The calcium scare--what would Austin Bradford Hill have thought?

Cardiovascular safety of calcium, magnesium and strontium: what does the evidence say?

Calcium, magnesium and strontium have all been implicated in both musculoskeletal and cardiovascular health and disease. However, despite these three elements being closely chemically related, there is marked heterogeneity of their characteristics in relation to cardiovascular outcomes. In this narrative review, we describe the relevant evidential landscape, focusing on clinical trials where possible and incorporating findings from observational and causal analyses, to discern the relative roles of these elements in musculoskeletal and cardiovascular health. We conclude that calcium supplementation (for bone health) is most appropriately used in combination with vitamin D supplementation and targeted to those who are deficient in these nutrients, or in combination with antiosteoporosis medications. Whilst calcium supplementation is associated with gastrointestinal side effects and a small increased risk of renal stones, purported links with cardiovascular outcomes remain unconvincing. In normal physiology, no mechanism for an association has been elucidated and other considerations such as dose response and temporal relationships do not support a causal relationship. There is little evidence to support routine magnesium supplementation for musculoskeletal outcomes; greater dietary intake and serum concentrations appear protective against cardiovascular events. Strontium ranelate, which is now available again as a generic medication, has clear anti-fracture efficacy but is associated with an increased risk of thromboembolic disease. Whilst a signal for increased risk of myocardial infarction has been detected in some studies, this is not supported by wider analyses. Strontium ranelate, under its current licence, thus provides a useful therapeutic option for severe osteoporosis in those who do not have cardiovascular risk factors.

Calcium Supplements and Risk of Cardiovascular Disease: A Meta-Analysis of Clinical Trials

Background: Recent systematic reviews and meta-analyses of randomized, double-blind, placebo-controlled trials (double-blind, placebo-controlled RCTs) have reported controversial findings regarding the associations between calcium supplements on the risk of cardiovascular disease (CVD). This meta-analysis aimed to investigate the association between them. Methods: We searched PubMed, EMBASE, the Cochrane Library, and the bibliographies of relevant articles for double-blind, placebo-controlled RCTs in November, 2020. Relative risks (RRs) with 95% confidence intervals (CIs) for the risk of cardiovascular disease were calculated using a random effects model. The main outcomes were CVD, coronary heart disease (CHD), and cerebrovascular disease. Results: A total of 13 double-blind, placebo-controlled RCTs (n = 28,935 participants in an intervention group and 14,243 in a control group)) were included in the final analysis. Calcium supplements significantly increased the risk of CVD (RR 1.15, 95% CI 1.06–1.25], I2 = 0.0%, n = 14) and CHD (RR 1.16, 95% CI 1.05–1.28], I2 = 0.0%, n = 9) in double-blind, placebo-controlled RCTs, specifically in healthy postmenopausal women. In the subgroup meta-analysis, dietary calcium intake of 700–1000 mg per day or supplementary calcium intake of 1000 mg per day significantly increased the risk of CVD and CHD. Conclusions: The current meta-analysis found that calcium supplements increased a risk of CVD by about 15% in healthy postmenopausal women.

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.

European guidance for the diagnosis and management of osteoporosis in postmenopausal women

Guidance is provided in a European setting on the assessment and treatment of postmenopausal women at risk from fractures due to osteoporosis.

INTRODUCTION

The International Osteoporosis Foundation and European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis published guidance for the diagnosis and management of osteoporosis in 2013. This manuscript updates these in a European setting.

METHODS

Systematic reviews were updated.

RESULTS

The following areas are reviewed: the role of bone mineral density measurement for the diagnosis of osteoporosis and assessment of fracture risk; general and pharmacological management of osteoporosis; monitoring of treatment; assessment of fracture risk; case-finding strategies; investigation of patients; health economics of treatment. The update includes new information on the evaluation of bone microstructure evaluation in facture risk assessment, the role of FRAX® and Fracture Liaison Services in secondary fracture prevention, long-term effects on fracture risk of dietary intakes, and increased fracture risk on stopping drug treatment.

CONCLUSIONS

A platform is provided on which specific guidelines can be developed for national use.

Calcium Intake From Diet and Supplements and the Risk of Coronary Artery Calcification and its Progression Among Older Adults: 10-Year Follow-up of the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Recent randomized data suggest that calcium supplements may be associated with increased risk of cardiovascular disease (CVD) events. Using a longitudinal cohort study, we assessed the association between calcium intake, from both foods and supplements, and atherosclerosis, as measured by coronary artery calcification (CAC).

METHODS AND RESULTS

We studied 5448 adults free of clinically diagnosed CVD (52% female; aged 45-84 years) from the Multi-Ethnic Study of Atherosclerosis. Baseline total calcium intake was assessed from diet (using a food frequency questionnaire) and calcium supplements (by a medication inventory) and categorized into quintiles. Baseline CAC was measured by computed tomography, and CAC measurements were repeated in 2742 participants ≈10 years later. At baseline, mean calcium intakes across quintiles were 313.3, 540.3, 783.0, 1168.9, and 2157.4 mg/day. Women had higher calcium intakes than men. After adjustment for potential confounders, among 1567 participants without baseline CAC, the relative risk (RR) of developing incident CAC over 10 years, by quintile 1 to 5 of calcium intake, were 1 (reference), 0.95 (0.79-1.14), 1.02 (0.85-1.23), 0.86 (0.69-1.05), and 0.73 (0.57-0.93). After accounting for total calcium intake, calcium supplement use was associated with increased risk for incident CAC (RR=1.22 [1.07-1.39]). No relation was found between baseline calcium intake and 10-year changes in log-transformed CAC among those participants with baseline CAC >0.

CONCLUSIONS

High total calcium intake was associated with a decreased risk of incident atherosclerosis over long-term follow-up, particularly if achieved without supplement use. However, calcium supplement use may increase the risk for incident CAC.

The association of calcium supplementation and incident cardiovascular events in the Multi-ethnic Study of Atherosclerosis (MESA)

BACKGROUND AND AIMS

Many US adults use calcium supplements to address inadequate dietary intake and improve bone health. However, recent reports have suggested that use of calcium supplements may elevate cardiovascular disease (CVD) risk. In this study, we examined associations between baseline calcium supplement use and incident myocardial infarction (MI) (n = 208 events) and CVD events (n = 641 events) over 10.3 years in men and women from the Multi-Ethnic Study of Atherosclerosis (MESA) cohort (n = 6236), with dietary calcium intake at baseline also examined as a supplementary objective.

METHODS AND RESULTS

Using Cox proportional hazards models, no compelling associations between calcium intake from supplements or diet and incident CVD events were observed upon multivariate adjustment for potential confounders. An association with lower MI risk was observed comparing those with low levels of calcium supplement use (1-499 mg) to those using no calcium supplements (hazard ratio 0.69, 95% CI 0.48, 0.98, p = 0.039). Relationships were homogeneous by gender, race/ethnicity, or chronic kidney disease. Results were also similar when the analysis was limited to postmenopausal women only.

CONCLUSION

Analysis of incident MI and CVD events in the MESA cohort does not support a substantial association of calcium supplement use with negative cardiovascular outcomes.

The predicted lifetime costs and health consequences of calcium and vitamin D supplementation for fracture prevention-the impact of cardiovascular effects

Some studies indicate that calcium supplementation increases cardiovascular risk. We assessed whether such effects could counterbalance the fracture benefits from supplementation. Accounting for cardiovascular outcomes, calcium may cause net harm and would not be cost-effective. Clinicians may do well considering cardiovascular effects when prescribing calcium supplementation.

INTRODUCTION

Accounting for possible cardiovascular effect of calcium and vitamin D supplementation (CaD), the aims of this study were to assess whether CaD on balance would improve population health and to evaluate the cost-effectiveness of such supplementation.

METHODS

We created a probabilistic Markov simulation model that was analysed at the individual patient level. We analysed 65-year-old Norwegian women with a 2.3 % 10-year risk of hip fracture and a 9.3 % risk of any major fracture according to the WHO fracture risk assessment tool (FRAX®). Consistent with a recent Cochrane review, we assumed that CaD reduces the risk of hip, vertebral, and wrist fractures by 16, 11, and 5 %, respectively. We included the increased risk of acute myocardial infarction (AMI) and stroke under a no-, medium-, and high-risk scenario.

RESULTS

Assuming no cardiovascular effects, CaD supplementation produces improved health outcomes resulting in an incremental gain of 0.0223 quality-adjusted life years (QALYs) and increases costs by €322 compared with no treatment (cost-effectiveness ratio €14,453 per QALY gained). Assuming a Norwegian cost-effectiveness threshold of €60,000 per QALY, CaD is likely to be considered a cost-effective treatment alternative. In a scenario with a medium or high increased risk of cardiovascular events, CaD produces net health losses, respectively, -0.0572 and -0.0784 QALY at additional costs of €481 and €1033.

CONCLUSIONS

We conclude that the magnitude of potential cardiovascular side effects is crucial for the effectiveness and cost-effectiveness of CaD supplementation in elderly women.

Calcium and bone health--goodbye, calcium supplements?

This review assesses (1) the potential role of calcium supplements in the prevention and treatment of osteoporosis and osteoporotic fractures, and (2) the safety of calcium supplements with respect to cardiovascular health as well. With regard to (1), a total calcium intake of < 800 mg/day is associated with increased loss of bone mineral density in peri- and postmenopausal women with an increase in fracture risk. Hereby, the effect of calcium supplements on fracture prevention is dependent primary on baseline calcium intake. The strongest protective effect has been reported in individuals with a calcium intake < 700 mg/day and in high-risk groups. A calcium intake of about 1000-1200 mg/day seems to be sufficient for general fracture prevention. With regard to (2), an analysis of the data based on the Hill criteria does not demonstrate convincing evidence that calcium supplements increase cardiovascular risk. In the long term, total calcium intake of 2500 mg/day (from food and supplements) continues to be classified as safe. This value should not be exceeded for an extended period of time.

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.

The effects of calcium supplementation on verified coronary heart disease hospitalization and death in postmenopausal women: a collaborative meta-analysis of randomized controlled trials

Calcium supplementation, particularly with vitamin D, has been an approved public health intervention to reduce fracture risk. Enthusiasm for this intervention has been mitigated by meta-analyses suggesting that calcium supplementation with or without vitamin D increases myocardial infarction (MI) risk; however, concern has been raised over the design of these meta-analyses. We, therefore, undertook a meta-analysis of randomized controlled trials with placebo or no-treatment control groups to determine if these supplements increase all-cause mortality and coronary heart disease (CHD) risk including MI, angina pectoris and acute coronary syndrome, and chronic CHD verified by clinical review, hospital record, or death certificate in elderly women. The Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE databases were searched from January 1, 1966, to May 24, 2013, for potentially eligible studies, reference lists were checked, and trial investigators were contacted where additional unpublished data were required. The search yielded 661 potentially eligible reports of which 18 met the inclusion criteria and contributed information on 63,563 participants with 3390 CHD events and 4157 deaths. Two authors extracted the data independently with trial data combined using random-effects meta-analysis to calculate the relative risk (RR). Five trials contributed CHD events with pooled relative RR of 1.02 (95% confidence interval [CI], 0.96-1.09; p = 0.51). Seventeen trials contributed all-cause mortality data with pooled RR of 0.96 (95% CI, 0.91-1.02; p = 0.18). Heterogeneity among the trials was low for both primary outcomes (I(2)  = 0%). For secondary outcomes, the RR for MI was 1.08 (95% CI, 0.92-1.26; p = 0.32), angina pectoris and acute coronary syndrome 1.09 (95% CI, 0.95-1.24; p = 0.22) and chronic CHD 0.92 (95% CI, 0.73-1.15; p = 0.46). In conclusion, current evidence does not support the hypothesis that calcium supplementation with or without vitamin D increases coronary heart disease or all-cause mortality risk in elderly women.

Cross-sectional analysis of calcium intake for associations with vascular calcification and mortality in individuals with type 2 diabetes from the Diabetes Heart Study

BACKGROUND

The use of calcium supplements to prevent declines in bone mineral density and fractures is widespread in the United States, and thus reports of elevated cardiovascular disease (CVD) risk in users of calcium supplements are a major public health concern. Any elevation in CVD risk with calcium supplement use would be of particular concern in individuals with type 2 diabetes (T2D) because of increased risks of CVD and fractures observed in this population.

OBJECTIVE

In this study, we examined associations between calcium intake from diet and supplements and measures of subclinical CVD (calcified plaque in the coronary artery, carotid artery, and abdominal aorta) and mortality in individuals affected by T2D.

DESIGN

We performed a cross-sectional analysis in individuals affected by T2D from the family-based Diabetes Heart Study (n = 720).

RESULTS

We observed no significant associations of calcium from diet or supplements with any of our measures of calcified plaque, and no greater mortality risk was observed with increased calcium intake. Instead, calcium supplement use was modestly associated with reduced all-cause mortality in women (HR: 0.62; 95% CI: 0.42, 0.92; P = 0.017).

CONCLUSION

Our results do not support a substantial association between calcium intake from diet or supplements and CVD risk in individuals with T2D.

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.

The effects of 3 years of calcium supplementation on common carotid artery intimal medial thickness and carotid atherosclerosis in older women: an ancillary study of the CAIFOS randomized controlled trial

Calcium is an essential nutrient for skeletal health; however, it has been suggested that supplemental calcium may be associated with adverse cardiovascular effects, raising widespread concern about their use. One suggested mechanism is via increasing carotid atherosclerosis, however few randomized controlled trials (RCT) of calcium supplements have assessed these mechanisms. The calcium intake fracture outcome study (CAIFOS) was a 5-year RCT (1998 to 2003) of 1.2 g of elemental calcium in the form of calcium carbonate in 1460 elderly women. An ancillary study of 1103 women assessed common carotid artery intimal medial thickness (CCA-IMT) and carotid atherosclerosis at year 3 (2001). The effects of supplementation were studied in intention-to-treat (ITT) and per-protocol (PP) analyses before and after adjustment for baseline cardiovascular risk factors. The mean age of participants at baseline was 75.2 ± 2.7 years. In ITT analyses, women randomized to calcium supplementation had no difference in multivariable-adjusted mean CCA-IMT (calcium 0.778 ± 0.006 mm, placebo 0.783 ± 0.006 mm, p = 0.491) and maximum CCA-IMT (calcium 0.921 ± 0.007 mm, placebo 0.929 ± 0.006 mm, p = 0.404). Women randomized to calcium did not have increased carotid atherosclerosis (calcium 47.2%, placebo 52.7%, p = 0.066). However, in women taking at least 80% of the supplements, a significant reduction in carotid atherosclerosis was observed in unadjusted but not in multivariate-adjusted models (p = 0.033 and p = 0.064, respectively). Participants in the highest tertile of total calcium (diet and supplements) had reduced carotid atherosclerosis in unadjusted and multivariable-adjusted analyses compared with participants in the lowest tertile (odds ratio [OR] = 0.67 [95% confidence interval (CI) 0.50-0.90], p = 0.008, and OR = 0.70 [95% CI 0.51-0.96], p = 0.028, respectively). In conclusion, these findings do not support the hypothesis that calcium supplementation increases carotid artery intimal medial thickness or carotid atherosclerosis, and high calcium intake may reduce this surrogate cardiovascular risk factor.

Clinical practice. Calcium supplements and fracture prevention

This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author’s clinical recommendations. A 62-year-old healthy woman presents for routine care. She has no history of fracture, but she is worried about osteoporosis because her mother had a hip fracture at 72 years of age. She exercises regularly and has taken over-the-counter calcium carbonate at a dose of 1000 mg three times a day since her menopause at 54 years of age. This regimen provides 1200 mg of elemental calcium per day. She eats a healthy diet with multiple servings of fruits and vegetables and consumes one 8-oz serving of low-fat yogurt and one glass of low-fat milk almost every day. She recently heard that calcium supplements could increase her risk of cardiovascular disease and wants your opinion about whether or not she should receive them. What would you advise?

Calcium supplements and cardiovascular risk: 5 years on

Calcium supplements have been widely used by older men and women. However, in little more than a decade, authoritative recommendations have changed from encouraging the widespread use of calcium supplements to stating that they should not be used for primary prevention of fractures. This substantial shift in recommendations has occurred as a result of accumulated evidence of marginal antifracture efficacy, and important adverse effects from large randomized controlled trials of calcium or coadministered calcium and vitamin D supplements. In this review, we discuss this evidence, with a particular focus on increased cardiovascular risk with calcium supplements, which we first described 5 years ago. Calcium supplements with or without vitamin D marginally reduce total fractures but do not prevent hip fractures in community-dwelling individuals. They also cause kidney stones, acute gastrointestinal events, and increase the risk of myocardial infarction and stroke. Any benefit of calcium supplements on preventing fracture is outweighed by increased cardiovascular events. While there is little evidence to suggest that dietary calcium intake is associated with cardiovascular risk, there is also little evidence that it is associated with fracture risk. Therefore, for the majority of people, dietary calcium intake does not require close scrutiny. Because of the unfavorable risk/benefit profile, widespread prescribing of calcium supplements to prevent fractures should be abandoned. Patients at high risk of fracture should be encouraged to take agents with proven efficacy in preventing vertebral and nonvertebral fractures.

Risk of high dietary calcium for arterial calcification in older adults

Concern has recently arisen about the potential adverse effects of excessive calcium intakes, i.e., calcium loading from supplements, on arterial calcification and risks of cardiovascular diseases (CVD) in older adults. Published reports that high calcium intakes in free-living adults have relatively little or no beneficial impact on bone mineral density (BMD) and fracture rates suggest that current recommendations of calcium for adults may be set too high. Because even healthy kidneys have limited capability of eliminating excessive calcium in the diet, the likelihood of soft-tissue calcification may increase in older adults who take calcium supplements, particularly in those with age or disease-related reduction in renal function. The maintenance of BMD and bone health continues to be an important goal of adequate dietary calcium consumption, but eliminating potential risks of CVDs from excessive calcium intakes needs to be factored into policy recommendations for calcium by adults.

New reference values for calcium

The nutrition societies of Germany, Austria and Switzerland are the joint editors of the 'reference values for nutrient intake'. They have revised the reference values for the intake of calcium and published them in June 2013. The reference values for the calcium intake for infants are derived from the calcium content of breast milk. For infants from 4 to <12 months of age, the calcium intake from solid foods is included in addition to the calcium intake from breast milk. Thus, the reference values for infants are estimated values; they are 220 mg/day for infants to <4 months and 330 mg/day for infants from 4 to <12 months of age. As a parameter for determining the calcium requirement in children and adolescents, calcium retention is taken into account. The average requirement is calculated by the factorial method. A balanced calcium metabolism is calculated based upon calcium balance studies and used as a parameter for the determination of the calcium requirement in adults. On the basis of the average requirement, recommended calcium intake levels for children, adolescents and adults are derived. Depending on age, the recommended calcium intake ranges between 600 mg/day for children aged 1 to <4 years and 1,200 mg/day for adolescents aged 13 to <19 years; for adults, it is 1,000 mg/day.

Dairy and blood pressure: a fresh look at the evidence

The Dietary Guidelines for Americans, 2010 indicated there is moderate evidence for an association between the consumption of dairy foods and lower blood pressure in adults; however, it also stated that more evidence was needed, especially in clinical trials, to fully delineate a causal relationship. The purpose of this review is to provide background by examining the historical literature and the evidence reviewed by the 2010 Dietary Guidelines Advisory Committee, to examine the gaps in knowledge indicated by that committee, and to determine if recently published evidence is sufficient to elucidate or dismiss an association between dairy foods and blood pressure maintenance. Examination of the newly published literature, together with evaluation of the evidence as a whole, shows that the preponderance of evidence indicates dairy foods are beneficially associated with blood pressure; however, additional research is necessary to identify the mechanism of action of dairy foods. New evidence should come from carefully designed clinical trials that examine not only blood pressure outcomes but also the ability of dairy foods to affect the vasculature.

Acute effect of calcium citrate on serum calcium and cardiovascular function

Calcium supplements have been associated with an increased risk of cardiovascular events. However, the validity of these findings has been questioned. A major concern is that the mechanism underlying an increase in cardiovascular events has not been demonstrated. Calcium initiates cardiac and vascular contraction following influx of calcium into cardiac and smooth muscle from extracellular fluid. We have investigated whether the acute rise in serum calcium following calcium supplement administration is associated with adverse changes in cardiovascular function. In an open interventional study, we recruited 25 volunteers (16 female, age 60.3 ± 6.5 years, body mass index 25.7 ± 2.7 kg/m2) from the community who were not taking calcium supplements. Participants were studied before and 3 hours after a single oral dose of 1000 mg calcium citrate. We assessed well-validated markers of arterial stiffness (pulse wave velocity [PWV]), arterial wave reflection (augmentation index [AIx]), and myocardial perfusion (subendocardial viability ratio [SEVR]) by pulse wave analysis and endothelial function (reactive hyperemia index [RHI]) by peripheral arterial tonometry. Total and ionized serum calcium were acutely increased by 0.10 ± 0.07 and 0.06 ± 0.03 mmol/L, respectively, 3 hours after calcium citrate administration (p < 0.0001 for both comparisons). Following administration of calcium citrate there was a fall in AIx from a median of 29.7% (23.8% to 34.0%) to 26.4% (22.7% to 34.0%, p = 0.03) and an increase in SEVR from 163% (148% to 174%) to 170% (149% to 185%, p = 0.007). PWV and RHI were not significantly altered. The change in total calcium was negatively correlated with the change in AIx (r = -0.48, p = 0.02). In summary, the acute increase in serum calcium following calcium supplement administration is associated with reduced arterial wave reflection and a marker of increased myocardial perfusion. If maintained long-term, these changes would be expected to reduce cardiovascular risk. Acute serum calcium-mediated changes in these parameters of cardiovascular function are unlikely to underlie an association between calcium supplementation and cardiovascular events.

European guidance for the diagnosis and management of osteoporosis in postmenopausal women

Guidance is provided in a European setting on the assessment and treatment of postmenopausal women at risk of fractures due to osteoporosis.

INTRODUCTION

The International Osteoporosis Foundation and European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis published guidance for the diagnosis and management of osteoporosis in 2008. This manuscript updates these in a European setting.

METHODS

Systematic literature reviews.

RESULTS

The following areas are reviewed: the role of bone mineral density measurement for the diagnosis of osteoporosis and assessment of fracture risk, general and pharmacological management of osteoporosis, monitoring of treatment, assessment of fracture risk, case finding strategies, investigation of patients and health economics of treatment.

CONCLUSIONS

A platform is provided on which specific guidelines can be developed for national use.

Calcium intakes and femoral and lumbar bone density of elderly U.S. men and women: National Health and Nutrition Examination Survey 2005-2006 analysis

OBJECTIVES

This analysis was aimed at assessing the benefits of total calcium intake from diet and supplements on both femoral neck and lumbar vertebral bone mineral density (BMD) in a representative sample of older U.S. women and men.

DESIGN

For 1384 women and men aged 50-70 and 71+ yr, quintiles of total calcium intake were tested for their association with hip and spine BMD after adjusting for body mass index. All data in this observational study were cross-sectional.

DATA SOURCE

Subjects included elderly residents statistically representative of the United States, women and men aged 50 yr and older in the National Health and Nutrition Examination Survey 2005-2006 cohort.

MAIN OUTCOME MEASURES

Calcium intakes and femoral and lumbar BMD were evaluated.

RESULTS

Total calcium intakes ranged from means of 400+ mg/d in quintile 1 to 2100+ in quintile 5. Little difference in hip or lumbar BMD was found in relation to total calcium consumption in women and men across five quintiles, especially for those aged 50-70, in models adjusted for body mass index only. Femoral hip BMD in men 71 and older increased slightly with high calcium intake (3.6% higher density, P = 0.0391), whereas femoral BMD in women 71 and older decreased slightly with high calcium intake (-3.2%, P = 0.0132). Lumbar BMD remained fairly consistent across all quintiles, but greater variation within each quintile was found compared with the hip.

CONCLUSIONS

A usual high calcium intake beyond the recommended dietary allowance of elderly women and men, most commonly achieved by calcium supplements, did not provide any benefit for hip or lumbar BMD. A dietary intake of calcium approaching or meeting the current recommendations was not related to higher BMD of the hip or lumbar spine in late life compared with lower intakes of calcium in older adults.

Calcium intake is not associated with increased coronary artery calcification: the Framingham Study

BACKGROUND

Adequate calcium intake is known to protect the skeleton. However, studies that have reported adverse effects of calcium supplementation on vascular events have raised widespread concern.

OBJECTIVE

We assessed the association between calcium intake (from diet and supplements) and coronary artery calcification, which is a measure of atherosclerosis that predicts risk of ischemic heart disease independent of other risk factors.

DESIGN

This was an observational, prospective cohort study. Participants included 690 women and 588 men in the Framingham Offspring Study (mean age: 60 y; range: 36-83 y) who attended clinic visits and completed food-frequency questionnaires in 1998-2001 and underwent computed tomography scans 4 y later in 2002-2005.

RESULTS

The mean age-adjusted coronary artery-calcification Agatston score decreased with increasing total calcium intake, and the trend was not significant after adjustment for age, BMI, smoking, alcohol consumption, vitamin D-supplement use, energy intake, and, for women, menopause status and estrogen use. Multivariable-adjusted mean Agatston scores were 2.36, 2.52, 2.16, and 2.39 (P-trend = 0.74) with an increasing quartile of total calcium intake in women and 4.32, 4.39, 4.19, and 4.37 (P-trend = 0.94) in men, respectively. Results were similar for dietary calcium and calcium supplement use.

CONCLUSIONS

Our study does not support the hypothesis that high calcium intake increases coronary artery calcification, which is an important measure of atherosclerosis burden. The evidence is not sufficient to modify current recommendations for calcium intake to protect skeletal health with respect to vascular calcification risk.

A review of calcium supplements and cardiovascular disease risk

A group of academic and industry experts in the fields of nutrition, cardiology, epidemiology, food science, bone health, and integrative medicine examined the data on the relationship between calcium supplement use and risk of cardiovascular events, with an emphasis on 4 of the Bradford Hill criteria for causal inference: strength, consistency, dose-response, and biological plausibility. Results from 2 epidemiological studies and a meta-analysis of randomized, controlled clinical trials, including a subgroup analysis from the Women's Health Initiative, have prompted concern about a potential association between calcium supplement use and a small increase in the risk of adverse cardiovascular events. However, a number of issues with the studies, such as inadequate compliance with the intervention, use of nontrial calcium supplements, potential bias in event ascertainment, and lack of information on and adjustment for known cardiovascular risk determinants, suggest that bias and confounding cannot be excluded as explanations for the reported associations. Findings from other cohort studies also suggest no detrimental effect of calcium from diet or supplements, with or without vitamin D, on cardiovascular disease risk. In addition, little evidence exists for plausible biological mechanisms to link calcium supplement use with adverse cardiovascular outcomes. The authors do not believe that the evidence presented to date regarding the hypothesized relationship between calcium supplement use and increased cardiovascular disease risk is sufficient to warrant a change in the Institute of Medicine recommendations, which advocate use of supplements to promote optimal bone health in individuals who do not obtain recommended intakes of calcium through dietary sources.

The out-of-focus bias in drug surveillance

PURPOSE

Existing drug safety systems with phase II and III studies and post-marketing surveillance by principle do not allow for the recognition of an important class of adverse drug reactions (ADRs). ADRs that are resistant to being detected reliably may a) appear as if they are age-related chronic diseases, which also manifest themselves in a high degree without drug treatment, b) arise in "old" drugs, c) arise during long-term application, and d) arise with the administration to frail and aged populations.

CONCLUSIONS

"Silent" and multi-factorial health problems evolving from long-term drug treatment must therefore be addressed with a systematic search strategy, as a third track along with the phase II and III studies and spontaneous reporting systems which still exist.

Vitamin D, calcium, and cardiovascular mortality: a perspective from a plenary lecture given at the annual meeting of the American Association of Clinical Endocrinologists

OBJECTIVE

To examine data showing associations between serum 25-hydroxyvitamin D levels and calcium intake and cardiovascular mortality.

METHODS

The articles reviewed include those published from 1992-2011 derived from search engines (PubMed, Scopus, Medscape) using the following search terms: vitamin D, calcium, cardiovascular events, cardiovascular mortality, all-cause mortality, vascular calcification, chronic kidney disease, renal stones, and hypercalciuria. Because these articles were not weighted (graded) on the level of evidence, this review reflects my own perspective on the data and how they should be applied to clinical management.

RESULTS

For skeletal health, vitamin D and calcium are both needed to ensure proper skeletal growth (modeling) and repair (remodeling). Nutritional deficiencies of either vitamin D or calcium may lead to a spectrum of metabolic bone disorders. Excessive consumption of either nutrient has been linked to a variety of medical disorders, such as hypercalcemia or renal stones. There have also been associations between vitamin D or calcium intake and cardiovascular disease. However, neither of these associations have established evidence nor known causality for increasing cardiovascular risk or all-cause mortality in patients with creatinine clearances greater than 60 mL/min. In patients with more severe chronic kidney disease, stronger data link excess calcium (or phosphorus) intake and increase in vascular calcification, but not mortality. The safe upper limit for vitamin D intake is at least 4000 IU daily and probably 10 000 IU daily; for calcium, the safe upper limit is between 2000 and 3000 mg daily.

CONCLUSIONS

While no solid scientific evidence validates that serum vitamin D levels between 15 and 70 ng/mL are associated with increased cardiovascular disease risk, stronger but inconsistent evidence shows an association between calcium supplementation greater than 500 mg daily and an increase in cardiovascular disease risk. Most professional societies suggest that replacement levels of these nutrients be personalized with the goal of reaching a 25-hydroxyvitamin D concentration between 30 and 50 ng/mL and a calcium intake of 1200 mg daily.

Assessing the potential adverse consequences of supplemental calcium on cardiovascular outcomes: should we change our approach to bone health?

OBJECTIVE

To assess cardiovascular risks associated with supplemental calcium use to assist clinicians with evidence-based recommendations for patients who have, or who are at risk for, osteoporosis or osteopenia.

DATA SOURCES

Literature was accessed through December 2011 using MEDLINE, Cochrane Library, and International Pharmaceutical Abstracts using the terms calcium compounds and cardiovascular disease. In addition, reference citations from the publications identified were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles were evaluated. Randomized controlled trials, observational studies, and meta-analyses were included.

DATA SYNTHESIS

While supplemental calcium and vitamin D have been demonstrated to improve bone mineral density and decrease the risk of fractures, there have been recent reports that calcium supplements may increase the risk for cardiovascular events. Nine clinical trials and/or meta-analyses were reviewed; 3 documented increases in cardiovascular risk associated with calcium supplements, and 6 did not. No studies were designed to assess cardiovascular outcomes as primary end points. Balancing the evidence from these analyses with the results of randomized controlled trials assessing the effect of calcium on fracture prevention suggests that the benefits of calcium outweigh the cardiovascular risk.

CONCLUSIONS

At this time, there is no cause to change routine practice surrounding supplemental calcium use in patients who have, or are at risk for, osteoporosis or osteopenia.