Factors that influence peak bone mass formation: a study of calcium balance and the inheritance of bone mass in adolescent females

Dietary calcium and bone mineral density in premenopausal women with systemic lupus erythematosus

The primary objective of this study was to determine the relationship between dietary calcium intake and bone mineral density (BMD) in premenopausal women with systemic lupus erythematosus (SLE) on corticosteroids (CS). The secondary aim was to identify other risk factors for osteoporosis in these patients. A cross-sectional sample of patients attending the SLE Clinic at a teaching hospital was recruited. BMD was measured using dual-energy X-ray absorptiometry. Daily dietary calcium intake was assessed using a structured validated food frequency questionnaire, in which patients were asked to estimate their food intake based on their recent 2-month dietary habits. Sixty subjects were recruited with a mean age of 33.70+/-8.46 years. The median duration of CS use was 5.5 years (range 0.08-24). The median cumulative dose of steroids was 17.21 g (range 0.16-91.37). The median daily dietary calcium intake was 483 mg (range 78-2101). There was no significant correlation between calcium intake and BMD, even after correcting for CS use. There were also no correlations between BMD and the duration of SLE, cumulative CS use, duration of CS use, smoking, alcohol intake, and SLE disease activity index score. Twenty-eight (46.7%) patients had normal BMD, 28 (46.7%) had osteopenia, and four (6.6%) had osteoporosis. Duration of SLE significantly correlated with cumulative CS dosage. In conclusion, 6.7% of these Asian premenopausal SLE women had osteoporosis and only 46.7% had normal BMD. Daily dietary calcium intake did not correlate with BMD.

Changes in bone mineral density in survivors of childhood acute lymphoblastic leukemia

BACKGROUND

There is little information about factors modulating bone mineral density (BMD) in survivors of childhood acute lymphoblastic leukemia (ALL).

PROCEDURE

We analyzed data from 57 survivors (26 male, 52 Caucasian) who underwent two serial quantitative computed tomography (QCT) studies of BMD. Using multiple linear regression, we evaluated the association of BMD change with demographic variables, treatment history, hormone therapy, exercise, and tobacco and alcohol use.

RESULTS

The median age was 3.4 years (range, 0.9-17.4 years) at diagnosis of ALL; the median age at the first QCT (Study I) was 15.0 years (range, 10.6-31.0 years) and at the second QCT (Study II) was 18.2 years (range, 14.2-35.3 years). Mean height increased 4.7 cm and mean weight increased 8.8 kg between Studies I and II. While the mean BMD increased 9.33 mg/cc (P = 0.003), the BMD Z-score increased only slightly (0.21 SD, P = 0.035). Cortical bone density increased significantly (approximately 25.3 mg/cc; P = 0.001), but the ratio of trabecular to cortical BMD decreased significantly (P = 0.045). Factors independently associated with unfavorable BMD changes included older age at diagnosis (P = 0.001), female sex (P = 0.018), and nutritional supplementation (0.032). Alcohol (P = 0.009) was an unfavorable factor in a univariable analysis.

CONCLUSIONS

Bone mineral accretion during adolescence is attenuated in childhood ALL survivors by a comparative deficit in trabecular versus cortical bone deposition. BMD is influenced favorably by exercise in early adolescence and unfavorably by the use of nutritional supplements and alcohol. These results provide new information about behavioral factors that affect bone accrual in survivors of childhood ALL and warrant definitive evaluation in a larger cohort.

Effect of micronutrient supplement on health and nutritional status of schoolchildren: bone health and body composition

OBJECTIVE

We investigated the effect of a micronutrient-enriched beverage on body composition, bone mineral content (BMC), bone area, and bone mineral density (BMD) at various sites in schoolchildren.

METHODS

A double-blind, placebo-controlled, matched-pair, cluster, randomization study was carried out in residential schoolchildren 6 to 16 y of age who lived near Hyderabad, India. Children (n = 268) were selected randomly from two classes of each grade (1 to 9) and were provided a micronutrient-enriched beverage (n = 146) or a placebo drink (n = 122). Bone parameters such as BMC, BMD, and bone area at various sites and the entire body were measured with dual-energy X-ray absorptiometry at the beginning and end of the study. Increments of outcome variables were subjected to paired t test with appropriate corrections to assess the effect of the supplement on bone health.

RESULTS

After 14 mo, increments for height, weight, fat-free mass, percentage of fat, whole-body BMC, whole-body bone area, and BMD at the neck of the femur were significantly greater (P < 0.05) in the supplemented group than in the placebo group.

CONCLUSIONS

The micronutrient-rich supplement increased tissue growth and skeletal shell in apparently normal children in the 14-mo period. It did not increase whole-body or site-specific BMD except at the neck of the femur. Amounts of calcium and other nutrients contained in the supplement were inadequate for tissue growth with density increases. This study raises important questions about the nutrient requirements of Indian children who consume a diet of cereals and pulses.

Genetic and environmental influences on bone mineral density in pre- and post-menopausal women

Genetic factors influencing acquisition of peak bone mass account for a substantial proportion of the variation in bone mineral density (BMD), although the extent to which genes also contribute to variation in bone loss is debatable. Few prospective studies of related individuals have been carried out to address this issue. To gain insights into the nature of the genetic factors contributing to variation in BMD, we studied 570 women from large Amish families. We evaluated and compared the genetic contributions to BMD in pre- and post-menopausal women, with the rationale that genetic variation in pre-menopausal women is due primarily to genetic determinants of peak bone mass, while genetic variation in post-menopausal women is due to the combined genetic effects of peak bone mass and bone loss. Bone mineral density was measured at one point in time at the hip and spine by dual energy X-ray absorptiometry (DXA). We used variance decomposition procedures to partition variation in BMD into genetic and environmental effects common to both groups and to pre- and post-menopausal women separately. Total variation in BMD was higher in post- compared to pre-menopausal women. Genes accounted for 58-88% of the total variation in BMD in pre-menopausal women compared to 37-54% of the total variation in post-menopausal women. In absolute terms, however, the genetic variance was approximately similar between the two groups because the environmental variance was 3 1/2- to 4-fold larger in the post-menopausal group. The genetic correlation in total hip BMD was 0.81 between pre- and post-menopausal women and differed significantly from one, consistent with the presence of at least some non-overlapping genetic effects in the two groups for BMD at this site. Overall, these analyses suggest that many, but not all, of the genetic factors influencing variation in BMD are common to both pre- and post-menopausal women.

Lifestyle questionnaire to evaluate risk for reduced bone mineral density in women

OBJECTIVE

To determine the contribution of various risk factors to quantitative ultrasound parameters in a sample of women, and to develop a tool to assess osteopenia risk, with a view to targeted early intervention.

DESIGN

Questionnaire study.

SETTING

A local center comprising a fitness center, conference center, and administrative offices for various businesses and sports.

PATIENTS OR PARTICIPANTS

A convenience sample of 187 Caucasian women who volunteered as part of a free public health screening initiative.

MAIN OUTCOME MEASUREMENTS

A questionnaire was designed to collect data on history of osteoporosis, current physical activity, calcium, alcohol and caffeine intakes, smoking, and various reproductive measures. Historical physical activity data were also collected, and lifetime energy expenditure and impact scores were calculated. Quantitative ultrasound was performed on the left calcaneus. Odds ratios (ORs) were calculated to determine the odds of being osteopenic (T-score < or =-1 SD) against not being osteopenic (T-score >-1SD), due to exposure to the aforementioned risk factors.

RESULTS

: Significant ORs were obtained for age (OR: 1.042; 95% CI: 1.016-1.068), current physical activity (> or =3 times/wk; OR: 0.320; 95% CI: 0.140-0.732), and lifetime energy expenditure score (OR: 0.957; 95% CI: 0.926-0.989). A regression model based on age and current physical activity correctly identified 57% of women with or without osteopenia.

CONCLUSIONS

Although the model we developed was not sensitive or specific enough to assess osteopenic risk accurately, the results show that frequency of physical activity, independent of age, is an important lifestyle factor to consider when quantifying osteopenic risk.

Increased bone turnover during the third trimester of pregnancy and decreased bone mineral density after parturition in adolescents as compared to age-matched control patients

To evaluate the impact of pregnancy on bone, we studied bone turnover at the first (T1) and third (T3) trimester of gestation in 58 adolescents and 28 healthy adolescents who had never been pregnant. Total body (TB) and lumbar spine (LS) bone mineral density (BMD) and body composition were evaluated by dual-energy X-ray absorptiometry in all control patients (C) and after parturition in 28 pregnant patients (G). Paired and unpaired t tests, Mann-Whitney and Pearson correlation tests were used. Bone turnover markers were above the reference range for adult women in more than 80% of the adolescents, with no difference between C and G patients at T1. Increase in urinary N-telopeptide crosslinks of type I collagen and serum bone-specific alkaline phosphatase, markers of bone turnover, was seen during pregnancy ( p < 0.0001). Body composition did not differ between groups, but LS BMD, percentage of expected LS BMD, LS Z-score, percentage of expected TB BMD and TB Z-score were lower in G than C patients ( p < 0.05). TB BMD was positively correlated with LS BMD (r2 = 0.52). The inverse correlations between bone markers and LS BMD suggest that the increased bone turnover during pregnancy probably explains the low bone density after parturition. The impact on future peak bone mass must be studied.

Increasing weight-bearing physical activity and calcium-rich foods to promote bone mass gains among 9-11 year old girls: outcomes of the Cal-Girls study

Background

A two-year, community-based, group-randomized trial to promote bone mass gains among 9–11 year-old girls through increased intake of calcium-rich foods and weight-bearing physical activity was evaluated.

Methods

Following baseline data collection, 30 5th-grade Girl Scout troops were randomized to a two-year behavioral intervention program or to a no-treatment control group. Evaluations were conducted at baseline, one year, and two years. Measures included bone mineral content, density, and area (measured by DXA), dietary calcium intake (24-hour recall), and weight-bearing physical activity (physical activity checklist interview). Mixed-model regression was used to evaluate treatment-related changes in bone mineral content (g) for the total body, lumbar spine (L1-L4), proximal femur, one-third distal radius, and femoral neck. Changes in eating and physical activity behavioral outcomes were examined.

Results

Although the intervention was implemented with high fidelity, no significant intervention effects were observed for total bone mineral content or any specific bone sites. Significant intervention effects were observed for increases in dietary calcium. No significant intervention effects were observed for increases in weight-bearing physical activity.

Conclusion

Future research needs to identify the optimal dosage of weight-bearing physical activity and calcium-rich dietary behavior change required to maximize bone mass gains in pre-adolescent and adolescent girls.

Risk factors associated with osteoporosis in Hispanic women

This study examined risk factors for osteoporosis in Hispanic women. Factors examined included ethnicity, gender, age, height, weight, family and personal history of fractures, height loss, exercise, diet, time since menopause or hysterectomy, hormone replacement therapy (HRT), calcium supplementation, hypertension, thyroid disease, diabetes, arthritis, chemotherapy, family history of breast cancer, use of water pills, fosamax, steroids, alcohol, and smoking. Most results found parallel those found in the Caucasian population. Heavier patients had greater bone density, as well as patients who exercised and those using HRT. Older patients had lower bone density as did diabetic patients. Results not anticipated were higher bone density in patients not taking calcium supplements, and in patients who consumed alcohol.

Nutritional concerns for the child and adolescent competitor

With exercise for sports competition in children and adolescents, acute nutrient needs will change. Fluid intake to ensure the replacement of water and minerals (electrolytes) lost in sweat is important. Energy needs also increase because of the elevated energy expenditure with physical activity. Arguably carbohydrate is the recommended source of training needs, although research has yet to be done to show performance benefits in young athletes on a high-carbohydrate diet. In the majority of sports, an increased intake of food naturally occurs to accommodate the day-to-day nutrient needs of young athletes, and unlike non-athlete, young competitors typically come closer to meeting their requirements for micronutrients. Nonetheless, certain athletic groups may be at risk for shortfalls in their diet. Compared to athletes in team sports, participants in weight-control sports may be at greater risk of failing to meet requirements for energy, protein, and some micronutrients. Endurance athletes, particularly female distance runners, may have intake deficits for the minerals iron and calcium. Acute issues such as heat illness and chronic concerns that include impaired growth and development, and the risk of injuries that include stress fractures may be an outcome of inadequate nutrition during physical training.

Calcium, dairy products, and bone health in children and young adults: a reevaluation of the evidence

OBJECTIVE

Numerous nutrition policy statements recommend the consumption of 800 to 1500 mg of calcium largely from dairy products for osteoporosis prevention; however, the findings of epidemiologic and prospective studies have raised questions about the efficacy of the use of dairy products for the promotion of bone health. The objective of this study was to review existing literature on the effects of dairy products and total dietary calcium on bone integrity in children and young adults to assess whether evidence supports (1) current recommended calcium intake levels and (2) the suggestion that dairy products are better for promoting bone integrity than other calcium-containing food sources or supplements.

METHODS

A Medline (National Library of Medicine, Bethesda, MD) search was conducted for studies published on the relationship between milk, dairy products, or calcium intake and bone mineralization or fracture risk in children and young adults (1-25 years). This search yielded 58 studies: 22 cross-sectional studies; 13 retrospective studies; 10 longitudinal prospective studies; and 13 randomized, controlled trials.

RESULTS

Eleven of the studies did not control for weight, pubertal status, and exercise and were excluded. Ten studies were randomized, controlled trials of supplemental calcium, 9 of which showed modest positive benefits on bone mineralization in children and adolescents. Of the remaining 37 studies of dairy or unsupplemented dietary calcium intake, 27 studies found no relationship between dairy or dietary calcium intake and measures of bone health. In the remaining 9 reports, the effects on bone health are small and 3 were confounded by vitamin D intake from milk fortified with vitamin D. Therefore, in clinical, longitudinal, retrospective, and cross-sectional studies, neither increased consumption of dairy products, specifically, nor total dietary calcium consumption has shown even a modestly consistent benefit for child or young adult bone health.

CONCLUSION

Scant evidence supports nutrition guidelines focused specifically on increasing milk or other dairy product intake for promoting child and adolescent bone mineralization.

Initial years of recreational artistic gymnastics training improves lumbar spine bone mineral accrual in 4- to 8-year-old females

Gymnasts' bone mineral characteristics are generally not known before starting their sport. Prepubertal females who enrolled in beginning artistic gymnastics (n = 65) had lower bone mineral than controls (n = 78). However, 2 years of gymnastics participation versus no participation led to a significantly greater accrual of forearm bone area and lumbar spine areal BMD.

INTRODUCTION

The skeletal response to exercise in children compared with adults is heightened because of the high bone turnover rate and the ability of bone to change its size and shape. Whereas child gymnasts generally have greater rates of bone mineral accrual compared with nongymnasts, it is unknown if some of these skeletal advantages are present before the onset of training or are caused entirely by training.

MATERIALS AND METHODS

Changes in bone area (BA; cm2), BMC (g), and areal BMD (aBMD; g/cm2) over 24 months were examined in prepubertal females, 4-8 years of age, who selected to perform recreational gymnastics (GYM; n = 65), nongymnastic activities, or no organized activity (CON; n = 78). Participants had essentially no lifetime history of organized athletic participation (< 12 weeks). Pubertal maturation was assessed annually by a physician. Total body, lumbar spine, total proximal femur, and forearm BA, BMC, and aBMD were measured every 6 months using DXA (Hologic QDR-1000W). Independent samples t-tests determined baseline group differences. Nonlinear mixed effects models were used to model 24-month changes in bone data. In subset analyses, high-level gymnasts advancing to competition (HLG; n = 9) were compared with low-level nonadvancing gymnasts (LLG; n = 56).

RESULTS

At baseline, GYM were shorter, lighter, and had lower BA, BMC, and aBMD compared with CON (p < 0.05), whereas HLG did not differ significantly in these measurements compared with LLG (p > 0.05). Controlling for differences in race, baseline measures of body mass, height, and calcium intake, and change in breast development beyond stage II at 24 months, GYM had greater long-term (asymptotic) mean responses for total body aBMD and forearm BMC (p < 0.04) and greater rates of increase in the mean responses of lumbar spine aBMD and forearm BA compared with CON over 24 months. Over time, forearm BA increased to a greater extent in HLG compared with LLG (p < 0.01).

CONCLUSIONS

Females participating in recreational gymnastics initiated during childhood have enhanced bone mineral gains at the total body, lumbar spine, and forearm over 24 months. Higher-level training promotes additional gains in forearm BA.

Limited nutritional energy supply differentially impairs growth and bone mineralization of the developing lumbar vertebrae in minipigs

Bone development during puberty and adolescence may influence the later risk of osteoporosis. The aim of this study was to investigate whether the three-dimensional development of the lumbar vertebrae is impaired in terms of bone mineral density and temporal control during the pubertal growth spurt when caloric intake is limited. Two groups of prepubertal female Gottingen minipigs (each n = 6) were fed either ad libitum (free fed) or with reduced food intake (controlled fed) for 12 months using a standard diet. Apparent volumetric bone mineral densities (vBMD) and size of the 4th vertebra were measured by quantitative CT in monthly intervals. The weight of free-fed animals was 29.5 +/- 0.9 kg compared to 25.9 +/- 3.5 kg in the controlled-fed group at the end of the observation period (mean +/- SD; p < 0.05). The maximal cross-sectional area of the 4th vertebra was 148.2 +/- 3.4 mm(2) in free-fed animals compared to 143.1 +/- 6.3 mm(2) in controlled-fed animals (P < 0.05) as both, the cortical and the medullary area were greater in the free-fed group. In contrast, cancellous and cortical bone mineral densities were not different between the two groups; however, maximal densities were reached earlier in the free-fed group. As regards the height of the vertebra, no difference was observed between the groups after 12 months (25.46 +/- 0.54 mm in controlled fed vs. 25.56 +/- 0.45 mm in free fed), although the peak height was reached earlier in the free-fed group. In both groups, the maximal growth rate in the cross-sectional direction was reached earlier compared to the longitudinal direction (both P < 0.05). Growth in the longitudinal direction that occurs in the primary and secondary epiphysis does not appear to depend on caloric intake contrary to the periosteal and endocortical bone generation in the cross-sectional direction. When limited energy is available, the organism seems to preserve the development of normal body height, while accepting reduced strength of the vertebra.

Assessment of sex-specific genetic and environmental effects on bone mineral density

Although it is widely accepted that genes contribute significantly to the variation in bone mineral density (BMD), the nature of the genetic contribution is poorly defined. There are large gender differences in BMD, although whether sex-specific genetic effects influencing variation in BMD contribute to these differences is not known. To address this issue, we studied 929 subjects from large families participating in the Amish Family Osteoporosis Study. Bone mineral density was measured at the hip and spine by dual energy X-ray absorptiometry (DXA). We used variance decomposition procedures to partition variation in BMD into genetic and environmental effects common to both sexes and to men and women separately. After accounting for covariate effects, the heritability of BMD ranged from 0.63 to 0.72 in men and 0.80 to 0.87 in women. The residual environmental variance in BMD at the spine, but not hip, was significantly higher in men than in women (P < 0.05), reflecting a greater variance in BMD due to unexplained non-genetic factors in men. In contrast, there were no significant differences between men and women in the magnitude of the genetic variance in BMD, nor did the genetic correlation in BMD between men and women differ significantly from one. Overall, these analyses do not provide evidence for sex-specific genetic effects, suggesting that many of the genes influencing variation in BMD should be detectable in both men and women.

Sustained effect of short-term calcium supplementation on bone mass in adolescent girls with low calcium intake

BACKGROUND

The effect of short-term calcium supplementation on peak bone mass in adolescent girls is not completely defined. In our previous double-blind, placebo-controlled, calcium-supplementation study (1000 mg calcium carbonate/d), we showed that calcium supplementation of postmenarcheal girls with low calcium intakes enhances bone mineral acquisition.

OBJECTIVE

The objective of this follow-up study, conducted 3.5 y after the end of calcium supplementation, was to investigate the sustained effect of calcium supplementation on bone mineral mass.

DESIGN

Anthropometric data, nutrient intakes, and bone variables were reassessed in 96 of the 100 adolescent girls whose data had been studied at the end of the supplementation period. Bone mineral content and bone mineral density (BMD) of the total body, lumbar spine, and femoral neck were determined by dual-energy X-ray absorptiometry.

RESULTS

The calcium-supplemented group tended to have a greater accretion of total-body BMD (TBBMD) than did the control group 3.5 y after the end of supplementation. The finding was statistically significant in the active-treatment cohort (n = 17 in the calcium-supplemented group and 28 in the placebo group), who had a compliance rate of > or =75% during the intervention study. In a multivariate linear-regression analysis, TBBMD accretion from the beginning of the intervention study to the follow-up study in the active-treatment cohort was attributed to calcium supplementation and to the time since inclusion in the initial study.

CONCLUSION

Calcium supplementation for 1 y in postmenarcheal girls with low calcium intakes may provide a sustained effect on the basis of TBBMD measurements in participants with compliance rates of > or =75%.

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.

Bone outcomes and technical measurement issues of bone health among children and adolescents: considerations for nutrition and physical activity intervention trials

Weight-bearing physical activity and calcium intake are two important behavioral influences for bone health. Physical-activity and calcium-intake intervention trials with youth have been implemented to evaluate their efficacy and effectiveness to decrease the risk for subsequent osteoporosis and fractures. Technical aspects of bone measurement have not been routinely reported in published trials of youth, even though they can have an impact on study findings and interpretation. This paper provides an overview of the outcome variables reported, and technical issues--such as software and bone detection, growth, and movement--that affect bone mass measurements among children and adolescents. It describes the implications of these issues for the interpretation of intervention effects observed in intervention trials, and provides recommendations for future research.

Sex differences in the effect of body-composition variables on bone mass in healthy children and adolescents

BACKGROUND

Prophylactic interventions against osteoporosis require a determination of the factors that influence the accumulation of bone mass during growth.

OBJECTIVE

The objective was to determine the independent sex-specific contribution of lean mass and fat mass to bone mineral content (BMC), after adjustment for anthropometric variables and lifestyle factors, in healthy children and adolescents.

DESIGN

Healthy schoolchildren (184 boys and 179 girls) aged 10-17 y (x+/- SD: 13.0 +/- 2.1 y) participated in this cross-sectional study. Total and regional (lumbar spine, femoral neck, and distal one-third of the radius) BMC and body composition were measured by dual-energy X-ray absorptiometry.

RESULTS

A significant effect of anthropometric variables and lifestyle factors on BMC was observed at all skeletal sites. Lean mass and fat mass showed robust correlations with BMC, even after adjustment for anthropometric variables and lifestyle factors. Lean mass contributed to 6-12% of the variance in BMC in boys and to 4-10% in girls. Fat mass accounted for 0.1-2% of BMC variance in boys and to 0.1-6.5% in girls.

CONCLUSIONS

Both lean mass and fat mass are consistent predictors of BMC at multiple skeletal sites in healthy children and adolescents. The contribution of lean mass to BMC variance was larger in boys than in girls. In both sexes, the highest contribution of lean mass to BMC was observed at the femoral neck.

Bone mass is recovered from lactation to postweaning in adolescent mothers with low calcium intakes

BACKGROUND

Adolescent mothers may be at increased risk of irreversible bone loss during pregnancy and lactation, particularly when calcium intake is low.

OBJECTIVE

Longitudinal changes in bone mass from lactation to postweaning were evaluated in 10 adolescent mothers aged 15-18 y who habitually consumed <500 mg Ca/d.

DESIGN

Total-body bone mineral content (TBBMC), total-body bone mineral density (TBBMD), and lumbar spine bone mineral density (LSBMD) were measured at lactation (6-24 wk postpartum) and after weaning (12-30 mo postpartum). Serum hormones (intact parathyroid hormone, estradiol, and prolactin), serum calcium, and markers of bone turnover [urinary N-telopeptide cross-linking region of type I collagen (NTx) and plasma activity of bone alkaline phosphatase] were measured at lactation.

RESULTS

TBBMC, total calcium content, TBBMD, and LSBMD increased from lactation to postweaning (P < 0.01). TBBMD and LSBMD were, respectively, 3.6% and 9.7% lower than predicted at lactation and 0.3% and 4.8% lower than predicted in the postweaning period. The increase in age-matched TBBMD adequacy was correlated with the time after resumption of menses (r = 0.86, P < 0.01). Calcium accretion from lactation to postweaning correlated negatively with estradiol (r = -0.86) and prolactin (r = -0.69) and positively with intact parathyroid hormone (r = 0.72) and NTx (r = 0.84) measured at lactation (P < 0.05).

CONCLUSIONS

It appears that adolescent mothers with habitually low calcium intakes recover from lactation-associated bone loss after weaning. The rate of bone accretion, however, may not be sufficient to attain peak bone mass at maturity. Hormones regulating bone turnover during lactation may influence bone recovery in adolescent mothers.

School-milk intervention trial enhances growth and bone mineral accretion in Chinese girls aged 10-12 years in Beijing

A 2-year milk intervention trial was carried out with 757 girls, aged 10 years, from nine primary schools in Beijing (April 1999 - March 2001). Schools were randomised into three groups: group 1, 238 girls consumed a carton of 330 ml milk fortified with Ca on school days over the study period; group 2, 260 girls received the same quantity of milk additionally fortified with 5 or 8 microg cholecalciferol; group 3, 259 control girls. Anthropometric and bone mineralisation measurements, as well as dietary, health and physical-activity data, were collected at baseline and after 12 and 24 months of the trial. Over the 2-year period the consumption of this milk, with or without added cholecalciferol, led to significant increases in the changes in height (> or =0.6 %), sitting height (> or =0.8 %), body weight (> or 2.9 %), and (size-adjusted) total-body bone mineral content (> or =1.2 %) and bone mineral density (> or =3.2 %). Those subjects receiving additional cholecalciferol compared with those receiving the milk without added 25-hydoxycholecalciferol had significantly greater increases in the change in (size-adjusted) total-body bone mineral content (2.4 v. 1.2 %) and bone mineral density (5.5 v. 3.2 %). The milk fortified with cholecalciferol significantly improved vitamin D status at the end of the trial compared with the milk alone or control groups. It is concluded that an increase in milk consumption, e.g. by means of school milk programmes, would improve bone growth during adolescence, particularly when Ca intake and vitamin D status are low.

Bone mineral density and total body bone mineral content in 18- to 22-year-old women

One hundred sixty-four (164) healthy, young Caucasian women enrolled as midshipmen at the United States Naval Academy with no known disease or bone injury were followed for 3.6 years. Change in bone mineral density (BMD) of the hip, lumbar spine and distal tibia, and total body bone mineral content (TBMC) was measured by dual energy X-ray absorptiometry (DXA). Bone mineral density and TBMC of these women were measured within 2 months (60 +/- 4 days) of entering the Academy and annually. Over the study period, hip BMD increased 2.26% (P < 0.001), lumbar spine BMD increased 3.27% (P < 0.001) and distal tibia BMD increased 5.2% (P < 0.001). Total body bone mineral content showed a 5.25% (P < 0.001) increase during the study period. In this group of young women, gain in BMD and TBMC continued until age 22. These results suggest that bone mass may accrue in certain groups of women beyond age 22. The significance of this increase in bone mass during early adulthood on risk for osteoporotic fractures in later life and its impact on exercise-related bone injuries are unknown and warrant further examination.

A pilot intervention to increase calcium intake in female collegiate athletes

Calcium intake in adolescent and young adult female athletes often is inadequate to optimize peak bone mass, an important determinant of osteoporosis risk. The purpose of this study was to determine if calcium supplementation in eumenorrheic female collegiate athletes increases intake to recommended levels and promotes increases in bone mineral density (BMD). Forty-eight eumenorrheic female athletes from several college teams (15 soccer, 7 cross-country, 8 indoor track, and 18 basketball) were randomized at the beginning of a competitive season to receive either an oral calcium supplement (1000 mg calcium citrate/400 I.U. Vitamin D) or placebo daily throughout the training season (16 weeks). Self-reported daily pill intake was obtained every 2 weeks to assess adherence. Calcium intake was evaluated using the Rapid Assessment Method, and total body and leg BMD was measured at pre-, mid-, and postseason using dual energy x-ray absorptiometry (DEXA; Hologic QDR-2000). Pre-season calcium intake was lower than national recommendations for this age group (12), averaging 842 mg/d (SD = 719) and was lower in the placebo group compared to the supplemented group (649 +/- 268 vs. 1071 +/- 986 mg/d, respectively; p = .064). Adherence to supplementation was good, averaging 70% across the training season. Supplementation boosted total calcium intake to a mean of 1397 +/- 411 mg/d, which is consistent with recommended levels for this group (37). Supplementation did not influence BMD change during this 16-week intervention. Across teams, a small increase of 0.8% was observed in leg BMD. Change in total body BMD was modified by team, with a significant increase of 1.5% observed in basketball players. These results indicate that providing calcium supplements of 1000 mg/d is adequate to boost total intake to recommended levels during athletic training. Longer intervention trials are required to determine whether calcium supplementation has a positive effect on BMD.

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.

Soy and Bone

Interest in the use of plant estrogens (phytoestrogens) to attenuate postmenopausal bone loss has increased during the past 10 years as healthcare consumers, practitioners, and scientists have searched for alternative treatments to the use of hormone replacement therapy. Promising research has emerged regarding the potential benefit of increased consumption of phytoestrogens, primarily from dietary soy products. Dietary phytoestrogens, primarily isoflavones found in soy foods, may alter bone turnover in postmenopausal women by decreasing bone resorption and increasing bone formation.

Response of Cortical and Cancellous Bones to Mild Calcium Deficiency in Young Growing Female Rats: A Bone Histomorphometry Study

The purpose of the present study was to clarify the differences in the alterations of cellular activities of osteoblasts and osteoclasts, mineralization, and bone mass in cortical and cancellous bones of young growing rats with mild calcium deficiency. Twenty female Sprague-Dawley rats, 6 weeks of age, were randomized by the stratified method into two groups with 10 rats in each group: 0.5% (normal) calcium diet group and 0.1% (low) calcium diet group. After 10 weeks of feeding, bone histomorphometric analysis was performed on cancellous bone of the proximal tibia as well as cortical bone of the tibial shaft. Calcium deficiency increased eroded surface (ES/bone surface [BS]) and the number of osteoclast (N.Oc/BS) with an increase in osteoblast surface (ObS/BS), but decreased bone formation rate (BFR/BS) in cancellous bone. However, cancellous bone volume was preserved, while cortical bone area was decreased as a result of decreased periosteal bone gain and enlargement of the marrow cavity. These results suggest that short-term mild calcium deficiency in young growing female rats increased bone resorption by increasing osteoclastic recruitment, and suppressed mineralization followed by increased osteoblastic recruitment in cancellous bone, but cancellous bone loss was counteracted through redistribution of calcium from cortical bone to cancellous bone.

Calcium supplementation provides an extended window of opportunity for bone mass accretion after menarche

BACKGROUND

High calcium intakes during adolescence may increase bone acquisition. The magnitude of the effect of dietary calcium supplementation and the timing of its administration to achieve significant effects on bone health are still incompletely defined.

OBJECTIVE

The objective of this study was to assess the effect of calcium supplementation on bone mass accretion in postmenarcheal adolescent girls with low calcium intakes.

DESIGN

A double-blind, placebo-controlled calcium supplementation study was implemented. One hundred girls with a mean (+/- SD) age of 14 +/- 0.5 y with habitual calcium intakes < 800 mg/d completed a 12-mo protocol. The treatment group received a daily supplement containing 1000 mg elemental calcium. Bone mineral density (BMD) and bone mineral content (BMC) of the total body, lumbar spine, and femoral neck were determined at inclusion, 6 mo, and 12 mo. Also measured were serum concentrations of biochemical markers of bone turnover (osteocalcin and deoxypyridinoline), parathyroid hormone, and vitamin D.

RESULTS

The calcium-supplemented group had greater accretion of total-body BMD and lumbar spine BMD but not BMC than did the control group. Calcium supplementation appeared selectively beneficial for girls who were 2 y postmenarcheal. Calcium supplementation significantly decreased bone turnover and decreased serum parathyroid hormone concentrations.

CONCLUSION

Calcium supplementation of postmenarcheal girls with low calcium intakes enhances bone mineral acquisition, especially in girls > 2 y past the onset of menarche.

RETRACTED: Comparative effects of vitamin K and vitamin D supplementation on prevention of osteopenia in calcium-deficient young rats

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. The Journal has been made aware of concerns regarding the integrity of the data, authorship and ethical approval for this study. Despite repeated attempts to contact the co-authors we have been unable to confirm the authorship of this paper.

Effect of sub-elite competitive running on bone density, body composition and sexual maturity of adolescent females

The attainment of optimal peak bone mass during adolescence is important in the primary prevention of osteoporosis. Exercise may contribute to skeletal development and bone density during growth, although competitive exercise is suggested to have an adverse effect. This study assesses the effect of moderate exercise on the bone density of adolescent females. Additionally, other factors which significantly influence attainment of peak bone mass were identified. This was a cross-sectional study of 42 adolescent females, classified as runners (n=15) or non-runners (n=27). Nutrient intake, energy expenditure, menstrual history and pubertal stage were recorded. Bone age, skinfold thickness, body composition and bone mineral density (BMD) of total body, lumbar spine and proximal femur were measured. Statistical analyses used Student's t-test, Pearson correlation and multiple regression analyses. Runners had lower fat mass and higher lean mass, with a trend to higher BMD in all sites measured. There were no significant differences in menstrual cycle regularity, age at menarche or number who had attained menarche. Pubic hair development was similar in both groups. Breast development was delayed in runners, although this may have been a function of lower fat mass in this group. When subjects were categorized according to menarchal status, postmenarchal girls were significantly taller and heavier, with higher fat mass and significantly higher total body and lumbar spine BMD. There was no significant relationship between BMD at any site and dietary nutrient intake. Multiple regression analyses, using BMD as the dependent variable, identified running status, pubertal stage, fat mass and lean mass as significant determinants. When BMD/height was used, significant determinants in total body BMD were fat mass, pubertal stage and running status, while in the lumbar spine, only the latter two variables remained significant. In conclusion, body composition, physical activity and sexual maturity were identified as significant determinants of bone density during adolescence. Runners had significantly lower body fat than non-runners, but this did not interfere with hormonal cyclicity, and caused no detriment to their bone density. The results of this study are reassuring, since they indicate that sub-elite competitive athletics has no detrimental effect on bone mass accrual in adolescent females.

Low body weight and its association with bone health and pubertal maturation in Chinese girls

OBJECTIVE

To investigate the prevalence of low body weight in Beijing pubertal girls and to establish the cut-off for body mass index (BMI) for underweight for Chinese pubertal girls.

DESIGN

Cross-sectional study.

SETTING

Three socioeconomic areas (rural, suburban and urban) in Beijing, China.

SUBJECTS

Random sample of 1214 adolescent girls aged 12-14 y from 13 middle schools.

RESULTS

Using a modified Chinese reference, the rate of low body weight (BMI<18) was 32.2% (95% CI 29.6-34.8%). Compared with desirable weight girls (BMI=18-21), girls with low body weight had a lower bone age, delayed breast and pubic hair development, a lower rate of menarche, lower distal one-third radius and ulna bone mineral content (BMC), bone mineral density and bone width. Logistic regression showed that BMI was one of the predictors of one-third ulna BMC after adjustment for confounding variables. When comparing BMI<18 vs BMI=18-21, the risk of BMC being less than the median increased by 82% (odds ratio 1.82, 95% CI 1.06-3.13). Thinness and stunting rates assessed by WHO recommended cut-offs are also reported.

CONCLUSIONS

High prevalence of low body weight (BMI<18) was found to be a major health problem among Beijing pubertal girls. BMI<18 is confirmed as the cut-off for delayed general growth and development for Chinese girls and for screening girls at risk of lower bone mineral status.

Extraordinarily low bone mineral density in an old female chimpanzee (Pan troglodytes schweinfurthii) from the Mahale Mountains National Park

We examined bone mineral density (BMD) of the femoral neck and lumbar vertebrae of four chimpanzee skeletons from Mahale Mountains National Park, Tanzania, and four captive ones, with a dual energy X-ray absorptiometer. The BMD of Wansombo, an old female chimpanzee from Mahale, was remarkably lower than the mean of the other six younger adult female chimpanzees and categorized as osteoporosis. Posture, locomotion, and trunk-sacral anatomy of chimpanzees may have prevented fractures in Wansombo, whose BMD was below human osteoporosis criteria.

Effect of 2 years of cortisol normalization on the impaired bone mass and turnover in adolescent and adult patients with Cushing's disease: a prospective study

BACKGROUND

Osteoporosis is a frequent, severe and often underestimated consequence of long-term hypercortisolism, often presenting as bone fracture.

OBJECTIVE

This prospective study was designed to evaluate whether the abnormalities of bone mass and turnover can be similarly reversed in adolescent and adult patients with Cushing's disease, after correction of hypercortisolism.

PATIENTS AND METHODS

Bone mineral density (BMD) at lumbar spine, serum osteocalcin (OC) and urinary cross-linked N-telopeptides of type I collagen (Ntx) levels were measured at diagnosis and 2 years after cure of Cushing's disease (CD) in six patients with childhood-onset and nine with adulthood-onset disease. Fifteen age-, sex- and body mass index (BMI)-matched healthy subjects served as controls.

RESULTS

At diagnosis, BMD Z scores at lumbar spine and OC levels were lower (2.3 +/- 0.1 vs.-0.2 +/- 0.01; P < 0.01 and 1.6 +/- 0.1 vs. 9.6 +/- 1.2; P < 0.01 respectively) while urinary Ntx levels were significantly higher (139.9 +/- 6.1 vs. 82.0 +/- 1.6; P < 0.01) in CD patients than in controls. Among CD patients, similar values of Z scores (-2.4 +/- 0.3 vs.-2.2 +/- 0.1, P = 0.4) and OC levels (1.7 +/- 0.2 vs. 1.6 +/- 0.2, P = 0.6) were observed in adolescent and adults patients, whereas urinary Ntx levels were significantly higher (159.7 +/- 7.9 vs. 125.9 +/- 3.3, P < 0.001) in the former than in the latter group. Two years after remission from hypercortisolism, OC levels (P < 0.001) and lumbar BMD Z scores (-2.2 +/- 0.3, P < 0.05; and -1.9 +/- 0.2; P < 0.01, respectively) increased significantly, while urinary Ntx levels reduced significantly (P < 0.001) in both adolescent and adult patients. However, biochemical markers and Z scores of BMD remained significantly suppressed compared to controls.

CONCLUSIONS

Bone impairment in childhood- and adulthood-onset Cushing's disease patients can be partly, but not completely, reversed 2 years after normalization of cortisol levels. Longer recovery times or additive therapeutic approaches are necessary to maximize peak bone mass in children and restore bone mass in adults with Cushing's disease.

Endocrine complications in pediatric patients with acute lymphoblastic leukemia

Endocrine complications of therapy for acute lymphoblastic leukemia (ALL) are common and are potentially debilitating both during and after therapy. Growth velocity slows during therapy for ALL, especially during the first year; however, children who do not receive cranial irradiation usually reach normal adult height. While growth hormone deficiency generally occurs in patients who have received 24Gy of cranial irradiation, it may also develop in those treated with lower doses (18Gy) of cranial radiation or with only high-dose methotrexate. Obesity commonly occurs during therapy and persists after completion of therapy. Osteopenia can occur early during therapy for ALL and can persist for many years. Adrenal insufficiency should be suspected in any child who has recently received glucocorticoid therapy, and stress doses of steroid should be administered in the event of metabolic stress. Screening of urine is useful for early detection of hyperglycemia during therapy with glucocorticoids and L-asparaginase. The syndrome of inappropriate secretion of anti-diuretic hormone is usually associated with vincristine therapy and may be aggravated by concurrent use of azole antifungals. Finally, patients who have received 18 or 24Gy of cranial irradiation may have clinical or subclinical deficiencies of thyroid hormones.

Upper-limb bone mineral density of female collegiate gymnasts versus controls

PURPOSE

We examined bilateral bone mineral density (BMD) in the arms of female college gymnasts to assess the relative contribution of high-impact loading forces versus daily activities on bone plasticity.

METHODS

Twenty-five female collegiate gymnasts and 25 controls were studied. BMD of the lumbar spine, proximal femur, and whole body were assessed via dual energy x-ray absorptiometry. Upper-limb BMD was determined by custom analyses of the whole-body scans to examine arms individually.

RESULTS

BMD of gymnasts was significantly (P < 0.0001) greater than controls at all sites. Whole-body BMD was 8% higher in gymnasts (1.270 +/- 0.078 vs 1.175 +/- 0.073 g x cm(-2)), with 18-19% differences in the lumbar spine (1.427 +/- 0.144 vs 1.212 +/- 0.106 g x cm(-2), right proximal femur (1.298 +/- 0.101 vs 1.100 +/- 0.129 g x cm(-2)), and left proximal femur (1.293 +/- 0.111 vs 1.104 +/- 0.133 g x cm(-2)). Arm BMD was 17% greater in gymnasts, with higher values in both dominant (1.013 + 0.067 vs 0.875 + 0.066 g x cm(-2)) and nondominant (1.002 + 0.060 vs 0.849 + 0.062 g x cm(-2)) arms. Intragroup comparisons revealed a significantly (P < 0.0001) greater BMD in the dominant arm of the controls but no side-to-side difference in the arms of the gymnasts.

CONCLUSIONS

Upper-limb BMD followed use patterns in both gymnasts and controls, demonstrating that the forces imposed on the arms with gymnastics training enhanced BMD and resulted in no bilateral differences. These findings illustrate the association between gymnastics training and increased BMD throughout the body, suggesting that the high BMD values observed in gymnasts are due primarily to the activity itself rather than selection bias.

Low peak bone mineral density in healthy Lebanese subjects

Osteoporosis is a major public health problem in Western countries and is projected to have a similar impact in the Middle East. It has been suggested that peak bone mineral density (BMD), a major determinant of osteoporotic fractures later in life, may be lower in this part of the world compared with the Western world. However, subjects have not been randomly selected or systematically screened to rule out secondary causes of bone loss. The purpose of this study was to determine peak bone mass and lifestyle risk factors for bone loss in a randomly chosen sample of healthy Lebanese subjects from the greater Beirut area. Subjects 25-35 years of age were randomly selected from greater Beirut, which comprises one third of the Lebanese at large, and studied during the Fall of 1999. BMD was measured at the lumbar spine, hip, forearm, and total body. A questionnaire on lifestyle factors was administered to all subjects. Results were compared with the database of subjects from the USA provided by the manufacturer, and to the NHANES database for the total hip. Two hundred thirteen subjects were studied; 45 subjects rotated at all three centers for cross-calibration purposes. Peak BMD in Lebanese subjects was 0.2-0.9 SD below that of peak BMD in American subjects, depending on skeletal site, gender, and densitometer. These differences persisted after attempting to adjust for body size. Osteoporosis and osteopenia were more prevalent than in healthy young Americans. Height, weight, and total body fat were the most significant correlates of BMD/bone mineral content (BMC), accounting for 0.3-0.7 of the variance in bone mass measurement. Lifestyle factors had a very modest but significant contribution to bone mass variance. This is the first population-based study from the Middle East demonstrating that peak BMD is slightly lower in Lebanese subjects compared as with an established database from the USA. Due to the selection of relatively healthier subjects in our study than in the NHANES study, the actual differences between the two populations may be even greater. The impact of our findings on the epidemiology of osteoporotic fractures in Lebanon remains to be determined.

Effect of decreased physical activity on bone mass in exercise-trained young rats

The aim of this study was to determine whether decreased physical activity in exercise-trained young rats would result in a lower rate of bone gain or a reversal of the benefits of exercise. Thirty-five female Wistar rats, 6 weeks of age, were randomized into seven groups: 7 weeks of exercise (7EX), 7 weeks of sedentary control (7CN), 11 weeks of exercise (11EX), 7 weeks of exercise followed by 4 weeks of exercise cessation (7EX4C), 7 weeks of exercise followed by 4 weeks of decreased exercise frequency (7EX4F), 7 weeks of exercise followed by 4 weeks of decreased exercise intensity (7EX4I), and 11 weeks of sedentary control (11CN). The running intensity (speed) and duration were 25 m/min for 60 min/day at a frequency of 5 days/week. During the last 4 weeks, exercise frequency was reduced to 1 day/week in the 11EX4F group, and exercise intensity (speed) was reduced to 12 m/min in the 7EX4I group. After each period of exercise, the bone mineral content (BMC) of the proximal, middle, and distal tibiae, determined by dual-energy X-ray absorptiometry (DXA), was significantly greater in the 7EX and 11EX groups than in the 7CN and 11CN groups, respectively, but it was significantly lower in the 7EX4C group than in the 11EX group and did not differ significantly from the values of the 11CN group. Although the BMC of the proximal and middle tibiae did not differ significantly among the 7EX4F, 7EX4I, 7EX4C, and 11CN groups, the BMC of the distal tibia was significantly greater in the 7EX4F and 7EX4I groups than in the 11CN group and tended to be greater than in the 7EX4C group. The results of this study suggest that the effect of decreased exercise intensity and frequency on bone mass appears to be site specific in the tibia of the exercise-trained young rats. This study shows that exercise-trained young rats lose the benefits gained from exercise when exercise is completely ceased, resulting in the reduction of bone mass to levels that do not differ significantly from those of sedentary controls. At least, continuous exercise appears to be necessary for the maintenance of high bone mass.

Effects of vitamin K2, vitamin D, and calcium on the bone metabolism of rats in the growth phase

Using 168 female Sprague-Dawley rats, we determined whether the peak bone mass could be increased, and which drugs would be effective in suppressing the rate of decrease in bone mass by continuous administration from childhood. At the age of 3 months, these 168 rats were divided into five groups depending on the type of diet that they were fed (control, regular; group A, vitamin K2; group B, vitamin D; group C, high calcium; group D, vitamins D and K2 and high calcium) and kept to the age of 16 months. Dual-energy X-ray absorptiometry (DXA) was used to measure the bone mineral density of the femoral epiphysis and microcomputed tomography (CT) to analyze its fine structure. The average bone mass increased rapidly with age and reached a peak at the age of 8 months. Peak bone mass for the four drug administration groups was higher than that for the control group. Among these four groups, the peak bone mass was the highest in group C and the rate of decrease the smallest in group D. The results of the present animal study suggest that the peak bone mass of humans can be raised by consuming sufficient amounts of vitamins K2 and D and calcium continuously from childhood, and that this diet will suppress the rate of decrease in bone mass, thus ultimately preventing bone fractures caused by osteoporosis.

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.

Pregnancy and lactation affect markers of calcium and bone metabolism differently in adolescent and adult women with low calcium intakes

Physiologic adaptation to the high calcium demand during pregnancy and lactation may be different in adolescents than in adults, particularly at low calcium intake. The aim of this cross-sectional study was to compare biochemical markers of calcium and bone metabolism between adolescent (14-19 y) and adult (21-35 y) women with calcium intake approximately 500 mg/d, in three different physiologic states, i.e., control (nonpregnant, nonlactating; NPNL), pregnant and lactating. Markers of calcium metabolism [serum Ca, P and intact parathyroid hormone (iPTH); urinary Ca and P] and of bone turnover [urinary deoxypyridinoline (D-Pyr) and plasma bone alkaline phosphatase (BAP)] were measured in NPNL (adolescents, n = 12 and adults, n = 25), pregnant (adolescents, n = 30 and adults, n = 36) and lactating (adolescents, n = 19 and adults, n = 26) women. In the NPNL women, iPTH, D-Pyr and BAP were higher (P < 0.001) and urinary Ca was lower (P < 0.001) in adolescents than in adults. Serum iPTH was higher (P < 0.001) and urinary Ca was lower (P < 0.01) in adolescents than in adults also in pregnancy and lactation. Compared with NPNL women, serum Ca decreased (P < 0.001) with pregnancy in adolescents but not in adults. The increase in D-Pyr with pregnancy and lactation was very pronounced in adults ( approximately 130%, P < 0.001) but less in adolescents (<25%, P < 0.01). BAP increased (P < 0.001) with pregnancy and lactation in adults ( approximately 60%) but decreased (P < 0.001) with pregnancy in adolescents ( approximately 13%). Pregnancy and lactation appear to affect bone turnover in adolescent and adult women with low calcium intake differently.

Prenatal and childhood influences on osteoporosis

Osteoporosis is a major cause of morbidity and mortality through its association with age-related fractures. Although most effort in fracture prevention has been directed at retarding the rate of age-related bone loss, and reducing the frequency and severity of trauma among elderly people, evidence is growing that peak bone mass is an important contributor to bone strength during later life. The normal patterns of skeletal growth have been well characterized in cross-sectional and longitudinal studies. It has been confirmed that boys have higher bone mineral content, but not volumetric bone density, than girls. Furthermore, in both genders there is a dissociation between the peak velocities for height gain and bone mineral accrual. Puberty is the period during which volumetric density appears to increase in both axial and appendicular sites. Many factors influence the accumulation of bone mineral during childhood and adolescence, including heredity, gender, diet, physical activity, endocrine status and sporadic risk factors such as cigarette smoking. Measures for maximizing bone mineral acquisition, particularly through encouraging physical activity and adequate dietary calcium intake, are likely to affect the risk of fracture in later generations. In addition to these modifiable factors during childhood, evidence has also accrued that the risk of fracture might be programmed during intrauterine life. Epidemiological studies have demonstrated a relationship between birthweight, weight in infancy and adult bone mass. This appears to be mediated through modulation of the set-point for basal activity of pituitary-dependent endocrine systems such as the hypothalamic - pitutiary - adrenal (HPA) and growth hormone/insulin-like growth factor I (GH/IGF-I) axes. Maternal smoking, diet and physical activity levels appear to modulate bone mineral acquisition during intrauterine life; furthermore, both low birth size and poor childhood growth are directly linked to the later risk of hip fracture. The optimization of maternal nutrition and intrauterine growth should also be included within preventive strategies against osteoporotic fracture, albeit for future generations.

Changes in Bone Turnover in Patients with Anorexia Nervosa during Eleven Weeks of Inpatient Dietary Treatment

Background: Many adolescents with anorexia nervosa suffer from severe osteopenia and osteoporosis. We hypothesized that individualized nutrition therapy may improve bone turnover in anorectic patients.

Methods: We studied 19 female patients [mean age, 14.2 ± 1.4 years; mean body weight, 39.3 ± 5.4 kg; mean body mass index (BMI), 14.2 ± 1.4 kg/m2] with anorexia nervosa (International Classification of Diseases-10: F50.0, F50.1) for a period of 3 months. Nutrition therapy began at the end of the first week and included individualized hypercaloric diets, high calcium intake (2000 mg/day), and administration of vitamin D (400 IU/day). Blood samples were taken at baseline and again in weeks 3, 7, and 11. We measured serum calcium, parathyroid hormone, bone formation and resorption markers, insulin-like growth factor 1 (IGF-1), and leptin.

Results: Mean BMI increased significantly, from 14.2 ± 1.4 to 17.1 ± 0.7 kg/m2 (P = 0.000001), during the course of treatment, whereas serum total calcium and phosphate concentrations remained unchanged. The bone formation markers procollagen-I carboxy-terminal propeptide and bone alkaline phosphatase almost doubled (P = 0.006). Both IGF-1 (P = 0.00001) and leptin (P = 0.000005) increased significantly by week 11. Parallel to this, the serum concentration of C-telopeptide, a bone resorption marker, decreased significantly (P = 0.009).

Conclusions: Nutritional rehabilitation, possibly as a result of increasing IGF-1 and leptin concentrations, may increase bone formation. It therefore provides additional objective evidence of the importance of nutrition for bone.

Severe impairment of bone mass and turnover in Cushing's disease: comparison between childhood-onset and adulthood-onset disease

BACKGROUND

Osteoporosis is an important, frequently unrecognized consequence of hypercortisolism.

OBJECTIVE

To evaluate whether the age of onset of hypercortisolism influences its effects on bone mass and turnover.

SUBJECTS

10 with childhood-onset (co) and 18 with adulthood-onset (ao) Cushing's disease (CD); 28 age-, sex- and body mass index (BMI)-matched healthy subjects served as controls.

STUDY DESIGN

Open, cross-sectional controlled.

MEASUREMENTS

Bone mineral density (BMD) at lumbar spine, serum osteocalcin (OC), and urinary N-telopeptides of type I collagen (Ntx) levels.

RESULTS

BMD at lumbar spine was significantly lower in all CD patients than in controls (Z score, -2.3 +/- 0.1 vs. -0.2 +/- 0.01; P < 0.001). co-CD and ao-CD patients had similar values of bone mass when expressed as Z score (-2.6 +/- 0.4 vs. -2.1 +/- 0.2; P = 0.27) or as BMD (0.728 +/- 0.03 vs. 0.78 +/- 0.03 g/cm2; P = 0.25). In particular, osteoporosis was observed in 16 patients (57.1%) [eight adolescents (80%) and eight adults (44.4%)] and none of the controls; osteopenia was found in two co-CD patients (20%) and none of the healthy adolescents, 10 ao-CD patients (55.6%) and four healthy adults (14.3%) (chi2 = 7.87, P < 0.01; chi2 = 2.99, P = 0.09, respectively). In co-CD and ao-CD patients, serum OC levels were similar and significantly lower than in controls (P < 0.01); urinary Ntx levels were significantly higher than in controls (P < 0.001) and were significantly higher in co-CD than in ao-CD patients (P < 0.001). No significant correlation was found between urinary cortisol levels, serum cortisol and age and lumbar Z score values, while a significant correlation was found between Ntx levels and disease duration (r = 0.434; P = 0.021) and plasma cortisol (r = 0.440; P = 0.019).

CONCLUSIONS

Cushing's disease causes bone loss and abnormalities of bone turnover both in childhood-onset and in adulthood-onset patients. A strict follow-up of bone mass and turnover is mandatory in all patients with Cushing's disease to prevent fractures later in life and specific treatment for bone loss is strongly suggested.

Phytoestrogen and multiple vitamin/mineral effects on bone mineral density in early postmenopausal women: a pilot study

The purpose of the study was to assess the effect of a combination regimen of herbs, vitamins, and minerals on bone mineral density (BMD) in early postmenopausal women via a 2-year, single-blind, uncontrolled, prospective trial. BMD was measured by dual energy x-ray absorptiometry (DEXA) at baseline and at 6, 12, and 24 months. Results of lumbar spine, hip, and forearm densities did not differ significantly from historical controls derived from other recent trials using a similar patient population. Bone mineral losses are reported on an annualized basis over the 2 years for the 12 women who completed the trial: spine (-1.42% per year), hip (-0.43% per year), forearm (-1.42% per year). Six women were withdrawn from the trial by the investigators because of excessive losses of bone mineral, and 1 of these women was diagnosed with hyperparathyroidism. There were no metabolic diseases to explain the losses in the remaining 5 withdrawn subjects. Four of 21 subjects experienced adverse side effects, necessitating dropping out by 3 of these women. In conclusion, the combined treatment regimen of a menopause symptom-oriented herbal blend plus a high potency vitamin/mineral was unsuccessful in protecting women against the predictable acceleration of bone mineral losses associated with early postmenopause.

Bone adaptation response to sham and bending stimuli in mice

This study presents inbred-strain-related differences in tibial bone adaptation response to low-force loading in four-point bending and sham (pad pressure) arrangements in mice. Our previous work in mice has shown that at relatively high but equal bending forces (9 N or a bending moment of 16.88 N-mm), C57BL/6J mice respond with significantly greater bone formation than C3H/HeJ mice. Because of high tibial strains, the majority of the bone response in our previous study was woven bone. In this, study, we reduced the loading forces to 5 N or a bending moment of 9.38 N-mm (to decrease the woven-bone formation response) and investigated inbred-strain-related bone adaptation differences resulting from bending and sham loading (reported here for the first time in C57BL/6J) in these mice. Twenty-four female mice within each inbred mouse strain (C3H/HeJ [C3H] and C57BL/6J [B6]) were randomly divided into the two loading groups (12 per group sham and bending, total of 48 mice). All of the external loading was done for 36 cycles at 2 Hz, 3 d/wk for 3 wk. The bone adaptation response at lower forces exhibited a pattern similar to that seen for the higher forces in the previous study, suggesting that the patterns of bone adaptation were inbred strain related and independent of bending force magnitude. The bending-related periosteal mineral apposition surface (pMS) and mineral apposition rate (MAR) were respectively 40% and 45% greater in B6 than in C3H. The cortical bone adaptation response to bending was greater when compared to sham or pad pressure for each inbred strain of mice, suggesting that the majority of the bone adaptation response was the result of bending stimulus and not local pressure from pad contact. In addition, regardless of loading arrangement (sham or bending), the bone adaptation response in C57BL/6J mice was greater than C3H/HeJ.

The effect of calcium intake on bone composition and bone resorption in the young growing rat

A low Ca intake by both rats and man increases bone resorption, decreases bone mass and increases the risk of osteoporosis. The skeletal effect of high Ca intakes is less clear, particularly during periods of bone mineral accrual. Twenty-four female 5-week-old rats, Wistar strain, were randomized by weight into three groups of eight rats each and fed ad libitum a semi-purified diet containing 2 (Ca-restricted), 5 (normal) or 20 (Ca-supplemented) g Ca/kg for 3 weeks. When compared with the normal Ca diet, urinary Ca excretion was unaffected by the dietary restriction of Ca for 3 weeks, but was greater (P<0.001) in Ca-supplemented rats. Urinary pyridinoline (Pyr) and deoxypyridinoline (Dpyr) levels were significantly greater during weeks 2 (Pyr P<0.05, Dpyr P<0.001) and 3 (Pyr P<0.01, Dpyr, P<0.001) of dietary Ca restriction, but were unaffected by Ca supplementation. Femoral dry weight and the concentration of Mg and P in femora were unaffected by dietary Ca concentration. Femoral Ca concentration was reduced (P<0.05) in the Ca-restricted group compared with the other two groups. In conclusion, these results suggest that increasing dietary Ca intake, well above the recommended level, had no effect on bone mineral composition or bone resorption (as assessed with urinary pyridinium crosslinks) in young growing female rats. In addition, these results confirm the findings of previous studies which have shown that bone Ca content in young growing rats was reduced by dietary Ca restriction and that this reduction results, at least in part, from an increased rate of bone resorption.

Calcium intake and bone mass development among Israeli adolescent girls

OBJECTIVE

To determine the possible relationship between food and life style habits and bone health in adolescent Israeli females.

METHODS

2,000 adolescent Israeli Jewish and Arab high-school girls (mean age 14.5) completed a semi-quantitative food frequency questionnaire and a personal history questionnaire. 27 food components were calculated for each subject. Bone mineral content and density were determined for 112 subjects with calcium intake below 800 mg/day.

RESULTS

Average calcium intake was found to be 1,260 mg/day, but 20% of all girls had a calcium intake below 800 mg/day. All low-energy diets were very low in calcium, as mean calcium intake per 1,000 calories was 411 128 grams. A large percentage of diets with less than 800 mg calcium were also deficient in phosphorus (95.2%), magnesium (84.8%). iron (90.5%) and zinc (100%). Due to differences in food sources. Jewish girls had more phosphorus in their diet, but less magnesium and iron compared to Arab girls. Calcium and zinc deficiencies in Jewish and Arab diets were similar. A negative correlation was found between body mass index (BMI) and age at menarche for all girls in the study. Bone mineral density (BMD) measured for girls with calcium intake below 800 mg/day distributed normally around the average when compared to age matched controls despite their low calcium intake. There was a strong positive correlation between BMD and bone mineral content (BMC) at all sites and body weights.

CONCLUSIONS

Low calcium intake, other nutritional deficiencies and delayed menarche due to low-energy diet in the growing period and in adolescence may prevent the formation of healthy bones. There is no evidence of lower bone mass among the low calcium intake group in the study population at this stage. It remains to be documented if the window of opportunity for optimal bone accretion for this group will be missed in the future. possibly leading to increased risk of osteoporosis.

Bone mineral decrements in survivors of childhood acute lymphoblastic leukemia: frequency of occurrence and risk factors for their development

We assessed the clinical and treatment factors that predispose survivors of childhood acute lymphoblastic leukemia (ALL) to low bone mineral density (BMD). Using quantitative computed tomography, we determined the frequency of low BMD (defined as >1.645 standard deviations (SD) below the mean) in leukemia survivors treated with multiagent chemotherapy including prednisone and antimetabolite. All participants had completed therapy at least 4 years earlier, remained in continuous complete remission, and had no second malignancies. We statistically correlated BMD results with patient characteristics and treatment histories. Among 141 survivors (median age, 15.9 years; median time after diagnosis, 11.5 years), median BMD z score was -0.78 SD (range, -3.23 to 3.61 SDs). Thirty participants (21%; 95% confidence interval, 15% to 29%) had abnormally low BMD, a proportion significantly (P < 0.0001) greater than the expected 5% in normal populations. Risk factors for BMD decrements included male sex (P = 0.038), Caucasian race (P < 0.0001), and cranial irradiation (P= 0.0087). BMD inversely correlated with cranial irradiation dose. BMD z scores of patients who received higher doses of antimetabolites were lower than those of other patients. Childhood ALL survivors are at risk to have low BMD, especially males, Caucasians, and those who received cranial irradiation.

Avaliação dietética em creches municipais de Teresina, Piauí, Brasil

Esta pesquisa foi conduzida para avaliar a qualidade nutricional das refeições consumida pelas crianças, pertencentes à faixa etária de 2 a 6 anos, matriculadas em creches municipais de Teresina. Os dados foram obtidos durante o período de outubro de 1997 a março de 1998, adotando-se o método da pesagem direta dos alimentos. Para o cálculo da adequação nutricional utilizaram-se as médias do consumo de energia e nutrientes, comparadas às recomendações nacionais. O estudo revelou oferta insuficiente de energia, ferro, cálcio e vitamina A, com um consumo protéico e de vitamina C excedendo as recomendações. Os carboidratos contribuíram com 58,5 ± 3,0% das energias totais, as proteínas com 16,0 ± 1,3% e as gorduras com 25,5 ± 3,7%. A deficiência de energia e a inadequação de proteínas e demais nutrientes demonstram a necessidade de um contínuo monitoramento das metas do programa e o aperfeiçoamento do serviço visando à melhoria da qualidade das dietas, com especial atenção ao atendimento das recomendações nutricionais.