A 4-year follow-up study of the effects of calcium supplementation on bone density in elderly postmenopausal women

A Review of Nutritional Requirements of Adults Aged ≥65 Years in the UK

Appropriate dietary choices in later life may reduce the risk of chronic diseases and rate of functional decline, however, there is little well-evidenced age-specific nutritional guidance in the UK for older adults, making it challenging to provide nutritional advice. Therefore, the aim of this critical review was to propose evidence-based nutritional recommendations for older adults (aged ≥65 y). Nutrients with important physiological functions in older adults were selected for inclusion in the recommendations. For these nutrients: 1) recommendations from the UK Scientific Advisory Committee for Nutrition (SACN) reports were reviewed and guidance retained if recent and age-specific, and 2) a literature search conducted where SACN guidance was not sufficient to set or confirm recommendations for older adults, searching Web of Science up to March 2020. Data extracted from a total of 190 selected publications provided evidence to support age-specific UK recommendations for protein (1.2 g·kg-1·d-1), calcium (1000 mg·d-1), folate (400 μg·d-1), vitamin B-12 (2.4 μg·d-1), and fluid (1.6 L·d-1 women, 2.0 L·d-1 men) for those ≥65 y. UK recommendations for carbohydrates, free sugars, dietary fiber, dietary fat and fatty acids, sodium, and alcohol for the general population are likely appropriate for older adults. Insufficient evidence was identified to confirm or change recommendations for all other selected nutrients. In general, significant gaps in current nutritional research among older adults existed, which should be addressed to support delivery of tailored nutritional guidance to this age group to promote healthy aging.

Physical Fitness, Adiposity, and Diets as Surrogate Measures of Bone Health in Schoolchildren: A Biochemical and Cross-Sectional Survey Analysis

This study aimed to investigate the associations between adiposity, muscular fitness (MF), diet, sun exposure, and physical activity profiles as surrogate measures with bone health status in a sample of schoolchildren aged 8-18 yr old. A total of 250 Egyptian schoolchildren aged 8-18 yr were randomly invited to participate in these cross-sectional survey analyses. Calcaneal broadband ultrasound attenuation (c-BUA), bone mineral density (BMD), and bone formation markers (total calcium, serum bone alkaline phosphatase, and osteocalcin) were measured as markers of bone health. Adiposity profile, MF, physical activity (PA), sun exposure, Ca, and vitamin D dietary intake as related cofactors of bone health were measured by using prevalidated questionnaires and standard analytical techniques. A total of 85% (n = 213) of the study population showed normal bone health and 14.8% (n = 37) had abnormal bone health; most of them are girls (67.6%) classified according to BMD and c-BUA Z-scores into osteopenia (9.6%) and osteoporosis (5.2%). Compared with boys, higher correlations between c-BUA, bone mineral content, and BMD measures in the femoral neck, lumbar spine, whole body, and bone markers were reported in girls with lower bone mass. There was a positive significant correlation between body mass index, adiposity, sun exposure, MF, PA status, Ca and vitamin D intake, and c-BUA and BMD score analyses. These parameters were shown to be associated with about ~57.3%-88.4% of bone health characteristics of children and adolescents with osteopenia and osteoporosis. In children and adolescents, sun exposure, Ca and vitamin D diets, adiposity, PA, and changes in the levels of Ca, osteocalcin, and serum bone alkaline phosphatase were shown to be associated with bone health. Also, a significant correlation was reported between c-BUA score, dual-energy X-ray absorptiometry-BMD measures, and bone markers at clinically important bone sites of girls and boys. However, further clinical trials should be studied to consider c-BUA and bone markers as the benchmark estimates of bone mass for diagnostic purposes in young ages.

Food Fortification and Supplement Use-Are There Health Implications?

Dietary supplements are a multi-billion dollar industry in the U.S., and their use is increasing exponentially. Additionally, many foods and beverages are increasingly being fortified with single or multiple vitamins and minerals. Consequently, nutrient intakes are exceeding the safe limits established by the Institute of Medicine. In this paper, we examine the benefits and drawbacks of vitamin and mineral supplements and increasing consumption of fortified foods (in addition to dietary intake) in the U.S.

POPULATION

The pros and cons are illustrated using population estimates of folic acid, calcium, and vitamin D intake, highlighting concerns related to overconsumption of nutrients that should be addressed by regulatory agencies.

The influence of osteoporosis in trauma

Osteoporosis is a descriptive term for a loss of bone mass and structure which predisposes to fracture in response to minimal trauma. These fractures cause pain, disability and significant mortality, with enormous resource costs to health and other services. Proximal femoral (hip) fractures account for most of the mortality and cost, and an estimated six million osteoporosis-related hip fractures occur world-wide each year, a number likely to increase dramatically due to changes in population demographics. The diagnosis of osteoporosis should be considered in all patients over the age of 50 years who sustain a fracture, unless there is obvious major trauma. Not only will this inform immediate management but it also allows measures aimed at prevention of further fractures to be implemented. Early surgery is often effective in limiting morbidity from osteoporotic fractures and in older people is best planned in collaboration with other health care professionals.

Calcium revisited: part II calcium supplements and their effects

Calcium supplements were tested in pregnancy and lactation, in childhood and adolescence, in pre- and postmenopausal women and in elderly persons with various effects on bone density and fracture incidence. They must be properly chosen and adequately used. In this case, the reported minor negative side-effects do not restrict their use. All these aspects are reviewed here.

Genetic markers of bone and joint health and physical capability in older adults: the HALCyon programme

BACKGROUND

Good bone and joint health is essential for the physical tasks of daily living and poorer indicators of physical capability in older adults have been associated with increased mortality rates. Genetic variants of indicators of bone and joint health may be associated with measures of physical capability.

METHODS

As part of the Healthy Ageing across the Life Course (HALCyon) programme, men and women aged between 52 and 90+ years from six UK cohorts were genotyped for a polymorphism associated with serum calcium (rs1801725, CASR), two polymorphisms associated with bone mineral density (BMD) (rs2941740, ESR1 and rs9594759, RANKL) and one associated with osteoarthritis risk rs3815148 (COG5). Meta-analysis was used to pool within-study effects of the associations between each of the polymorphisms and measures of physical capability: grip strength, timed walk or get up and go, chair rises and standing balance.

RESULTS

Few important associations were observed among the several tests. We found that carriers of the serum calcium-raising allele had poorer grip strength compared with non-carriers (pooled p=0.05, n=11,239) after adjusting for age and sex. Inconsistent results were observed for the two variants associated with BMD and we found no evidence for an association between rs3815148 (COG5) and any of the physical capability measures.

CONCLUSION

Our findings suggest elevated serum calcium levels may lead to lower grip strength, though this requires further replication. Our results do not provide evidence for a substantial influence of these variants in ESR1, RANKL and COG5 on physical capability in older adults.

Calcium and bone

OBJECTIVE

Evaluate the role of calcium on bone health.

METHODS

Review of literatures on calcium and bone development during childhood and bone health in adulthood and older age.

RESULTS

Calcium intake influences skeletal calcium retention during growth and thus affects peak bone mass achieved in early adulthood. Increased calcium intake is associated with increased bone mineral accretion rate up to a threshold level in all ethnic groups. The minimum intake to achieve maximal retention is 1140 mg/day for white boys and 1300 mg/day for white girls. Calcium also plays a role in preventing bone loss and osteoporotic fractures in later life. Meta-analyses report that calcium supplementation reduce bone loss by 0.5-1.2% and the risk of fracture of all types by at least 10% in older people. Low calcium intake is a widespread problem across countries and age groups.

CONCLUSION

Adequate calcium intake throughout lifetime is important for bone health and the prevention of osteoporosis and related fractures.

The bioactivity and ion release of titanium-containing glass polyalkenoate cements for medical applications

The ion release profiles and bioactivity of a series of Ti containing glass polyalkenoate cements. Characterization revealed each material to be amorphous with a T(g) in the region of 650-660°C. The network connectivity decreased (1.83-1.35) with the addition of TiO(2) which was also evident with analysis by X-ray photoelectron spectroscopy. Ion release from cements were determined using atomic absorption spectroscopy for zinc (Zn(2+)), calcium (Ca(2+)), strontium (Sr(2+)), Silica (Si(4+)) and titanium (Ti(4+)). Ions such as Zn(2+) (0.1-2.0 mg/l), Ca(2+) (2.0-8.3 mg/l,) Sr(2+) (0.1-3.9 mg/l), and Si(4+) (14-90 mg/l) were tested over 1-30 days. No Ti(4+) release was detected. Simulated body fluid revealed a CaP surface layer on each cement while cell culture testing of cement liquid extracts with TW-Z (5 mol% TiO(2)) produced the highest cell viability (161%) after 30 days. Direct contact testing of discs resulted in a decrease in cell viability of the each cement tested.

An Asian viewpoint on the use of vitamin D and calcium in osteoporosis treatment: physician and patient attitudes and beliefs

BACKGROUND

Osteoporosis treatment guidelines recommend calcium and vitamin D supplementation for both prevention as well as treatment, however, compliance with these guidelines is often unsatisfactory. This study investigated the opinion of Asian physicians and Asian patients regarding vitamin D and calcium and patients' use of both.

METHODS

Physicians selected from Malaysia, Taiwan, Philippines, Korea and Singapore were asked to grade the significance of vitamin D and calcium in the treatment of osteoporosis and their patients' use of these supplements. In addition, physicians recruited seven eligible osteoporotic women to answer a questionnaire to determine their use of vitamin D and calcium, and their attitudes and beliefs regarding these supplements.

RESULTS

In total, 237 physicians and 1463 osteoporosis patients completed the questionnaire. The results revealed that 22% of physicians in Malaysia, 12% in Taiwan, 72% in the Philippines, 50% in Korea and 24% in Singapore rated the importance of vitamin D supplementation as being extremely important. For calcium, 27% of physicians in Malaysia, 30% in Taiwan, 80% in the Philippines, 50% in Korea and 38% in Singapore rated the importance as being extremely important. Forty-three percent of patients in Malaysia, 38% in Taiwan, 73% in the Philippines, 35% in Korea and 39% in Singapore rated the importance of vitamin D as being extremely important. For calcium, 69% of patients in Malaysia, 58% in Taiwan, 90% in the Philippines, 70% in Korea and 55% in Singapore rated the importance as being extremely important. In addition, results of the patient questionnaire revealed that only a very small number regularly took both supplements. In addition, the results indicated that, with the exception of patients from the Philippines, the majority of patients had no or infrequent discussion with their physician about vitamin D and calcium.

CONCLUSIONS

There is generally suboptimal appreciation by both physicians and patients of the importance of vitamin D and calcium for maintenance of bone health as reflected in the low number of patients who reported regularly taking these supplements. Recognition of this problem should translate to appropriate action to improve education for both physicians and patients, with a goal to increase use of these supplements among Asian patients with osteoporosis.

Acute suppression of bone turnover with calcium infusion in persons with spinal cord injury

BACKGROUND

Some people with chronic spinal cord injury (SCI) have low vitamin D levels and secondary hyperparathyroidism.

OBJECTIVE

To determine whether, and to what extent, an acute calcium infusion decreased levels of N-telopeptide (NTx), a marker of osteoclastic activity, in individuals with chronic SCI.

STUDY DESIGN

Case series.

SUBJECTS

Eight men with chronic SCI. A relatively low serum 25 hydroxyvitamin D concentration (25[OH]D < or =20 ng/mL) and/or a high parathyroid hormone (PTH) (>55 pg/mL) was a prerequisite for study inclusion.

METHODS

Calcium gluconate bolus 0.025 mmol elemental calcium/kg over 20 minutes followed by a constant infusion of 0.025 mmol/kg per hour for 6 hours was infused; blood samples were collected every 2 hours for measurement of serum total calcium, creatinine, NTx, and PTH.

RESULTS

All results are expressed as means (+/- SDs). Baseline serum 25-hydroxyvitamin D level was 14.5 +/- 3.5 ng/mL (range: 10.2-19.6 ng/mL); PTH, 70 +/- 25 pg/mL (range: 37-100 pg/mL); and NTx, 21 +/- 7 nM bone collagen equivalents (BCE) (range: 14-34 nM). At 2, 4, and 6 hours after the calcium infusion, serum calcium rose from 9.3 +/- 0.2 to 10.8 +/- 0.9, 10.5 +/- 0.8, and 10.6 +/- 0.6 mg/d; PTH was suppressed from 70 +/- 25 pg/mL to 18 +/- 12, 16 +/- 9, and 15 +/- 9 pg/mL, respectively; NTx fell from 21 +/- 8 nM BCE to 17 +/- 5, 12 +/- 4, and 12 +/- 3 nM BCE, respectively.

CONCLUSIONS

Serum NTx is a marker for bone collagen catabolism, and its reduction suggests that bone turnover was decreased. A relative deficiency of vitamin D associated with chronically elevated levels of PTH would be expected to increase bone turnover and to worsen the bone loss associated with immobilization.

Physical activity and dietary calcium interactions in bone mass in Scottish postmenopausal women

In this population-based cohort of 1,254 older Scottish women we found significant interactions between the mechanical component of self-reported habitual physical activity (PA) and dietary calcium (Ca) in BMD, independent of other risk factors. At low and/or medium Ca intakes BMD was higher amongst the most active people.

INTRODUCTION

Although there is general agreement that increased activity (PA) and dietary calcium (Ca) consumption may help maintain bone mass in later life and prevent fractures, the amount required remains uncertain.

METHODS

In 2001-2003, 1,847 postmenopausal women (mean +/- SD age: 69.3 +/- 5.5 years) underwent bone mineral density (BMD) measurement and, in 2004, 68.7% (n = 1,254) completed a bone-specific Physical Activity Questionnaire (bsPAQ) and a food frequency questionnaire. The bsPAQ measures the metabolic and mechanical components of PA. Interactions of PA and Ca in BMD were examined using ANCOVA.

RESULTS

Significant interactions were identified in the BMD of the lumbar spine (LS), right hip (RH) and left hip (LH), after adjustment for confounders, between tertiles of PA classified according to the mechanical component and tertiles of energy-adjusted Ca intake (ANCOVA p = 0.006, p = 0.004 and p = 0.013 respectively). For example, at medium Ca intakes LH BMD was higher by 7.8% in the highest tertile of PA compared with the lowest tertile of PA.

CONCLUSIONS

These data suggest that health promotion campaigns to increase PA would be most effective in populations with a low/medium calcium intake.

The search for good compliance: economic aspects of a conveyed combination pharmaco-therapy, exemplified by an osteoporosis therapy

The discussion of adequate compliance in health care often refers to a lack of information between patients and physicians. In our setting, we show that contract arrangements as well as the distribution of information are important for an adequate alignment of the interest of patients and physicians. The analysis emphasises the benefit of organised pharmaco-therapy enhancing the concomitant compliance. Therefore, the results can work as a proxy for the need of good economic-based approaches discussing compliance in chronic diseases.

Effects of calcium and vitamin D supplementation on hip bone mineral density and calcium-related analytes in elderly ambulatory Australian women: a five-year randomized controlled trial

CONTEXT

Effects of long-term calcium, with or without vitamin D, on hip bone mineral density (BMD) and bone turnover in sunny climates have not been reported.

OBJECTIVE

The aim was to evaluate the effect of vitamin D added to calcium supplementation on hip dual-energy x-ray absorptiometry BMD and calcium-related analytes.

DESIGN, SETTING, AND PARTICIPANTS

The study was a 5-yr randomized, controlled, double-blind trial of 120 community-dwelling women aged 70-80 yr.

INTERVENTIONS

The interventions were 1200 mg/d calcium with placebo vitamin D (Ca group) or with 1000 IU/d vitamin D2 (CaD group), or double placebo (control).

MAIN OUTCOME MEASURES

Hip BMD, plasma 25-hydroxyvitamin D, biomarkers of bone turnover, PTH, and intestinal calcium absorption were measured.

RESULTS

Hip BMD was preserved in CaD (-0.17%) and Ca (0.19%) groups but not controls (-1.27%) at yr 1 and maintained in the CaD group only at yr 3 and 5. The beneficial effects were mainly in those with baseline 25-hydroxyvitamin D levels below the median (68 nmol/liter). At yr 1, compared with controls, the Ca and CaD groups had 6.8 and 11.3% lower plasma alkaline phosphatase, respectively (P<or=0.02), and 28.7 and 34.5% lower urinary deoxypyridinoline to creatinine ratio, respectively (P<or=0.05). At 5 yr, this suppression was maintained only in the CaD group. CaD reduced PTH at 3 and 5 yr cf. controls (27.8 and 31.3%, P<or=0.005) in those with baseline PTH levels above the median (3.6 pmol/liter). Therapy did not affect intestinal calcium absorption at high carrier loads.

CONCLUSIONS

Addition of vitamin D to calcium has long-term beneficial effects on bone density in elderly women living in a sunny climate, probably mediated by a long-term reduction in bone turnover rate.

The skeletal benefits of calcium- and vitamin D3-fortified milk are sustained in older men after withdrawal of supplementation: an 18-mo follow-up study

BACKGROUND

In a previous 2-y randomized controlled trial, we showed that calcium- and vitamin D3-fortified milk stopped or slowed bone loss at several clinically relevant skeletal sites in older men.

OBJECTIVE

The present study aimed to determine whether the skeletal benefits of the fortified milk were sustained after withdrawal of the supplementation.

DESIGN

One hundred nine men >50 y old who had completed a 2-y fortified milk trial were followed for an additional 18 mo, during which no fortified milk was provided. Bone mineral density (BMD) of the total hip, femoral neck, lumbar spine, and forearm was measured by using dual-energy X-ray absorptiometry.

RESULTS

Comparison of the mean changes from baseline between the groups (adjusted for baseline age, BMD, total calcium intake, and change in weight) showed that the net beneficial effects of fortified milk on femoral neck and ultradistal radius BMD at the end of the intervention (1.8% and 1.5%, respectively; P < 0.01 for both) were sustained at 18-mo follow-up (P < 0.05 for both). The nonsignificant between-group differences at the total hip (0.8%; P = 0.17) also persisted at follow-up (0.7%; P = 0.10), but there were no lasting benefits at the lumbar spine. The average total dietary calcium intake in the milk supplementation group at follow-up approximated recommended amounts for Australian men >50 y old (1000 mg/d) but did not differ significantly from that in the control subjects (1021 versus 890 mg/d).

CONCLUSION

Supplementation with calcium- and vitamin D3-fortified milk for 2 y may provide some sustained benefits for BMD in older men after withdrawal of supplementation.

Effects of dietary calcium intake on body weight and prevalence of osteoporosis in early postmenopausal women

BACKGROUND

High calcium intakes seem to be ineffective at reducing bone loss in early postmenopausal women. However, the inverse relation between calcium intake and body weight can attenuate the negative effect of a low dietary calcium intake.

OBJECTIVE

The objective was to assess the role of dietary calcium and body mass index (BMI) on osteoporosis, defined according to World Health Organization criteria as a lumbar bone density >2.5 SD below the T score.

DESIGN

This was a cross-sectional, retrospective, observational study conducted in 1771 healthy, early postmenopausal women, who were not taking calcium supplements at the first densitometric evaluation. Weekly frequency of dairy food consumption was used to estimate the relative intake of dietary calcium. Total dairy intake was classified into 4 categories by quartile cutoffs. Multiple logistic regression analyses were used to study this sample.

RESULTS

BMI and prevalence of overweight showed significant inverse trends with increasing dairy intake. Calcium intake was not associated with osteoporosis when overweight was not considered. However, when overweight was considered in the analysis, women with the lowest calcium intake were more likely to have osteoporosis (odds ratio: 1.46; 95% CI: 1.12, 1.89; P = 0.008) than were women with the highest calcium intake.

CONCLUSIONS

In early postmenopausal women, a low dietary calcium intake may increase the risk of osteoporosis, but its negative effect can be offset by the greater BMI found in women with a low calcium intake.

Physician and patient perceptions on the use of vitamin D and calcium in osteoporosis treatment: a European and Latin American perspective

OBJECTIVE

Although osteoporosis treatment guidelines include recommendations for calcium and vitamin D intake, routine use of adequate supplementation often is low. This study explored the attitudes of physicians and patients towards vitamin D and calcium and patient use of both supplements.

METHODS

A survey of randomly selected physicians in the United Kingdom, Mexico, and Austria, and the first seven eligible women with osteoporosis from each of their practices, was conducted. Physicians were asked to rate the importance of vitamin D and calcium in osteoporosis management on a scale of 1 to 10 (1 = not important at all, 10 = extremely important) and to estimate use of calcium and vitamin D supplements by their patients. Patients were asked about their own use of vitamin D and calcium, and their perceptions regarding these supplements.

RESULTS

Altogether 151 physicians (50 in Austria, 51 in the UK, and 50 in Mexico), and 910 osteoporosis patients (350 in Austria, 212 in UK, and 348 in Mexico) completed telephone surveys. Approximately, 86%, 28%, and 46% of physicians rated importance of vitamin D and calcium as being 9 or 10 in Austria, UK, and Mexico, respectively. Overall, 50% of patients reported taking calcium and vitamin D supplements (47% of these on a daily basis and 46% on a regular basis), and 19% of patients reported that they had no discussions with their physicians about calcium, while 39% reported no discussion about vitamin D.

CONCLUSIONS

Despite the recognition by physicians and patients that vitamin D and calcium are important for bone health, only a small proportion of patients regularly take supplements. This is the case even when vitamin D and calcium supplements are provided free with osteoporosis drug prescriptions, as occurs in Austria. However, these results rely on patient self-report of compliance which can lead to overestimation. In addition this study's participants may not be representative of other patient populations. This study provides additional evidence that compliance with treatment guidelines is suboptimal, and highlights the need for further study to explore the discrepancy between the highly perceived importance of vitamin D and calcium and the low use of both supplements, and to improve use among osteoporosis patients.

The effect of physical activity and its interaction with nutrition on bone health

Physical activity (PA) is a popular therapy for the prevention and treatment of bone loss and osteoporosis because it has no adverse side effects, it is low cost, and it confers additional benefits such as postural stability and fall prevention. Bone mass is regulated by mechanical loading, and is limited but not controlled by diet. The mechanism by which strain thresholds turn bone remodelling ‘on’ and ‘off ’ is known as the mechanostat theory. Research in animals has shown that optimal strains are dynamic, with a high change rate, an unusual distribution and a high magnitude of strain, but the results of randomized controlled trials in human subjects have been somewhat equivocal. In the absence of weight-bearing activity nutritional or endocrine interventions cannot maintain bone mass. Biochemical markers of bone turnover predict bone mass changes, and findings from our research group and others have shown that both acute and chronic exercise can reduce bone resorption. Similarly, Ca intervention studies have shown that supplementation can reduce bone resorption. Several recent meta-analytical reviews concur that changes in bone mass with exercise are typically 2–3%. Some of these studies suggest that Ca intake may influence the impact of PA on bone, with greater effects in Ca-replete subjects. Comparative studies between Asian (high PA, low Ca intake) and US populations (low PA, high Ca intake) suggest that PA may permit an adaptation to low Ca intakes. Whether Ca and PA interact synergistically is one of the most important questions unanswered in the area of lifestyle-related bone health research.

Calcium from LactoCalcium milk mineral after digestion with pepsin stimulates mineralized bone nodule formation in human osteoblast-like SaOS-2 cells in vitro and may be rendered bioavailable in vivo

Many individuals cannot obtain the optimum calcium requirement from food for a variety of reasons. Therefore, calcium supplements are important sources of dietary calcium. One of the calcium sources commercially available is LactoCalcium (milk minerals) that has 28% calcium, and a 2:1 ratio of calcium to phosphorus. The objectives of this study were (a) to examine whether calcium can be released from LactoCalcium by using digestive enzymes and (b) to determine its biological activity by examining its ability to stimulate bone formation. LactoCalcium was treated in vitro by using simulated gastric and intestinal fluids or porcine gastric, pancreatic and intestinal extracts. Our results indicate the role of enzymes or bile extract in the digestion of the product. We show that, by increasing the concentration of pepsin at a fixed concentration of LactoCalcium (substrate), the percentage of released calcium increased in a dose-dependent manner, showing that, at the right enzyme concentration, as much as 100% of the calcium present in LactoCalcium can be made available. The biological activity of the digested calcium was demonstrated by the stimulation of mineralized bone nodules in SaOS-2 cells in a dose-dependent manner. Thus, 1 mM and 3 mM calcium released from LactoCalcium increased the nodule area by 23.17 mm(2) (p<0.0001) and 77.78 mm(2) (p<0.0001), respectively, as compared to a value of 0.99 mm(2) at 0.5 mM calcium from LactoCalcium. These results demonstrate the in vitro bioavailability and bioactivity of calcium from LactoCalcium and serve as a basis for carrying out in vivo analyses to determine the suitability of using LactoCalcium as a source of calcium for individuals at risk of developing osteoporosis.

The role of calcium in peri- and postmenopausal women

OBJECTIVE

To update the evidence-based consensus opinion published by The North American Menopause Society (NAMS) in 2001 on the role of calcium in peri- and postmenopausal women.

DESIGN

NAMS followed the general principles established for evidence-based guidelines to create this document. A panel of clinicians and researchers acknowledged to be experts in the field of calcium and women's health was enlisted to review the previous position statement and data published since then, compile supporting statements, and make recommendations. Their advice was used to assist the NAMS Board of Trustees in publishing this position statement.

RESULTS

Adequate calcium intake (in the presence of adequate vitamin D status) has been shown to reduce bone loss in peri- and postmenopausal women and reduce fractures in postmenopausal women older than age 60 with low calcium intakes. Adequate calcium is considered a key component of any bone-protective therapeutic regimen. Calcium has also been associated with beneficial effects in several nonskeletal disorders, primarily hypertension, colorectal cancer, obesity, and nephrolithiasis, although the extent of those effects has not been fully elucidated. The calcium requirement rises at menopause. The target calcium intake for most postmenopausal women is 1,200 mg/day. Adequate vitamin D status, defined as 30 ng/mL or more of serum 25-hydroxyvitamin D (usually achieved with a daily oral intake of at least 400 to 600 IU), is required to achieve the nutritional benefits of calcium. The best source of calcium is food, and the best food source is dairy products. High-quality calcium supplements (taken in divided doses) are alternative sources for women unable to consume enough dietary calcium. There are no reported cases of calcium intoxication from food sources, and cases associated with supplements are rare (high intake levels of 2,150 mg/day have resulted in a 17% increase in renal calculi in one recent study, but not others). Because no accurate test to determine calcium deficiency exists, clinicians should focus instead on encouraging women to consume enough calcium to meet the recommended levels.

CONCLUSIONS

The most definitive role for calcium in peri- and postmenopausal women is in bone health, but, like most nutrients, calcium has beneficial effects in many body systems. Based on the available evidence, there is strong support for the importance of ensuring adequate calcium intake in all women, particularly those in peri- or postmenopause.

Osteoporosis Preventive Behavior in Thai Older Adults: Feasibility and Acceptability

The authors used a one-group pre-test-post-test design to examine the feasibility and acceptability of an osteoporosis prevention program and the effects of the program on knowledge, health beliefs, self-efficacy; and osteoporosis preventive behaviors in older adults. Participants included 48 older adults who attended a health center in Thailand. Results revealed that the program was feasible and acceptable. A significant improvement in osteoporosis knowledge, health beliefs, self-efficacy, and osteoporosis preventive behaviors occurred. Findings suggest that the program helps older adults incorporate new knowledge and skills into their daily lives and helps them maintain bone health.

Exercise frequency and calcium intake predict 4-year bone changes in postmenopausal women

The aim of this study was to examine the association of exercise frequency and calcium intake (CI) with change in regional and total bone mineral density (BMD) in a group of postmenopausal women completing 4 years of progressive strength training. One hundred sixty-seven calcium-supplemented (800 mg/day) sedentary women (56.1+/-4.5 years) randomized to a progressive strength training exercise program or to control were followed for 4 years. Fifty-four percent of the women were using hormone therapy (HT) at baseline. At 1 year, controls were permitted to begin the exercise program (crossovers). The final sample included 23 controls, 55 crossovers, and 89 randomized exercisers. Exercisers were instructed to complete two sets of six to eight repetitions of exercises at 70-80% of one repetition maximum, three times weekly. BMD was measured at baseline and thereafter annually using dual-energy X-ray absorptiometry. Four-year percentage exercise frequency (ExFreq) averaged 26.8%+/-20.1% for crossovers (including the first year at 0%), and 50.4%+/-26.7% for exercisers. Four-year total CI averaged 1,635+/-367 mg/day and supplemental calcium intake, 711+/-174 mg/day. In adjusted multiple linear regression models, ExFreq was positively and significantly related to changes in femur trochanter (FT) and neck (FN), lumbar spine (LS), and total body (TB) BMD. Among HT users, FT BMD increased 1.5%, and FN and LS BMD, 1.2% (p<0.01) for each standard deviation (SD) of percentage ExFreq (29.5% or 0.9 days/week). HT non-users gained 1.9% and 2.3% BMD at FT and FN, respectively, (p<0.05) for every SD of CI. The significant, positive, association between BMD change and ExFreq supports the long-term usefulness of strength training exercise for the prevention of osteoporosis in postmenopausal women, especially HT users. The positive relationship of CI to change in BMD among postmenopausal women not using HT has clinical implications in light of recent evidence of an increased health risk associated with HT.

Join the Movement to Have Healthy Bone Project (JHBP): changing behavior among older women in Thailand

Osteoporosis is a common silent disease in older adults presenting with fragility fractures. Lifestyle modifications may be an imperative strategy to minimize the increase of either osteoporosis or osteoporosis-related fractures. Targeted education is one way to promote osteoporosis preventive behaviors. Our aim of this study was to test the feasibility of the Join the Movement to Have Healthy Bone Project (JHBP) that was developed on osteoporosis preventive behaviors for Thai older women. By succeeding in making appropriate lifestyle changes, these women ultimately may reduce the risk of osteoporosis or fractures in later life.

Calcium-fortified beverage supplementation on body composition in postmenopausal women

BACKGROUND

We investigated the effects of a calcium-fortified beverage supplemented over 12 months on body composition in postmenopausal women (n = 37, age = 48-75 y).

METHODS

Body composition (total-body percent fat, %FatTB; abdominal percent fat, %FatAB) was measured with dual energy x-ray absorptiometry. After baseline assessments, subjects were randomly assigned to a free-living control group (CTL) or the supplement group (1,125 mg Ca++/d, CAL). Dietary intake was assessed with 3-day diet records taken at baseline and 12 months (POST). Physical activity was measured using the Yale Physical Activity Survey.

RESULTS

At 12 months, the dietary calcium to protein ratio in the CAL group (32.3 +/- 15.6 mg/g) was greater than the CTL group (15.2 +/- 7.5 mg/g). There were no differences from baseline to POST between groups for changes in body weight (CAL = 0.1 +/- 3.0 kg; CTL = 0.0 +/- 2.9 kg), %FatTB (CAL = 0.0 +/- 2.4%; CTL = 0.5 +/- 5.4%), %FatAB (CAL = -0.4 +/- 8.7%; CTL = 0.6 +/- 8.7%), or fat mass (CAL = 1.3 +/- 2.6 kg; CTL = 1.3 +/- 2.7 kg).

CONCLUSION

These results indicate that increasing the calcium to protein ratio over two-fold by consuming a calcium-fortified beverage for 12 months did not decrease body weight, body fat, or abdominal fat composition in postmenopausal women.

Physical activity and calcium consumption are important determinants of lower limb bone mass in older women

A population-based study of 1363 older women showed that the 24% who achieved high physical activity and dietary calcium intakes had a 5.1% higher hip BMD than those who did not, supporting the concept that lifestyle factors play an important role in the maintenance of lower extremity bone mass in older women.

INTRODUCTION

Although there is general agreement that increased dietary calcium consumption and exercise can slow bone loss in older women, the amount required to have this effect in an older population remains uncertain. This study was devised to examine the effects of calcium consumption (CC) and physical activity (PA) (lifestyle management) on bone mass in an older female population.

MATERIALS AND METHODS

Using a cross-sectional study design, a population-based sample of older women (mean age, 75 +/- 3 years) had hip and heel bone mass measured using DXA (Hologic 4500A; n = 1076) and quantitative ultrasound (QUS, Lunar Achilles; n = 1363), respectively. CC and PA were measured by a validated habitual food frequency and activity questionnaire, respectively. Dose-response effects of PA and CC on bone mass were examined using ANOVA.

RESULTS AND CONCLUSIONS

Division of the PA and CC into tertiles best described the dose-response effects. After adjustment for CC, age, weight, alcohol consumption, and cigarette smoking, high PA compared with medium or low PA was associated with higher hip BMD and heel QUS (total hip BMD, 3.1%; p < 0.001; QUS stiffness, 2.7%; p = 0.002). After adjustment for PA and covariates, high or medium CC compared with low CC was associated with higher total hip BMD (1.8%; p = 0.027), with no effect at the QUS heel site. PA and CC were dichotomized at the cut-points for effects on BMD. The combination of high PA and CC, achieved by 24% of the population, was associated with a total hip BMD that was 5.1% higher (34% of SD) than those individuals in the low PA and CC group. Stiffness was 3.6% (23% of SD) higher in the high PA and CC group than in the low PA and CC group. If the whole population undertook and achieved a high PA and high CC lifestyle, the population risk of hip fractures may be expected to be reduced by about 17% in this age group as a result of beneficial effects on the musculoskeletal system.

Two to three years of hormone replacement treatment in healthy women have long-term preventive effects on bone mass and osteoporotic fractures: the PERF study

Hormone replacement therapy (HRT) is often prescribed for a few years to suppress menopausal symptoms. Although its long-term use of HRT for the primary prevention of osteoporosis is not currently recommended, the long-term skeletal benefits of the limited therapy are of great interest. To determine whether administration of HRT for 2-3 years in the early postmenopausal years provides long-term benefits, such as prevention of bone loss and osteoporotic fractures, we studied a group of 347 healthy postmenopausal women with normal bone mass who had earlier completed one of four placebo-controlled HRT trials and who were reexamined 5, 11, or 15 years after stopping HRT. Of these women, 263 received either HRT or placebo for 2-3 years with no further bone-sparing treatment until follow-up, and the remaining 84 women reported either prolonged or current use of HRT at reexamination. Bone mineral density (BMD) at the spine (L1-L4) and bone mineral content (BMC) in the forearm were measured at baseline, the end of the trials, and follow-up. At follow-up, we assessed the radiological presence of vertebral fracture and collected information on the new incidence of nonvertebral fractures. Compared with that of the placebo-treated women, the BMD and BMC of HRT-treated women continued to show significantly higher values (>5%) even many years after stopping HRT. After stopping treatment, the rate of bone loss returned to normal postmenopausal rates. The preservation of bone mass in the HRT group was accompanied by a significantly reduced risk of all osteoporotic fractures as compared with the placebo group [OR = 0.48 (95% CI, 0.26-0.88)]. 'Fast losers' on placebo had more than a 4-fold higher risk of fractures than had the women on limited HRT with a normal rate of bone loss after withdrawal. In conclusion, limited HRT administered in the early postmenopausal years offers long-lasting benefits for the prevention of postmenopausal bone loss and osteoporotic fracture.

Impact of preventive osteoporosis education on patient behavior: immediate and 3-month follow-up

OBJECTIVE

To evaluate the effectiveness of an educational video on osteoporosis at increasing knowledge and preventive health behaviors.

DESIGN

A total of 195 women between 35 and 80 years of age without documented osteopenia or osteoporosis, who presented for a gynecological examination in an outpatient setting, were enrolled. Of this number, 98 women were randomly assigned to the intervention group that viewed the video before their office visit, and 97 women were assigned to a control group and saw their physician in a routine manner. After their visit, all participants answered a questionnaire that assessed their knowledge of osteoporosis and baseline health-related behaviors. Three months later, a follow-up questionnaire was mailed to participants, eliciting whether preventive behavior had commenced. Frequencies were compared using the Fisher exact test (2-tailed). Continuous variables were analyzed using the Student's t test.

RESULTS

The two groups had no statistically significant differences in demographics. The intervention group scored a mean of 92% compared with a mean of 80% in the control group on the initial osteoporosis assessment questionnaire (P < 0.001). The 3-month follow-up questionnaire demonstrated that significantly more women in the intervention group started taking calcium supplements (26.5% v 4.9%; P < 0.001), started taking vitamin D supplements (20.6% v 6.6%; P = 0.02), started a program of weight-bearing exercise (13.3% v 1.7%; P = 0.03), and started hormone therapy (8% v 1%; P = 0.04).

CONCLUSION

The use of an educational video on osteoporosis seems to improve patient knowledge and may positively impact health-related behaviors.

Effect of yogurt on a urinary marker of bone resorption in postmenopausal women

Adding three servings of yogurt to the daily diet of older women with habitually low calcium intakes resulted in a significant reduction in urinary excretion of N-telepeptide, a marker for bone resorption. Results were compared to the effects of three servings of a nutrition-poor snack and differences were apparent 7-10 days of starting the diet change. The satiety effect of the snacks resulted in a decrease in intake of other foods. The added nutrients of the yogurt improved overall diet quality substantially, while diet quality declined with the nutrient-poor snack. The results show that diets low in dairy intake are often marginal for several nutrients and that, so far as calcium is concerned, bone makes up for what the diet lacks. Moreover, bone resorption responds rapidly and sensitively to improvements in calcium intake that are readily achievable by an older female population.

Milk supplementation prevents bone loss in postmenopausal Chinese women over 3 years

Previously published results from a 2 year randomized, controlled clinical trial on supplementing the diet of postmenopausal Chinese women with high-calcium milk powder (containing 800 mg of calcium) showed that bone loss, as measured by bone mineral density (BMD), was prevented. To determine whether the effect of calcium supplementation could be sustained, the study was extended for 1 additional year. According to the intention-to-treat analysis, the differences in the rate of bone loss (percentage decrease in control group--percentage decrease in milk supplementation group) in the third year of the study were: total body BMD, 0.23% (95% confidence interval [CI] 0.07%-0.39%); total spine BMD, 0.31% (95% CI - 0.02%-0.65%); and total hip BMD, 0.44% (95% CI 0.19%-0.69%). Analysis by the per-protocol method showed a similar effect size. These results indicate that the effects of milk supplementation in preventing bone loss in postmenopausal Chinese women were sustained after 2 years.

Intervention thresholds for osteoporosis

The aim of this study was to determine the threshold of fracture probability at which interventions become cost-effective. We modeled the effects of a treatment costing $500/year, given for 5 years, that decreased the risk of all osteoporotic fractures by 35%, followed by a waning of effect for 5 years. Sensitivity analyses included a range of effectiveness (10%-50%) and a range of intervention costs (200-500 dollars/year). Data on costs and risks were from Sweden. Costs included direct costs and costs in added years of life, but excluded indirect costs due to morbidity. A threshold for cost-effectiveness of 60,000 dollars per quality-adjusted life-year (QALY) gained was used. Costs of added years were excluded in a sensitivity analysis for which a threshold value of 30,000 dollars per QALY was used. In the base case, intervention was cost-effective when treatment was targeted to women at average risk at age of >or=65 years. Irrespective of the efficacy modeled (10%-50%) or of cost of intervention (200-500 dollars/year) segments of the population at average risk could be targeted cost-effectively: The lower the intervention cost and the higher the effectiveness, the lower the age at which intervention was cost-effective. With the base case (500 dollars/year; 35% efficacy) treatment in women was cost-effective with a 10 year hip fracture probability that ranged from 1.4% at the age of 50 years to 4.4% at the age of 65 years. The exclusion of osteoporotic fractures other than hip fracture would increase the threshold to a 9%-11% 10 year probability because of the substantial morbidity from fractures other than hip fracture, particularly at younger ages. We conclude that the inclusion of all osteoporotic fractures has a marked effect on intervention thresholds, that these vary with age, and that available treatments can be cost-effectively targeted to individuals at moderately increased risk.

Long-term effects of nutrient intervention on markers of bone remodeling and calciotropic hormones in late-postmenopausal women

BACKGROUND

Adequate intakes of calcium and vitamin D reduce bone loss and fracture risk in the elderly. Other nutrients also affect bone health, and adequate intakes may influence bone turnover and balance.

OBJECTIVE

We compared the long-term effects on bone turnover markers and calciotropic hormones of a multinutrient supplement, a calcium and vitamin D supplement, and dietary instruction aimed at increasing calcium intake through foods.

DESIGN

Ninety-nine healthy postmenopausal women participated in a 3-y, randomized trial, receiving either 1) supplemental calcium (1450 mg/d) and vitamin D [10 microg (400 IU)/d], 2) calcium, vitamin D, and other nutrients (multinutrient supplement), or 3) dietary instruction (dietary control group). Data are from 83 subjects who completed the trial.

RESULTS

Increases over baseline in calcium intakes and serum 25-hydroxyvitamin D concentrations were sustained over 3 y in all treatment groups. Circulating parathyroid hormone concentrations were reduced at year 1 in all treatment groups but trended toward baseline thereafter. Bone turnover markers followed a similar pattern, and none of the changes in biochemical concentrations differed significantly between groups.

CONCLUSIONS

All 3 interventions offer long-term feasibility for increasing calcium intake and serum 25-hydroxyvitamin D concentrations. The dietary addition of micronutrients implicated in skeletal physiology confers no obvious bone-sparing effect in healthy postmenopausal women beyond that of calcium and vitamin D alone. The attenuation over time in suppression of parathyroid hormone and bone turnover might help explain why nutrient intervention tends to have less of a bone-sparing effect than do skeletally active medications such as estrogen or bisphosphonates.

Optimal age for preventing osteoporosis after menopause depends on effects of stopping treatment

The aim of this study was to model the effect of short (3 year) treatments for osteoporosis at different times after menopause on the risk of osteoporotic fracture and to assess the impact of strategies to target high-risk individuals. Treatment efficacy for hip, proximal forearm, shoulder, and spine fracture were computed from the relationship between bone mineral density (BMD) and fracture in women from Sweden. Treatment that increased hip bone mineral density by 6% over untreated women saved 126 vertebral, hip, proximal humerus, and forearm fractures per 1000 women at the age of 50 years, provided that the effects of treatment persisted. Targeting women with osteoporosis at this age would save an additional 50% of fractures. With age, the number of fractures saved decreased moderately. At the age of 70 years, 133 fractures would be saved in women with osteoporosis compared to 198 in women with osteoporosis at the age of 50 years. Where the effect of treatment was assumed to wear off over 20 years after stopping treatment, the efficacy of treatment was reduced at all ages, but most markedly at the age of 50 years. Where all women aged 50 years were treated, the number of fractures saved per 1000 women decreased from 127 to 15 and, in the case of targeting women with osteoporosis, decreased from 198 to 27 per 1000 women. By contrast, with a persisting effect of treatment, the number of fractures saved increased markedly with advancing age. If all women were targeted at the age of 50 years, 15 fractures would be saved, whereas this increased to 55 per 1000 women at the age of 70 years. When treatment effects wore off more rapidly with an offset half-time of 2.5 years only 5 fractures were saved per 1000 women at the age of 50 years. This figure rose to 23 per 1000 at the age of 70 years. We conclude that, although uncertainty exists concerning the offset of effect of treatments, treatments should be optimally given to women without prior fractures in later life.

Pharmacotherapy of osteoporosis in postmenopausal women: focus on safety

The therapy of osteoporosis has made enormous strides in the last decade. There is now a range of interventions, each with its pros and cons. Calcium and vitamin D supplementation remain the foundation and have few safety issues. Bisphosphonates are widely used, though gastrointestinal tolerance is a problem with some oral preparations. Intravenous administration may circumvent this, although this introduces the smaller problem of acute phase reactions. The side effect profile of hormone replacement therapy (HRT) is still being delineated after 40 years of use, with substantial new information expected in the next few years. This will clarify its place in the medical management of the menopause. Raloxifene appears to have a superior safety profile to HRT, though its efficacy on bone may be less. While none of these options is suitable for everyone, the range of available therapies does mean that most patients can find an intervention that is effective and acceptable.

Milk supplementation of the diet of postmenopausal Chinese women on a low calcium intake retards bone loss

The Chinese diet is low in calcium (less than 500 mg/day on average), and previous observational studies have suggested an association between a low calcium intake and risk of hip and vertebral fracture. In this study, we randomly assigned 200 postmenopausal Chinese women (age range, 55-59 years) to receive 50 g of milk powder containing 800 mg of calcium per day or to a control group. The following are the mean percentage changes (and SEs) in height and bone mineral density (BMD) over 24 months: for height, -0.1 +/- 0.2 cm in the milk supplementation group and -0.2 +/- 0.1 cm in the control group; for BMD at the total hip, -0.06 +/- 0.22% in the milk supplementation group and -0.88 +/- 0.26% in the control group; for BMD at the spine (L1-L4), -0.56 +/- 0.29% in the milk supplementation group and -1.5 +/- 0.29% in the control group; for total body BMD, -0.32 +/- 0.16% in the milk supplementation group and -1.2 +/- 0.19% in the control group (p < 0.05 by analysis of covariance [ANCOVA] for repeated measures for height and BMD at all sites). The milk supplementation group had less loss in terms of both height and BMD than the control group (p < 0.05 by ANCOVA for repeated measures). Serum parathyroid hormone (PTH) concentration was lower and serum 25-hyroxyvitamin D [25(OH)D] level was higher in the milk supplementation group than the control group at 12 months (p < 0.05 by paired t-test). We conclude that supplementing the diet of postmenopausal Chinese women with high calcium milk powder retards bone loss.

The role of calcium in peri- and postmenopausal women: consensus opinion of The North American Menopause Society

OBJECTIVE

The North American Menopause Society (NAMS) established a goal to review the published medical data and develop an evidence-based consensus opinion regarding the role of calcium in peri- and postmenopausal women.

DESIGN

In building this consensus opinion, NAMS followed the general principles established for evidence-based guidelines. As part of that process, NAMS appointed a panel of clinicians and researchers acknowledged to be experts in the field of calcium. Their advice was used to assist the NAMS Board of Trustees in developing this consensus opinion.

RESULTS

Adequate calcium intake (in the presence of adequate vitamin D intake) has been shown to prevent bone loss and reduce fracture risk in peri- and postmenopausal women. Although calcium is not as effective as antiresorptive agents (e.g., estrogen, selective estrogen-receptor modulators, or bisphosphonates), it is an essential component of antiresorptive agent therapy for osteoporosis. Calcium has also been associated with beneficial effects in several nonskeletal disorders, primarily hypertension, colorectal cancer, obesity, and nephrolithiasis, although the extent of those effects and mechanisms involved have not been fully explored. Estimates of adequate intakes of calcium for peri- and postmenopausal women are based on evidence relating to osteoporosis prevention. At least 1,200 mg/day of calcium is required for most women; levels greater than 2,500 mg/day are not recommended. To ensure adequate calcium absorption, a daily intake of 400-600 IU of vitamin D is recommended, either through sun exposure or through diet or supplementation. Since no accurate test to determine calcium deficiency exists, clinicians should focus instead on ensuring that a woman consumes enough calcium to meet the recommended levels.

CONCLUSION

Although the most definitive role for calcium in peri- and postmenopausal women is in bone health, it is clear that adequate calcium intake has implications that encompass a woman's overall health. Based on the available evidence, a strong statement can be made regarding the importance of ensuring adequate calcium intake in all women, particularly those in peri- or postmenopause.

Targeting of hormone replacement therapy immediately after menopause

The aim of this study was to model the effect of short (3-year) treatments with hormone replacement therapy (HRT) at the time of menopause on the risk of osteoporotic fracture, and to assess the impact of strategies to target high-risk individuals. From the relationship between bone mineral density (BMD) and fracture risk, treatment that increased bone mineral density at the hip by 6% over untreated women would save 35 vertebral, 62 hip, 13 proximal humeral, and 16 forearm fractures per 1000 women. The number needed to treat (NNT) to prevent one of these fractures was 8. The NNT fell modestly by targeting HRT to women with low bone mass or osteoporosis (NNT 6 and 5, respectively). The gains in fractures saved from targeting women with low bone mass or osteoporosis were offset by the requirement for assessment by BMD. Changes in the assumptions about the efficacy of HRT had a modest impact on fractures saved compared with the effect of changing assumptions concerning the offset of effect when treatment was stopped. We conclude that comparatively short courses of HRT might be effectively offered to all suitable women at menopause provided that the effects on bone persist when treatment is stopped.

[Treatment of osteoporosis with calcium and vitamin D. Systematic review]

BACKGROUND

Systematic review of the efficacy of calcium and vitamin D for the treatment of osteoporosis.

MATERIAL AND METHOD

Review of the database MEDLINE between 1996 and may 1998, by the key words: osteoporosis, calcium, vitamin D (and related terms) and randomized clinical trial. Review of the electronic versions of Best Evidence, The Cochrane Library, congress abstracts and references from two main textbooks. Ascending review of the literature. All the reviews were performed independently by two of the authors. Design parameters and main results of the primary publications of the identified trials were tabulated. Two independent observers carried out methodological scoring of the studies. Results were tabulated and a judgement made for the results.

RESULTS

Eleven studies on calcium, 8 of vitamin D and 12 about calcitriol and other hormone derivatives were included. Studies with calcium were mainly performed on non-clinical populations and in three anti-fracture efficacy was analyzed. Results were positive in population with low baseline intake and substantial supplementation. Trials on vitamin D were done in non-clinical and on institutionalized populations. Trials with calcitriol were developed mainly in osteoporotic fracture populations and reached poorer methodological validity scores. Heterogeneity of the studies precluded a meta-analysis of the different treatments. Studies on calcium showed clinical efficacy in a more consistent way. Inter-observer score was good (kappa = 0.81) and there were no significant correlations between sample size and effect in the different studies.

CONCLUSIONS

Calcium treatment is efficacious in populations with low intake receiving substantial supplementation. Vitamin D is efficacious associated with calcium mainly in deficient populations. Efficacy of calcitriol and other derivatives is more controversial.

Prevention of bone demineralization by calcium supplementation in precocious puberty during gonadotropin-releasing hormone agonist treatment

We have previously demonstrated a negative impact on peak bone mass in girls with precocious puberty treated with GnRH agonist (GnRHa). Several studies have shown that a high calcium intake positively influences bone mass in prepubertal girls and leads to a higher peak bone mass. The aim of this study was to evaluate the effect of calcium supplementation in girls with precocious puberty during GnRHa treatment. Forty girls affected by true central precocious puberty and treated with the GnRHa triptorelin were studied for 2 yr. After diagnosis, the patients were randomly assigned to three groups: group A, treated only with GnRHa; group B, treated for 12 months solely with GnRHa and then supplemented with calcium gluconolactate/carbonate (1 g calcium/day in two doses) for 12 months; and group C, treated from the beginning with combined GnRHa and calcium. Bone mineral density (BMD) at the lumbar spine was measured by dual energy x-ray absorptiometry at the beginning of the study and after 12 and 24 months and was expressed as the calculated true volumetric density (BMDv) in milligrams per cm3. Group A showed a decrease in absolute BMDv levels, in SD score for chronological age (CA), and even more in SD score for bone age (BA). Group B showed the same behavior during the first year, but this trend was reversed in the second year, when calcium supplementation was added to GnRHa treatment. Group C showed an increase in absolute BMDv levels and in SD score for CA and BA. BMDv variations (expressed as absolute values, SD score for CA, and SD score for BA) became statistically significant at 24 months between groups C and A (P = 0.036, P = 0.032, and P = 0.025, respectively). The behavior of the lumbar spine BMDv in the three groups is consistent with a positive effect of calcium supplementation during GnRHa treatment. In calcium-supplemented patients, the normal process of bone mass accretion at puberty is preserved despite GnRHa treatment. Therefore, the reduction in BMD during GnRHa treatment in girls with precocious puberty is at least completely reversible and preventable if calcium supplementation is associated from the beginning.

Calcium and osteoporosis

Calcium is an essential nutrient that is involved in most metabolic processes and the phosphate salts of which provide mechanical rigidity to the bones and teeth, where 99% of the body's calcium resides. The calcium in the skeleton has the additional role of acting as a reserve supply of calcium to meet the body's metabolic needs in states of calcium deficiency. Calcium deficiency is easily induced because of the obligatory losses of calcium via the bowel, kidneys, and skin. In growing animals, it may impair growth, delay consolidation of the skeleton, and in certain circumstances give rise to rickets but the latter is more often due to deficiency of vitamin D. In adult animals, calcium deficiency causes mobilization of bone and leads sooner or later to osteoporosis, i.e., a reduction in the "amount of bone in the bone" or apparent bone density. The effects of calcium deficiency and oophorectomy (ovariectomy) are additive. In humans, osteoporosis is a common feature of aging. Loss of bone starts in women at the time of the menopause and in men at about age 55 and leads to an increase in fracture rates in both sexes. Individual fracture risk is inversely related to bone density, which in turn is determined by the density achieved at maturity (peak bone density) and the subsequent rate of bone loss. At issue is whether either or both of these variables is related to calcium intake. The calcium requirement of adults may be defined as the mean calcium intake needed to preserve calcium balance, i.e., to meet the significant obligatory losses of calcium through the gastrointestinal tract, kidneys, and skin. The calcium allowance is the higher intake recommended for a population to allow for individual variation in the requirement. The mean requirement defined in this way, calculated from balance studies, is about 20 mmol (800 mg) a day on Western diets, implying an allowance of 25 mmol (1000 mg) or more. Corresponding requirements and allowances have been calculated for pregnancy and lactation and for children and adolescents, taking into account the additional needs of the fetus, of milk production, and of growth. There is a rise in obligatory calcium excretion at menopause, which increases the theoretical calcium requirement in postmenopausal women to about 25 mmol (1000 mg) and implies an allowance of perhaps 30 mmol (1200 mg) or even more if calcium absorption declines at the same time. At issue here, however, is whether menopausal changes in calcium metabolism are the cause or the result of postmenopausal bone loss. The first interpretation relies on evidence of a positive action of estrogen on the gastrointestinal absorption and renal tubular reabsorption of calcium; the latter interpretation relies on evidence of a direct inhibitory effect of estrogen on bone resorption. The calcium model for postmenopausal bone loss tends to be supported by the effect of calcium therapy. An analysis of the 20 major calcium trials in postmenopausal women reported in the last 20 years yielded a mean rate of bone loss of 1.00% per annum (p.a.) in the controls and 0.014% p.a. (NS) in the treated subjects (P < 0.001). However, trials in which calcium and estrogen have been directly compared have shown that the latter is generally more effective than calcium in that it produces a small, but often significant bone gain. This superiority of estrogen over calcium could be due to the former's dual action on calcium absorption and excretion or to a direct action of estrogen on bone itself. In older women, the importance of calcium intake is overshadowed by the strong association between vitamin D insufficiency and hip fracture. Whether this insufficiency arises primarily from lack of exposure to sunlight or to a progressive failure to activate the vitamin D precursor in the skin or both is uncertain but it is compounded by a general decline in dietary vitamin D intake with age. The biological effect is probably an impairment of calcium absorption and c