseases. The purpose of this paper is to provide a review of this new information.

Calcium plus vitamin D supplementation has limited effects on femoral geometric strength in older postmenopausal women: the Women's Health Initiative

Calcium plus vitamin D (CaD) supplementation has a modest but significant effect on slowing loss of femoral bone mass and reducing risk of hip fractures in adherent postmenopausal women. The goal of this study was to determine if CaD supplementation influences hip structural parameters that are associated with fracture risk. We studied 1,970 postmenopausal women enrolled in the Women's Health Initiative randomized controlled trial of CaD at one of three bone mineral density (BMD) clinical centers. Hip structural analysis software measured BMD and strength parameters on DXA scans at three regions: femoral narrow neck, intertrochanter, and shaft. Random effects models were used to test the average differences in hip BMD and geometry between intervention and placebo. There was greater preservation of hip BMD at the narrow neck with CaD relative to placebo across 6 years of intervention. CaD also altered the underlying cross-sectional geometry at the narrow neck in the direction of greater strength, with small increases in cross-sectional area and section modulus and a decrease in buckling ratio with CaD relative to placebo. While trends at both the intertrochanter and shaft regions were similar to those noted at the narrow neck, no significant intervention effects were evident. There was no significant interaction of CaD and age or baseline calcium levels for hip structural properties. CaD supplementation is associated with modest beneficial effects on hip structural features at the narrow neck, which may explain some of the benefit of CaD in reducing hip fracture risk.

How pleiotropic genetics of the musculoskeletal system can inform genomics and phenomics of aging

Genetic study can provide insight into the biologic mechanisms underlying inter-individual differences in susceptibility to (or resistance to) organisms' aging. Recent advances in molecular genetics and genetic epidemiology provide the necessary tools to perform a study of the genetic sources of biological aging. However, to be successful, the genetic study of a complex condition requires a heritable phenotype to be developed and validated. Genome-wide association studies offer an unbiased approach to identify new candidate genes for human diseases. It is hypothesized that convergent results from multiple aging-related traits will point out the genes responsible for the general aging of the organism. This perspective focuses on the musculoskeletal aging as an example of an approach to identify a downstream common pathway that summarizes aging processes. Since the musculoskeletal traits are linked to the state of many vital functions, disability, and ultimately survival rates, we postulate that there is significance in studying musculoskeletal aging. Construction of an integrated phenotype of aging can be achieved based on shared genetics among multiple musculoskeletal biomarkers. Valid biomarkers from other systems of the organism should be similarly explored. The new composite aging score needs to be validated by determining whether it predicts all-cause mortality, incidences of major chronic diseases, and disability late in life. Comprehensive databases on biomarkers of musculoskeletal aging in multiple large cohort studies, along with information on various health outcomes, are needed to validate the proposed measure of biological aging.

Effects of alfacalcidol on muscle strength, muscle fatigue, and bone mineral density in normal and ovariectomized rats

Vitamin D affects not only bone but also muscle to prevent falls and osteoporotic fractures. However, these effects on muscle and the mechanisms of fall prevention are still unclear. The purpose of this study was to investigate the effects of alfacalcidol [1α(OH)D(3)] on muscle strength, muscle fatigue, and bone mineral density (BMD) in ovariectomized rats. Seven-month-old female Wistar rats were orally administered 1α(OH)D(3) or its vehicle everyday for 4 weeks after ovariectomy (OVX) or sham operation. Calf muscle strength and fatigue were evaluated by electrical stimulation of the sciatic nerve under general anesthesia. 1α(OH)D(3) administration significantly increased the maximum muscle strength in the sham-operated (P < 0.01) and the OVX (P < 0.01) groups compared to their respective control groups. However, 1α(OH)D(3) administration did not significantly affect muscle fatigue in these groups. The BMD of the femur in the 1α(OH)D(3)-treated OVX group was significantly higher than that in the vehicle-treated OVX group (P = 0.04). These results suggested that 1α(OH)D(3) increases muscle strength but does not affect muscle fatigue in this rat model. The effectiveness of activated vitamin D in preventing bone fractures may be partly owing to its effect on muscle strength in addition to its known effect on bone metabolism.

Changes in balance, functional performance and fall risk following whole body vibration training and vitamin D supplementation in institutionalized elderly women. A 6 month randomized controlled trial

Falls in the elderly constitute a growing public health problem. This randomized controlled trial investigated the potential benefit of 6 months of whole body vibration (WBV) training and/or vitamin D supplementation on balance, functionality and estimated fall risk in institutionalized elderly women. A total of 113 women (mean age: 79.6) were randomly assigned to either a WBV or a no-training group, receiving either a conventional dose (880 IU/d) or a high dose (1600 IU/d) of vitamin D3. The WBV group performed exercises on a vibration platform 3×/week. Balance was evaluated by computerized posturography. Functionality was assessed by 10 m walk test, Timed up and Go (TUG) performance and endurance capacity (Shuttle Walk). Fall risk was determined with the Physiological Profile Assessment. Performance on the 10 m walk test and on TUG improved over time in all groups. For none of the parameters, high-dose vitamin D resulted in a better performance than conventional dosing. The improvements in the WBV group in endurance capacity, walking at preferred speed, and TUG were significantly larger than the changes with supplementation alone. No additional benefit of WBV training could be detected on fall risk and postural control, although sway velocity and maximal isometric knee extension strength improved only in the WBV group. This trial showed that a high-dose vitamin D supplementation is not more efficient than conventional dosing in improving functionality in institutionalized elderly. WBV training on top of vitamin D supplementation provided an added benefit with regard to walking, TUG performance, and endurance capacity.

Serum 25-hydroxyvitamin D concentration and physical function in adult men

OBJECTIVE

Recent reports suggest that vitamin D status influences musculoskeletal health; yet, there are limited data in adult men. This study investigated whether serum 25-hydroxyvitamin D [25(OH)D] concentration was associated with lean body mass, muscle strength and physical performance in men.

DESIGN

Population-based, observational survey.

PARTICIPANTS

1219 black, Hispanic and white randomly selected men aged 30-79 years from the Boston Area Community Health/Bone Survey.

MEASUREMENTS

Lean body mass by dual-energy X-ray absorptiometry, hand grip strength, a composite physical function score (chair stand and walking speed), 25(OH)D, parathyroid hormone (PTH), testosterone, age, race, body mass index, socioeconomic status, education, smoking, arthritis, self-reported health, calcium intake, physical activity.

RESULTS

The distributions of serum 25(OH)D quartiles differed by race/ethnicity, education and smoking status. After adjustment for multiple lifestyle factors, serum 25(OH)D was not related to lean body mass, grip strength or the composite physical function score (all P>0.20). There was no variation in the associations between 25(OH)D level and outcomes by race/ethnicity. The relationship between PTH and the outcomes revealed similar results.

CONCLUSION

In this population-based sample of adult men with a broad age range, there was no association between serum 25(OH)D concentration and lean body mass, muscle strength and physical function after controlling for multiple lifestyle factors.

Vitamin D, neurocognitive functioning and immunocompetence

PURPOSE OF REVIEW

Vitamin D deficiency is recognized as one of the most common medical conditions in children and adults. The major causes are inadequate sun exposure and inadequate intakes of dietary and supplemental vitamin D. Vitamin D deficiency and insufficiency defined as a 25-hydroxyvitamin D level less than 20 and 21-29 ng/ml, respectively, have been linked to increased risk for a variety of medical conditions including cancer, heart disease, type II diabetes, infectious diseases, autoimmune diseases, metabolic bone diseases and neurological disorders.

RECENT FINDINGS

The skeletal muscle and brain have a vitamin D receptor and the central nervous system has a capacity to activate vitamin D. Low vitamin D status has been linked to poor performance in neurocognitive testing in elderly. Vitamin D deficiency has been associated with muscle weakness, depression, schizophrenia, Alzheimer's disease, multiple sclerosis and a lower motor neuron-induced muscle atrophy.

SUMMARY

Correcting vitamin D deficiency and preventing vitamin D deficiency in children and adults should be a high priority for healthcare professionals to reduce risk for a wide variety of neurological disorders. Children and adults should take at least 400 international unit IU and 2000 IU vitamin D/day, respectively, to prevent vitamin D deficiency and insufficiency.

What is the best balance of benefits and risks among anti-resorptive therapies for postmenopausal osteoporosis?

Pharmacologic osteoporosis therapy, particularly anti-resorptives, is recommended in postmenopausal women with clinical risk factors for fracture. Treatment decisions should be made based on the relative benefit-risk profile in different patient populations. Emerging options [e.g., selective estrogen receptor modulators (SERMs) and denosumab] may hold promise for providing protection from bone loss and for fracture risk reduction.Osteoporosis, the most common clinical disorder of bone metabolism, is characterized by low bone mineral density, deterioration of microarchitecture, and a consequent increase in bone fragility and risk of fracture. Pharmacologic therapy is recommended in postmenopausal women with clinical risk factors for fracture and includes anti-resorptive agents such as bisphosphonates, hormone therapy, SERMs, and calcitonin. The anabolic agent teriparatide (parathyroid hormone) is usually reserved for high-risk patients or those with glucocorticoid-induced osteoporosis. Strontium ranelate, available outside the USA, has both anti-resorptive and anabolic properties. Supplementation with calcium and vitamin D is recommended for all women aged 50 years and older. Bisphosphonates are often considered first-line therapy for osteoporosis and have the largest base of clinical trial data showing efficacy for global fracture risk reduction. Low-dose hormone therapy is appropriate for younger women who are experiencing other menopausal symptoms. In women for whom bisphosphonates are not appropriate or not tolerated or in younger postmenopausal women who have a low risk for hip fracture, SERMs are a suitable treatment option. Calcitonin is designated for patients who are unable or unwilling to tolerate other osteoporosis agents. Emerging options, including newer SERMs (e.g., bazedoxifene and lasofoxifene) and the monoclonal antibody denosumab, may hold promise for providing protection from bone loss and for fracture risk reduction. Because no single agent is appropriate for all patients, treatment decisions should be made on an individual basis, taking into account the relative benefits and risks in different patient populations.

Vitamin D supplementation: a pharmacologic perspective

PURPOSE OF REVIEW

Vitamin D supplementation is expected to increase as clinicians try to optimize their patients' vitamin D status. This review integrates newer information into a perspective on vitamin D disposition and effect.

RECENT FINDINGS

Vitamin D is being considered for indications beyond bone health. The limited dose-response data vary by indication, but generally target a goal serum 25(OH)D concentration of 80-120 nmol/l. Although oral vitamin D is adequately absorbed, distributed, metabolized, and utilized before being excreted, these factors may vary with baseline vitamin D status, genetic polymorphism, and the form of vitamin D being administered. Additionally, the responses to vitamin D can be tissue-specific and are not always well described.

SUMMARY

There is still a need to better characterize the disposition and effect of vitamin D supplementation. Data will need to be more specific to the therapeutic indication and demonstrate health outcomes. Long-term effects of high-dose supplementation at the tissue level will be especially important to describe.

Vitamin D: a hormone for all seasons

Vitamin D is principally obtained from skin through the action of ultraviolet B irradiation on 7-dehydrocholesterol. It is further metabolized to 25-hydroxyvitamin D, the major circulating vitamin D compound, and then to 1,25-dihydroxyvitamin D, the hormonal form. The major function of vitamin D compounds is to enhance active absorption of calcium (and phosphate) from the gut, ensuring that bone does not need to be resorbed to maintain blood calcium concentrations despite obligatory urinary losses. Vitamin D compounds have direct effects to enhance bone and muscle function. Based on good evidence, target levels for 25-hydroxyvitamin D in blood are at least 50 nmol/l and there may be a case for higher targets of 75-80 nmol/l. Adequate calcium intakes help to reduce vitamin D degradation. Vitamin D and calcium together reduce the risk of falls and fractures in older people. There are vitamin D receptors in most nucleated cells and preliminary evidence that adequate vitamin D levels may be important in reducing the incidence of, or mortality from, some cancers, and in reducing autoimmune disease. Adequate vitamin D may also allow for a normal innate immune response to pathogens, improve cardiovascular function and mortality, and reduce type 2 diabetes. Supplemental vitamin D seems to work in a generally similar manner to skin-derived vitamin D.

Alfacalcidol improves muscle power, muscle function and balance in elderly patients with reduced bone mass

We investigated the effect of daily therapy with 1 mcg alfacalcidol (Doss(®)-TEVA/AWD-pharma) on muscle power, muscle function, balance performance and fear of falls in an open, multi-centered, uncontrolled, prospective study on a cohort of patients with reduced bone mass. Among the 2,097 participants, 87.1% were post-menopausal women and 12.9% were men. Mean age was 74.8 years and mean body mass index (BMI) 26.3 kg/m². A total of 75.3% of the study population had osteoporosis, 81% a diagnosis of "increased risk of falls" and 70.1% had a creatinine clearance (CrCl) of <65 ml/min. Participants underwent muscle function and muscle power tests at onset and after 3 and 6 months: the timed up and go test (TUG) and the chair rising test (CRT). At baseline and after 6 months, participants performed the tandem gait test (TGT) and filled out a questionnaire evaluating fear of falling. Successful performance in the muscle tests is associated with a significantly lower risk of falls and non-vertebral fractures in elderly patients (successful test performance: TUG ≤ 10 s (sec), CRT ≤ 10 s, TGT ≥ 8 steps). A significant improvement in the performance of the two muscle tests was proved already after 3 months of treatment with alfacalcidol and further increased by the end of the therapeutic intervention. There were significant increases in the number of participants able to successfully perform the tests: 24.6% at baseline and 46.3% at the end of trial for the TUG (P < 0.0001) and 21.7% at baseline and 44.2% at the end for the CRT test (P = 0.0001). The mean time used for the TUG was decreased by 3.0 s from the average onset value of 17.0 s and by 3.1 s from the initial average 16.5 s for the CRT. The percentage of participants able to perform the balance test (TGT) increased from 36.0% at onset to 58.6% at the end of the trial (P < 0.0001). An increased fear of falling was reduced by the end of the study in 74.4% of the patients. Throughout the study, there were 26 adverse drug reactions in 11 out of 2,097 patients (incidence 0.52%). No serious adverse drug reactions and no cases of hypercalcemia were documented. We conclude that treatment with alfacalcidol is safe, increases muscle power, muscle function and balance and reduces fear of falls. The significant improvement in the three muscle and balance tests and fear of falls may have a preventative effect on falls and fractures. We suggest that the quantitative risk tests used in this study could be reliable surrogate parameters for the risk of falls and fractures in elderly patients.

Benefit-risk assessment of vitamin D supplementation

Current intake recommendations of 200 to 600 IU vitamin D per day may be insufficient for important disease outcomes reduced by vitamin D.

INTRODUCTION

This study assessed the benefit of higher-dose and higher achieved 25-hydroxyvitamin D levels [25(OH)D] versus any associated risk.

METHODS AND RESULTS

Based on double-blind randomized control trials (RCTs), eight for falls (n = 2426) and 12 for non-vertebral fractures (n = 42,279), there was a significant dose-response relationship between higher-dose and higher achieved 25(OH)D and greater fall and fracture prevention. Optimal benefits were observed at the highest dose tested to date for 700 to 1000 IU vitamin D per day or mean 25(OH)D between 75 and 110 nmol/l (30-44 ng/ml). Prospective cohort data on cardiovascular health and colorectal cancer prevention suggested increased benefits with the highest categories of 25(OH)D evaluated (median between 75 and 110 nmol/l). In 25 RCTs, mean serum calcium levels were not related to oral vitamin D up to 100,000 IU per day or achieved 25(OH)D up to 643 nmol/l. Mean levels of 75 to 110 nmol/l were reached in most RCTs with 1,800 to 4,000 IU vitamin D per day without risk.

CONCLUSION

Our analysis suggests that mean serum 25(OH)D levels of about 75 to 110 nmol/l provide optimal benefits for all investigated endpoints without increasing health risks. These levels can be best obtained with oral doses in the range of 1,800 to 4,000 IU vitamin D per day; further work is needed, including subject and environment factors, to better define the doses that will achieve optimal blood levels in the large majority of the population.

Effect of vitamin D(3) and calcium on fracture risk in 65- to 71-year-old women: a population-based 3-year randomized, controlled trial--the OSTPRE-FPS

Antifracture efficacy of high-dose vitamin D (800 IU) and calcium (1000 mg) remains controversial. To determine whether daily 800 IU of vitamin D and 1000 mg of calcium supplementation prevents fractures, we randomized 3432 women of the population-based Osteoporosis Risk Factor and Prevention (OSTPRE) Study cohort (ages 65 to 71 years) living in the region of northern Savonia, Finland (latitude 62 degrees to 64 degrees N) for 3 years to receive 800 IU of cholecalciferol and 1000 mg of calcium as calcium carbonate or to a control group that did not receive placebo. The main outcome measure was incident fractures. Fracture data were collected in telephone interviews and validated. Data on 3195 women, 1586 in the intervention group and 1609 in the control group, were available for analysis. In adjusted Cox proportional hazards models, the risk of any fracture decreased in the vitamin D and calcium group by 17% [adjusted hazard ratio (aHR) = 0.83; 95% confidence interval (CI) 0.61-1.12], and the risk of any nonvertebral fracture decreased by 13% (aHR = 0.87; 95% CI 0.63-1.19). The risk of distal forearm fractures decreased by 30% (aHR = 0.70; 95% CI 0.41-1.20), and the risk of any upper extremity fractures decreased by 25% (aHR = 0.75; 95% CI 0.49-1.16), whereas the risk of lower extremity fractures remained essentially equal (aHR = 1.02; 95% CI 0.58-1.80). None of these effects reached statistical significance. In conclusion, this study did not produce statistically significant evidence that vitamin D and calcium supplementation prevents fractures in a 65- to 71-year-old general population of postmenopausal women.

Impact of supplementation with bicarbonate on lower-extremity muscle performance in older men and women

This study describes the impact of bicarbonate treatment for 3 months on net acid excretion (NAE), nitrogen excretion, and muscle performance in older men and women. Bicarbonate reduced NAE, and the decrement was associated with a decrease in nitrogen excretion. Treatment also improved muscle power and endurance in the women.

INTRODUCTION

Bicarbonate enhances muscle performance during strenuous exercise, but its effect on performance during normal activity in older subjects is unknown.

METHODS

In this trial, healthy subjects age 50 and older were randomized to 67.5 mmol of bicarbonate or to no bicarbonate daily for 3 months. Changes in lower-extremity muscle power, endurance, urinary nitrogen, and NAE were compared across treatment groups in the 162 participants included in the analyses.

RESULTS

In the men and the women, bicarbonate was well tolerated, and as expected, it significantly decreased NAE. The change in NAE correlated with change in nitrogen excretion in women (r = 0.32, P = 0.002) with a similar trend in men (r = 0.23, P = 0.052). In the women, bicarbonate increased double leg press power at 70% one repetition maximum by 13% (P = 0.003) compared with no bicarbonate and improved other performance measures. Treatment with bicarbonate had no significant effect on muscle performance in the men.

CONCLUSIONS

Ingestion of bicarbonate decreased nitrogen excretion and improved muscle performance in healthy postmenopausal women. The bicarbonate-induced decline in NAE was associated with reduced nitrogen excretion in both men and women. These findings suggest that bicarbonate merits further evaluation as a safe, low-cost intervention that may attenuate age-related loss of muscle performance and mass in the elderly.

Vitamin D treatment for the prevention of falls in older adults: systematic review and meta-analysis

OBJECTIVES

To systematically review and quantitatively synthesize the effect of vitamin D therapy on fall prevention in older adults.

DESIGN

Systematic review and meta-analysis.

SETTING

MEDLINE, CINAHL, Web of Science, EMBASE, Cochrane Library, LILACS, bibliographies of selected articles, and previous systematic reviews through February 2009 were searched for eligible studies.

PARTICIPANTS

Older adults (aged > or = 60) who participated in randomized controlled trials that both investigated the effectiveness of vitamin D therapy in the prevention of falls and used an explicit fall definition.

MEASUREMENTS

Two authors independently extracted data, including study characteristics, quality assessment, and outcomes. The I(2) statistic was used to assess heterogeneity in a random-effects model.

RESULTS

Of 1,679 potentially relevant articles, 10 met inclusion criteria. In pooled analysis, vitamin D therapy (200-1,000 IU) resulted in 14% (relative risk (RR)=0.86, 95% confidence interval (CI)=0.79-0.93; I(2)=7%) fewer falls than calcium or placebo (number needed to treat =15). The following subgroups had significantly fewer falls: community-dwelling (aged <80), adjunctive calcium supplementation, no history of fractures or falls, duration longer than 6 months, cholecalciferol, and dose of 800 IU or greater. Meta-regression demonstrated no linear association between vitamin D dose or duration and treatment effect. Post hoc analysis including seven additional studies (17 total) without explicit fall definitions yielded smaller benefit (RR=0.92, 95% CI=0.87-0.98) and more heterogeneity (I(2)=36%) but found significant intergroup differences favoring adjunctive calcium over none (P=.001).

CONCLUSION

Vitamin D treatment effectively reduces the risk of falls in older adults. Future studies should investigate whether particular populations or treatment regimens may have greater benefit.

Independent from muscle power and balance performance, a creatinine clearance below 65 ml/min is a significant and independent risk factor for falls and fall-related fractures in elderly men and women diagnosed with osteoporosis

We assessed in a cross-sectional study in elderly men and women with osteoporosis, the association between the creatinine clearance (CrCl) and the performance in different balance and muscle power and function tests and found that a decreasing creatinine clearance was significantly associated with lower balance and muscle power.

INTRODUCTION

To determine if a creatinine clearance of <65 ml/min is significantly associated with decreasing muscle power and balance and an increased risk for falls and fractures.

METHODS

We assessed in a cross-sectional-study in 1781 German osteoporotic patients, the association between the CrCl, the physical performance, and the number of falls and fractures.

RESULTS

Controlling for age, gender, BMI, and osteoporosis treatment (fracture analysis only), a decreasing CrCl was associated with lower physical performance in the timed-up-and-go test (corr -0.2337, P < 0.0001), chair-rising test (corr -0.1706, P < 0.001), and tandem-stand test (corr 0.2193, P < 0.0001), and a CrCl of <65 ml/min was associated with a significantly higher risk for falls (47.7% vs. 36.2%, P = 0.0008) and fall-related fractures (33.1% vs. 22.9%, P = 0.0003) compared with a CrCl of >or=65 ml/min.

CONCLUSIONS

In this study, we found a significant gender-independent correlation between decreasing CrCl and lower performance in balance and muscle power tests. Reduced muscle power and balance may therefore be involved in the low creatinine clearance associated increased risk for falls and fall-related fractures. Furthermore, we found that a CrCl <65 ml/min., independent from the performance in muscle power, muscle function, and balance tests, is a significant risk factor for falls and fractures.

Vitamin D and bone health: potential mechanisms

Osteoporosis is associated with increased morbidity, mortality and significant economic and health costs. Vitamin D is a secosteriod hormone essential for calcium absorption and bone mineralization which is positively associated with bone mineral density [BMD]. It is well-established that prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults. Sub-optimal vitamin D status has been reported in many populations but it is a particular concern in older people; thus there is clearly a need for effective strategies to optimise bone health. A number of recent studies have suggested that the role of vitamin D in preventing fractures may be via its mediating effects on muscle function (a defect in muscle function is one of the classical signs of rickets) and inflammation. Studies have demonstrated that vitamin D supplementation can improve muscle strength which in turn contributes to a decrease in incidence of falls, one of the largest contributors to fracture incidence. Osteoporosis is often considered to be an inflammatory condition and pro-inflammatory cytokines have been associated with increased bone metabolism. The immunoregulatory mechanisms of vitamin D may thus modulate the effect of these cytokines on bone health and subsequent fracture risk. Vitamin D, therefore, may influence fracture risk via a number of different mechanisms.

Multi-step immunofluorescent analysis of vitamin D receptor loci and myosin heavy chain isoforms in human skeletal muscle

Vitamin D receptors have been shown to be present in human skeletal muscle using different techniques. We developed a multi-staining immunofluorescent method to detect vitamin D receptor expression and co-localize it with myosin heavy chain isoform expression in skeletal muscle biopsies in older female subjects. Serial sections were cut from frozen samples obtained by needle biopsy of the vastus lateralis. Samples were probed with a primary vitamin D receptor monoclonal antibody and then re-probed with a type IIa myosin heavy chain isoform-specific antibody. Independent unfixed sections followed a similar protocol and were probed with type IIx and type I myosin heavy chain isoform-specific antibodies. Immunohistochemistry and fluorescent microscopy co-localized vitamin D receptor loci and myosin heavy chain isoforms in whole skeletal muscle sections. We quantified intranuclear vitamin D receptor staining patterns and number of individual muscle fiber subtypes within a muscle section. Immunohistochemical staining of the vitamin D receptor was confirmed by Western blot using the same monoclonal antibody. This multi-staining immunofluorescent technique allows for measurement of intranuclear vitamin D receptor expression in the context of the specific muscle fiber type profile in a single section. This method can thus be a useful approach to study potential relationships between muscle fiber subtypes and vitamin D receptor expression.

Vitamin D and fracture prevention

This article discusses the amount of vitamin D supplementation needed and the desirable 25-hydroxyvitamin D level to be achieved for optimal fracture prevention.

Management of osteoporosis in postmenopausal women: 2010 position statement of The North American Menopause Society

OBJECTIVE

To update the evidence-based position statement published by The North American Menopause Society (NAMS) in 2006 regarding the management of osteoporosis in postmenopausal women.

METHODS

NAMS followed the general principles established for evidence-based guidelines to create this updated document. A panel of clinicians and researchers expert in the field of metabolic bone diseases and/or women's health was enlisted to review the 2006 NAMS position statement, compile supporting statements, and reach consensus on recommendations. The panel's recommendations were reviewed and approved by the NAMS Board of Trustees.

RESULTS

Osteoporosis, which is especially prevalent among older postmenopausal women, increases the risk of fractures. Hip and spine fractures are associated with particularly high morbidity and mortality in this population. Given the health implications of osteoporotic fractures, the primary goal of osteoporosis therapy is to prevent fractures, which is accomplished by slowing or stopping bone loss, maintaining bone strength, and minimizing or eliminating factors that may contribute to fractures. The evaluation of postmenopausal women for osteoporosis risk requires a medical history, physical examination, and diagnostic tests. Major risk factors for postmenopausal osteoporosis (as defined by bone mineral density) include advanced age, genetics, lifestyle factors (such as low calcium and vitamin D intake, smoking), thinness, and menopause status. The most common risk factors for osteoporotic fracture are advanced age, low bone mineral density, and previous fracture as an adult. Management focuses first on nonpharmacologic measures, such as a balanced diet, adequate calcium and vitamin D intake, adequate exercise, smoking cessation, avoidance of excessive alcohol intake, and fall prevention. If pharmacologic therapy is indicated, government-approved options are bisphosphonates, selective estrogen-receptor modulators, parathyroid hormone, estrogens, and calcitonin.

CONCLUSIONS

Management strategies for postmenopausal women involve identifying those at risk for fracture, followed by instituting measures that focus on reducing modifiable risk factors through dietary and lifestyle changes and, if indicated, pharmacologic therapy.