Decreased bone mass in adolescents with bone fragility fracture but not in young children: a case-control study.

Background: The incidence of distal forearm fracture due to minimal/moderate trauma shows a bimodal distribution for age at event, with one peak occurring during early adolescence, in both boys and girls and the other one in postmenopausal females. The aim of this study was, therefore, to document whether the relationship between bone mineral density and fracture is different in young children compared with adolescents. Methods: A matched-pair, case-control study has been conducted to evaluate bone mineral density in 469 young children and 387 adolescents of both sexes, with/without fracture due to minimal/moderate trauma with assurance that the compared groups were equally susceptible to the outcome event. All fractures were radiographically confirmed. The study utilized bone mineral areal density of the total body, spine, hips, and forearm; volumetric bone mineral density of the forearm; and metacarpal radiogrammetry measurements. The study controlled for skeletal development, bone geometry, body composition, hand grip strength, calcium intake, and vitamin D status. Results: Adolescents with distal forearm fracture have reduced bone mineral density at multiple skeletal regions of interest. This was documented by the bone mineral areal density measurements at multiple skeletal sites (p < 0.001), volumetric bone mineral density measurements of the forearm (p < 0.0001), and metacarpal radiogrammetry (p < 0.001). Adolescent females with fracture had reduced cross-sectional areas of the radius and metacarpals. The bone status of young female and male children with fracture was no different to its controls. Increased body fatness was more prevalent among fracture cases than in controls. Around 72% of young female and male children with fracture had serum 25-hydroxyvitamin D levels below the threshold of 31 ng/ml, compared with only 42% of female controls and to 51% of male controls. Conclusions: Adolescents with bone fragility fracture had reduced bone mineral density at multiple skeletal regions of interest, whereas this was not the case with younger children. The results of the study may have implications for the prevention of bone fragility in this segment of the pediatric population.

Skeletal health in Duchenne dystrophy: bone-size and subcranial dual-energy X-ray absorptiometry analyses.

INTRODUCTION: We performed subcranial and bone-size-adjusted whole body dual-energy X-ray absorptiometry (DXA) to evaluate skeletal health in Duchenne dystrophy (DMD). METHODS: Total body bone mineral density (TBBMD)-for-age, subcranial, and size-adjusted DXA analyses were performed on 22 DMD patients (5-17 years) and compared with 267 controls from a database. The skull contribution to total body bone mineral content (TBBMC) and corticosteroid effects were also examined. RESULTS: DMD boys had deficits in TBBMD-for-age (Z = -1.2), which increased with age. The skull's contribution to TBBMC decreased from 45% to 15% with growth. Z-scores for subcranial skeleton were significantly lower than TBBMC-for-area and TBBMD-for-age. CONCLUSIONS: Size-adjusted and subcranial analyses improve evaluation of whole body DXA. DMD boys have low BMD for size not commensurate with total body areal BMD-for-age. Bone fragility fractures in DMD may result from both decreased BMD and smaller bones. This information is vital to determine appropriate intervention. Muscle Nerve 49:512-519, 2014.

Dairy-rich diets augment fat loss on an energy-restricted diet: a multicenter trial.

A 12-week randomized controlled multi-center clinical trial was conducted in 106 overweight and obese adults. Diets were designed to produce a 2,093 kJ/day energy deficit with either low calcium (LC; ~600 mg/day), high calcium (HC; ~1,400 mg/day), or high dairy (HD; three dairy servings, diet totaling ~1,400 mg/day). Ninety-three subjects completed the trial, and 68 met all a priori weekly compliance criteria. Both HC and HD contained comparable levels of calcium, but HC was only ~30% as effective as HD in suppressing 1,25-(OH)(2)D and exerted no significant effects on weight loss or body composition compared to LC. In the group that met compliance criteria, HD resulted in ~two-fold augmentation of fat loss compared to LC and HC (HD: -4.43 ± 0.53 kg; LC: -2.69 ± 0.0.53 kg; HC: -2.23 ± 0.73 kg, p < 0.025); assessment of all completers and an intent-to-treat analysis produced similar trends. HD augmentated central (trunk) fat loss (HD: -2.38 ± 0.30 kg; HC: -1.42 ± 0.30 kg; LC: -1.36 ± 0.42 kg, p < 0.05) and waist circumference (HD: -7.65 ± 0.75 cm; LC: -4.92 ± 0.74 cm; LC: -4.95 ± 1.05 cm, p < 0.025). Similar effects were noted among all subjects completing the study and in an intent-to-treat analysis. These data indicate that dairy-rich diets augment weight loss by targeting the fat compartment during energy restriction.

Calcium and dairy product modulation of lipid utilization and energy expenditure.

OBJECTIVE: The purpose of this study was to investigate the impact of dietary calcium or dairy product intake on total energy expenditure (TEE), fat oxidation, and thermic effect of a meal (TEM) during a weight loss trial. METHODS AND PROCEDURES: The intervention included a prescribed 500-kcal deficit diet in a randomized placebo-controlled calcium or dairy product intervention employing twenty-four 18 to 31-year-old (22.2+/-3.1 years, mean +/- s.d.) overweight women (75.5+/-9.6 kg). TEM and fat oxidation were measured using respiratory gas exchange after a meal challenge, and TEE was measured by doubly labeled water. Fat mass (FM) and lean mass (fat-free mass (FFM)) were measured by dual-energy X-ray absorptiometry. Subjects were randomized into one of these three intervention groups: (i) placebo (<800 mg/day calcium intake); (ii) 900 mg/day calcium supplement; (iii) three servings of dairy products/day to achieve an additional 900 mg/day. RESULTS: There were no group effects observed in change in TEE; however, a group effect was observed for fat oxidation after adjusting for FFM (P=0.02). The treatment effect was due to an increase in fat oxidation in the calcium-supplemented group of 1.5+/-0.6 g/h, P=0.02. Baseline 25-hydroxyvitamin D (25OHD) was positively correlated with TEM (R=0.31, P=0.004), and trended toward a correlation with fat oxidation (P=0.06), independent of group assignment. Finally, the change in log parathyroid hormone (PTH) was positively correlated with the change in trunk FM (R=0.27, P=0.03). DISCUSSION: These results support that calcium intake increases fat oxidation, but does not change TEE and that adequate vitamin D status may enhance TEM and fat oxidation.

A comparison of fatigue failure responses of old versus middle-aged lumbar motion segments in simulated flexed lifting.

STUDY DESIGN: Survival analysis techniques were used to compare the fatigue failure responses of elderly motion segments to a middle-aged sample. OBJECTIVES: To compare fatigue life of a middle-aged sample of lumbosacral motion segments to a previously tested elderly cohort. An additional objective was to evaluate the influence of bone mineral content on cycles to failure. SUMMARY OF BACKGROUND DATA: A previous investigation evaluated fatigue failure responses of 36 elderly lumbosacral motion segments (average age, 81 +/- 8 years) subjected to spinal loads estimated when lifting a 9-kg load in 3 torso flexion angles (0 degrees, 22.5 degrees, and 45 degrees). Results demonstrated rapid fatigue failure with increased torso flexion; however, a key limitation of this study was the old age of the specimens. METHODS: Each lumbosacral spine was dissected into 3 motion segments (L1-L2, L3-L4, and L5-S1). Motion segments within each spine were randomly assigned to a spinal loading condition corresponding to lifting 9 kg in 3 torso flexion angles (0 degrees, 22.5 degrees, or 45 degrees). Motion segments were statically loaded and allowed to creep for 15 minutes, then cyclically loaded at 0.33 Hz. Fatigue life was taken as the number of cycles to failure (10 mm displacement after creep loading). RESULTS: Compared with the older sample of spines, the middle-aged sample exhibited increased fatigue life (cycles to failure) in all the torso flexion conditions. Increased fatigue life of the middle-aged specimens was associated with the increased bone mineral content (BMC) in younger motion segments (mean +/- SD, 30.7 +/- 11.1 g per motion segment vs. 27.8 +/- 9.4 g). Increasing bone mineral content had a protective influence with each additional gram increasing survival times by approximately 12%. CONCLUSION: Younger motion segments survive considerably longer when exposed to similar spine loading conditions that simulate repetitive lifting in neutral and flexed torso postures, primarily associated with the increased bone mineral content possessed by younger motion segments. Cycles to failure of young specimens at 22.5 degrees flexion were similar to that of older specimens at 0 degrees flexion, and survivorship of young specimens at 45 degrees flexion was similar to the older cohort at 22.5 degrees.

Potential use of biochemical markers of bone turnover for assessing the effect of calcium supplementation and predicting fracture risk.

BACKGROUND: Biochemical markers of bone remodeling have been extensively used (independent of bone mass measurements) to document the efficacy of various anticatabolic and anabolic bone-modifying medications in reducing fracture risk. Nonetheless, their usefulness in determining the effectiveness of osteoporosis prevention and treatment, particularly calcium supplementation, has not been well established. OBJECTIVE: This article reviews the use of biochemical markers of bone remodeling as a measure of the effect of calcium supplementation and the implications for prediction of fracture risk. METHODS: A generalized search of MEDLINE from 1966 through April 2004 using the terms osteoporosis, fracture risk, and the specific bone biomarkers of interest was conducted to identify articles relating to these biomarkers and their relationship to prediction of fracture risk. A second MEDLINE search for the same period used the terms calcium, biological markers, and fracture risk to identify studies of calcium supplementation and bone biomarkers. In both cases, the reference lists of identified review articles were searched for additional publications. RESULTS: : Several biochemical markers of bone remodeling have been shown to be positively correlated with bone mineral density and fracture risk. Furthermore, calcium supplementation has been shown to have a significant correlation with levels of a number of these biomarkers (P < 0.05): the markers of bone formation procollagen type I carboxy and amino terminal peptides and serum bone-specific alkaline phosphatase, and the markers of bone resorption urinary hydroxyproline, urinary pyridinoline, urinary deoxypyridinoline, urinary amino terminal crosslinked telopeptide, and urinary and serum carboxy terminal crosslinked telopeptide. CONCLUSIONS: Calcium supplementation has a significant effect on a number of biomarkers of bone remodeling, an effect that is, in turn, correlated with decreased fracture risk. Most studies of the efficacy of calcium supplementation in reducing bone remodeling and influencing bone mineral density and fracture risk have involved calcium carbonate, although a few studies have found that other calcium salts may produce similar results.

Calcium supplementation and bone mineral density in females from childhood to young adulthood: a randomized controlled trial.

BACKGROUND: Short-term studies established that calcium influences bone accretion during growth. Whether long-term supplementation influences bone accretion in young adults is not known. OBJECTIVE: This study evaluated the long-term effects of calcium supplementation on bone accretion among females from childhood to young adulthood. DESIGN: A 4-y randomized clinical trial recruited 354 females in pubertal stage 2 and optionally was extended for an additional 3 y. The mean dietary calcium intake of the participants over 7 y was approximately 830 mg/d; calcium-supplemented persons received an additional approximately 670 mg/d. Primary outcome variables were distal and proximal radius bone mineral density (BMD), total-body BMD (TBBMD), and metacarpal cortical indexes. RESULTS: Multivariate analyses of the primary outcomes indicated that calcium-supplementation effects vary over time. Follow-up univariate analyses indicated that all primary outcomes were significantly larger in the supplemented group than in the placebo group at the year 4 endpoint. However, at the year 7 endpoint, this effect vanished for TBBMD and distal radius BMD. Longitudinal models for TBBMD and proximal radius BMD, according to the time since menarche, showed a highly significant effect of supplementation during the pubertal growth spurt and a diminishing effect thereafter. Post hoc stratifications by compliance-adjusted total calcium intake and by final stature or metacarpal total cross-sectional area showed that calcium effects depend on compliance and body frame. CONCLUSIONS: Calcium supplementation significantly influenced bone accretion in young females during the pubertal growth spurt. By young adulthood, significant effects remained at metacarpals and at the forearm of tall persons, which indicated that the calcium requirement for growth is associated with skeletal size. These results may be important for both primary prevention of osteoporosis and prevention of bone fragility fractures during growth.

Calcium needs in children.

Adequate calcium intake and physical activity during childhood and adolescence may be an important factor in bone acquisition and primary prevention of osteoporosis. Inadequate calcium intake during the pubertal growth spurt, in particular, may compromise an individual's volumetric bone density and predispose children to bone fragility fractures. In addition, it may compromise an individual's ability to reach his or her genetic potential in bone mass acquisition, or peak bone mass. National standards have been set for optimal calcium intake for childhood and adolescence. Most children and teenagers do not meet these requirements; therefore, there is a strong need to influence their behavior to consume foods rich in calcium.

Nutrition influences skeletal development from childhood to adulthood: a study of hip, spine, and forearm in adolescent females.

This study evaluated the long-term efficacy of supplemental calcium and dairy products on bone mineral areal density of the hip and spine and on the bone geometry and volumetric bone mineral density of the forearm in young females during late adolescence. The study was conducted among participants of a randomized double-blinded, placebo-controlled clinical trial with calcium supplements and among participants of an observational study with higher consumption of dairy products. Hip and spine measurements by dual-energy X-ray absorptiometry were done every 6 mo (dairy group every 12 mo) during last 3 y of the follow-up while peripheral quantitative computerized tomography of the forearm was done at the last visit. The results of the study show a positive influence of calcium supplementation and dairy products on bone mineral density of the hip and the forearm. Dairy products were also associated with a higher bone mineral density of the spine while calcium supplementation did not have an effect. Calcium exerts its action on bone accretion during growth primarily by influencing volumetric bone mineral density while milk may have an additional impact on bone growth and periosteal bone expansion.

Selenium intakes, absorption, retention, and status in adolescent girls.

OBJECTIVES: To assess selenium intakes, absorption, retention, and status in healthy adolescent girls and the effect of calcium supplementation on selenium parameters. DESIGN: Annual 2-week study conducted each year for 3 consecutive years in which yearly selenium intakes, absorption, and retention and blood selenium status were measured. SETTING: A metabolic unit in a large metropolitan hospital located in Columbus, Ohio--a low selenium region of the United States. SUBJECTS: Healthy white girls aged 11 to 14 years (n=16) enrolled in a calcium balance study and randomly assigned to receive a placebo of methylcellulose (n=9) or a calcium supplement containing 1,000 mg supplemental calcium as calcium citrate malate (n=7). INTERVENTIONS: Each subject consumed a diet with approximately 100 microg selenium/day during the yearly 2-week balance studies. RESULTS: Selenium status measurements (serum and erythrocyte selenium and glutathione peroxidase activity) were all within normal ranges for adults during the study. Apparent selenium absorption averaged 71%, 76%, and 74% for years 1, 2, and 3 of the study, respectively, and did not vary significantly (P>.05). Average daily selenium retention did not differ among the years of the study (P>.05) and indicated that the usual selenium intake was approximately 100 microg daily. Measurements of selenium status and retention did not differ between calcium-supplemented and placebo groups. CONCLUSIONS: An intake of approximately 100 microg selenium/day is the typical intake of the mineral among the subjects and appeared adequate to maintain selenium status in these healthy adolescent girls; in addition, calcium supplementation of 1,000 mg daily does not have a negative impact on selenium parameters.