Calcium intake and hip fracture risk in men and women: a meta-analysis of prospective cohort studies and randomized controlled trials

BACKGROUND: The role of total calcium intake in the prevention of hip fracture risk has not been well established. OBJECTIVE: The objective of the study was to assess the relation of calcium intake to the risk of hip fracture on the basis of meta-analyses of cohort studies and clinical trials. RESULTS: In women (7 prospective cohort studies, 170,991 women, 2,954 hip fractures), there was no association between total calcium intake and hip fracture risk [pooled risk ratio (RR) per 300 mg total Ca/d = 1.01; 95% CI: 0.97, 1.05]. In men (5 prospective cohort studies, 68,606 men, 214 hip fractures), the pooled RR per 300 mg total Ca/d was 0.92 (95% CI: 0.82, 1.03). On the basis of 5 clinical trials (n = 5666 women, primarily postmenopausal, plus 1074 men) with 814 nonvertebral fractures, the pooled RR for nonvertebral fractures between calcium supplementation (800-1600 mg/d) and placebo was 0.92 (95% CI: 0.81, 1.05). On the basis of 4 clinical trials with separate results for hip fracture (6,504 subjects with 139 hip fractures), the pooled RR between calcium and placebo was 1.64 (95% CI:1.02, 2.64). Sensitivity analyses including 2 additional small trials with <100 participants or per-protocol results did not substantially alter results. CONCLUSIONS: Pooled results from prospective cohort studies suggest that calcium intake is not significantly associated with hip fracture risk in women or men. Pooled results from randomized controlled trials show no reduction in hip fracture risk with calcium supplementation, and an increased risk is possible. For any nonvertebral fractures, there was a neutral effect in the randomized trials.     

Considerations concerning the definition of sarcopenia

In this commentary, we describe the sarcopenia spectrum that results in frailty and consider the impact of several components of the frailty definition on its global prevalence. We review proposed operational definitions of sarcopenia and the extent to which they have been shown to predict hard clinical outcomes, such as hip fracture, falls, and mortality. A head-to-head comparison of nine proposed operational definitions of sarcopenia as predictors of falls revealed that the definition involving appendicular lean mass (ALM)/ht² alone was a significant predictor; the prevalence of sarcopenia by this definition was 11 %. We consider the strengths and limitations of definitions that include functional measurements, such as gait speed and grip strength, along with measures of lean tissue mass. The functional assessments are harder to standardize than the more objective ALM measurements. The prevalence of sarcopenia by definitions that include functional and lean mass measurements tends to be lower than the prevalence by definitions that include lean mass alone. A low prevalence limits opportunity for early identification and application of prevention strategies. For these and other reasons, it seems advantageous to base the operational definition of sarcopenia on ALM/ht² alone. This commentary addresses the importance of a globally applicable operational definition of sarcopenia and both desirable and undesirable features of such a definition.     

Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes

Recent evidence suggests that vitamin D intakes above current recommendations may be associated with better health outcomes. However, optimal serum concentrations of 25-hydroxyvitamin D [25(OH)D] have not been defined. This review summarizes evidence from studies that evaluated thresholds for serum 25(OH)D concentrations in relation to bone mineral density (BMD), lower-extremity function, dental health, and risk of falls, fractures, and colorectal cancer. For all endpoints, the most advantageous serum concentrations of 25(OH)D begin at 75 nmol/L (30 ng/mL), and the best are between 90 and 100 nmol/L (36-40 ng/mL). In most persons, these concentrations could not be reached with the currently recommended intakes of 200 and 600 IU vitamin D/d for younger and older adults, respectively. A comparison of vitamin D intakes with achieved serum concentrations of 25(OH)D for the purpose of estimating optimal intakes led us to suggest that, for bone health in younger adults and all studied outcomes in older adults, an increase in the currently recommended intake of vitamin D is warranted. An intake for all adults of > or =1000 IU (25 microg) [corrected] vitamin D (cholecalciferol)/d is needed to bring vitamin D concentrations in no less than 50% of the population up to 75 nmol/L. The implications of higher doses for the entire adult population should be addressed in future studies.     

Vitamin D intake and risk of incident hypertension: results from three large prospective cohort studies

Emerging evidence suggests an inverse relation between vitamin D and blood pressure. We examined the independent association between intake of vitamin D and the risk of incident hypertension among participants of 3 large and independent prospective cohorts: Nurses Health Study I (NHS I; n=77,436), NHS II (n=93,803), and Health Professionals' Follow-up Study (HPFS; n=38,074). Relative risks and 95% confidence intervals for incident hypertension were computed according to quintiles of vitamin D intake using Cox proportional hazards regression and adjusted for relevant covariates. Each cohort was followed for > or =8 years. Vitamin D intake was not associated with the risk of developing hypertension. The multivariable relative risk estimates for the highest compared with lowest quintile of intake were 0.98 (0.93 to 1.04) in NHS I, 1.13 (0.99 to 1.29) in NHS II, and 1.03 (0.93 to 1.15) in HPFS. When we compared participants who consumed > or =1600 to <400 IU per day and those who consumed > or =1000 to <200 IU per day, no association was found. We conclude that higher intake of vitamin D is not associated with a lower risk of incident hypertension.     

Association between Caregiver Role and Short- and Long-Term Functional Recovery after Hip Fracture: A Prospective Study

Objectives

After a hip fracture, 50% of senior patients are left with permanent functional decline and 30% lose their autonomy. The aim of this prospective study was to evaluate whether seniors who are in a caregiver role have better functional recovery after hip fracture compared with noncaregivers.

Vitamin D deficiency is common in kidney transplant recipients,but is not associated with infections after transplantation

The relevance of vitamin D for infections after kidney transplantation is poorly defined. 25-OH vitamin D (25-OHD) levels of 135 kidney transplant recipients, enrolled in the Swiss Transplant Cohort Study, were determined peri-transplant and 6 months post-transplant. Logistic regression was used to address the associations of 25-OHD and overall infections and bacterial infections, respectively. For the first 6 months post-transplant, 25-OHD peri-transplant, and for the second period (after 6 to 30 months post-transplant), 25-OHD at 6 months post-transplant was considered. Vitamin D deficiency was common peri-transplant and remained highly prevalent 6 months after transplantation despite frequent supplementation. Median 25-OHD levels increased from 12.0 ng/mL (IQR 5.3-19.5) peri-transplant to 16.5 ng/mL (IQR 10.6-22.6) 6 months post-transplant (P = .005). We did not detect a significant association between 25-OHD and overall infections (adjusted odds ratio (aOR) 1.05, 95% confidence interval (95%CI) 0.44-2.51; aOR 0.67, 95%CI 0.31-1.43) or bacterial infections (aOR 0.79, 95%CI 0.32-1.96; aOR 0.79, 95%CI 0.35-1.75) for the first and second period. To conclude, at both time points, vitamin D deficiency was observed in more than 50% of kidney recipients, albeit an increase in 25-OHD in the longitudinal course was observed. No significant association between 25-OHD and infections was detected.     

Vitamin D and fracture prevention

Based on evidence from double-blind RCTs, vitamin D supplementation reduces falls and nonvertebral fractures, including those at the hip. However, this benefit is dose-dependent. According to 2 meta-analysis in 2009 of double-blind RCTs, no fall reduction was observed for a dose of less than 700 IU per day. A higher dose of 700 to 1000 IU supplemental vitamin D per day reduced falls by 19%. Similarly, no fracture reduction was observed for a received dose of 400 IU or less per day. A higher received dose of 482 to 770 IU supplemental vitamin D per day reduced nonvertebral fractures by 20% and hip fractures by 18%. The antifracture effect was present in all subgroups of the older population and was most pronounced among community-dwellers (-29%) and those ages 65 to 74 years (-33%). Consistently, fall prevention and nonvertebral fracture prevention increased significantly with higher achieved 25-hydroxyvitamin D levels in the 2009 meta-analyses. Fall prevention occurred with 25-hydroxyvitamin D levels of 60 to 95 nmol/L; levels of 75 to 112 nmol/L were required for nonvertebral fracture prevention. Given the absence of data beyond this beneficial range, these recent meta-analyses do not preclude the possibility that higher doses or higher achieved 25-hydroxyvitamin D concentrations would have been even more efficient in reducing falls and nonvertebral fractures.