Adolescent nutrition in the prevention of postmenopausal osteoporosis

Effect of soluble corn fiber supplementation for 1 year on bone metabolism in children, the MetA-bone trial: Rationale and design

Calcium intake is critical for adequate bone mineralization in adolescence, but it is usually inadequate in US adolescents. A strategy to maximize bone mineralization is to increase calcium absorption, which could be achieved by soluble corn fiber (SCF). There are no studies determining the long-term effects of SCF on bone mass in children.

OBJECTIVES

To determine the effect of one-year SCF supplementation compared to placebo on bone mass and bone biomarkers in children with low habitual calcium intake. We hypothesize that SCF supplementation will result in a higher bone mineral content and higher levels of bone formation and lower bone resorption biomarkers.

METHODS

240 healthy children (10-13 years), with usual low calcium intake, will be randomized to four experimental groups for 1 year: (1) SCF (12 g/d); (2) SCF (12 g/d) + 600 mg/d of calcium; (3) Placebo (maltodextrin); and (4) Placebo +600 mg/d of calcium. The supplements have been pre-mixed with a flavored powder beverage and participants will only need to dilute it in water and drink this twice per day. Bone will be measured using dual energy x-ray absorptiometry (DXA) at baseline, 6 and 12 months. Serum bone biomarkers will be measured at baseline and at 12 months.

CONCLUSIONS

If supplementing diets with SCF lead to higher bone mass during adolescence, this could help achieve the genetic potential for PBM and to start adult life with stronger bones. If successful, SCF can be incorporated into diets for promoting bone health in adolescents.

Could use of Selective Serotonin Reuptake Inhibitors During Lactation Cause Persistent Effects on Maternal Bone?

The lactating mammary gland elegantly coordinates maternal homeostasis to provide calcium for milk. During lactation, the monoamine serotonin regulates the synthesis and release of various mammary gland-derived factors, such as parathyroid hormone-related protein (PTHrP), to stimulate bone resorption. Recent evidence suggests that bone mineral lost during prolonged lactation is not fully recovered following weaning, possibly putting women at increased risk of fracture or osteoporosis. Selective Serotonin Reuptake Inhibitor (SSRI) antidepressants have also been associated with reduced bone mineral density and increased fracture risk. Therefore, SSRI exposure while breastfeeding may exacerbate lactational bone loss, compromising long-term bone health. Through an examination of serotonin and calcium homeostasis during lactation, lactational bone turnover and post-weaning recovery of bone mineral, and the effect of peripartum depression and SSRI on the mammary gland and bone, this review will discuss the hypothesis that peripartum SSRI exposure causes persistent reductions in bone mineral density through mammary-derived PTHrP signaling with bone.

Effect of Calcium Derived from Lithothamnion sp. on Markers of Calcium Metabolism in Premenopausal Women

A double-blind crossover pilot trial tested the hypothesis that botanically derived calcium could demonstrate greater influence over calcium metabolism markers compared with a nonplant-derived calcium carbonate supplement or placebo. Twelve fasting female subjects received a single oral dose of Aquamin F™ (derived from the marine algal Lithothamnion sp.), or calcium carbonate, or placebo. Blood and urine samples were collected at baseline and over 12 h to evaluate ionized and total calcium and parathyroid hormone (PTH). Subjects treated with Aquamin F demonstrated significantly greater urinary clearance of calcium after 12 h compared with placebo (P = .004). Following a meal at 90 min, subjects treated with Aquamin F demonstrated a more prolonged suppression of serum PTH concentration (significantly lower than placebo at 90, 120, and 240 min). Calcium carbonate provided an intermediate response; urinary clearance was not significantly different from placebo treatment and PTH was only significantly lower than placebo at 90 min. Aquamin F may demonstrate greater influence over these markers of calcium metabolism than calcium carbonate or placebo, as suggested by a greater calciuric response and a more prolonged suppression of serum PTH concentrations following a meal in premenopausal women.

DNA methylation and the social gradient of osteoporotic fracture: A conceptual model

INTRODUCTION

Although there is a documented social gradient for osteoporosis, the underlying mechanism(s) for that gradient remain unknown. We propose a conceptual model based upon the allostatic load theory, to suggest how DNA methylation (DNAm) might underpin the social gradient in osteoporosis and fracture. We hypothesise that social disadvantage is associated with priming of inflammatory pathways mediated by epigenetic modification that leads to an enhanced state of inflammatory reactivity and oxidative stress, and thus places socially disadvantaged individuals at greater risk of osteoporotic fracture.

METHODS/RESULTS

Based on a review of the literature, we present a conceptual model in which social disadvantage increases stress throughout the lifespan, and engenders a proinflammatory epigenetic signature, leading to a heightened inflammatory state that increases risk for osteoporotic fracture in disadvantaged groups that are chronically stressed.

CONCLUSIONS

Our model proposes that, in addition to the direct biological effects exerted on bone by factors such as physical activity and nutrition, the recognised socially patterned risk factors for osteoporosis also act via epigenetic-mediated dysregulation of inflammation. DNAm is a dynamic modulator of gene expression with considerable relevance to the field of osteoporosis. Elucidating the extent to which this epigenetic mechanism transduces the psycho-social environment to increase the risk of osteoporotic fracture may yield novel entry points for intervention that can be used to reduce individual and population-wide risks for osteoporotic fracture. Specifically, an epigenetic evidence-base may strengthen the importance of lifestyle modification and stress reduction programs, and help to reduce health inequities across social groups.

MINI ABSTRACT

Our conceptual model proposes how DNA methylation might underpin the social gradient in osteoporotic fracture. We suggest that social disadvantage is associated with priming of inflammatory signalling pathways, which is mediated by epigenetic modifications, leading to a chronically heightened inflammatory state that places disadvantaged individuals at greater risk of osteoporosis.

Dietary calcium requirements do not differ between Mexican-American boys and girls

Mexican Americans are an understudied ethnic group for determinants of bone health, although the risk of age-related osteoporosis is high in this rapidly growing sector of the U.S. population. Thus, the objective of the present study was to establish the dietary calcium requirements for bone health in Mexican-American adolescents by measuring calcium retention calculated from balance in response to a range of dietary calcium intakes and to determine predictors of skeletal calcium retention. Adolescents aged 12-15 y were studied twice on paired calcium intakes ranging from 600 to 2300 mg/d using randomized-order, crossover 3-wk balance studies. Skeletal calcium retention was calculated as dietary calcium intake minus calcium excreted in feces and urine over the last 2 wk of balance. A linear model was developed to explain the variation in calcium retention. Boys (n = 20) were taller and had higher lean mass, usual dietary calcium intake, bone mineral content, and serum alkaline phosphatase compared with girls, whereas girls (n = 20) had higher Tanner scores and greater fat mass. Calcium retention increased with calcium intake (P < 0.0001) and did not differ by sex (P = 0.66). In boys and girls considered together, calcium intake explained 33% of the variation in calcium retention. Serum alkaline phosphatase explained an additional 11% of the variation in calcium retention. Other variables measured, including the urine N-telopeptide of type I collagen/creatinine ratio, Tanner score, serum parathyroid hormone and 25-hydroxyvitamin D, weight, height, and body mass index, did not contribute to the variance in calcium retention. In adolescence, calcium retention in both Mexican-American boys and girls was higher than determined previously in adolescent nonHispanic white girls. This trial was registered at clinicaltrials.gov as NCT01277185.

Diet quality among Iranian adolescents needs improvement

Objective

Diet in adolescence is important not only because of adolescents’ rapid growth but also due to its influence on future chronic diseases. On the other hand, dietary quality indices are noteworthy and useful approaches to evaluate dietary intakes. Thus the present study was conducted to assess dietary quality indices in adolescents.

Design

Cross-sectional.

Settings

The data were collected from schools in Isfahan, Iran.

Subjects

Female students (n 265) aged 11–13 years were enrolled using systematic cluster-random sampling in Isfahan (Iran). Dietary intakes were assessed by a validated FFQ. Diet quality indices including dietary diversity score (DDS), the Healthy Eating Index (HEI) and mean adequacy ratio (MAR) across ten nutrients were calculated.

Results

Mean DDS, HEI score and MAR were 6·15 (sd 1·61) out of 10 points, 63·90 (sd 19·86) out of 100 points and 1·32 (sd 0·61), respectively. Mean nutrient adequacy ratio of all nutrients was above 1 except for vitamin D (0·53 (sd 0·51)). Those in the highest tertile of DDS had the most favourable anthropometric variables in comparison to the lowest tertile. There were no significant associations between HEI score and BMI, central or abdominal obesity and blood pressure. Those in the highest tertile of MAR had higher BMI, waist circumference and hip circumference.

Conclusions

Diet quality of Isfahani adolescents needs improvement. It may imply the necessity of implementing nutritional instructive policies in this age group and their parents.

School-based calcium-vitamin D with micronutrient supplementation enhances bone mass in underprivileged Indian premenarchal girls

Low adult bone mass is linked to osteoporosis and fractures and is dependent on the extent of childhood and adolescent bone mineralization. The aim of the study was to investigate the effect of 1-year supplementation of calcium, multivitamin with zinc along with vitamin-D on bone mass accrual of school-going premenarchal girls from low income groups in Pune, India. Double-blind, matched-pair, cluster, randomization study was carried out in 214 premenarchal girls (8-12 years) from 2 schools in Pune, India. The two schools together formed 3 classes with 3 clusters each of age-matched girls of which one cluster was allocated to either one of the intervention groups (Ca-group:500 mg/d calcium, Ca+MZ-group:500 mg/d calcium+multivitamin tablet containing 15 mg/d zinc) or control group (C-group: multivitamin tablet without any minerals); all subjects received vitamin-D supplementation. Anthropometry, biochemical parameters, total body bone mineral content (TBBMC) and bone mineral density (TBBMD) (Dual energy X-ray absorptiometry) were assessed at baseline and endline. Post supplementation, mean percent increase in TBBMC was significantly higher in Ca-group (22.3%) and Ca+MZ-group (20.8%) compared to C-group (17.6%) (p<0.05) with no significant differences observed between Ca+MZ and Ca groups (p>0.1). Improvement in TBBMC-for-age Z-scores was higher in the two calcium supplemented groups (13.6%-22%) compared to the C-group (no improvement). Calcium supplementation, with or without multivitamins and zinc, showed a promising improvement in bone health especially with regards to improvement in bone related Z-scores in our population of underprivileged premenarchal girls.

Impact of two regimens of vitamin D supplementation on calcium - vitamin D - PTH axis of schoolgirls of Delhi

OBJECTIVE

To determine the efficacy of supplementation with oral vitamin D₃ (cholecalciferol) on bone mineral biochemical parameters of school-going girls.

SETTING

Government school (government-aided) and Private school (fee paying) in Delhi.

DESIGN

Randomized controlled trial.

INTERVENTION

Cholecalciferol granules (60,000 IU) orally with water, either once in two months (two-monthly D₃ group) or once a month (one-monthly D₃ group) for one year.

PARTICIPANTS

290 healthy schoolgirls (6-17 y), 124 from lower socioeconomic strata (LSES) (attending government schools) and 166 from upper socioeconomic strata (USES) (attending private schools).

OUTCOME MEASURES

Serum 25(OH)D, calcium, phosphorus, parathyroid hormone, and alkaline phosphatase levels at 6 and 12 months after start of supplementation.

RESULTS

At baseline, 93.7% schoolgirls were vitamin D deficient [25(OH)D<50 nmol/L]. While significant increase in serum calcium and decrease in alkaline phosphatase levels was noted in both groups with both interventions, PTH response was inconsistent. In LSES subjects, two-monthly D₃ and one-monthly D₃ supplementation resulted in a significant increase in serum 25(OH)D levels by 8.3 nmol/L and 11.0 nmol/L, respectively at 6 months (P<0.05). Similarly, the increase in the two intervention arms in USES subjects was 10.5 nmol/L and 16.0 nmol/L, respectively (P<0.05). In both groups, this increase in serum 25(OH)D levels persisted at 12 months (P<0.05). Despite supplementation with 60,000 IU of Vitamin D₃ (monthly or two-monthly), only 47% were vitamin D sufficient at the end of one year.

CONCLUSIONS

60,000 IU of cholecalciferol, monthly or two-monthly, resulted in a significant increase in serum 25(OH)D levels in vitamin D deficient schoolgirls.

Dietary fatty acid intake affects the risk of developing bone marrow lesions in healthy middle-aged adults without clinical knee osteoarthritis: a prospective cohort study

Introduction

Fatty acids have been implicated in osteoarthritis (OA), yet the mechanism by which fatty acids affect knee structure and consequently the risk of knee OA has not been fully elucidated. Higher intakes of fatty acids have been shown to be associated with the risk of bone marrow lesions (BMLs) in a healthy population. The aim of this study was to examine the association between fatty acid consumption and the incidence of BMLs in healthy middle-aged adults without clinical knee OA.

Methods

Two hundred ninety-seven middle-aged adults without clinical knee OA underwent magnetic resonance imaging (MRI) of their dominant knee at baseline. BMLs were assessed. Of the 251 participants with no BMLs in their knee at baseline, 230 underwent MRI of the same knee approximately 2 years later. Intakes of fatty acids were estimated from a food frequency questionnaire.

Results

Increased consumption of saturated fatty acids was associated with an increased incidence of BMLs over 2 years after adjusting for energy intake, age, gender, and body mass index (odds ratio of 2.56 for each standard deviation increase in dietary intake, 95% confidence interval 1.03 to 6.37, P = 0.04). Intake of monounsaturated or polyunsaturated fatty acids was not significantly associated with the incidence of BMLs.

Conclusions

Increased fatty acid consumption may increase the risk of developing BMLs. As subchondral bone is important in maintaining joint integrity and the development of OA, this study suggests that dietary modification of fatty acid intake may be one strategy in the prevention of knee OA which warrants further investigation.

Quantitative Ultrasonography of Calcaneal Bone Mass and Its Relationship to Calcium Consumption Among Impoverished Hispanic Women

Perimenopausal Hispanic women need to be able to build and sustain peak bone mass, but this may be affected by their low socioeconomic status. This feasibility research study provided descriptive information on the relationship between calcium consumption and bone mass measured with sonography at the calcaneus. Little research exists to examine bone health with this specific age or ethnic group of women. This research found a strong positive correlation between the amount of self-reported calcium food consumed and the bone stiffness index recorded using quantitative sonography. The translational impact of this project will inform the development of culturally relevant patient education for Hispanic women of low socioeconomic status to encourage the development of peak bone mass.

Short- and long-term safety of weekly high-dose vitamin D3 supplementation in school children

BACKGROUND

Hypovitaminosis D is prevalent in youth worldwide, but the safety of vitamin D at doses exceeding 200 IU/d is unknown in this age group. We assessed the safety of high doses of vitamin D(3) administered to apparently healthy schoolchildren.

METHODS

To assess short-term safety, 25 subjects randomly received placebo or vitamin D(3) at doses of 14,000 IU/wk for 8 wk. To assess long-term safety, 340 subjects randomly received placebo, vitamin D(3) as 1,400 IU/wk or 14,000 IU/wk for 1 yr. Biochemical variables were monitored at 0, 2, 4, 6, and 8 wk and 8 wk off therapy in the short-term study and at 0, 6, and 12 months in the long-term study.

RESULTS

In both the short- and long-term studies, mean serum calcium and 1,25-hydroxyvitamin levels did not change in any group. In the short-term study, mean 25-hydroxyvitamin concentrations increased from 44 (+/- 11) to 54 (+/- 19) ng/ml in the treated groups (P = 0.033). In the long-term study, mean 25-hydroxyvitamin D levels increased from 15 +/- 8 to 19 +/- 7 ng/ml (P < 0.0001) in subjects receiving 1,400 IU/wk and from 15 +/- 7 to 36 +/- 22 ng/ml (P < 0.0001) in the group receiving 14,000 IU/wk. No subject developed vitamin D intoxication.

CONCLUSION

Vitamin D(3) at doses equivalent to 2000 IU/d for 1 yr is safe in adolescents and results in desirable vitamin D levels.

Effect of fatty acids on bone marrow lesions and knee cartilage in healthy, middle-aged subjects without clinical knee osteoarthritis

OBJECTIVE

There is evidence that omega-3 polyunsaturated fatty acids alleviate the progression of osteoarthritis (OA). However, little work has been done to investigate the effect of fatty acids on bone marrow lesions and knee cartilage in healthy subjects. We examined this in a cohort of healthy middle-aged subjects without clinical knee OA.

METHODS

Two hundred and ninety-three healthy adults without knee pain or injury were recruited from an existing community-based cohort. Intakes of fatty acids and food sources of these were estimated from a food frequency questionnaire at baseline. Tibial cartilage volume, tibial plateau bone area, tibiofemoral cartilage defects and bone marrow lesions were assessed approximately 10 years later using magnetic resonance imaging.

RESULTS

In multivariate analyses, higher intakes of monounsaturated fatty acids (OR=2.14, 95% CI 1.04-4.39, P=0.04), total (OR=1.77, 95% CI 1.13-2.77, P=0.01) and n-6 polyunsaturated fatty acids (OR=1.69, 95% CI 1.10-2.61, P=0.02) were associated with an increased risk of bone marrow lesions. Intake of fatty acids was not significantly associated with cartilage volume or cartilage defects.

CONCLUSION

These findings support the dietary recommendation towards a shift to foods rich in n-3 polyunsaturated fatty acids in order to maintain an optimal balance between dietary n-3 and n-6 polyunsaturated fatty acids, which is also important in the prevention of atherosclerosis. Although our findings will need to be confirmed in longitudinal studies, they suggest the potential of fatty acids to adversely effect the knee joint.

Prospective study on food fortification with vitamin D among adolescent females in Finland: minor effects

Vitamin D insufficiency is common particularly during winter time. After the recommendation by the Ministry of Social Affairs and Health, Finnish fluid milks and margarines have been fortified with vitamin D since February 2003. The aims of the present study were to examine the impact of vitamin D fortification of food supplies on serum 25-hydroxyvitamin D (S-25(OH)D) concentrations and on daily dietary vitamin D intake among adolescent females. One hundred and forty-two girls of Caucasian ethnicity aged 12-18 years completed semi-quantitative FFQ from which the dietary vitamin D and Ca intakes were calculated. S-25(OH)D was measured by radioimmunoassay. The study was performed from February-March 2000 to February-March 2004, one year after the initiation of fortification. The mean dietary intake of vitamin D was < 7.5 microg in 91.5 % of the adolescent girls in 2000 and 83.8 % in 2004. The midwinter mean S-25(OH)D concentration did not change significantly during the follow-up period (48.3 v. 48.1 nmol/l, NS). The proportion of participants who had S-25(OH)D concentration < 50 nmol/l was 60.6 % in 2000 and 65.5 % in 2004. Only 7.0 % of the participants had an adequate S-25(OH)D ( >or= 75 nmol/l) level in 2000 or 4 years later. The vitamin D fortification of fluid milks and margarines was inadequate to prevent vitamin D insufficiency. There are numerous adolescent girls and women who are not reached by the current fortification policy. Therefore new innovative and feasible ways of improving vitamin D nutrition are urged.

Higher prevalence of osteoporosis among female Holocaust survivors

The prevalence of osteoporosis was statistically significantly higher among female Holocaust survivors than among those who were not exposed to the Holocaust. These findings support the importance of nutrition and environmental conditions during childhood and adolescence on BMD in older adults.

INTRODUCTION

Holocaust survivors during childhood and adolescence experienced undernutrition and lack of exercise and sunlight. The study aimed to establish if Holocaust survivors have higher prevalence of osteoporosis than subjects who were not Holocaust survivors.

METHODS

Seventy-three female Jewish Holocaust survivors > or = 60 years old and 60 female European-born Jews > or =60 years old who were not in the Holocaust were examined. BMD was measured using DXA of the lumbar spine and hips. The Cochran-Armitage trend test was used to test for an increasing trend in decreased BMD in the Holocaust survivors versus controls.

RESULTS

Among Holocaust survivors 54.8% had osteoporosis, 39.7% osteopenia, and 5.5% normal BMD, whereas among controls 25.0% had osteoporosis, 55.0% osteopenia, and 20.0% normal BMD (p = 0.0001). In those who were <17 years old in 1945, among Holocaust survivors 58.0% had osteoporosis, 34.0% osteopenia, and 8.0% normal BMD, whereas among controls 20.0% had osteoporosis, 57.8% osteopenia, and 22.2% normal BMD (p = 0.0003). In those > or =17 years old in 1945, among Holocaust survivors 47.8% had osteoporosis, 52.2% osteopenia and none had normal BMD, whereas among controls 40.0% had osteoporosis, 46.7% osteopenia, and 13.3% normal BMD (p = 0.28).

CONCLUSION

The prevalence of osteoporosis was significantly higher among Holocaust survivors.

Vitamin D status of apparently healthy schoolgirls from two different socioeconomic strata in Delhi: relation to nutrition and lifestyle

Forty to fifty per cent of skeletal mass, accumulated during childhood and adolescence, is influenced by sunlight exposure, physical activity, lifestyle, endocrine status, nutrition and gender. In view of scarce data on association of nutrition and lifestyle with hypovitaminosis D in Indian children and adolescents, an in-depth study on 3,127 apparently healthy Delhi schoolgirls (6-18 years) from the lower (LSES, n 1,477) and upper socioeconomic strata (USES, n 1650) was carried out. These girls were subjected to anthropometry and clinical examination for hypovitaminosis D. Girls randomly selected from the two strata (LSES, n 193; USES, n 211) underwent detailed lifestyle, dietary, biochemical and hormonal assessment. Clinical vitamin D deficiency was noted in 11.5 % girls (12.4 % LSES, 10.7 % USES). USES girls had significantly higher BMI than LSES counterparts. Prevalence of biochemical hypovitaminosis D (serum 25-hydroxyvitamin D < 50 nmol/l) was seen in 90.8 % of girls (89.6 % LSES, 91.9 % USES, NS). Mean intake of energy, protein, fat, Ca, vitamin D and milk/milk products was significantly higher in USES than LSES girls. Conversely, carbohydrate, fibre, phytate and cereal intakes were higher in LSES than USES girls. Physical activity and time spent outdoors was significantly higher in LSES girls (92.8 v. 64 %, P = 0.000). Significant correlation between serum 25-hydroxyvitamin D and estimated sun exposure (r 0.185, P = 0.001) and percentage body surface area exposed (r 0.146, P = 0.004) suggests that these lifestyle-related factors may contribute significantly to the vitamin D status of the apparently healthy schoolgirls. Hence, in the absence of vitamin D fortification of foods, diet alone appears to have an insignificant role.

Aspectos alimentares e nutricionais dos usuários do "restaurante popular Mesa do Povo"

O objetivo deste estudo foi averiguar aspectos alimentares e nutricionais dos usuários do "Restaurante Popular Mesa do Povo", situado em Fortaleza (CE), Brasil. Foram selecionados aleatoriamente 51 usuários, os quais foram submetidos à aplicação do inquérito alimentar recordatório 24 h e hábitos alimentares. A amostra foi estratificada por nível de sexo, nível de adequação. O consumo alimentar foi avaliado pelo Índice de Qualidade da Dieta e a adequação calórica, pela Pirâmide Alimentar Adaptada. Macro e micronutrientes tiveram adequações de acordo com "Dietary Reference Intakes". Após freqüentar o restaurante, 42,85% dos homens e 37,5% das mulheres declararam estar consumindo mais verduras. Dos problemas de saúde, a hipertensão arterial, associada ao diabetes mellitus, em 11,76%, e o diabetes mellitus, associado à doença cardiovascular, em 3,92%, foram os mais citados. Das calorias totais, verificou-se que a média de ingestão para homens foi de 2.278,9 calorias e, para as mulheres, 1.785,65 calorias, havendo diferença significativa entre os sexos. As inadequações de calorias evidenciaram-se em 31,4% abaixo e 49% acima do padrão recomendado. Constatou-se que 100% dos usuários estão com contribuição calórica de proteínas dentro do recomendado, sendo 94,12% para carboidratos, e 90,2% para os lipídios adequados à recomendação. Notou-se que o cálcio e tocoferol apresentaram a menor adequação na dieta dos usuários; no entanto, houve uma satisfatória adequação quanto ao teor médio em vitaminas e minerais. Faz-se necessário ajustar a operacionalização do atendimento por meio de critérios seletivos e adequados para atingir, em maior número, os usuários mais vulneráveis no aspecto nutricional e socioeconômico.

Ready-to-eat breakfast cereal consumption enhances milk and calcium intake in the US population

BACKGROUND

Inadequate intake of calcium-rich foods among US adults and children is a public health concern. Fluid milk is one of the best calcium sources because of its bioavailability and its versatility as both a beverage and a complement to various solid foods. One of the foods commonly consumed with milk is ready-to-eat breakfast cereal (RTEC).

OBJECTIVE

We aimed to establish the association between the intake of RTEC, milk, and calcium within the context of the most current population dietary practices. We hypothesized that RTEC consumption facilitates milk consumption and is associated with adequacy of calcium intake in the US population.

DESIGN

The most recent National Health and Nutrition Examination Survey, 1999-2000, data set was used as the source of data for this research.

SUBJECTS/SETTING

US subjects aged 4 years and older (n=7,403), excluding pregnant and/or lactating women. Data were stratified according to sex and age (4 to 8 years, 9 to 13 years, 14 to 18 years, 19 to 30 years, 31 to 50 years, 51 to 70 years, and 71+ years), and then by consumption of breakfast, RTEC, and milk.

STATISTICAL ANALYSES PERFORMED

SAS (release 8.1, 2000, SAS Institute Inc, Cary, NC) and SUDAAN (release 8.0.2, 2003, Research Triangle Institute, Research Triangle Park, NC) were used to calculate sample weighted means, standard errors, and population percentages. Multiple regression and multiple logistic regression models, with controls for covariates, were used to determine the predictability of total calcium intake from breakfast consumption compared to breakfast nonconsumption, and from inclusion of RTEC and milk in the breakfast meal compared with breakfast meal content without RTEC and milk.

RESULTS

RTEC was predominantly consumed at breakfast. Average calcium intake at breakfast was seven times greater when RTEC was consumed with milk than when RTEC was consumed without milk. In multiple regression analyses, breakfast consumption, and milk consumption with or without RTEC all strongly predicted total daily calcium intake (P<0.05) while controlling for covariates. The percentage of respondents below the Adequate Intake level for calcium was higher for non-RTEC breakfast consumers than for RTEC breakfast consumers in all age-sex categories except those older than age 70 years, and girls aged 9 to 13 years.

CONCLUSIONS

Consumption of RTEC at breakfast was associated with greater daily intake of both milk and calcium in all age and sex groups in the US population.

Calcium supplementation for improving bone mineral density in children

BACKGROUND

Clinical trials have shown that calcium supplementation in children can increase bone mineral density (BMD) although this effect may not be maintained. There has been no quantitative systematic review of this intervention.

OBJECTIVES

. To determine the effectiveness of calcium supplementation for improving BMD in children. . To determine if any effect varies by sex, pubertal stage, ethnicity or level of physical activity, and if any effect persists after supplementation is ceased.

SEARCH STRATEGY

We searched CENTRAL, (Cochrane Central Register of Controlled Trials) (Issue 3, 2005), MEDLINE (1966 to 1 April 2005), EMBASE (1980 to 1 April 2005), CINAHL (1982 to 1 April 2005), AMED (1985 to 1 April 2005), MANTIS (1880 to 1 April 2005) ISI Web of Science (1945 to 1 April 2005), Food Science and Technology Abstracts (1969 to 1 April 2005) and Human Nutrition (1982 to 1 April 2005). Conference abstract books (Osteoporosis International, Journal of Bone and Mineral Research) were hand-searched.

SELECTION CRITERIA

Randomised controlled trials of calcium supplementation (including by food sources) compared with placebo, with a treatment period of at least 3 months in children without co-existent medical conditions affecting bone metabolism. Outcomes had to include areal or volumetric BMD, bone mineral content (BMC), or in the case of studies using quantitative ultrasound, broadband ultrasound attenuation and ultrasonic speed of sound, measured after at least 6 months of follow-up.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data including adverse events. We contacted study authors for additional information.

MAIN RESULTS

The 19 trials included 2859 participants, of which 1367 were randomised to supplementation and 1426 to placebo. There was no heterogeneity in the results of the main effects analyses to suggest that the studies were not comparable. There was no effect of calcium supplementation on femoral neck or lumbar spine BMD. There was a small effect on total body BMC (standardised mean difference (SMD) +0.14, 95% CI+0.01, +0.27) and upper limb BMD (SMD +0.14, 95%CI +0.04, +0.24). Only the effect in the upper limb persisted after supplementation ceased (SMD+0.14, 95%CI+0.01, +0.28). This effect is approximately equivalent to a 1.7% greater increase in supplemented groups, which at best would reduce absolute fracture risk in children by 0.1-0.2%per annum. There was no evidence of effect modification by baseline calcium intake, sex, ethnicity, physical activity or pubertal stage. Adverse events were reported infrequently and were minor.

AUTHORS' CONCLUSIONS

While there is a small effect of calcium supplementation in the upper limb, the increase in BMD which results is unlikely to result in a clinically significant decrease in fracture risk. The results do not support the use of calcium supplementation in healthy children as a public health intervention. These results cannot be extrapolated to children with medical conditions affecting bone metabolism.

Osteoporosis in children and adolescents: etiology and management

Bone mass increases progressively during childhood, but mainly during adolescence when approximately 40% of total bone mass is accumulated. Peak bone mass is reached in late adolescence, and is a well recognised risk factor for osteoporosis later in life. Thus, increasing peak bone mass can prevent osteoporosis. The critical interpretation of bone mass measurements is a crucial factor for the diagnosis of osteopenia/osteoporosis in children and adolescents. To date, there are insufficient data to formally define osteopenia/osteoporosis in this patient group, and the guidelines used for adult patients are not applicable. In males and females aged <20 years the terminology 'low bone density for chronologic age' may be used if the Z-score is less than -2. For children and adolescents, this terminology is more appropriate than osteopenia/osteoporosis. Moreover, the T-score should not be used in children and adolescents. Many disorders, by various mechanisms, may affect the acquisition of bone mass during childhood and adolescence. Indeed, the number of disorders that have been identified as affecting bone mass in this age group is increasing as a consequence of the wide use of bone mass measurements. The increased survival of children and adolescents with chronic diseases or malignancies, as well as the use of some treatment regimens has resulted in an increase in the incidence of reduced bone mass in this age group. Experience in treating the various disorders associated with osteoporosis in childhood is limited at present. The first approach to osteoporosis management in children and adolescents should be aimed at treating the underlying disease. The use of bisphosphonates in children and adolescents with osteoporosis is increasing and their positive effect in improving bone mineral density is encouraging. Osteoporosis prevention is a key factor and it should begin in childhood. Pediatricians should have a fundamental role in the prevention of osteoporosis, suggesting strategies to achieve an optimal peak bone mass.

Effects of calcium, dairy product, and vitamin D supplementation on bone mass accrual and body composition in 10-12-y-old girls: a 2-y randomized trial

BACKGROUND

Little is known about the relative effectiveness of calcium supplementation from food or pills with or without vitamin D supplementation for bone mass accrual during the rapid growth period.

OBJECTIVE

The purpose was to examine the effects of both food-based and pill supplements of calcium and vitamin D on bone mass and body composition in girls aged 10-12 y.

DESIGN

This placebo-controlled intervention trial randomly assigned 195 healthy girls at Tanner stage I-II, aged 10-12 y, with dietary calcium intakes <900 mg/d to 1 of 4 groups: calcium (1000 mg) + vitamin D3 (200 IU), calcium (1000 mg), cheese (1000 mg calcium), and placebo. Primary outcomes were bone indexes of the hip, spine, and whole body by dual-energy X-ray absorptiometry and of the radius and tibia by peripheral quantitative computed tomography.

RESULTS

With the use of intention-to-treat or efficacy analysis, calcium supplementation with cheese resulted in a higher percentage change in cortical thickness of the tibia than did placebo, calcium, or calcium + vitamin D treatment (P = 0.01, 0.038, and 0.004, respectively) and in higher whole-body bone mineral density than did placebo treatment (P = 0.044) when compliance was >50%. With the use of a hierarchical linear model with random effects to control for growth velocity, these differences disappeared.

CONCLUSIONS

Increasing calcium intake by consuming cheese appears to be more beneficial for cortical bone mass accrual than the consumption of tablets containing a similar amount of calcium. Diverse patterns of growth velocity may mask the efficacy of supplementation in a short-term trial of children transiting through puberty.

Improvement of nutrition stimulates bone mineral gain in Japanese school children and adolescents

Calcium supplementation could accelerate bone mineral accrual, but the effect of other dietary factors in children is unclear. The aim of this study was to determine associations of changes in diet with bone accrual in Japanese children. All female (n=262) and male (n=286) school children aged 10-15 years living in a small town were recruited. We measured bone status at the os calcis using quantitative ultrasound (QUS) and assessed diet and other lifestyle factors using questionnaires annually for 5 years. The greatest increase in QUS values was observed between ages 11-13 years in boys and girls and peak bone status was attained typically by age 14-15 years (approximately 2 years since menarche) in girls and 1-2 years later in boys. Initial bone status adjusted by height and weight in 10-year-old or 11-year-old children was associated positively with intake of small fish and dairy products, and negatively with age of menarche in girls, and negatively with preference for meat in boys. Annual increase in QUS bone status in girls age 10 years or 11 years was associated positively with increased intake of fish, fruit, vegetables, soybeans, and intake of milk products and negatively with preference for meat. Annual increase in QUS bone status in boys was associated positively with increased height and weight, increased intake of small fish and vegetables, intake of dairy products, and awareness of bone measurement. Thus, a dietary change incorporating an increased intake of fish, fruit, vegetables, and soy products could lead to higher bone QUS values in children.

Low calcium and vitamin D intake in healthy children and adolescents and their correlates

BACKGROUND

Optimal dietary calcium and possibly vitamin D intake throughout childhood and adolescence may enhance bone mineral accrual. Little data on the intake of these nutrients in Mediterranean countries exist, and predictors of their suboptimal intake are not well defined.

OBJECTIVE

To evaluate systematically the effect of gender, lifestyle factors, and socioeconomic status on mean calcium and vitamin D intake in healthy school children and adolescents from Lebanon.

DESIGN

A total of 385 students aged 10-16 y were selected from four public and four private schools between Fall 1999 and Spring 2000. Information on calcium and vitamin D intake, through a semiquantitative food frequency questionnaire that was validated against a 7-day daily record, and on socioeconomic and lifestyle factors were obtained.

RESULTS

Only 12% of the students met the adequate intake (AI) recommendation of 1300 mg of calcium/day, and only 16% met the AI recommendation of 200 IU of vitamin D/day. Boys had a significantly higher mean daily calcium intake than girls. Socioeconomic status as assessed by children's pocket money was a predictor of higher calcium and vitamin D intake. Eating breakfast and physical activity were other correlates of daily calcium and vitamin D intake.

CONCLUSIONS

Only a minority of students in our study met the AI for calcium and vitamin D. Gender, lifestyle factors, and socioeconomic status were significant predictors of calcium and vitamin D intake. Our findings have important implications regarding the institution of dietary public health strategies to promote skeletal health in Mediterranean countries during a critical time for bone mass accrual.

Teenage girls and elderly women living in northern Europe have low winter vitamin D status

OBJECTIVE

To determine the vitamin D status (serum 25-hydroxyvitamin D; S-25OHD) in adolescent girls and elderly community-dwelling women living in four countries of northern Europe and to explain differences in S-25OHD concentrations between and within the countries.

DESIGN

A cross-sectional observational study conducted in a standardised way during February-March. S-25OHD was analysed by high-performance liquid chromatography. Vitamin D and calcium intake was calculated using a standardised food composition database.

SETTING

Denmark, Finland, Ireland, and Poland.

SUBJECTS

A total of 199 girls (mean (s.d.) age 12.6 (0.5) y) and 221 women (mean (s.d.) age 71.8 (1.4) y).

RESULTS

The median (inter quartiles) concentration of S-25OHD was 29.4 (20.3, 38.3) nmol/l for the girls and 40.7 (28.0, 54.2) nmol/l for the women. S-25OHD below 25 nmol/l was found in 37% of the girls and 17% of the women, and S-25OHD below 50 nmol/l was found in 92% of the girls and 37% of the women. Positive significant determinants for S-25OHD in girls were use of vitamin D supplements, and in women sun habits, dietary vitamin D intake, use of vitamin D and calcium supplements. Body mass index and smoking were negative determinants in women. For women predictors could explain the differences between countries (P(country) = 0.09, R(2) = 0.39), but for girls the difference remained significant even after including predictors (P(country) = 0.03, R(2) = 0.15).

CONCLUSION

Vitamin D status is low in northern Europe during winter. More than one-third of the adolescent girls have vitamin D status below 25 nmol/l and almost all are below 50 nmol/l. Two-thirds of the elderly community-dwelling women have vitamin D status below 50 nmol/l. Use of vitamin D supplements is a significant positive determinant for S-25OHD for both girls and women (P = 0.001).

SPONSORSHIP

The European Fifth Framework Programme (Contract No. QLK1-CT-2000-00623).

Girls on a high-calcium diet gain weight at the same rate as girls on a normal diet: A pilot study

OBJECTIVE

To determine whether pubertal girls assigned to calcium-rich diets or their usual calcium intakes differ significantly in weight gain.

DESIGN

This is a pilot study conducted on data from an experimental research project.

SUBJECTS/SETTING

The sample included 59 girls, 9 years of age, from Omaha metropolitan communities.

INTERVENTION

Participants were randomly assigned to a calcium-rich diet supplying at least 1,500 mg of calcium per day or their usual diet.

MAIN OUTCOME MEASURE

The outcome measure was change in weight during 2 years of study.

STATISTICAL ANALYSES

Data were analyzed using descriptive statistics, Mann-Whitney U, t tests of paired and independent samples, and analysis of covariance.

RESULTS

The girls in the calcium-rich diet group had a mean (+/-standard deviation) calcium intake of 1,656+/-191 mg/day, whereas the girls on their usual diets averaged 961+/-268 mg/day. Although the participants in the treatment group consumed nearly twice as much dietary calcium--primarily from dairy foods--they did not have greater increases in body weight, body mass index, or fat or lean mass than the control group. These findings held when the data were grouped by tertile of calcium intake. Compared with girls on their usual diets, the girls who consumed the calcium-rich diet also significantly increased their intake of essential nutrients.

CONCLUSION

We conclude that calcium-rich diets do not cause excessive weight gain in pubertal girls but do contribute positively to overall nutrition. These findings provide support for programs to promote calcium-rich diets, which are critical for attaining peak bone mass.

Adolescent dairy consumption and physical activity associated with bone mass

BACKGROUND

This study identifies key modifiable factors influencing Asian and White adolescent bone development. Cross-sectional analysis of baseline data of cohort.

METHODS

Three hundred and twenty-three girls were examined from age-eligible girls at Kaiser Permanente Oahu in Hawaii. Girls' age, ethnicity, Tanner stage, 3-day diet record, level of physical activity, anthropometry, and calcaneal bone status were obtained by questionnaire and measurement, respectively. Lunar Achilles calcaneal was used to measure calcaneal bone mass. Multiple regression was used for analysis of factors influencing bone mass.

RESULTS

The mean age of adolescents was 11.6 +/- 1.5 years. Girls were generally ethnically mixed; the mean Asian ethnic proportion was 48% while White ethnic proportion was 43% and other ethnic proportion was 10%. Multiple regression explained 40.8% and 25.6% of the variation in calcaneal broadband ultrasound attenuation (BUA) and speed of sound (SOS), respectively, in a model where age, weight, biacromial breadth, Tanner pubic hair stage, Asian ethnicity, dairy intake, and physical activity positively influenced bone mass.

CONCLUSIONS

Tanner pubic hair stage, ethnicity, and biacromial breadth had the greatest influence on SOS; while physical activity, body weight, and dairy product intake had the greatest influence on BUA.

Nutrition-related habits of Greek adolescents

OBJECTIVE

To investigate nutrition-related habits of Greek school-aged adolescents.

DESIGN

Epidemiological survey.

SETTING AND SUBJECTS

The study was part of the Health Behavior in School Aged Children (HBSC) survey. A representative sample of school-aged adolescents aged 11.5, 13.5, and 15.5 y was obtained. The final sample consisted of 4211 students (51.6% girls and 48.4% boys). They were asked to complete a translated form of the international HBSC questionnaire, including several thematic entities. The Unhealthy Food Choices Score (UFCS) was devised in order to evaluate the overall quality of reported eating habits of respondents; the higher the score, the lower the diet quality.

RESULTS

Among all students surveyed, 14.7% were reported to be on a diet to lose weight (girls: 19.5%; boys: 9.7%; P<0.001), and 22.9% were dissatisfied with their body weight but not on a diet. Girls were found to have lower UFCS values compared to boys (24.7 +/- 4.6 vs 24.1 +/- 4.5, P<0.001). Girls dissatisfied with their weight, but not on a diet, showed the highest UFCS values compared to both those on a diet and those not on a diet. TV viewing was positively associated with the consumption of sodas, crisps, cakes and pastries, and sweets and chocolates.

CONCLUSIONS

Dieting is becoming a major problem, especially among older girls. The findings of this study suggest that eating habits of Greek school-aged adolescents are in the process of changing from more traditional to more Westernized ones.

Dietary n-3 fatty acids decrease osteoclastogenesis and loss of bone mass in ovariectomized mice

The mechanisms of action of dietary fish oil (FO) on osteoporosis are not fully understood. This study showed FO decreased bone loss in ovariectomized mice because of inhibition of osteoclastogenesis. This finding supports a beneficial effect of FO on the attenuation of osteoporosis.

INTRODUCTION

Consumption of fish or n-3 fatty acids protects against cardiovascular and autoimmune disorders. Beneficial effects on bone mineral density have also been reported in rats and humans, but the precise mechanisms involved have not been described.

METHODS

Sham and ovariectomized (OVX) mice were fed diets containing either 5% corn oil (CO) or 5% fish oil (FO). Bone mineral density was analyzed by DXA. The serum lipid profile was analyzed by gas chromatography. Receptor activator of NF-kappaB ligand (RANKL) expression and cytokine production in activated T-cells were analyzed by flow cytometry and ELISA, respectively. Osteoclasts were generated by culturing bone marrow (BM) cells with 1,25(OH)2D3. NF-kappaB activation in BM macrophages was measured by an electrophoretic mobility shift assay.

RESULTS AND CONCLUSION

Plasma lipid C16:1n6, C20:5n3, and C22:6n3 were significantly increased and C20:4n6 and C18:2n6 decreased in FO-fed mice. Significantly increased bone mineral density loss (20% in distal left femur and 22.6% in lumbar vertebrae) was observed in OVX mice fed CO, whereas FO-fed mice showed only 10% and no change, respectively. Bone mineral density loss was correlated with increased RANKL expression in activated CD4+ T-cells from CO-fed OVX mice, but there was no change in FO-fed mice. Selected n-3 fatty acids (docosahexaenoic acid [DHA] and eicosapentaenoic acid [EPA]) added in vitro caused a significant decrease in TRACP activity and TRACP+ multinuclear cell formation from BM cells compared with selected n-6 fatty acids (linoleic acid [LA] and arachidonic acid [AA]). DHA and EPA also inhibited BM macrophage NF-kappaB activation induced by RANKL in vitro. TNF-alpha, interleukin (IL)-2, and interferon (IFN)-gamma concentrations from both sham and OVX FO-fed mice were decreased in the culture medium of splenocytes, and interleukin-6 was decreased in sham-operated FO-fed mice. In conclusion, inhibition of osteoclast generation and activation may be one of the mechanisms by which dietary n-3 fatty acids reduce bone loss in OVX mice.

Normal bone accretion and effects of nutritional disorders in childhood

Although osteoporosis is usually considered to be a health concern of the elderly, increased attention is being paid to children and adolescents who are at risk for developing this devastating disease. As osteoporosis is a preventable condition with no identified cure, focus has been placed on modifiable areas in a young person's life that may prevent the development of the disease. A child or adolescent's nutrition is an example of such an area. This review examines factors influencing normal bone development and emphasizes the importance of the adolescent years as a time for peak bone accretion. Current methods to evaluate skeletal status are examined, including the challenges that arise in interpreting bone densities in children who have growing bones. Children and adolescents who are at high risk for osteoporosis are discussed, with an emphasis on groups in whom poor nutrition likely mediates bone loss. Two models of malnutrition, anorexia nervosa and the female athlete triad, are discussed, with emphasis on the way in which each has deleterious effects on the adolescent skeleton. The promotion of skeletal health is ultimately the encouragement of good general health principles for all young people. Approaches for working with children and adolescents are reviewed, including literature supporting each strategy.

Testing the effectiveness of an osteoporosis educational program for nursing students in Thailand

OBJECTIVE

Osteoporosis, a health problem that is on the rise, has received considerable attention among the health care community and the public. The majority of primary prevention programs for osteoporosis have been focused on women in mid-life. A concern is that young women may not be aware of osteoporosis risk factors and therefore may not be engaging in preventive behaviors. The purpose of this study was to test the effectiveness of an osteoporosis educational program for young women.

METHODS

A sample of 100 female undergraduate students who were enrolled in the first year of a nursing program in Thailand were randomly assigned to a control group or an experimental group. Participants in the experimental group participated in a 3-hour osteoporosis educational program (OEP). At entry to and exit from the study, all participants completed the Osteoporosis Knowledge Test, the Osteoporosis Health Belief Scale, and the Osteoporosis Self-Efficacy Scale.

RESULTS

The experimental group had higher change scores for knowledge, health belief, and self-efficacy than the control group. The OEP increased knowledge of osteoporosis in these young women.

CONCLUSION

These findings indicate the need for further health education concerning the importance of dietary calcium and exercise on osteoporosis prevention in young women.

Calcium and vitamin D nutrition and bone disease of the elderly

Osteoporosis, a systemic skeletal disease characterized by a low bone mass, is a major public health problem in EC member states because of the high incidence of fragility fractures, especially hip and vertebral fracture. In EC member states the high incidence of osteoporotic fractures leads to considerable mortality, morbidity, reduced mobility and decreased quality of life. In 1995 the number of hip fractures in 15 countries of EC has been 382,000 and the estimated total care cost of about 9 billion of ECUs. Given the magnitude of the problem public health measures are important for preventive intervention. Skeletal bone mass is determined by a combination of endogenous (genetic, hormonal) and exogenous (nutritional, physical activity) factors. Nutrition plays an important role in bone health. The two nutrients essential for bone health are calcium and vitamin D. Reduced supplies of calcium are associated with a reduced bone mass and osteoporosis, whereas a chronic and severe vitamin D deficiency leads to osteomalacia, a metabolic bone disease characterized by a decreased mineralization of bone. Vitamin D insufficiency, the preclinical phase of vitamin D deficiency, is most commonly found in the elderly. The major causes of vitamin D deficiency and insufficiency are decreased renal hydroxylation of vitamin D, poor nutrition, scarce exposition to sunlight and a decline in the synthesis of vitamin D in the skin. The daily average calcium intake in Europe has been evaluated in the SENECA study concerning the diet of elderly people from 19 towns of 10 European countries. In about one third of subjects the dietary calcium intake results were very low, between 300 and 600 mg/day in women, and 350 and 700 mg/day in men. Calcium supplements reduce the rate of bone loss in osteoporotic patients. Some recent studies have reported a significant positive effect of calcium treatment not only on bone mass but also on fracture incidence. The SENECA study, has also shown that vitamin D insufficiency is frequent in elderly populations in Europe. There are a number of studies on the effects of vitamin D supplementation on bone loss in the elderly, showing that supplementations with daily doses of 400-800 IU of vitamin D, given alone or in combination with calcium, are able to reverse vitamin D insufficiency, to prevent bone loss and to improve bone density in the elderly. In recent years, there has been much uncertainty about the intake of calcium for various ages and physiological states. In 1998, the expert committee of the European Community in the Report on Osteoporosis-Action on prevention, has given the recommended daily dietary allowances (RDA) for calcium at all stage of life. For the elderly population, above age 65 the RDA is 700-800 mg/day. The main source of calcium in the diet are dairy products (milk, yoghurts and cheese) fish (sardines with bones), few vegetables and fruits. The optimal way to achieve adequate calcium intake is through the diet. However, when dietary sources are scarce or not well tolerated, calcium supplementation may be used. Calcium is generally well tolerated and reports of significant side-effects are rare. Adequate sunlight exposure may prevent and cure vitamin D insufficiency. However, the sunlight exposure or the ultraviolet irradiation are limited by concern about skin cancer and skin disease. The most rational approach to reducing vitamin D insufficiency is supplementation. In Europe, the RDA is 400-800 IU (10-20 microg) daily for people aged 65 years or over. This dose is safe and free of side effects. In conclusion, in Europe a low calcium intake and a suboptimal vitamin D status are very common in the elderly. Evidence supports routine supplementation for these people at risk of osteoporosis, by providing a daily intake of 700-800 mg of calcium and 400-800 IU of vitamin D. This is an effective, safe and cheap means of preventing osteoporotic fractures.

Hypovitaminosis D in healthy schoolchildren

BACKGROUND

Vitamin D is essential for skeletal growth, but there are currently no guidelines for vitamin D supplementation after infancy. This study investigates vitamin D insufficiency in healthy children.

METHODS

Children ages 10 to 16 years from 3 private schools in Beirut, Lebanon, with differing socioeconomic status (SES) were studied: 169 in the spring of 1999 and 177 in the following fall; 83 students participated in both study phases. They had a physical examination, answered a dietary questionnaire, and blood was drawn for calciotropic hormones and indices of bone turnover.

RESULTS

Overall, 52% of the students were vitamin D-insufficient; the proportion of insufficiency was 65% in the winter and 40% at the end of the summer. During both seasons, girls had lower vitamin D levels than did boys; those who followed the dress code of covered head, arms, and legs had the lowest levels. Students in the mid-SES school had lower 25-hydroxyvitamin D (25-OHD) levels than did the ones from the high-SES school. After adjusting for confounders, gender, SES, and body mass index remained the significant predictors of vitamin D levels in both seasons (R(2) = 0.53, for spring and 0.28 for fall). There was a significant inverse correlation between 25-OHD levels and parathyroid hormone levels that was best fitted by a curvilinear model (R(2) = 0.19).

CONCLUSION

Even in a sunny country, hypovitaminosis D is common in schoolchildren, more so in the winter. Girls, especially those with a lower SES, are at particular risk. The inverse changes in parathyroid hormone suggest that insufficient vitamin D levels may deleteriously affect skeletal metabolism in healthy adolescents. Vitamin D insufficiency may be prevalent in many other countries where supplementation of milk with vitamin D is not mandatory. Our results call to a reconsideration of vitamin D supplementation in high-risk adolescents to further optimize skeletal health. vitamin D insufficiency, bone metabolism, nutrition, gender, socioeconomic status.

Pathogenesis of osteoporosis

Osteoporosis is a very common disorder affecting millions of post-menopausal women and men of various ages. Although the disease is manifested by painful fractures of the spine, hip or radius, the underlying pathogenesis is complex and multifactorial. One of the strongest predictors of future osteoporotic fractures is low bone mineral density. The determinants of adult bone density include the rate of bone acquisition during adolescence and the absolute loss of bone during the six decades of adult life. Recent studies have clarified how bone mass is acquired during the early teen years in both boys and girls. Genetic factors play an enormous role in defining the height of acquisition of bone mass; however, these factors also interact with environmental and hormonal determinants. Many more studies have focused on adult bone loss. Disorders in bone remodelling result in an imbalance in bone turnover, favouring resorption over formation. Systemic factors such as oestrogen deprivation and parathyroid hormone strongly activate remodelling and can, in several circumstances, lead to imbalances in the remodelling cycle. The molecular cues that couple bone formation to resorption have recently been elucidated, and those factors may themselves become therapeutic targets for future treatment regimens to prevent osteoporosis and its resultant fractures.