Milk consumption and bone mineral content in Chinese adolescent girls

Prevalence of Overweight, Obesity, and Dietary Behaviors among Adolescents in Dubai Schools: A Complex Design Survey 2019

Background: Overweight and obesity in adolescence have become a public health challenge. Health effects due to overweight and obesity appear during adolescence and continue into adulthood. Modifiable factors associated with overweight and obesity include unhealthy dietary behaviors and lack of exercise. Assessment of the prevalence of overweight and obesity and unhealthy dietary behaviors is essential to plan for preventive programs at the population level. Objectives: The aim of the study was to estimate the prevalence of overweight, obesity, and unhealthy dietary behaviors among adolescents of grades 8–12 in Dubai schools, 2019. Method: The Adolescents Risk Behavioral Survey (ARBS) is a 2-stage stratified cluster study. The 1st stage involved randomly selecting schools with a probability proportional to the size and the 2nd stage was randomly selecting classes, and all students in the selected classes were invited to participate; the total participants were 1,683 adolescents from grades 8–12 from 28 private and government schools. Students answered a self-administrated electronic questionnaire. Anthropometric measures including height and weight were assessed by a trained school nurse. Body mass index was calculated and classified according to World Health Organization (WHO) growth charts for sex and age. Data were analyzed with adjustment for weight, primary sampling unit, and stratum. Results: Among the adolescents of Dubai schools studying in grades 8–12, the prevalence of overweight was 25.3% (95% confidence interval [CI]: 22.7–28.2) and obesity was 15% (95% CI: 13.0–18.9). Overweight did not vary between male and female students, but obesity was higher among male students 19.9% (95% CI: 15.4–25.1) than female students 11.8% (95% CI: 8.7–15.6) (p = 0.0261). Age and grade were not found to be associated with overweight or obesity. The prevalence of unhealthy dietary behaviors was common. Examining dietary habits from 30 days prior to the survey, 21.3% of adolescents (95% CI: 17.2–26.1) reported not eating fruits and 19.7% (95% CI: 15.7–24.4) not eating vegetables. With regard to consuming dairy, 3.3% of adolescents (95% CI: 10.9–16.1) did not drink milk or consume dairy products in the 7 days prior to the survey, 31% of adolescents (95% CI: 26.8–35.5) consumed a carbonated drink daily, and 18.4% did not eat breakfast on all 7 days during and before the survey. Eating fast food was high among adolescents as 78.9% reported eating fast food one or more days in the week preceding the survey. Conclusion: School programs for overweight and obesity need further strengthening and to extend their scope to outside of the school community.

Milk Consumption and Bone Mineral Density in Adults: Using Data from the Korea National Health and Nutrition Examination Survey 2008-2011

Background

Milk consumption is associated with bone mineral density (BMD), but reports are limited in terms of participant age, sex, and number of study subjects. We investigated the association between milk consumption and BMD in South Korean adults (≥20 years).

Methods

We analyzed men and women aged ≥20 years who participated in the Korean National Health and Nutrition Examination Survey, 2008–2011. We used linear regression to calculate the mean BMD and 95% confidence interval (CI) based on the frequency of milk consumption. Multivariate logistic regression analysis was used to estimate the odds ratios (ORs) and 95% CI for T-scores ≤-2.5 (osteoporosis) in both men aged ≥50 years and postmenopausal women.

Results

In total 8,539 subjects were studied. Drinking milk more than once a day was associated with higher BMD in the total femur and femoral neck in men aged <50 years and lumbar spine in men aged ≥50 years, compared to less than once a week. It was also associated with lower ORs for osteoporosis of the femoral neck and lumbar spine in men aged ≥50 years (OR, 0.35; 95% CI, 0.125–0.979 and OR, 0.34; 95% CI, 0.143–0.804, respectively). In postmenopausal women who consumed milk 2–6 times weekly, higher BMD and lower OR for osteoporosis were observed in the total femur (OR, 0.23; 95% CI, 0.055–0.958).

Conclusion

This study suggests that frequent milk consumption could potentially reduce osteoporosis incidence in South Korean adults. Further prospective study is necessary to elucidate the effect of milk consumption on BMD.

Community-based interventions to increase dairy intake in healthy populations: a systematic review

Background

Considering the low frequency of dairy intake in the population, interventions aiming to increase its consumption can be a priority for any health system.

Objective

This study aims to summarize community-based interventions for improving dairy consumption and their effectiveness to help policy-makers in designing coherent public health strategies.

Methods

This study was conducted in 2019, using PubMed/MEDLINE, Scopus, EMBASE, Cochrane Library, Web of Science, ProQuest, and Google Scholar. Two independent reviewers selected the eligible studies, and the outcomes of interest were extracted. The quality of eligible studies was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for randomized controlled trials and quasi-experimental studies.

Results

Out of 521 initially identified articles, 25 studies were included. Interventions reported in 19 studies were effective in increasing dairy consumption. Interventions in high-income countries were more effective than those in middle- and low-income countries. Interventions in health centers and supermarkets were more effective than the community and school-level interventions. Interventions in supermarkets and adolescents as target groups were more effective than children, middle-aged people, and the elderly. Also, educational interventions and changing buying/selling pattern were more effective than multiple interventions. Interventions longer than 24 and 48 weeks were more effective than shorter interventions.

Conclusion

Three policy options including educational interventions, multiple interventions, and changing the purchase pattern are suggested. It seems that applying all of the interventions together can be more effective. Also, long-term and well-designed future studies in different settings are recommended to confirm these results.

Lactose Intolerance and Bone Health: The Challenge of Ensuring Adequate Calcium Intake

Calcium is an important nutrient with impact upon many biological systems, most notably bone. Ensuring adequate calcium intake throughout the lifespan is essential to building and maintaining bone. Lactose intolerance may predispose individuals to low calcium intake as the number of lactose-free, calcium-rich food sources is limited. In this review, we summarize data from human and animal studies on the influence of lactose and lactase deficiency on calcium absorption and bone health. Based on the available evidence, neither dietary lactose nor lactase deficiency have a significant impact on calcium absorption in adult humans. However, lactose intolerance may lead to reduced bone density and fragility fractures when accompanied by decreased intake or avoidance of dairy. Recently published human trials and meta-analyses suggest a weak but significant association between dairy consumption and bone health, particularly in children. Given the availability of simple dietary approaches to building lactose tolerance and the nutritional deficiencies associated with dairy avoidance, multiple public health organizations recommend that all individuals—including those that are lactose intolerant—consume three servings of dairy per day to ensure adequate nutrient intakes and optimal bone health.

Are milk and alternatives and fruit and vegetable intakes during adolescence associated with cortical and trabecular bone structure, density, and strength in adulthood?

We investigated the impact of food group intake during adolescence on bone structure and strength during adulthood. In females, we found a beneficial effect of adolescent milk and alternatives and fruit and vegetable intake on adult radius shaft and distal tibia bone structure, respectively. No association was observed in males.

INTRODUCTION

The purpose of this study was to investigate whether adolescents with high intake of milk and alternatives (M&A) or fruit and vegetables (F&V) had better adult bone structure and strength compared to those with low intake levels.

METHODS

We analyzed data from 47 males and 69 females enrolled in the Pediatric Bone Mineral Accrual Study (PBMAS 1991-2011), who had one peripheral quantitative computed tomography scan at age 29 ± 2 years. We measured radius and tibia shaft total area (ToA), cortical area (CoA), cortical content (CoC), cortical density, bone strength (SSI_p), and muscle area, as well as distal radius and tibia ToA, total density, trabecular area, trabecular content, trabecular density, and bone strength (BSI_c). Sequential 24-h recalls were used to assess M&A and F&V intake; participants were grouped for their mean intake during adolescence (low = bottom quartile, moderate = middle quartiles, high = top quartile) and were compared using multivariate analysis of covariance while adjusting for adult height, muscle area, physical activity, energy and calcium intake and adolescent energy intake, and physical activity.

RESULTS

Females with high M&A intake compared to low M&A intake group (mean 3.8 vs. 1.3 servings/day, respectively) had greater adult ToA (14 %, p < 0.05), CoA (15 %, p < 0.01), and CoC (16 %, p < 0.01) at radius shaft. Females with moderate F&V intake compared to low F&V intake group (mean 3.7 vs. 2.1 servings/day, respectively) had greater adult ToA (8.5 %, p < 0.05) at distal tibia.

CONCLUSION

Higher intake of M&A or F&V during adolescence had a long-term beneficial effect on bone structure in females, an association not observed in males.

Osteoporosis: Is milk a kindness or a curse?

Cow's milk is often severely criticized as a cause of multiple health problems, including an increased risk of fractures. A close look at the scientific literature shows a striking contradiction. On the one hand, experimental studies of surrogate markers (e.g., bone turnover markers and bone mineral density [BMD]) usually indicate benefits from drinking cow's milk. On the other, the findings from epidemiological studies are conflicting and disconcerting. In all age groups, including children and postmenopausal women, consuming cow's milk, powdered milk supplements, or whey protein is associated with a slower bone turnover and unchanged or higher BMD values. These benefits are particularly marked in populations where calcium deficiency is prevalent, for instance in Asian countries. No interventional studies have addressed the fracture risk potentially associated with drinking cow's milk. The only available data come from epidemiological observational studies, whose results are conflicting, with a lower fracture risk in some cases and no difference or a higher risk in others. Several hypotheses have been offered to explain these findings, such as a deleterious effect of D-galactose, lactose intolerance, and acid overload. Epidemiological studies face many obstacles when seeking to detect effects of a single food, particularly the multiplicity of interactions among foods. Furthermore, reliable dietary intake data must be collected over prolonged periods, often long before the occurrence of a fracture, and defective recall may therefore introduce a major yet often unrecognized bias, particularly in populations where calcium deficiency is uncommon. To date, there is no conclusive evidence that we should modify our currently high level of consumption of cow's milk.

Fluid intake from beverages across age groups: a systematic review

BACKGROUND

Fluid intake, especially water, is essential for human life and also necessary for physical and mental function. The present study aimed to assess beverage consumption across age groups.

METHODS

A systematic review was conducted. Original research in English language publications and available studies (or abstracts in English) from 2000 to 2013 was searched for by using the medical subheading (MeSH) terms: ('beverage' OR 'fluid' [Major]) AND ('consumption' [Mesh] OR 'drinking' [Mesh] OR 'intake' [Mesh]) AND ('child' [Mesh] OR 'adolescent' [Mesh] OR 'adult' [Mesh]). Article selection was restricted to those papers covering healthy populations of all age groups in a nationwide sample, or from a representative sample of the population of a city or cities, which examined the trends or patterns of beverage intake and the determinants of beverage intake. Sixty-five studies were identified with respect to beverage consumption across age groups. The papers were screened by thoroughly reading titles or abstracts. Full-text articles were assessed by three investigators.

RESULTS

Total beverage intake varied between 0.6 and 3.5 L day(-1) among all age groups (males more than females). Plain water contributed up to 58%, 75% and 80% of the total beverage intake in children, adolescents and adults, respectively. Milk consumption was higher among children; consumption of soft drinks was higher among adolescents; and the consumption of tea, coffee and alcoholic beverages was higher among adults.

CONCLUSIONS

Plain water is the main water source for all age groups and the consumption of other beverages varies according to age.

Nutritional status and dietary intakes of children aged 6 months to 12 years: findings of the Nutrition Survey of Malaysian Children (SEANUTS Malaysia)

The dual burden of malnutrition reportedly coexists in Malaysia; however, existing data are scarce and do not adequately represent the nutritional status of Malaysian children. The Nutrition Survey of Malaysian Children was carried out with the aim of assessing the nutritional status in a sample of nationally representative population of children aged 6 months to 12 years. A total of 3542 children were recruited using a stratified random sampling method. Anthropometric measurements included weight, height, mid-upper arm circumference, and waist and hip circumferences. Blood biochemical assessment involved analyses of Hb, serum ferritin, and vitamins A and D. Dietary intake was assessed using semi-quantitative FFQ, and nutrient intakes were compared with the Malaysian Recommended Nutrient Intakes (RNI). The prevalence of overweight (9·8 %) and obesity (11·8 %) was higher than that of thinness (5·4 %) and stunting (8·4 %). Only a small proportion of children had low levels of Hb (6·6 %), serum ferritin (4·4 %) and vitamin A (4·4 %), but almost half the children (47·5 %) had vitamin D insufficiency. Dietary intake of the children was not compatible with the recommendations, where more than one-third did not achieve the Malaysian RNI for energy, Ca and vitamin D. The present study revealed that overnutrition was more prevalent than undernutrition. The presence of high prevalence of vitamin D insufficiency and the inadequate intake of Ca and vitamin D are of concern. Hence, strategies for improving the nutritional status of Malaysian children need to consider both sides of malnutrition and also put emphasis on approaches for the prevention of overweight and obesity as well as vitamin D insufficiency.

Vitamin d, calcium, and dairy intakes and stress fractures among female adolescents

OBJECTIVE To identify whether calcium, vitamin D, and/or dairy intakes are prospectively associated with stress fracture risk among female adolescents. DESIGN Prospective cohort study. SETTING Adolescent girls living throughout the United States. PARTICIPANTS A total of 6712 girls aged 9 to 15 years at baseline in the Growing Up Today Study, an ongoing prospective cohort study. MAIN EXPOSURES Dairy, calcium, and vitamin D intakes assessed by food frequency questionnaire every 12 to 24 months between 1996 and 2001. MAIN OUTCOME MEASURE Incident stress fracture that occurred between 1997 and 2004 as reported by mothers of the participants in 2004. Cox proportional hazards models were used to examine associations. RESULTS During 7 years of follow-up, 3.9% of the girls developed a stress fracture. Dairy and calcium intakes were unrelated to risk of developing a stress fracture. However, vitamin D intake was inversely related to stress fracture risk. The multivariable-adjusted hazard ratio of stress fracture for the highest vs the lowest quintile of vitamin D intake was 0.49 (95% CI, 0.24-1.01; Ptrend = .07). We conducted a stratified analysis to estimate the association between vitamin D intake and stress fracture risk among girls participating in at least 1 h/d of high-impact activity, among whom 90.0% of the stress fractures occurred, and found that higher vitamin D intake predicted significantly lower risk of stress fracture (Ptrend = .04). CONCLUSIONS Vitamin D intake is associated with lower stress fracture risk among adolescent girls who engage in high levels of high-impact activity. Neither calcium intake nor dairy intake was prospectively associated with stress fracture risk.

A milk and cereal dietary pattern is associated with a reduced likelihood of having a low bone mineral density of the lumbar spine in Korean adolescents

The traditional rice-based Korean diet has been changing toward a Western-style diet. This change has been especially rapid among adolescents. The purpose of this study was to investigate the association between dietary patterns and bone health among Korean adolescents. This cross-sectional study was conducted on 196 adolescents aged 12 to 15 years. Information on the general characteristics of the subjects was obtained through a questionnaire, and dietary intake was assessed with 6-day food records. Bone mineral densities (BMDs) of the lumbar spine and femur were measured by dual-energy x-ray absorptiometry. Dietary patterns were derived from 24 food groups using factor analysis. Four distinct dietary patterns-traditional Korean, fast food, milk and cereal, and snacks-were identified and accounted for 28.4% of the total variance. After adjusting for sex, age, body mass index percentiles, weight loss attempts, pubertal status, and regular exercise, the adolescents in the highest tertile of the "milk and cereal" dietary pattern score had significantly a reduced likelihood of having low BMD compared with those in the lowest tertile of this diet at the lumbar spine (odds ratio, 0.36; 95% confidence interval, 0.14-0.93; P = .0461). The other dietary patterns were not associated with the BMD of Korean adolescents. These results indicate that the intake of milk and cereal is important for the bone health of Korean adolescents, whose diets are composed mainly of grains and vegetables.

Epigenetic influences in the developmental origins of osteoporosis

Osteoporosis is a major public health problem due to consequent fragility fractures; data from the UK suggest that up to 50% of women and 20% men aged 50 years will have an osteoporosis-related fracture in their remaining lifetime. Skeletal size and density increase from early embryogenesis through intrauterine, infant, childhood and adult life to reach a peak in the third to fourth decade. The peak bone mass achieved is a strong predictor of later osteoporosis risk. Epidemiological studies have demonstrated a positive relationship between early growth and later bone mass, both at peak and in later life, and also with reduced risk of hip fracture. Mother-offspring cohorts have allowed the elucidation of some of the specific factors in early life, such as maternal body build, lifestyle and 25(OH)-vitamin D status, which might be important. Most recently, the phenomenon of developmental plasticity, whereby a single genotype may give rise to different phenotypes depending on the prevailing environment, and the science of epigenetics have presented novel molecular mechanisms which may underlie previous observations. This review will give an overview of these latter developments in the context of the burden of osteoporosis and the wider data supporting the link between the early environment and bone health in later life.

Physical activity, calcium intake and childhood bone mineral: a population-based cross-sectional study

In a free-living cohort of 4-year old children, mean daily time in moderate-vigorous physical activity and daily calcium intake at 3 years, were positively related to hip bone size and density. Relationships between physical activity and bone indices were stronger when calcium intake was above compared with below median (966 mg/day).

INTRODUCTION

We examined the cross-sectional relationships between childhood physical activity, dietary calcium intake and bone size and density.

METHODS

Children aged 4 years were recruited from the Southampton Women's Survey. They underwent measurement of bone mass by DXA (Hologic Discovery). Physical activity was assessed by accelerometry (Actiheart, Cambridge Neurotechnology Ltd, Cambridge, UK) for seven continuous days.

RESULTS

Four hundred twenty-two children (212 boys) participated. In a cross-sectional analysis, after adjusting for gender, daily mean time(minutes per day) spent in moderate to very vigorous activity (MVPA) was positively related to hip BA (R(2) = 3%, p < 0.001), BMC (R(2) = 4%, p < 0.001), aBMD (R (2) = 3%, p = 0.001) and estimated vBMD (R(2) = 2%, p = 0.01), but not height (r (s) = 0.04, p = 0.42) or weight (r(s) = 0.01, p = 0.76). Mean daily calcium intake (assessed at 3 years old) positively predicted bone indices in those with a calcium intake below the median (966 mg/day), but there was a much attenuated relationship in those above this. These associations persisted after inclusion of total energy, protein and phosphorus in multivariate models. The relationships between MVPA and bone indices were stronger in children with calcium intakes above the median. Thus, for aBMD, the variance explained by MVPA when daily calcium intake was below the median was 2% (p = 0.1) and above median was 6% (p = 0.001).

CONCLUSIONS

These results support the notion that adequate calcium intake may be required for optimal action of physical activity on bone development and that improving levels of physical activity and calcium intake in childhood may help to optimise accrual of bone mass.

Dietary patterns are associated with physical growth among school girls aged 9-11 years

The purpose of this study was to identify dietary patterns among Korean elementary school girls based on the change in body mass index (BMI), body fat, bone mineral density (BMD), and bone mineral content (BMC) during 22 months and to explore the characteristics of dietary patterns identified. Girls aged 9-11 years were recruited and 3-day dietary data were collected four times. Subjects with a diet record of 8 or more days and anthropometric data measured at baseline and 22 months later were included (n = 198). Reduced rank regression was utilized to derive dietary patterns using a change in BMI, body fat, and calcaneus BMD and BMC as response variables. Two dietary patterns were identified: the "Egg and Rice" dietary pattern and "Fruit, Nuts, Milk Beverage, Egg, Grain" (FNMBEG) dietary pattern. Subjects who had high score on the FNMBEG pattern consumed various food groups, including fruits, nuts and seeds, and dairy products, whereas subjects in the "Egg and Rice" dietary pattern group did not. Both dietary patterns showed a positive association with change in BMI and body fat. However, subjects who had a higher score on the "Egg and Rice" dietary pattern had less of a BMC increase, whereas subjects who had a higher score on the FMBEG dietary pattern had more increased BMC over 22 months after adjusting for age, body and bone mass, and Tanner stage at baseline. Our results provide evidence that a well-balanced diet contributes to lean body mass growth among young girls.

Lactase persistence and milk consumption are associated with body height in Swedish preadolescents and adolescents

BACKGROUND

Body height is a classic polygenic trait. About 80%-90% of height is inherited and 10%-20% owed to environmental factors, of which the most important ones are nutrition and diseases in preadolescents and adolescents.

OBJECTIVE

The aim of this study was to explore potential relations between the LCT (lactase) C>T-13910 polymorphism, milk consumption, and body height in a sample of Swedish preadolescents and adolescents.

DESIGN

In a cross-sectional study, using a random sample of preadolescents and adolescents (n = 597), dietary intakes were determined. Anthropometric measurements including sexual maturity (Tanner stage) and birth weight were assessed. Parental body height and socio-economic status (SES) were obtained by questionnaires. Genotyping for the LCT C>T-13910 polymorphism that renders individuals lactase persistent (LP) or lactase non-persistent (LNP) was performed by DNA sequencing. Stepwise backward multivariate linear regression was used.

RESULTS

Milk consumption was significantly and positively associated with body height (β = 0.45; 95% CI: 0.040, 0.87, p = 0.032). Adjustments were performed for sex, parental height, birth weight, body mass index (BMI), SES, and Tanner stage. This model explains 90% of the observed variance of body height (adjusted R(2) = 0.89). The presence of the -13910 T allele was positively associated with body height (β = 2.05; 95% CI: 0.18, 3.92, p = 0.032).

CONCLUSIONS

Milk consumption is positively associated with body height in preadolescents and adolescents. We show for the first time that a nutrigenetic variant might be able to explain in part phenotypic variation of body height in preadolescents and adolescents. Due to the small sample size further studies are needed.

Reduced tibial speed of sound in Chinese infants at birth compared with Caucasian peers: the effects of race, gender, and vitamin D on fetal bone development

SUMMARY

This study compared bone status between Chinese and Caucasian infants at birth, showing that Chinese neonates have lower tibial speed of sound, which is influenced by gender, gestational age, season of birth, and maternal vitamin D status. The effects of these factors on fetal bone development were discussed.

INTRODUCTION

We compared the differences of speed of sound (SOS) accessed by quantitative ultrasound between Chinese and Caucasian infants at birth and explored the relationship between the concentrations of serum 25-hydroxyvitamin D [25(OH)D] and bone SOS in maternal-infant pairs.

METHODS

SOS for the tibial bone was measured at birth in 267 Chinese infants. We used the Z-scores for the direct comparisons which were available from the instrument based data of gender and age-matched Caucasian peers. The concentrations of serum 25(OH)D and bone SOS in 32 maternal-infant pairs were measured at birth in winters.

RESULTS

the Chinese infants had lower SOS demonstrated by the Z-scores. Significant differences of SOS and Z-scores were found between genders, gestational ages, birth weight, and seasons of birth. The differences of Z-scores negatively decreased with gestational age, suggesting that the bone status of Chinese infants lags behind that of the Caucasian infants during the last trimester of pregnancy in utero. The tibial SOS of infants born in winters was 2.0% higher than those born in summers after adjustment. The infant SOS correlated with maternal serum 25(OH)D (r = 0.399, P = 0.024) and infant serum 25(OH)D (r = 0.394, P = 0.026).

CONCLUSIONS

Chinese neonates have lower SOS which is influenced by gender, gestational age, season of birth, and maternal vitamin D status. It is inferred that, in pace with gestational age, race and gender effects on fetal bone development are modified by materno-fetal vitamin D status.

Calcium requirements and metabolism in Chinese-American boys and girls

Calcium requirements of North American adolescents were set at 1300 mg/day based on data from white girls. Calcium requirements for Asian-American adolescents have not been studied. Using metabolic balance protocols and a range in calcium intakes, skeletal calcium retention was determined in Chinese-American adolescents. A sample of 29 adolescents, 15 boys aged 12 to 15 years and 14 girls aged 11 to 15 years, was studied twice on paired calcium intakes ranging between 629 to 1835 mg/day using a randomized-order crossover design. Calcium absorption and bone turnover rates using double-stable calcium isotope kinetic analysis on two calcium intakes per subject were measured and compared in boys and girls. Girls and boys had low habitual mean calcium intakes of 648 and 666 mg/day, respectively, and low mean serum 25-hydroxyvitamin D concentrations of 19.1 and 22.2 ng/mL, respectively. True fractional calcium absorption varied inversely with calcium load. Boys had significantly higher bone turnover rate than girls at the same calcium intake. Calcium retention increased with calcium intake; calcium intakes to achieve maximal calcium retention were 1100 mg/day in boys and 970 mg/day in girls. Recommendations for calcium requirements should be lowered for Chinese-American adolescents.

Calcium and bone health: position statement for the Australian and New Zealand Bone and Mineral Society, Osteoporosis Australia and the Endocrine Society of Australia

This position statement was prepared by the Working Group of the Australian and New Zealand Bone and Mineral Society and Osteoporosis Australia. The final statement was endorsed by the Endocrine Society of Australia. Currently, the balance of evidence remains in favour of fracture prevention from combined calcium and vitamin D supplementation in elderly men and women. Adequate vitamin D status is essential for active calcium absorption in the gut and for bone development and remodelling. In adults with a baseline calcium intake of 500-900 mg/day, increasing or supplementing this intake by a further 500-1000 mg/day has a beneficial effect on bone mineral density. Calcium intake significantly above the recommended level is unlikely to achieve additional benefit for bone health.

Milk, rather than other foods, is associated with vertebral bone mass and circulating IGF-1 in female adolescents

SUMMARY

Low calcium intake hampers bone mineral acquisition in adolescent girls. This study explores dietary calcium sources and nutrients possibly associated with vertebral mass. Milk intake is not influenced by genetic variants of the lactase gene and is positively associated with serum IGF-1 and with lumbar vertebrae mineral content and density.

INTRODUCTION

Low calcium intake hampers bone mineral acquisition during adolescence. We identified calcium sources and nutrients possibly associated with lumbar bone mineralization and calcium metabolism in adolescent girls and evaluated the possible influence of a genetic polymorphic trait associated with adult-type hypolactasia.

METHODS

Lumbar bone mineral content (BMC), bone mineral density (BMD), and area, circulating IGF-1, markers of bone metabolism, and -13910 LCT (lactase gene) polymorphism; and intakes of milk, dairy products, calcium, phosphorus, magnesium, proteins, and energy were evaluated in 192 healthy adolescent girls.

RESULTS

After menarche, BMC, BMD, serum IGF-1, and serum PTH were tightly associated with milk consumption, but not with other calcium sources. All four parameters were also associated with phosphorus, magnesium, protein, and energy from milk, but not from other sources. Girls with milk intakes below 55 mL/day have significantly lower BMD, BMC, and IGF-1 and higher PTH compared to girls consuming over 260 mL/day. Neither BMC, BMD, calcium intakes, nor milk consumption were associated with -13910 LCT polymorphism.

CONCLUSIONS

Milk consumption, preferably to other calcium sources, is associated with lumbar BMC and BMD in postmenarcheal girls. Aside from being a major source of calcium, milk provides phosphates, magnesium, proteins, and as yet unidentified nutrients likely to favor bone health.

Impact of dairy products and dietary calcium on bone-mineral content in children: results of a meta-analysis

OBJECTIVE

Although calcium is essential for maintaining bone health in children, the optimum dietary intake of calcium in this age group, particularly in the form of dairy foods, is not well defined. A meta-analysis was conducted to examine the impact of dietary calcium/dairy supplementation on bone mineral content in this age group.

METHODS

Data were pooled from randomized controlled intervention trials and observational studies using previously described methods. The outcome of interest was a summary mean difference bone mineral content. Sensitivity analyses were employed to evaluate any observed statistical heterogeneity and to examine the influence of specific study characteristics on the summary estimate of effect.

RESULTS

Initially combining data from twenty-one randomized controlled trials (RCTs) using total body bone mineral content (TB-BMC) as the outcome of interest, yielded a non-statistically significant increase in TB-BMC of 2 g (supplemented versus controls). These data demonstrated substantial statistical heterogeneity with sensitivity analyses revealing that among study subjects with normal or near normal baseline dietary calcium/dairy intakes, supplemental dairy/calcium showed little impact on bone mineral content. Sensitivity analyses suggested that baseline calcium intake could potentially account for the statistical heterogeneity. Pooling the three reports utilizing low intake subjects yielded a statistically significant summary mean BMC of 49 g (24.0-76-6). Pooling two RCTs using calcium/dairy supplement plus vitamin D was also associated with an increase in lumbar spine BMC of, on average, 35 g (-6.8-41.8). The lack of data using BMC measurements at other anatomic sites as well as sparse data from non-randomized studies, precluded further statistical pooling.

CONCLUSION

Increased dietary calcium/dairy products, with and without vitamin D, significantly increases total body and lumbar spine BMC in children with low base-line intakes.

Influence of body composition, muscle strength, diet and physical activity on total body and forearm bone mass in Chinese adolescent girls

The aim of the present study was to determine association between body composition, muscle strength, diet and physical exercise with bone mineral content (BMC) and bone area (BA) in 283 Chinese adolescent girls aged 15 years in Beijing, China. Body composition, pubertal stage, physical activity and dietary intakes were assessed using standard validated protocols. Total body and forearm bone, lean body mass (LBM) and fat body mass (FBM) were determined by dual X-ray absorptiometry. Multivariate linear regression analyses were carried out to examine the predictors of BMC and BA, after controlling for potential confounders. The subjects had a mean age of 15·0 (sd 0·9) years and 99·6 % of them had reached menarche. Multivariate analyses showed that LBM, FBM, handgrip muscle strength and milk intake were significant independent determinants of BMC and BA of the total body and/or forearm sites. LBM was found to be a stronger independent determinant than FBM of BMC and BA, whereas handgrip muscle strength was only found as significant determinant of BMC and BA at the forearm sites than in total body BMC and BA. Further, total physical activity level had a significant positive association with handgrip and LBM. This suggested that greater muscle strength and higher LBM may reflect higher levels of physical activity. Therefore, continuous healthy lifestyle practices such as adequate intake of milk and continuous participation in physical activity should be encouraged throughout adolescence to optimise bone growth during this period.

Dietary protein intake and bone mineral content in adolescents-The Copenhagen Cohort Study

Data indicate that various protein sources may exhibit a differential effect on bone metabolism. We investigated associations of milk and meat protein intake with bone mineral content (BMC) in adolescents. Milk, but not meat, protein intake was positively associated with size-adjusted BMC. Milk-derived protein may be beneficial for bone mineralization.

INTRODUCTION

Milk and meat protein intake has been reported to exhibit a differential effect on serum insulin-like growth factor-I (IGF-I). IGF-I plays a key role in bone metabolism. Therefore, we investigated associations of different protein sources with BMC and bone area (BA) in adolescents.

METHODS

This was a cross-sectional study of 17-year-old girls (n = 63) and boys (n = 46) participating in the second follow-up of The Copenhagen Cohort Study. We measured dietary intake (7-day food record), BMC and BA (dual-energy X-ray absorptiometry), serum markers for bone turnover and serum IGF-I (immunoassays).

RESULTS

The mean total protein intake ( approximately 1.2 g/kg) was modestly higher than that recommended. Total and milk ( approximately 0.3 g/kg) protein intake, but not meat protein intake ( approximately 0.4 g/kg), was positively associated with size-adjusted BMC (P <or= 0.05). The positive association between milk protein intake and size-adjusted BMC remained significant after correction for energy, calcium, and physical activity (P <or= 0.01) and did not seem to be mediated via current serum IGF-I. None of the analyzed protein sources was significantly associated with size-adjusted BA.

CONCLUSIONS

Our results suggest that some components of milk protein may promote bone mineralization. Further studies are needed to elucidate this phenomenon.

Milk Supplementation and Bone Health in Young Adult Chinese Women

BACKGROUND

Milk is potentially beneficial for bone health, particularly for Chinese populations where consumption of dairy products is low. There are few data about milk consumption by Chinese women aged 20-35 years. This study examines whether milk supplement over 2 years caused increased bone mineral density (BMD) in Chinese women aged 20-35 years.

METHODS

Four hundred forty-one community-living women living in Hong Kong SAR (221) and Beijing (220) China were randomized to receive milk supplement or nothing. The supplement consisted of two sachets of milk powder (1000 mg calcium, 80 microg vitamin K(1)), for 24 months. BMD at total hip, total spine, and whole body was measured at baseline and at 6, 12, 18, and 24 months; blood specimens were analyzed at baseline and at 3 and 24 months for biochemical indices of bone turnover and vitamin K. Urine samples also were collected. Analysis was by intention to treat as well as per protocol. Differences in change from baseline between the milk and control groups were analyzed using the mixed models approach to repeated measures, including the baseline value as a covariate.

RESULTS

Both groups had an increase in BMD and a decrease in bone turnover markers over time, as an indicator of the process of attainment of peak bone mass during this period. Apart from a higher total spine BMD at 6 months in the milk group using per protocol analysis, there was little significant difference observed between the milk group and the control group.

CONCLUSIONS

Age-related bone metabolism and lack of compliance most likely explain the lack of consistent changes in BMD or bone biochemical measures in response to milk supplementation for 2 years in Chinese women aged 20-35 years.

The effect of milk basic protein supplementation on bone metabolism during training of young thoroughbred racehorses

REASONS FOR PERFORMING STUDY

In laboratory animals, man and cell culture experiments, milk basic protein was reported to suppress bone resorption and promote bone formation. However, no studies in horses have previously examined the effect of milk basic protein.

OBJECTIVES

To evaluate the effect of milk basic protein supplementation on bone metabolism in young Thoroughbred horses in training.

METHODS

Twenty 2-year-old horses in training were used for 90 days in this study. The treatment group was fed a basal diet with 1 g of milk basic protein and the control group a basal diet only. Blood samples were collected on Days 0, 45 and 90 to determine serum calcium (Ca) and biochemical markers of bone metabolism. Radiographs were taken at the start and end of the study to determine radiographic bone aluminium equivalence (RBAE).

RESULTS

Serum osteocalcin (OC) was significantly higher at Day 45 after the beginning of the study in the treatment group compared to that in the control group. The treatment group showed a greater increase in the total RBAE change at the end of this study compared to that in the control group. However, there were no significant differences in serum Ca and carboxy-terminal telopeptide of type I collagen (ICTP) between groups.

CONCLUSIONS AND POTENTIAL RELEVANCE

These findings provide preliminary evidence that milk basic protein has an effect on bone formation in 2-year-old Thoroughbred horses in training. However, further studies in larger groups of horses are now required to substantiate our findings.

The genetic, environmental and phenotypic correlations of bone phenotypes at the spine and hip in Chinese

BACKGROUND

Bone mineral density (BMD), bone mineral content (BMC), and bone size have been widely studied individually as important risk factors for osteoporotic fracture, but little is known about the correlation and the degree of sharing genetic and environmental factors between the pairs of the three phenotypes.

AIM

The study investigated genetic correlation (rhoG), environmental correlation (rhoE) and phenotypic correlation (rhoP) between BMD, BMC and bone size.

SUBJECTS AND METHODS

Bivariate variance decomposition analyses were performed in 904 subjects from 287 Chinese nuclear families.

RESULTS

Significant rhoE, rhoG and rhoP were detected between BMD, BMC and bone size, except for rhoE between BMD and bone size at the hip (rhoE = 0.121, p = 0.361). Common shared genetic factors explained 86.1% and 60% of BMD and BMC genetic variations at the spine and hip, respectively. However, the genetic and environmental correlations between BMD and bone size were limited. rhoE and rhoG at the spine were 0.392 and 0.381, and at the hip were 0.121 and -0.205, respectively. Only 14.5% and 4.2% of variations between BMD and bone size at the spine and hip may be due to the shared genetic factors.

CONCLUSION

The obtained results suggested that bone size may be used as another surrogate phenotype independently of BMD for eventual elucidation of the pathogenesis of osteoporosis because of the limited correlations between BMD and bone size.

Bone mass in Chinese premenarcheal girls: the roles of body composition, calcium intake and physical activity

The association of growth and anthropometric characteristics and lifestyle factors with bone mass and second metacarpal radiogrammetry parameters was evaluated in 373 healthy Chinese premenarcheal girls aged 9–11 years. Bone mineral content (BMC) and density (BMD) and bone area (BA) of distal forearm, proximal forearm and total body, bone mineral-free lean (BMFL) mass and fat mass were measured by dual-energy X-ray absorptiometry. Metacarpal bone periosteal and medullary diameters were measured. Dietary intakes were assessed by 7d food record and physical activity (PA) by questionnaire. BMFL and fat mass together explained 6·3 and 51·6% of the variation in total body BMC and BMD, respectively. BMFL mass contributed to a substantial proportion of the variation in forearm BMC and BMD and periosteal diameter (10·4–41·0%). The corresponding BA explained 14·8–80·4% of the variation in BMC. Other minor but significant predictors of total body bone mass were Ca intake, height, age and PA score (BMD only), and of forearm bone mass were PA score, bone age, height and fat mass. Nevertheless, after adjusting for bone and body size and for age or bone age, subjects with Ca intake above the median (417mg/d) had 1·8% greater total body BMC (P<0·001), and subjects with PA scores above the median had 2·4–2·5% greater distal and proximal forearm BMC (P<0·05) than those below. Vitamin D intake negatively associated with medullary diameter (partialR21·7%). The results indicate that premenarcheal girls should be encouraged to optimise nutrition and Ca intake and exercise regularly to achieve maximum peak bone mass.

High intake of milk, but not meat, decreases bone turnover in prepubertal boys after 7 days

OBJECTIVE

To compare the short-term effect of a high milk and a high meat intake, identical in protein amount, on bone turnover during prepuberty.

SETTING

A University department.

DESIGN AND SUBJECTS

From 28, randomly recruited, 8-year-old boys, first 14 were assigned to the milk group and next 14 to the meat group. In each group, 12 boys finished the dietary intervention.

INTERVENTION

Milk (1.5 l/day) and meat (250 g/d), both containing approximately 53 g of protein, were given together with the habitual diet for 7 days. At baseline and day-7, serum osteocalcin (s-OC), bone-specific alkaline phosphatase (s-BAP) and C-terminal telopeptides of type I collagen (s-CTX) were measured (immunoassay) and dietary intake was estimated (a 3-day weighted food record).

RESULTS

Baseline s-OC, s-BAP and s-CTX were not significantly different between the groups. After 7 days, the average protein intake increased in both groups by 47.5 g; the milk group had higher (P<0.0001) calcium intake; s-OC and s-CTX decreased (P< or =0.04) in the milk group (-30.9%; -18.7%, respectively) compared with the meat group (+6.4%; -1.0%, respectively) and s-BAP decreased (P=0.06) both in the milk (-3.9%) and the meat group (-7.5%).

CONCLUSIONS

At the equal protein intake, milk, but not meat, decreased bone turnover in prepubertal boys after 7 days. This effect was probably due to some milk-derived compounds, rather than to the total protein intake. Future studies should elucidate the mechanism(s) of milk-related decline of bone turnover and its relevance for peak bone mass during growth.

SPONSORSHIP

University PhD scholarships.

Girls' calcium intake is associated with bone mineral content during middle childhood

We examined longitudinally the association between calcium intake and total body bone mineral content (TBBMC) in 151 non-Hispanic white girls. Intakes of dairy, energy, and calcium were assessed using three 24-h dietary recalls in girls at ages 5, 7, 9, and 11 y. We assessed their total-body bone mineral content with dual-energy X-ray absorptiometry at ages 9 and 11 y. Dairy foods comprised the major contributor (70%) to calcium intake over the 6-y period; 28% of calcium came from other foods, and 2% from supplements. By age 9 and 11 y, the majority of girls did not meet calcium recommendations. Higher calcium intake at ages 7 and 9 y was associated with higher TBBMC at age 11 y. Calcium intake at age 9 y was also positively associated with TBBMC gained from age 9 to 11 y. Calcium intake at age 11 y was not correlated with TBBMC at the same age. Relations between calcium intake and TBBMC did not differ for total calcium and for calcium from dairy sources, likely reflecting the fact that dairy products were the major source of calcium in this sample. Results from the present study provide new longitudinal evidence that calcium intake, especially calcium from dairy foods, can have a favorable effect on girls' TBBMC during middle childhood.

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.

Calcium Supplementation Trials and Bone Mass Development in Children, Adolescents, and Young Adults

The development of bone mass during childhood through young adulthood is an important determinant of bone health later in life, and calcium is the major building block. Most randomized, double-blind, placebo-controlled trials of calcium supplementation have been done in girls; however, calcium supplementation in boys has been investigated in recent studies. Positive short-term effects on bone measures during growth has been shown in boys and girls, particularly in weight-bearing appendicular bone, although the lifelong effect is not certain.

Growth, bone mass, and vitamin D status of Chinese adolescent girls 3 y after withdrawal of milk supplementation

BACKGROUND

A 2-y school milk intervention trial showed that 330 mL of a dietary milk supplement (fortified with calcium alone or with both calcium and vitamin D) enhanced the growth and bone mineral accretion of Chinese girls aged 10 y at baseline. Girls who received milk fortified with both calcium and vitamin D also had better vitamin D status than did girls who received nothing or girls who received milk fortified only with calcium.

OBJECTIVE

The aim was to evaluate whether these effects were sustained 3 y after supplement withdrawal.

DESIGN

Anthropometric measures and dietary intake were reassessed in 501 of the 698 girls whose data had been studied at the end of the intervention. As in the intervention phase, total-body bone mineral content and bone mineral density and serum 25-hydroxyvitamin D concentrations were measured in half of these subjects.

RESULTS

At follow-up, 99% of girls had reached menarche, at a mean (+/-SD) menarcheal age of 12.1 +/- 1.1 y. No significant differences in the timing of menarche were observed between the 3 groups (P = 0.6). No significant differences in the changes of total-body bone mineral content and bone mineral density since baseline were observed between the groups. The group receiving calcium-fortified milk had significantly greater gains in sitting height (0.9 +/- 0.3%; P = 0.02) than did the control group. The group that received calcium- and vitamin D-fortified milk had 17.1 +/- 6.7% lower serum 25-hydroxyvitamin D concentrations than did the control group (P = 0.04), but the difference was attenuated by additional adjustment for physical activity level (14.2 +/- 6.7%; P = 0.08).

CONCLUSION

Milk supplementation during early puberty does not have long-lasting effects on bone mineral accretion.

Two-year changes in bone and body composition in young children with a history of prolonged milk avoidance

No previous longitudinal studies of calcium intake, anthropometry and bone health in young children with a history of avoiding cow's milk have been undertaken. We report the 2-year changes of a group of 46 Caucasian children (28 girls, l8 boys) aged 8.1+/-2.0 years (mean +/- SD) who had low calcium intakes at baseline and were short in stature, with elevated body mass index, poor skeletons and lower Z scores for both areal bone mineral density (BMD, in grams per square centimeter) and volumetric density (bone mineral apparent density, BMAD, in grams per cubic centimeter), compared with a reference population of milk drinkers. At follow-up, adverse symptoms to milk had diminished and modest increases in milk consumption and calcium intake had occurred. Total body bone mineral content (BMC) and bone area assessed by dual energy X-ray absorptiometry had increased (P<0.05), and calcium intake from all sources was associated with both these measures (P<0.05). However, although some catch-up in height had taken place, the group remained significantly shorter than the reference population (Z scores -0.39+/-1.14), with elevated body mass index (Z scores 0.46+/-1.0). The ultradistal radius BMC Z scores remained low (-0.31+/-0.98). The Z scores for BMD had improved to lie within the normal range at predominantly cortical sites (33% radius, neck of femur and hip trochanter) but had worsened at predominantly trabecular sites (ultradistal radius and lumbar spine), where values lay below those of the reference group (P<0.05). Similarly, although volumetric BMAD Z scores at the 33% radius had normalized, BMAD Z scores at the lumbar spine remained below the reference population at follow-up (-0.67+/-1.12, P<0.001). Our results demonstrate persisting height reduction, overweight and osteopenia at the ultradistal radius and lumbar spine in young milk avoiders over 2 years of follow-up.

Positive effects of vegetable and fruit consumption and calcium intake on bone mineral accrual in boys during growth from childhood to adolescence: the University of Saskatchewan Pediatric Bone Mineral Accrual Study

BACKGROUND

Nutrition is an important modifiable factor in the development of bone mass during adolescence. Recent studies of children and adolescents examined the effects of foods such as milk products and fruit and vegetables on bone growth; however, few studies included both boys and girls.

OBJECTIVE

The purpose was to ascertain the role of consumption of milk products and vegetables and fruit in the accrual of total-body bone mineral content (TBBMC) in boys and girls from childhood to late adolescence.

DESIGN

Seven-year longitudinal data were obtained from 85 boys and 67 girls aged 8-20 y. Biological maturity was defined by the number of years from the age at peak height velocity. Dietary intake was assessed by serial 24-h recalls. Anthropometric measurements and physical activity were assessed every 6 mo. TBBMC assessed with dual-energy X-ray absorptiometry in the fall of each year was the indicator of bone mass.

RESULTS

Most boys (87.8%) met Canadian recommendations for milk product intake. Few subjects (<30%) consumed vegetables and fruit in recommended amounts. Using a multilevel modeling statistical approach containing important biological and environmental factors, we found that vegetable and fruit intakes, calcium intake, and physical activity were significant independent environmental predictors of TBBMC in boys but not in girls.

CONCLUSIONS

In addition to adequate dietary calcium intake, appropriate intakes of vegetables and fruit have a beneficial effect on TBBMC in boys aged 8-20 y. Underreporting of dietary intake by girls may explain why this effect was not apparent in girls.

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.

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.

Vitamin D-deficiency in Asia

Vitamin D-deficiency rickets is an important disease of childhood in China. It occurs in all regions (20-53 degrees N) but is more prevalent in the north. A survey in Beijing indicated that Vitamin D-deficiency (plasma 25(OH)D concentration <12.5 nmol/l) occurred in more than 40% of adolescent girls in winter. Dietary calcium was often as low as 350 mg per day and a positive correlation was found between this and both bone mineral density (BMD) and Vitamin D status. In a subsequent intervention study with 757 Beijing schoolgirls, a daily supplement of milk, fortified with calcium, was provided on school days for 24 months. From anthropometric and bone density data, it is evident that the increased calcium intake from milk, had significant effects on bone and that deficiencies of both calcium and of Vitamin D had been affecting bone growth and development. In neighboring Mongolia (42 degrees -50 degrees N), rickets is also common, but its prevalence has increased since 1990. A 2-year survey (2000-2002) in Mongolia indicated that, as in China, a low intake of calcium and limited exposure to solar ultraviolet (UV) light in summer were associated with Vitamin D-deficiency. However, over the last decade, malnutrition has become widespread. It now appears that malnutrition impairs the efficiency of the utilization of Vitamin D obtained in summer. Hence, a number of factors need to be addressed to prevent Vitamin D-deficiency during growth.

Associations of Adequate Intake of Calcium with Diet, Beverage Consumption, and Demographic Characteristics among Children and Adolescents

OBJECTIVE

The objective of this study is to examine various factors associated with total calcium intake and percent adequate intake (% AI) of calcium by children and adolescents, with respect to age, gender, race/ethnicity, and diet and beverage choices.

DESIGN

Data from the U.S. Department of Agriculture's Continuing Survey of Food Intake by Individuals 1994-96, 98 were used in the analyses. Age groupings (2-3, 4-8, 9-13, and 14-18 year olds) were based on the National Academy of Sciences recommendations for AI of calcium-500, 800, 1,300, and 1,300 mg calcium per day, respectively.

RESULTS

Consumption of milk products was strongly and positively associated with calcium intake. Consumption of carbonated soft drinks and other non-dairy beverages was also positively associated with calcium intake, but this association was very weak. Beverage choices of African-American children and adolescents are significantly different than white and Hispanic children and adolescents. For example, African-American adolescent girls consume fewer milk products and more fruit drinks/ades. Average daily carbonated soft drink consumption is approximately 1.6 and 1.0 twelve ounce cans among 14-18 year old boys and girls, respectively.

CONCLUSION

Carbonated soft drink consumption among adolescent girls is modest and does not appear to be linked to decreased calcium intake. The analyses in this paper show that creative effective, efficient, and targeted policies should be considered to help adolescent girls increase calcium intake. Making low-fat milk products, flavored milks, calcium-fortified beverages and foods more attractive and available will help encourage girls to consume more of this important mineral. When adequate calcium intake is not achieved through foods, health professionals should consider recommending calcium supplements.

Carbonated soft drink consumption and bone mineral density in adolescence: the Northern Ireland Young Hearts project

In an observational study of 1335 boys and girls aged 12 and 15 years, higher intakes of carbonated soft drinks (CSDs) were significantly associated with lower bone mineral density at the heel, but only in girls. Owing to the upward trend in CSD intake in adolescence, this finding may be of concern.

INTRODUCTION

High consumption of carbonated soft drinks (CSD) during adolescence may reduce bone mineral accrual and increase fracture risk. The aim of this study was to examine the relationship between CSD consumption and bone mineral density (BMD) in a representative sample of adolescents.

MATERIALS AND METHODS

This was a cross-sectional observational study in 36 postprimary schools in Northern Ireland. Participants included 591 boys and 744 girls either 12 or 15 years old. BMD was measured by DXA, and usual beverage consumption was assessed by the diet history method. Adjusted regression modeling was used to investigate the influence of CSD on BMD.

RESULTS

A significant inverse relationship between total CSD intake and BMD was observed in girls at the dominant heel (beta, -0.099; 95% CI, -0.173 to -0.025). Non-cola consumption was inversely associated with dominant heel BMD in girls (beta, -0.121; 95% CI, -0.194 to -0.048), and diet drinks were also inversely associated with heel BMD in girls (beta, -0.087; 95% CI, -0.158 to -0.016). However, no consistent relationships were observed between CSD intake and BMD in boys. Cola consumption and nondiet drinks were not significantly related to BMD in either sex.

CONCLUSION

CSD consumption seems to be inversely related to BMD at the dominant heel in girls. It is possible that the apparent association results from the displacement of more nutritious beverages from the diet. Although the inverse association observed between CSD consumption and BMD is modest and confined to girls, this finding may have important public health implications given the widespread use and current upward trend in CSD consumption in Western populations.

Can Chinese Children Drink Milk?

A controlled milk-intervention trial in Chinese schoolchildren showed that participants were able to consume 330 mL of milk every school day for 2 years.