Effect of calcium supplementation on bone loss in postmenopausal women

The Influences of Macronutrients on Bone Mineral Density, Bone Turnover Markers, and Fracture Risk in Elderly People: A Review of Human Studies

Osteoporosis is a health condition that involves weak bone mass and a deteriorated microstructure, which consequently lead to an increased risk of bone fractures with age. In elderly people, a fracture attributable to osteoporosis elevates mortality. The objective of this review was to examine the effects of macronutrients on bone mineral density (BMD), bone turnover markers (BTMs), and bone fracture in elderly people based on human studies. A systematic search was conducted in the PubMed®/MEDLINE® database. We included human studies published up to April 2023 that investigated the association between macronutrient intake and bone health outcomes. A total of 11 meta-analyses and 127 individual human studies were included after screening the records. Carbohydrate consumption seemed to have neutral effects on bone fracture in limited studies, but human studies on carbohydrates' effects on BMD or/and BTMs are needed. The human studies analyzed herein did not clearly show whether the intake of animal, vegetable, soy, or milk basic proteins has beneficial effects on bone health due to inconsistent results. Moreover, several individual human studies indicated an association between eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and osteocalcin. Further studies are required to draw a clear association between macronutrients and bone health in elderly people.

Association between a Calcium-to-Magnesium Ratio and Osteoporosis among Puerto Rican Adults

BACKGROUND

The ratio of calcium-to-magnesium intake (Ca:Mg) may be important for bone due to their competitive absorption. The Ca:Mg ratio has been related to health outcomes, but few studies have related it to bone.

OBJECTIVES

The purpose of this analysis was to examine associations between the Ca:Mg intake with bone mineral density (BMD) and osteoporosis among Puerto Rican adults.

METHODS

Adults, aged 47-79 y, from the Boston Puerto Rican Osteoporosis Study, with complete BMD and dietary data (n = 955) were included. BMD was assessed with dual-energy X-ray absorptiometry and diet by a food frequency questionnaire. Calcium and magnesium intakes from food were energy adjusted, and the Ca:Mg was calculated. Adjusted linear and logistic regression models were utilized for testing associations between Ca:Mg and bone outcomes.

RESULTS

Calcium intake was greater in the highest compared with lowest tertile, whereas magnesium intake was similar across tertiles. Mean BMD at hip sites was higher in the middle, compared with the lowest, tertile. Higher odds of osteoporosis were observed for the highest and lowest tertiles, compared with the middle tertile, after adjustment (T3 compared with T2 OR: 2.79; 95% CI: 1.47, 5.3; T1 compared with T2 OR: 2.01; 95% CI: 1.03, 3.92). Repeated analyses without supplement users (n = 432) led to stronger differences and ORs, but lost significance for some comparisons.

CONCLUSIONS

Dietary calcium and magnesium are important for bone, perhaps not independently. The Ca:Mg intake ratio appeared most protective within a range of 2.2-3.2, suggesting that a balance of these nutrients may be considered in recommendations for osteoporosis..

Role of calcium &/or vitamin D supplementation in preventing osteoporotic fracture in the elderly: A systematic review & meta-analysis

Background & objectives

Calcium and vitamin D, separately or in combination are usually prescribed to prevent fragility fractures in elderly population. However, there are conflicting results regarding the ideal dosage and overall efficacy obtained from randomized controlled trials (RCTs) conducted in the past. The objective of this study was to assess the fracture risk with the administration of calcium or vitamin D alone or in combination in elderly population (>60 yr).

Methods

PubMed, Cochrane and Embase databases were searched to identify the studies from inception to February 2021 with keywords, 'vitamin D', 'calcium' and 'fracture' to identify RCTs. The trials with comparing vitamin D, calcium or combination with either no medication or placebo were included for final analyses. The data were extracted and the study quality was assessed by two reviewers. The principal outcome measure was fractures around hip joint and secondary outcomes assessed were vertebral and any other fracture.

Results

Eighteen RCTs were considered for the final analysis. Neither calcium nor vitamin D supplementation was associated with risk of fractures around hip joint [risk ratio (RR) 1.56; 95% confidence interval (CI), 0.91 to 2.69, I[2]=28%; P=0.11]. In addition, the combined administration of calcium and vitamin D was also not associated with fractures around the hip joint in comparison to either no treatment or placebo. The incidence of vertebral (RR 0.95; 95% CI, 0.82 to 1.10, I[2]=0%; P=0.49) or any other fracture (RR 0.83; 95% CI 0.65 to 1.06, I[2]=0%; P=0.14) was not significantly associated with the administration of calcium and vitamin D either individually or in combination. Further subgroup analysis of the results did not vary with the dosage of calcium or vitamin D, dietary calcium intake sex, or serum 25-hydroxyvitamin D levels.

Interpretation & conclusions

The present meta-analysis of RCTs on calcium, vitamin D or a combination of the two in comparison to no treatment or placebo did not support the routine administration protocol of calcium and vitamin D either alone or in combination to lower the risk of fractures in elderly population.

EXTENSIVE EXPERTISE IN ENDOCRINOLOGY: Osteoporosis management

Fractures occur in about half of older White women, and almost a third of older White men. However, 80% of the older individuals who have fractures do not meet the bone density definition of osteoporosis, suggesting that this definition is not an appropriate threshold for offering treatment. Fracture risk can be estimated based on clinical risk factors with or without bone density. A combination of calculated risk, fracture history, and bone density is used in treatment decisions. Medications available for reducing fracture risk act either to inhibit bone resorption or to promote bone formation. Romosozumab is unique in that it has both activities. Bisphosphonates are the most widely used interventions because of their efficacy, safety, and low cost. Continuous use of oral bisphosphonates for >5 years increases the risk of atypical femoral fractures, so is usually punctuated with drug holidays of 6-24 months. Denosumab is a further potent anti-resorptive agent given as 6-monthly s.c. injections. It is comparable to the bisphosphonates in efficacy and safety but has a rapid offset of effect after discontinuation so must be followed by an alternative drug, usually a bisphosphonate. Teriparatide stimulates both bone formation and resorption, substantially increases spine density, and reduces vertebral and non-vertebral fracture rates, though data for hip fractures are scant. Treatment is usually limited to 18-24 months, followed by the transition to an anti-resorptive. Romosozumab is given as monthly s.c. injections for 1 year, followed by an anti-resorptive. This sequence prevents more fractures than anti-resorptive therapy alone. Because of cost, anabolic drugs are usually reserved for those at very high fracture risk. 25-hydroxyvitamin D levels should be maintained above 30 nmol/L, using supplements if sunlight exposure is limited. Calcium intake has little effect on bone density and fracture risk but should be maintained above 500 mg/day using dietary sources.

Coordination Compounds As Multi-Delivery Systems for Osteoporosis

Osteoporosis therapies leveraging bisphosphonates and mineral components (e.g., magnesium, calcium, and strontium) have been raising attention because of their potential for managing this ever-growing disease. The administration of multicomponent therapeutics (combined therapy) in elderly patients is complex and suffers from low patient adherence. Herein, we report an all-in-one combination of four antiosteoporotic components into a new family of coordination complexes: [M₂(H₄alen)₄(H₂O)₂]·1.5H₂O [where M²⁺ = Mg²⁺ (1), (Mg_0.535Ca_0.465)²⁺ (2) and (Mg_0.505Ca_0.450Sr_0.045)²⁺ (3)]. These solid-state complexes were prepared, for the first time, through microwave-assisted synthesis. It is demonstrated that the compounds are capable of releasing their antiosteoporotic components, both in conditions that mimic the path along the gastrointestinal tract and in long periods under physiological conditions (pH ∼7.4). More importantly, when administered in low concentrations, the compounds did not elicit a cytotoxic effect toward liver, kidney, and osteoblast-like cell lines. Besides, it is important to highlight the unique coordination complex with four bone therapeutic components, [(Mg_0.505Ca_0.450Sr_0.045)₂(H₄alen)₄(H₂O)₂]·1.5H₂O (3), which significantly promoted osteoblast metabolic activity up to ca. 1.4-fold versus the control group. These findings bring this type of compounds one-step closer to be considered as an all-in-one and more effective treatment for managing chronic bone diseases, prompting further research on their therapeutic properties.

Identical summary statistics were uncommon in randomized trials and cohort studies

OBJECTIVE

To examine the proposition that identical summary statistics (mean and/or SD) in different randomized controlled trials (RCT) or clinical cohorts can be explained by common or homogeneous source populations.

STUDY DESIGN

We estimated the probability of identical summary data in studies with high proportions of identical summary statistics, in simulations, and in control datasets.

RESULTS

The probability of both an identical mean and an identical SD for a variable in separate RCT is low (<~3%), unless the variable is rounded to 1 significant figure. In two RCT with identical summary statistics for 16 of 39 shared variables, simulations indicated the probability of the observed matches was <1 in 100,000. In 34 clinical cohorts with publication integrity concerns, the proportion of summary statistics from variables reported in ≥10 studies that were identical in ≥2 cohorts were high (42% for means, 52% for SD, and 29% for both), and improbable based on simulations and comparisons to control datasets.

CONCLUSIONS

The likelihood of multiple identical summary statistics within an individual RCT or across a body of RCT or cohort studies by the same research group is low, especially when both the mean, and the SD are identical, unless the variables are rounded to 1 significant figure.

Risk of keratinocyte carcinomas with vitamin D and calcium supplementation: a secondary analysis of a randomized clinical trial

BACKGROUND

It is unknown whether dietary supplementation with vitamin D or calcium prevents keratinocyte carcinomas, also known as nonmelanoma skin cancers.

OBJECTIVES

This study aimed to determine whether daily vitamin D or calcium supplementation alters the risk of basal cell carcinoma (BCC) or invasive cutaneous squamous cell carcinoma (SCC).

METHODS

The Vitamin D/Calcium Polyp Prevention Study is a completed multicenter, double-blind, placebo-controlled, partial 2 × 2 factorial, randomized clinical trial of vitamin D, calcium, or both for the prevention of colorectal adenomas. During 2004-2008, a total of 2259 men and women, 45-75 y of age, recently diagnosed with a colorectal adenoma, were randomly assigned to 1000 IU/d of vitamin D3 or placebo and 1200 mg/d of calcium carbonate or placebo for 3 or 5 y, and followed after treatment ended. Reports of incident BCC or SCC were confirmed from pathology records.

RESULTS

During a median follow-up of 8 y, 200 (9%) participants were diagnosed with BCC and 68 (3%) participants were diagnosed with SCC. BCC incidence was unrelated to treatment with vitamin D compared with no vitamin D (HR: 0.96; 95% CI: 0.73, 1.26), calcium compared with no calcium (HR: 1.01; 95% CI: 0.74, 1.39), and both agents compared with neither (HR: 0.99; 95% CI: 0.65, 1.51). SCC incidence was unrelated to treatment with vitamin D compared with no vitamin D (HR: 0.79; 95% CI: 0.49, 1.27), but there was suggestive evidence of beneficial treatment effects for calcium compared with no calcium (HR: 0.60; 95% CI: 0.36, 1.01) and both agents compared with neither (HR: 0.42; 95% CI: 0.19, 0.91).

CONCLUSIONS

Calcium alone or in combination with vitamin D may reduce the risk of SCC, but not BCC. This trial was registered at clinicaltrials.gov as NCT00153816.

Insights into the Role of Bioactive Food Ingredients and the Microbiome in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease mainly associated with aging and, to date, its causes are still largely unknown. It has been shown that dietary habits can accelerate or delay the occurrence of aging-related diseases; however, their potential role in IPF development has been underestimated so far. The present review summarizes the evidence regarding the relationship between diet and IPF in humans, and in animal models of pulmonary fibrosis, in which we discuss the bioactivity of specific dietary food ingredients, including fatty acids, peptides, amino acids, carbohydrates, vitamins, minerals and phytochemicals. Interestingly, many animal studies reveal preventive and therapeutic effects of particular compounds. Furthermore, it has been recently suggested that the lung and gut microbiota could be involved in IPF, a relationship which may be linked to changes in immunological and inflammatory factors. Thus, all the evidence so far puts forward the idea that the gut-lung axis could be modulated by dietary factors, which in turn have an influence on IPF development. Overall, the data reviewed here support the notion of identifying food ingredients with potential benefits in IPF, with the ultimate aim of designing nutritional approaches as an adjuvant therapeutic strategy.

Impact of calcium, vitamin D, vitamin K, oestrogen, isoflavone and exercise on bone mineral density for osteoporosis prevention in postmenopausal women: a network meta-analysis

The aim of this network meta-analysis is to compare bone mineral density (BMD) changes among different osteoporosis prevention interventions in postmenopausal women. We searched MEDLINE, Embase and Cochrane Library from inception to 24 February 2019. Included studies were randomised controlled trials (RCT) comparing the effects of different treatments on BMD in postmenopausal women. Studies were independently screened by six authors in three pairs. Data were extracted independently by two authors and synthesised using Bayesian random-effects network meta-analysis. The results were summarised as mean difference in BMD and surface under the cumulative ranking (SUCRA) of different interventions. A total of ninety RCT (10 777 participants) were included. Ca, vitamin D, vitamin K, oestrogen, exercise, Ca + vitamin D, vitamin D + vitamin K and vitamin D + oestrogen were associated with significantly beneficial effects relative to no treatment or placebo for lumbar spine (LS). For femoral neck (FN), Ca, exercise and vitamin D + oestrogen were associated with significantly beneficial intervention effects relative to no treatment. Ranking probabilities indicated that oestrogen + vitamin D is the best strategy in LS, with a SUCRA of 97·29 % (mean difference: +0·072 g/cm2 compared with no treatment, 95 % credible interval (CrI) 0·045, 0·100 g/cm2), and Ca + exercise is the best strategy in FN, with a SUCRA of 79·71 % (mean difference: +0·029 g/cm2 compared with placebo, 95 % CrI –0·00093, 0·060 g/cm2). In conclusion, in postmenopausal women, many interventions are valuable for improving BMD in LS and FN. Different intervention combinations can affect BMD at different sites diversely.

Calcium and Bone

The maintenance of extracellular calcium levels within a narrow range is necessary for normal function of the nervous system, muscle, and coagulation, to maintain mineralization of the skeleton but to avoid calcification of soft tissues. Accordingly, absorption and excretion of calcium is closely regulated, and adult humans can adapt to a wide range of calcium intakes from 300 to 2,000 mg/day. The evidence that low calcium intakes contribute to osteoporosis development is weak, as is evidence that increasing these intakes significantly changes fracture risk. Consistent with this view, the United States Preventive Services Task Force does not support the use of calcium supplements in healthy community-dwelling adults. While some groups continue to recommend that supplements of calcium and vitamin D are given with drug treatments for osteoporosis, this view is not supported by clinical trials which demonstrate anti-fracture efficacy of estrogens and bisphosphonates in the absence of such supplementation. Thus, calcium supplements have only a minor place in contemporary medical practice.

Comparison of fracture risk using different supplemental doses of vitamin D, calcium or their combination: a network meta-analysis of randomised controlled trials

OBJECTIVE

Inconsistent findings in regard to association between different concentrations of vitamin D, calcium or their combination and the risk of fracture have been reported during the past decade in community-dwelling older people. This study was designed to compare the fracture risk using different concentrations of vitamin D, calcium or their combination.

DESIGN

A systematic review and network meta-analysis.

DATA SOURCES

Randomised controlled trials in PubMed, Cochrane library and Embase databases were systematically searched from the inception dates to 31 December 2017.

OUTCOMES

Total fracture was defined as the primary outcome. Secondary outcomes were hip fracture and vertebral fracture. Due to the consistency of the original studies, a consistency model was adopted.

RESULTS

A total of 25 randomised controlled trials involving 43 510 participants fulfilled the inclusion criteria. There was no evidence that the risk of total fracture was reduced using different concentrations of vitamin D, calcium or their combination compared with placebo or no treatment. No significant associations were found between calcium, vitamin D, or combined calcium and vitamin D supplements and the incidence of hip or vertebral fractures.

CONCLUSIONS

The use of supplements that included calcium, vitamin D or both was not found to be better than placebo or no treatment in terms of risk of fractures among community-dwelling older adults. It means the routine use of these supplements in community-dwelling older people should be treated more carefully.

PROSPERO REGISTRATION NUMBER

CRD42017079624.

Supplemental calcium intake in the aging individual: implications on skeletal and cardiovascular health

Adequate calcium intake during childhood is necessary to achieve optimal peak bone mass and this has the potential by increasing bone reserves, to modulate the rate of age-associated bone loss. However, data regarding the efficacy of calcium obtained either through the diet or in the form of medicinal supplementation, for prevention of bone loss and osteoporotic fractures in the elderly is conflicting. Calcium alone is unlikely to be of benefit for this purpose though the co-administration of calcium and vitamin D may have modest fracture risk benefits. Supplemental calcium with or without vitamin D has recently come into the spotlight after the publication of the findings from a controversial randomized controlled trial that associated calcium supplementation with an increased risk of myocardial infarction. Since then, multiple studies have explored this potential link. The data remains conflicting and the potential mechanistic link if any exists, remains elusive. This review examines the relationship between supplemental calcium intake and skeletal and cardiovascular health in the aging individual through an appraisal of studies done on the subject in the last three decades. It also briefly details some of the studies evaluating fractional absorption of calcium in the elderly and the rationale behind the current recommended dietary allowances of calcium.

Molecular-Based Treatment Strategies for Osteoporosis: A Literature Review

Osteoporosis is an unavoidable public health problem in an aging or aged society. Anti-resorptive agents (calcitonin, estrogen, and selective estrogen-receptor modulators, bisphosphonates, anti-receptor activator of nuclear factor κB ligand antibody along with calcium and vitamin D supplementations) and anabolic agents (parathyroid hormone and related peptide analogs, sclerostin inhibitors) have major roles in current treatment regimens and are used alone or in combination based on the pathological condition. Recent advancements in the molecular understanding of bone metabolism and in bioengineering will open the door to future treatment paradigms for osteoporosis, including antibody agents, stem cells, and gene therapies. This review provides an overview of the molecular mechanisms, clinical evidence, and potential adverse effects of drugs that are currently used or under development for the treatment of osteoporosis to aid clinicians in deciding how to select the best treatment option.

Prevalence and Predictors of Osteoporosis Among the Chinese Population in Klang Valley, Malaysia

The prevalence of osteoporosis is forecasted to escalate in Malaysia with an increasing elderly population. This study aimed to analyze the prevalence and the risk factors of osteoporosis among middle-aged and elderly Chinese Malaysians. Three hundred sixty seven Malaysian Chinese aged ≥40 years in Klang Valley, Malaysia, were recruited. All subjects completed a structured questionnaire comprised of demographic details, medical history, diet, and lifestyle practices. Body anthropometry and bone mineral density measurements were also performed. The relationship between bone health status and risk factors was determined using multivariate logistic regression. Fifteen-point-three percent of the overall study population and 32.6% of those aged ≥71 years had osteoporosis. The prevalence of osteoporosis among women (18.9%) was higher than men (11.5%). The significant predictors of osteoporosis were age, body weight, and low monthly income. Lean mass, low education level, and being underweight predicted osteoporosis in women. Lean mass was the only significant predictor of osteoporosis in men. Overall, 15.3% of the Malaysian Chinese aged ≥40 years from Klang Valley, Malaysia, had osteoporosis. Osteoporosis was associated positively with increased age and low monthly income and negatively with body weight. Therefore, osteoporosis preventive strategies targeting Chinese elderly from a low socioeconomic background is necessary.

Bone mineral density in osteoporotic patients with pyogenic vertebral osteomyelitis: effect of early versus late treatment for osteoporosis

Patients with pyogenic vertebral osteomyelitis (PVO) are at greater risk of bone loss. However, treatment guidelines for bone loss have been lacking. Early bisphosphonate treatment within 6 weeks after PVO diagnosis was significantly associated with superior outcome in femoral BMD at 2-year follow-up, compared to that with late treatment.

INTRODUCTION

Due to absence of concern and proper guidelines, management of bone loss or osteoporosis in PVO is often neglected or delayed. A retrospective cohort study was planned to investigate differences in bone mineral density (BMD) in PVO patients with osteoporosis according to the timing of osteoporosis treatment.

METHODS

The PVO cohort consisted of 192 patients with osteoporosis who visited our institution between January 2003 and March 2015 and received bisphosphonate treatment for osteoporosis. According to the interval between PVO diagnosis and initiation of bisphosphonate, the patients were divided into three groups: group A (within 6 weeks after PVO diagnosis), group B (between 6 weeks and 3 months after diagnosis), and group C (more than 3 months after PVO diagnosis).

RESULTS

The percent increase in total femoral BMD in group A was significantly larger than that in group B at 2-year follow-up (p = 0.036). Similarly, the percent increase in trochanteric (p = 0.008) and total femoral (p = 0009) BMD in group A was significantly larger than that in group C at 2-year follow-up. Even after multivariate adjustment, total femoral BMD changes were significantly associated with the treatment group. Group B (odds ratio = 2.824, p = 0.013) and group C (odds ratio = 3.591, p = 0.001) were more significantly associated with total femoral BMD decreases at 2-year follow-up compared with group A.

CONCLUSIONS

Early bisphosphonate treatment within 6 weeks after PVO diagnosis (group A) was significantly associated with superior outcome in femoral BMD at 2-year follow-up, compared to that with late treatment (groups B and C).

Mechanism of melatonin combined with calcium carbonate on improving osteoporosis in aged rats

The effects of melatonin and calcium carbonate on aged rats with osteoporosis (OP) were assessed. Forty female Sprague-Dawley (SD) rats aged 15 months were randomly divided into a model group (group OP), melatonin group (group M), calcium carbonate group (group Ca) and melatonin combined with calcium carbonate group (group M+Ca), while 10 rats aged 3 months were set as the control group (group NC). The changes of bone density and bone mineral level of lumbar vertebra and bilateral femur in rats of each group were observed. The levels of serum calcium, phosphorus, superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) in rats of each group were determined. Compared with those in group NC, bone density of lumbar vertebra and bilateral femur and bone mineral level were distinctly reduced, serum calcium and activities of SOD and GSH-Px were obviously decreased, and MDA content was remarkably increased in rats of groups OP, M and Ca; the differences were statistically significant (P<0.05 or P<0.01); compared with that in group OP, bone density of lumbar vertebra and bilateral femur and bone mineral level were remarkably increased, serum calcium and activities of SOD and GSH-Px were obviously increased, and MDA content was remarkably decreased in rats of groups M, Ca and M+Ca; the differences were statistically significant (P<0.05 or P<0.01); compared with those in groups M and Ca, bone density of lumbar vertebra and bilateral femur and bone mineral level were obviously elevated, serum calcium and activities of SOD and GSH-Px were evidently elevated, and MDA content was remarkably decreased in rats of group M+Ca; the differences were statistically significant (P<0.05). Melatonin and calcium carbonate can significantly improve antioxidative ability in rats with osteoporosis, increase bone density, elevate serum calcium level and reduce bone mineral loss, thus preventing and treating osteoporosis, and the combination displays more remarkable effects.

Association Between Calcium or Vitamin D Supplementation and Fracture Incidence in Community-Dwelling Older Adults: A Systematic Review and Meta-analysis

IMPORTANCE

The increased social and economic burdens for osteoporosis-related fractures worldwide make the prevention of such injuries a major public health goal. Previous studies have reached mixed conclusions regarding the association between calcium, vitamin D, or combined calcium and vitamin D supplements and fracture incidence in older adults.

OBJECTIVE

To investigate whether calcium, vitamin D, or combined calcium and vitamin D supplements are associated with a lower fracture incidence in community-dwelling older adults.

DATA SOURCES

The PubMed, Cochrane library, and EMBASE databases were systematically searched from the inception dates to December 24, 2016, using the keywords calcium, vitamin D, and fracture to identify systematic reviews or meta-analyses. The primary randomized clinical trials included in systematic reviews or meta-analyses were identified, and an additional search for recently published randomized trials was performed from July 16, 2012, to July 16, 2017.

STUDY SELECTION

Randomized clinical trials comparing calcium, vitamin D, or combined calcium and vitamin D supplements with a placebo or no treatment for fracture incidence in community-dwelling adults older than 50 years.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers performed the data extraction and assessed study quality. A meta-analysis was performed to calculate risk ratios (RRs), absolute risk differences (ARDs), and 95% CIs using random-effects models.

MAIN OUTCOMES AND MEASURES

Hip fracture was defined as the primary outcome. Secondary outcomes were nonvertebral fracture, vertebral fracture, and total fracture.

RESULTS

A total of 33 randomized trials involving 51 145 participants fulfilled the inclusion criteria. There was no significant association of calcium or vitamin D with risk of hip fracture compared with placebo or no treatment (calcium: RR, 1.53 [95% CI, 0.97 to 2.42]; ARD, 0.01 [95% CI, 0.00 to 0.01]; vitamin D: RR, 1.21 [95% CI, 0.99 to 1.47]; ARD, 0.00 [95% CI, -0.00 to 0.01]. There was no significant association of combined calcium and vitamin D with hip fracture compared with placebo or no treatment (RR, 1.09 [95% CI, 0.85 to 1.39]; ARD, 0.00 [95% CI, -0.00 to 0.00]). No significant associations were found between calcium, vitamin D, or combined calcium and vitamin D supplements and the incidence of nonvertebral, vertebral, or total fractures. Subgroup analyses showed that these results were generally consistent regardless of the calcium or vitamin D dose, sex, fracture history, dietary calcium intake, and baseline serum 25-hydroxyvitamin D concentration.

CONCLUSIONS AND RELEVANCE

In this meta-analysis of randomized clinical trials, the use of supplements that included calcium, vitamin D, or both compared with placebo or no treatment was not associated with a lower risk of fractures among community-dwelling older adults. These findings do not support the routine use of these supplements in community-dwelling older people.

Low calcium diet increases 4T1 mammary tumor carcinoma cell burden and bone pathology in mice

Breast cancer metastasizes to bone in the majority of patients with advanced disease. We investigated the effects of inadequate dietary calcium (Ca) on bone turnover, tumor growth, and bone response to tumor in tibia inoculated with 4T1 mammary carcinoma cells. Nine-month-old female Balb/c mice were placed on an adequate Ca (5 g/kg diet, n = 30) or low Ca (80 mg/kg diet, n = 31) diet for 14 days, then injected intratibially with 1,000 4T1 cells (transfected with luciferase for bioluminescence imaging), and sacrificed at 5, 10, or 21 days post-inoculation (n = 7–10 mice/group). Control mice (n = 6/group) were injected with carrier and sacrificed at 10 days post-inoculation. Tibiae with muscle intact were excised and evaluated by microcomputed tomography and histology. In vivo bioluminescent imaging revealed that 4T1 cells metastasized to lung. Therefore, lungs were removed for quantification of tumor. Mice fed low Ca exhibited higher bone turnover and higher tibial lesion scores than mice fed adequate Ca. Lesion severity, manifested as cortical osteolysis and periosteal woven bone formation, and tumor cell infiltration to muscle, increased with time, irrespective of diet. However, for most skeletal endpoints the rates of increase were greater in mice consuming low Ca compared to mice consuming adequate Ca. Infiltration of tumor cells into adjacent muscle, but not metastasis to lung, was also greater in mice consuming low Ca diet. The findings suggest that high bone turnover due to Ca insufficiency results in greater local mammary tumor cell growth, cortical osteolysis, woven bone formation, and invasion to muscle in mice.

Quantitative analysis of efficacy and associated factors of calcium intake on bone mineral density in postmenopausal women

A model-based meta-analysis method was performed to quantitatively analyze the efficacy characteristics of calcium intake in BMD increase among postmenopausal women. We found that age and calcium intake dose were key factors affecting the efficiency and onset of BMD change, and daily 1200 mg calcium was suggested to be a beneficial dosage.

INTRODUCTION

This paper aims to quantify the efficacy of calcium intake in preventing bone mineral density (BMD) decrease among postmenopausal women and to investigate the factors that may affect the efficacy.

METHODS

Comprehensive literature search was conducted in PubMed and EMBASE from January 2016. Placebo-controlled or no-treatment controlled randomized trials focused on calcium intake for the management of osteoporosis in postmenopausal women were included. The clinical and demographic characteristics of participants and efficacy data, defined as the mean percentage change of spine BMD (L2-L4) at each observation time point compared with that of baseline, were extracted from the studies. Model-based meta-analysis (MBMA) was used to describe the time course of BMD change by calcium intake and identify the related factors.

RESULTS

This study includes 17 trials involving 2537 subjects. The results showed that a classic pharmacodynamic maximal effect (E _max) model could describe the time course of BMD change by calcium intake. Using this model, we found that age and calcium intake dose were key factors affecting the efficiency and onset of BMD change. A 60-year-old woman administered with 800 mg/day calcium can achieve a maximum BMD increasing rate of 2.38%, and the time to reach 50% of this maximum (known as onset time) was 9.44 months. An increase of 0.0817% per year was noted in the maximal effect value for women aged between 50 and 83 years. For calcium dose interval from 250 to 2000 mg/day, the onset time was expressed as 9.44 × (dose/800)^-1.33 months. Two-year calcium intake of 700, 1200, and 2000 mg/day resulted in a maximum efficacy of BMD of 68.0, 81.3, and 89.6%, respectively. This indicates that the final efficacy had already reached the plateau (>80% E _max) under the 1200-mg/day dose.

CONCLUSION

Calcium intake can effectively postpone the tendency of BMD decrease in postmenopausal women. An increased calcium dose contributes to the shortening of the onset time. Considering the drug-acting rate and safety into account, menopausal women can be administered with a rational dose of 1200 mg/day to reduce bone loss.

Highly bioavailable nanocalcium from oyster shell for preventing osteoporosis in rats

Oyster shell is one of the foremost natural sources of calcium and is used as an alternative treatment for osteoporosis. In this study, we demonstrated that zinc-activated nanopowdered oyster shell (Zn-NPOS) effectively reduced bone loss compared with powdered oyster shell (POS) in an ovariectomized rat (OVX) model. As a result of nanosizing, the solubility and bioavailability of the oyster shell were greatly improved, and its effectiveness was further enhanced by zinc activation. Bone analysis indicated greater recovery from ovariectomy-induced bone loss following Zn-NPOS treatment. Moreover, Zn-NPOS treatment resulted in higher bone strength and superior trabecular architecture compared with NPOS and POS treatments. Furthermore, Zn-NPOS showed greater efficiency in increasing bone formation and reducing bone resorption markers. Therefore, nanosizing with zinc activation could be a viable strategy for improving the efficiency of oyster shells used for osteoporosis prevention.

Investigation of membrane condensation induced by CaCO3 nanoparticles and its effect on membrane protein function

Investigation of membrane condensation induced by calcium ions released from nano-CaCO₃.

Dietary Supplements and Risk of Cause-Specific Death, Cardiovascular Disease, and Cancer: A Systematic Review and Meta-Analysis of Primary Prevention Trials

Our aim was to assess the efficacy of dietary supplements in the primary prevention of cause-specific death, cardiovascular disease (CVD), and cancer by using meta-analytical approaches. Electronic and hand searches were performed until August 2016. Inclusion criteria were as follows: 1) minimum intervention period of 12 mo; 2) primary prevention trials; 3) mean age ≥18 y; 4) interventions included vitamins, fatty acids, minerals, supplements containing combinations of vitamins and minerals, protein, fiber, prebiotics, and probiotics; and 5) primary outcome of all-cause mortality and secondary outcomes of mortality or incidence from CVD or cancer. Pooled effects across studies were estimated by using random-effects meta-analysis. Overall, 49 trials (69 reports) including 287,304 participants met the inclusion criteria. Thirty-two trials were judged as low risk-, 15 trials as moderate risk-, and 2 trials as high risk-of-bias studies. Supplements containing vitamin E (RR: 0.88; 95% CI: 0.80, 0.96) significantly reduced cardiovascular mortality risk, whereas supplements with folic acid reduced the risk of CVD (RR: 0.81; 95% CI: 0.70, 0.94). Vitamins D, C, and K; selenium; zinc; magnesium; and eicosapentaenoic acid showed no significant risk reduction for any of the outcomes. On the contrary, vitamin A was linked to an increased cancer risk (RR: 1.16; 95% CI: 1.00, 1.35). Supplements with β-carotene showed no significant effect; however, in the subgroup with β-carotene given singly, an increased risk of all-cause mortality by 6% (RR: 1.06; 95% CI: 1.02, 1.10) was observed. Taken together, we found insufficient evidence to support the use of dietary supplements in the primary prevention of cause-specific death, incidence of CVD, and incidence of cancer. The application of some supplements generated small beneficial effects; however, the heterogeneous types and doses of supplements limit the generalizability to the overall population.

Long-Term Prolactin Exposure Differentially Stimulated the Transcellular and Solvent Drag-Induced Calcium Transport in the Duodenum of Ovariectomized Rats

Prolactin, having been shown to stimulate transcellular active and solvent drag-induced calcium transport in the duodenum of female rats, was postulated to improve duodenal calcium transport in estrogen-deficient rats. The aim of the present study was, therefore, to demonstrate the effects of long-term prolactin exposure produced by anterior pituitary (AP) transplantation on the duodenal calcium transport in young (9-week-old) and adult (22-week-old) ovariectomized rats. We found that ovariectomy did not alter the transcellular active duodenal calcium transport in young and adult rats fed normal calcium diet (1.0% w/w Ca) but decreased the solvent drag-induced duodenal calcium transport from 75.50 ± 10.12 to 55.75 ± 4.77 nmol·hr–1 cm–2 (P < 0.05) only in adult rats. Long-term prolactin exposure stimulated the transcellular active calcium transport in young and adult AP-grafted ovariectomized rats fed with normal calcium diet by more than 2-fold from 7.56 ± 0.79 to 16.54 ± 2.05 (P < 0.001) and 9.78 ± 0.72 to 15.99 ± 1.75 (P < 0.001) nmol·hr–1 cm–2, respectively. However, only the solvent drag-induced duodenal calcium transport in young rats was enhanced by prolactin from 95.51 ± 10.64 to 163.20 ± 18.03 nmol·hr–1 cm–2 (P < 0.001) whereas that in adult rats still showed a decreased flux from 75.50 ± 10.12 to 47.77 ± 5.42 nmol·hr–1 cm–2 (P < 0.05). Because oral calcium supplement has been widely used to improve calcium balance in estrogen-deficient animals, the effect of a high-calcium diet (2.0% w/w Ca) was also investigated. The results showed that stimulatory action of long-term prolactin on the transcellular active duodenal calcium transport in both young and adult rats was diminished after being fed a high-calcium diet. The same diet also abolished prolactin-enhanced solvent drag-induced duodenal calcium transport in young and further decreased that in adult AP-grafted ovariectomized rats. We concluded that the solvent drag-induced duodenal calcium transport in adult rats was decreased after ovariectomy. Long-term prolactin exposure stimulated the transcellular active duodenal calcium transport in both young and adult rats whereas enhancing the solvent drag-induced duodenal calcium transport only in young rats. Effects of prolactin were abolished by a high-calcium diet.

Racial Differences in Association of Serum Calcium with Mortality and Incident Cardio- and Cerebrovascular Events

CONTEXT

Abnormalities in calcium metabolism may potentially contribute to the development of vascular disease. Calcium metabolism may be different in African American (AA) vs white individuals, but the effect of race on the association of serum calcium with clinical outcomes remains unclear.

OBJECTIVE

This study sought to examine race-specific associations of serum calcium levels with mortality and with major incident cardiovascular events.

DESIGN AND SETTING

This was a historical cohort study in the U.S. Department of Veterans Affairs health care facilities.

PARTICIPANTS

Participants included veterans (n = 1 967 622) with estimated glomerular filtration rate ≥ 60 mL/min/1.73 m².

MAIN OUTCOME MEASURES

The association between serum calcium levels with all-cause mortality, incident coronary heart disease (CHD), and ischemic stroke incidence was examined in multivariable adjusted Cox proportional hazards models, including an interaction term for calcium and race.

RESULTS

The association of calcium with all-cause mortality was U-shaped in both AA and white patients, but race modified the association of calcium with all-cause mortality. Compared with white patients, AA patients experienced lower risk of mortality when calcium was ≥ 8.8 mg/dL, with a statistically significant interaction (P < .001). Conversely, AA vs white race was associated with higher mortality when calcium was < 8.8 mg/dL. Calcium showed no significant association with ischemic stroke or CHD in both races; and race did not modify these associations (P = .37 and 0.11, respectively for interaction term).

CONCLUSIONS

Race modified the U-shaped association between calcium and all-cause mortality. Serum calcium is not associated with incident stroke or CHD in either AA or white patients. The race-specific difference in the association of calcium levels with mortality warrants further examination.

Food fortification for bone health in adulthood: a scoping review

Food fortification can deliver essential micronutrients to large population segments without modifications in consumption pattern, suggesting that fortified foods may be formulated for populations at risk for fragility fractures. This scoping review determined the extent to which randomized controlled studies have been carried out to test the impact of fortified foods on bone outcomes, searching PubMed for all studies using the terms 'fortified AND bone', and 'fortification AND bone'. Studies were restricted to English language, published between 1996 and June 2015. From 360 articles, 24 studies met the following criteria: human study in adults ⩾18 years (excluding pregnancy or lactation); original study of a fortified food over time, with specific bone outcomes measured pre- and post intervention. Six studies involved adults <50 years; 18 involved adults ⩾50 years. Singly or in combination, 17 studies included calcium and 16 included vitamin D. There were 1 or 2 studies involving either vitamin K, magnesium, iron, zinc, B-vitamins, inulin or isoflavones. For adults <50 years, the four studies involving calcium or vitamin D showed a beneficial effect on bone remodeling. For adults ⩾50 years, n=14 provided calcium and/or vitamin D, and there was a significant bone turnover reduction. No consistent effects were reported in studies in which addition of vitamin K, folic acid or isoflavone was assessed. Results from this scoping review indicate that up to now most studies of fortification with bone health have evaluated calcium and/or vitamin D and that these nutrients show beneficial effects on bone remodeling.

Cytotoxicity, Uptake Behaviors, and Oral Absorption of Food Grade Calcium Carbonate Nanomaterials

Calcium is the most abundant mineral in human body and essential for the formation and maintenance of bones and teeth as well as diverse cellular functions. Calcium carbonate (CaCO₃) is widely used as a dietary supplement; however, oral absorption efficiency of CaCO₃ is extremely low, which may be overcome by applying nano-sized materials. In this study, we evaluated the efficacy of food grade nano CaCO₃ in comparison with that of bulk- or reagent grade nano CaCO₃ in terms of cytotoxicity, cellular uptake, intestinal transport, and oral absorption. Cytotoxicity results demonstrated that nano-sized CaCO₃ particles were slightly more toxic than bulk materials in terms of oxidative stress and membrane damage. Cellular uptake behaviors of CaCO₃ nanoparticles were different from bulk CaCO₃ or Ca²⁺ ions in human intestinal epithelial cells, showing efficient cellular internalization and elevated intracellular Ca²⁺ levels. Meanwhile, CaCO₃ nanoparticles were efficiently transported by microfold (M) cells in vitro model of human intestinal follicle-associated epithelium, in a similar manner as Ca²⁺ ions did. Biokinetic study revealed that the biological fate of CaCO₃ particles was different from Ca²⁺ ions; however, in vivo, its oral absorption was not significantly affected by particle size. These findings provide crucial information to understand and predict potential toxicity and oral absorption efficiency of food grade nanoparticles.

Calcium supplements: benefits and risks

Calcium is an essential element in the diet, but there is continuing controversy regarding its optimal intake, and its role in the pathogenesis of osteoporosis. Most studies show little evidence of a relationship between calcium intake and bone density, or the rate of bone loss. Re-analysis of data from the placebo group from the Auckland Calcium Study demonstrates no relationship between dietary calcium intake and rate of bone loss over 5 years in healthy older women with intakes varying from <400 to >1500 mg day(-1) . Thus, supplements are not needed within this range of intakes to compensate for a demonstrable dietary deficiency, but might be acting as weak anti-resorptive agents via effects on parathyroid hormone and calcitonin. Consistent with this, supplements do acutely reduce bone resorption and produce small short-term effects on bone density, without evidence of a cumulative density benefit. As a result, anti-fracture efficacy remains unproven, with no evidence to support hip fracture prevention (other than in a cohort with severe vitamin D deficiency) and total fracture numbers are reduced by 0-10%, depending on which meta-analysis is considered. Five recent large studies have failed to demonstrate fracture prevention in their primary analyses. This must be balanced against an increase in gastrointestinal side effects (including a doubling of hospital admissions for these problems), a 17% increase in renal calculi and a 20-40% increase in risk of myocardial infarction. Each of these adverse events alone neutralizes any possible benefit in fracture prevention. Thus, calcium supplements appear to have a negative risk-benefit effect, and so should not be used routinely in the prevention or treatment of osteoporosis.

Calcium intake and bone mineral density: systematic review and meta-analysis

OBJECTIVE

To determine whether increasing calcium intake from dietary sources affects bone mineral density (BMD) and, if so, whether the effects are similar to those of calcium supplements.

DESIGN

Random effects meta-analysis of randomised controlled trials.

DATA SOURCES

Ovid Medline, Embase, Pubmed, and references from relevant systematic reviews. Initial searches were undertaken in July 2013 and updated in September 2014.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials of dietary sources of calcium or calcium supplements (with or without vitamin D) in participants aged over 50 with BMD at the lumbar spine, total hip, femoral neck, total body, or forearm as an outcome.

RESULTS

We identified 59 eligible randomised controlled trials: 15 studied dietary sources of calcium (n=1533) and 51 studied calcium supplements (n=12,257). Increasing calcium intake from dietary sources increased BMD by 0.6-1.0% at the total hip and total body at one year and by 0.7-1.8% at these sites and the lumbar spine and femoral neck at two years. There was no effect on BMD in the forearm. Calcium supplements increased BMD by 0.7-1.8% at all five skeletal sites at one, two, and over two and a half years, but the size of the increase in BMD at later time points was similar to the increase at one year. Increases in BMD were similar in trials of dietary sources of calcium and calcium supplements (except at the forearm), in trials of calcium monotherapy versus co-administered calcium and vitamin D, in trials with calcium doses of ≥ 1000 versus <1000 mg/day and ≤ 500 versus >500 mg/day, and in trials where the baseline dietary calcium intake was <800 versus ≥ 800 mg/day.

CONCLUSIONS

Increasing calcium intake from dietary sources or by taking calcium supplements produces small non-progressive increases in BMD, which are unlikely to lead to a clinically significant reduction in risk of fracture.

Calcium intake and risk of fracture: systematic review

OBJECTIVE

To examine the evidence underpinning recommendations to increase calcium intake through dietary sources or calcium supplements to prevent fractures.

DESIGN

Systematic review of randomised controlled trials and observational studies of calcium intake with fracture as an endpoint. Results from trials were pooled with random effects meta-analyses.

DATA SOURCES

Ovid Medline, Embase, PubMed, and references from relevant systematic reviews. Initial searches undertaken in July 2013 and updated in September 2014.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised controlled trials or cohort studies of dietary calcium, milk or dairy intake, or calcium supplements (with or without vitamin D) with fracture as an outcome and participants aged >50.

RESULTS

There were only two eligible randomised controlled trials of dietary sources of calcium (n=262), but 50 reports from 44 cohort studies of relations between dietary calcium (n=37), milk (n=14), or dairy intake (n=8) and fracture outcomes. For dietary calcium, most studies reported no association between calcium intake and fracture (14/22 for total, 17/21 for hip, 7/8 for vertebral, and 5/7 for forearm fracture). For milk (25/28) and dairy intake (11/13), most studies also reported no associations. In 26 randomised controlled trials, calcium supplements reduced the risk of total fracture (20 studies, n=58,573; relative risk 0.89, 95% confidence interval 0.81 to 0.96) and vertebral fracture (12 studies, n=48,967. 0.86, 0.74 to 1.00) but not hip (13 studies, n=56,648; 0.95, 0.76 to 1.18) or forearm fracture (eight studies, n=51,775; 0.96, 0.85 to 1.09). Funnel plot inspection and Egger's regression suggested bias toward calcium supplements in the published data. In randomised controlled trials at lowest risk of bias (four studies, n=44,505), there was no effect on risk of fracture at any site. Results were similar for trials of calcium monotherapy and co-administered calcium and vitamin D. Only one trial in frail elderly women in residential care with low dietary calcium intake and vitamin D concentrations showed significant reductions in risk of fracture.

CONCLUSIONS

Dietary calcium intake is not associated with risk of fracture, and there is no clinical trial evidence that increasing calcium intake from dietary sources prevents fractures. Evidence that calcium supplements prevent fractures is weak and inconsistent.

Change of Bone Mineral Density and Biochemical Markers of Bone Turnover in Patients on Suppressive Levothyroxine Therapy for Differentiated Thyroid Carcinoma

Untreated hyperthyroidism and high-dose thyroid hormone are associated with osteoporosis, and increased bone mineral density (BMD) has been demonstrated in postmenopausal females with hypoparathyroidism. Studies on the effect of suppressive levothyroxine (LT4) therapy on BMD and bone metabolism after total thyroidectomy in patients with differentiated thyroid carcinoma have presented conflicting results, and few studies in relation to the status of hypoparathyroidism have been studied. One hundred postmenopausal women and 24 premenopausal women on LT4 suppression therapy were included in this study. BMD of lumbar spine and femur and bone turnover markers were measured at the baseline and during the follow-up period up to 18 months using dual energy X-ray absorptiometry. Biochemical marker of bone resorption was measured by urine deoxypyridinoline and bone formation by serum osteocalcin. The age ranged from 36 to 64 years old. Thyroid stimulating hormone (TSH) was suppressed during the study. The results showed that BMD of femur and lumbar spine were not significantly changed in both pre- and postmenopausal women except femur neck in postmenopausal women without hypoparathyroidism. Patients with hypoparathyroidism had higher BMD gain than those without hypoparathyroidism in total hip (1.25 vs. -1.18%, P=0.015). Biochemical markers of bone turnover, serum osteocalcin, and urine deoxypyridinoline did not show significant change. In conclusion, patients with well differentiated thyroid carcinoma are not at a great risk of bone loss after LT4 suppressive therapy. The state of hypoparathyroidism is associated with increased BMD, particularly in postmenopausal women.

The fate of calcium carbonate nanoparticles administered by oral route: absorption and their interaction with biological matrices

BACKGROUND

Orally administered particles rapidly interact with biological fluids containing proteins, enzymes, electrolytes, and other biomolecules to eventually form particles covered by a corona, and this corona potentially affects particle uptake, fate, absorption, distribution, and elimination in vivo. This study explored relationships between the biological interactions of calcium carbonate particles and their biokinetics.

METHODS

We examined the effects of food grade calcium carbonates of different particle size (nano [N-Cal] and bulk [B-Cal]: specific surface areas of 15.8 and 0.83 m(2)/g, respectively) on biological interactions in in vitro simulated physiological fluids, ex vivo biofluids, and in vivo in gastrointestinal fluid. Moreover, absorption and tissue distribution of calcium carbonates were evaluated following a single dose oral administration to rats.

RESULTS

N-Cal interacted more with biomatrices than bulk materials in vitro and ex vivo, as evidenced by high fluorescence quenching ratios, but it did not interact more actively with biomatrices in vivo. Analysis of coronas revealed that immunoglobulin, apolipoprotein, thrombin, and fibrinogen, were the major corona proteins, regardless of particle size. A biokinetic study revealed that orally delivered N-Cal was more rapidly absorbed into the blood stream than B-Cal, but no significant differences were observed between the two in terms of absorption efficiencies or tissue distributions. Both calcium carbonates were primarily present as particulate forms in gastrointestinal fluids but enter the circulatory system in dissolved Ca(2+), although both types showed partial phase transformation to dicalcium phosphate dihydrate. Relatively low dissolution (about 4%), no remarkable protein-particle interaction, and the major particulate fate of calcium carbonate in vivo gastrointestinal fluids can explain its low oral absorption (about 4%) regardless of particle size.

CONCLUSION

We conclude that calcium carbonate nanoparticles can act more actively with biological matrices in vitro and ex vivo, but that in vivo, their biological interactions and biokinetics are not affected by particle size.

Building healthy bones throughout life: an evidence-informed strategy to prevent osteoporosis in Australia

Osteoporosis imposes a tremendous burden on Australia: 1.2 million Australians have osteoporosis and 6.3 million have osteopenia. In the 2007–08 financial year, 82 000 Australians suffered fragility fractures, of which > 17 000 were hip fractures. In the 2000–01 financial year, direct costs were estimated at $1.9 billion per year and an additional $5.6 billion on indirect costs. Osteoporosis was designated a National Health Priority Area in 2002; however, implementation of national plans has not yet matched the rhetoric in terms of urgency. Building healthy bones throughout life, the Osteoporosis Australia strategy to prevent osteoporosis throughout the life cycle, presents an evidence-informed set of recommendations for consumers, health care professionals and policymakers. The strategy was adopted by consensus at the Osteoporosis Australia Summit in Sydney, 20 October 2011. Primary objectives throughout the life cycle are: to maximise peak bone mass during childhood and adolescence to prevent premature bone loss and improve or maintain muscle mass, strength and functional capacity in healthy adults to prevent and treat osteoporosis in order to minimise the risk of suffering fragility fractures, and reduce falls risk, in older people. The recommendations focus on three affordable and important interventions — to ensure people have adequate calcium intake, vitamin D levels and appropriate physical activity throughout their lives. Recommendations relevant to all stages of life include: daily dietary calcium intakes should be consistent with Australian and New Zealand guidelines serum levels of vitamin D in the general population should be above 50nmol/L in winter or early spring for optimal bone health regular weight-bearing physical activity, muscle strengthening exercises and challenging balance/mobility activities should be conducted in a safe environment.

Calcium supplementation increases blood creatinine concentration in a randomized controlled trial

Background

Calcium supplements are widely used among older adults for osteoporosis prevention and treatment. However, their effect on creatinine levels and kidney function has not been well studied.

Methods

We investigated the effect of calcium supplementation on blood creatinine concentration in a randomized controlled trial of colorectal adenoma chemoprevention conducted between 2004–2013 at 11 clinical centers in the United States. Healthy participants (N = 1,675) aged 45–75 with a history of colorectal adenoma were assigned to daily supplementation with calcium (1200 mg, as carbonate), vitamin D₃ (1000 IU), both, or placebo for three or five years. Changes in blood creatinine and total calcium concentration were measured after one year of treatment and multiple linear regression was used to estimate effects on creatinine concentrations.

Results

After one year of treatment, blood creatinine was 0.013±0.006 mg/dL higher on average among participants randomized to calcium compared to placebo after adjustment for other determinants of creatinine (P = 0.03). However, the effect of calcium treatment appeared to be larger among participants who consumed the most alcohol (2–6 drinks/day) or whose estimated glomerular filtration rate (eGFR) was less than 60 ml/min/1.73 m² at baseline. The effect of calcium treatment on creatinine was only partially mediated by a concomitant increase in blood total calcium concentration and was independent of randomized vitamin D treatment. There did not appear to be further increases in creatinine after the first year of calcium treatment.

Conclusions

Among healthy adults participating in a randomized clinical trial, daily supplementation with 1200 mg of elemental calcium caused a small increase in blood creatinine. If confirmed, this finding may have implications for clinical and public health recommendations for calcium supplementation.

Trial Registration

ClinicalTrials.gov NCT00153816

Calcium revisited: part II calcium supplements and their effects

Calcium supplements were tested in pregnancy and lactation, in childhood and adolescence, in pre- and postmenopausal women and in elderly persons with various effects on bone density and fracture incidence. They must be properly chosen and adequately used. In this case, the reported minor negative side-effects do not restrict their use. All these aspects are reviewed here.

Calcium supplement intake and risk of cardiovascular disease in women

Some recent reports suggest that calcium supplement use may increase risk of cardiovascular disease. In a prospective cohort study of 74,245 women in the Nurses' Health Study with 24 years of follow-up, we found no independent associations between supplemental calcium intake and risk of incident coronary heart disease (CHD) and stroke.

INTRODUCTION

Some recent reports suggest that calcium supplements may increase cardiovascular disease (CVD) risk. The objective was to examine the independent associations between calcium supplement use and risk of CVD.

METHODS

We conducted a prospective cohort study of supplemental calcium use and incident CVD in 74,245 women in the Nurses' Health Study (1984-2008) free of CVD and cancer at baseline. Calcium supplement intake was assessed every 4 years. Outcomes were incident CHD (nonfatal or fatal MI) and stroke (ischemic or hemorrhagic), confirmed by medical record review.

RESULTS

During 24 years of follow-up, 4,565 cardiovascular events occurred (2,709 CHD and 1,856 strokes). At baseline, women who took calcium supplements had higher levels of physical activity, smoked less, and had lower trans fat intake compared with those who did not take calcium supplements. After multivariable adjustment for age, body mass index, dietary calcium, vitamin D intake, and other CVD risk factors, the relative risk of CVD for women taking >1,000 mg/day of calcium supplements compared with none was 0.82 (95% confidence interval [CI] 0.74 to 0.92; p for trend <0.001). For women taking >1,000 mg/day of calcium supplements compared with none, the multivariable-adjusted relative risk for CHD was 0.71 (0.61 to 0.83; p for trend < 0.001) and for stroke was 1.03 (0.87 to 1.21; p for trend = 0.61). The relative risks were similar in analyses limited to non-smokers, women without hypertension, and women who had regular physical exams.

CONCLUSIONS

Our findings do not support the hypothesis that calcium supplement intake increases CVD risk in women.