The bone remodeling transient: interpreting interventions involving bone-related nutrients

Effect of 24-Week, Late-Evening Ingestion of a Calcium-Fortified, Milk-Based Protein Matrix on Biomarkers of Bone Metabolism and Site-Specific Bone Mineral Density in Postmenopausal Women with Osteopenia

Dietary calcium intake is a modifiable, lifestyle factor that can affect bone health and the risk of fracture. The diurnal rhythm of bone remodelling suggests nocturnal dietary intervention to be most effective. This study investigated the effect of daily, bed-time ingestion of a calcium-fortified, milk-derived protein matrix (MBPM) or control (CON), for 24 weeks, on serum biomarkers of bone resorption (C-terminal telopeptide of type I collagen, CTX) and formation (serum pro-collagen type 1 N-terminal propeptide, P1NP), and site-specific aerial bone mineral density (BMD), trabecular bone score (TBS), in postmenopausal women with osteopenia. The MBPM supplement increased mean daily energy, protein, and calcium intake, by 11, 30, and 107%, respectively. 24-week supplementation with MBPM decreased CTX by 23%, from 0.547 (0.107) to 0.416 (0.087) ng/mL (p < 0.001) and P1NP by 17%, from 60.6 (9.1) to 49.7 (7.2) μg/L (p < 0.001). Compared to CON, MBPM induced a significantly greater reduction in serum CTX (mean (CI95%); −9 (8.6) vs. −23 (8.5)%, p = 0.025 but not P1NP −19 (8.8) vs. −17 (5.2)%, p = 0.802). No significant change in TBS, AP spine or dual femur aerial BMD was observed for CON or MBPM. This study demonstrates the potential benefit of bed-time ingestion of a calcium-fortified, milk-based protein matrix on homeostatic bone remodelling but no resultant treatment effect on site-specific BMD in postmenopausal women with osteopenia.

Antigen receptor therapy in bone metastasis via optimal control for different human life stages

In this work we propose a bone metastasis model using power law growth functions in order to describe the biochemical interactions between bone cells and cancer cells. Experimental studies indicate that bone remodeling cycles are different for human life stages: childhood, young adulthood, and adulthood. In order to include such differences in our study, we estimate the model parameter values for each human life stage via bifurcation analysis. Results reveal an intrinsic relationship between the active period of remodeling cycles and the proliferation of cancer cells. Subsequently, using optimal control theory we analyze a possible antigen receptor therapy as a new treatment for bone metastasis. Theoretical results such as existence of optimal solutions are proved. Numerical simulations for late stages of bone metastasis are presented and a discussion of our results is carried out.

Effect of Vitamin D-Enriched Gouda-Type Cheese Consumption on Biochemical Markers of Bone Metabolism in Postmenopausal Women in Greece

Considering the role of bone metabolism in understanding the pathogenesis of osteoporosis, the aim of the present study was to examine the effects of vitamin D-enriched cheese on the serum concentrations of the parathyroid hormone (PTH) and certain bone remodeling biomarkers in postmenopausal women in Greece. In a randomised, controlled dietary intervention, 79 postmenopausal women (55–75 years old) were randomly allocated either to a control (CG: n = 39) or an intervention group (IG: n = 40), consuming 60 g of either non-enriched or vitamin D3-enriched Gouda-type cheese (5.7 μg of vitamin D3), respectively, daily and for eight weeks during the winter. The serum concentrations of 25-hydroxy vitamin D (25(OH)D), PTH, bone formation (i.e., osteocalcin, P1NP) and bone resorption (i.e., TRAP-5b) biomarkers were measured. Consumption of the vitamin D-enriched cheese led to higher serum 25(OH)D concentrations of 23.4 ± 6.39 (p = 0.022) and 13.4 ± 1.35 (p < 0.001) nmol/L in vitamin D-insufficient women being at menopause for less and more than 5 years, respectively. In vitamin D-insufficient women that were less than 5 years at menopause, consumption of vitamin D-enriched cheese was also associated with lower serum PTH (Beta −0.63 ± 1.11; p < 0.001) and TRAP-5b (Beta −0.65 ± 0.23; p = 0.004) levels at follow-up, compared with the CG. The present study showed that daily intake of 5.7 μg of vitamin D through enriched cheese increased serum 25(OH)D concentrations, prevented PTH increase and reduced bone resorption in vitamin D-insufficient early postmenopausal women, thus reflecting a potential food-based solution for reducing the risk of bone loss occurring after menopause.

Partial Replacement of Animal Proteins with Plant Proteins for 12 Weeks Accelerates Bone Turnover Among Healthy Adults: A Randomized Clinical Trial

BACKGROUND

Plant-based diets may reduce the risk of chronic diseases, but can also lead to low calcium and vitamin D intakes, posing a risk for bone health.

OBJECTIVES

We investigated whether partial replacement of animal proteins with plant-based proteins using a whole-diet approach affects bone and mineral metabolism in healthy adults in 3 groups fed diets differing in protein composition.

METHODS

This 12-week clinical trial was comprised of 107 women and 29 men (20-69 years old; BMI mean ± SD, 24.8 ± 3.9) randomly assigned to consume 1 of 3 diets designed to provide 17 energy percent (E%) protein: "animal" (70% animal protein, 30% plant protein of total protein intake), "50/50" (50% animal, 50% plant), and "plant" (30% animal, 70% plant) diets. We examined differences in bone formation [serum intact procollagen type I amino-terminal propeptide (S-iPINP)], bone resorption [serum collagen type 1 cross-linked C-terminal telopeptide (S-CTX)], mineral metabolism markers (primary outcomes), and nutrient intakes (secondary outcomes) by ANOVA/ANCOVA.

RESULTS

S-CTX was significantly higher in the plant group (mean ± SEM, 0.44 ± 0.02 ng/mL) than in the other groups (P values < 0.001 for both), and differed also between the animal (mean ± SEM, 0.29 ± 0.02 ng/mL) and 50/50 groups (mean ± SEM, 0.34 ± 0.02 ng/mL; P = 0.018). S-iPINP was significantly higher in the plant group (mean ± SEM, 63.9 ± 1.91 ng/mL) than in the animal group (mean ± SEM, 55.0 ± 1.82 ng/mL; P = 0.006). In a subgroup without a history of vitamin D supplement use, plasma parathyroid hormone was significantly higher in the plant than in the animal group (P = 0.018). Vitamin D and calcium intakes were below recommended levels in the plant group (mean ± SEM, 6.2 ± 3.7 μg/d and 733 ± 164 mg/d, respectively).

CONCLUSIONS

Partial replacement of animal proteins with plant-based proteins for 12 weeks increased the markers of bone resorption and formation among healthy adults, indicating a possible risk for bone health. This is probably caused by lower vitamin D and calcium intakes from diets containing more plant-based proteins, but it is unclear whether differences in protein intake or quality play a major role. This trial was registered at clinicaltrials.gov as NCT03206827.

Temporal Change in Biomarkers of Bone Turnover Following Late Evening Ingestion of a Calcium-Fortified, Milk-Based Protein Matrix in Postmenopausal Women with Osteopenia

The diurnal rhythm of bone remodeling suggests nocturnal dietary intervention to be most effective. This study investigated the effect of bedtime ingestion of a calcium-fortified, milk-derived protein matrix (MBPM) or maltodextrin (CON) on acute (0–4 h) blood and 24-h urinary change in biomarkers of bone remodeling in postmenopausal women with osteopenia. In CON, participants received 804 ± 52 mg calcium, 8.2 ± 3.2 µg vitamin D and 1.3 ± 0.2 g/kg BM protein per day. MBPM increased calcium intake to 1679 ± 196 mg, vitamin D to 9.2 ± 3.1 µg and protein to 1.6 ± 0.2 g/kg BM. Serum C-terminal cross-linked telopeptide of type I collagen (CTX) and procollagen type 1 amino-terminal propeptide (P1NP), and urinary N-telopeptide cross-links of type I collagen (NTX), pyridinoline (PYD) and deoxypyridinoline (DPD) was measured. Analyzed by AUC and compared to CON, a −32% lower CTX (p = 0.011, d = 0.83) and 24% (p = 0.52, d = 0.2) increase in P1NP was observed for MBPM. Mean total 24 h NTX excreted in MBPM was −10% (p = 0.035) lower than CON. Urinary PYD and DPD were unaffected by treatment. This study demonstrates the acute effects of bedtime ingestion of a calcium-fortified, milk-based protein matrix on bone remodeling.

Daily oligofructose-enriched inulin intake impacts bone turnover markers but not the cytokine profile in pediatric patients with celiac disease on a gluten-free diet: Results of a randomised, placebo-controlled pilot study

BACKGROUND

Bone metabolism disturbances are commonly observed in patients with newly diagnosed celiac disease (CD). The only available treatment for CD-the intake of a gluten-free diet (GFD)-has been found to be insufficient in effectively improving bone health in some patients. Therefore, there is an urgent need to modify the GFD so as to allow for the provision of all the necessary nutrients and improved absorption. Prebiotics intake reportedly improves the absorption of bone-related vitamin D and calcium as well as bone metabolism. The effect of prebiotic intake on bone health in CD patients has not been studied yet. This study aimed to evaluate the effect of oligofructose-enriched inulin intake on bone metabolism and immune response in children with CD on a GFD.

METHODS

A total of 34 children with CD were randomised into two groups receiving 10 g of oligofructose-enriched inulin (Synergy 1) or a placebo (maltodextrin) for three months, together with a strict GFD. The children's bone metabolism marker levels and cytokine profiles were analysed before and after the intervention.

RESULTS

After supplementation, the concentration of osteocalcin increased significantly in children receiving Synergy 1, while the concentration of bone alkaline phosphatase increased in both groups, independent of supplementation. After the intervention, the level of pyridinoline increased significantly in the placebo group, resulting in a concentration that was two times higher than that in the Synergy 1 group, in which it remained stable. Moreover, the plasma concentrations of N-terminal telopeptides of type I collagen decreased in both the groups, whereas the tartrate-resistant acid phosphatase 5b level increased particularly in the Synergy 1 group. The intervention did not lead to immunological response changes.

CONCLUSIONS

The proposed supplementation beneficially altered bone metabolism, through increased bone formation rates and decreased bone resorption process rates. Supplementation of GFD with prebiotic oligofructose-enriched inulin may be a promising auxiliary therapy for bone metabolism improvements in children with CD.

Effect of a hypocaloric, nutritionally complete, higher-protein meal plan on bone density and quality in older adults with obesity: a randomized trial

Background

Dietary protein and micronutrients are important to the maintenance of bone health and may be an effective countermeasure to weight-loss-associated bone loss.

Objectives

We aimed to determine the effect of a 6-mo hypocaloric, nutritionally complete, higher-protein meal plan on change in bone density and quality as compared with weight stability in older adults using a randomized post-test design. We hypothesized that participants randomly assigned to this meal plan would maintain similar bone density and quality to weight-stable controls, despite significant reductions in body mass.

Methods

Ninety-six older adults (aged 70.3 ± 3.7 y, 74% women, 27% African American) with obesity [body mass index (kg/m2): 35.4 ± 3.3] were randomly assigned to a 6-mo hypocaloric, nutritionally complete, higher-protein meal plan targeting ≥1.0 g protein · kg body weight-1 · d-1 [weight-loss (WL) group; n = 47] or to a weight-stability (WS) group targeting 0.8 g protein · kg body weight-1 · d-1, the current Recommended Dietary Allowance (n = 49). The primary outcome was total hip bone mineral density (BMD), with femoral neck BMD, lumbar spine BMD, and lumbar spine trabecular bone score (TBS) as secondary outcomes, all assessed at baseline and 3 and 6 mo with dual-energy X-ray absorptiometry.

Results

Baseline total hip, femoral neck, and lumbar spine BMDs were 1.016 ± 0.160, 0.941 ± 0.142, and 1.287 ± 0.246 g/cm2, respectively; lumbar TBS was 1.398 ± 0.109. Despite significant weight loss achieved in the WL group (6.6 ± 0.4 kg; 8.6% ± 0.4% of baseline weight), 6-mo regional BMD estimates were similar to those in the WS group (all P > 0.05). Lumbar spine TBS significantly increased at 6 mo in the WL group (mean: 1.421; 95% CI: 1.401, 1.441) compared with the WS group (1.390: 95% CI: 1.370, 1.409; P = 0.02).

Conclusions

Older adults following a hypocaloric, nutritionally complete, higher-protein meal plan maintained similar bone density and quality to weight-stable controls. Our data suggest that adherence to this diet does not produce loss of hip and spine bone density in older adults and may improve bone quality. This trial was registered at clinicaltrials.gov as NCT02730988.

THE USE OF VITAMINS AND MINERALS IN SKELETAL HEALTH: AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND THE AMERICAN COLLEGE OF ENDOCRINOLOGY POSITION STATEMENT

ABBREVIATIONS

25(OH)D = 25-hydroxyvitamin D; BMD = bone mineral density; CV = cardiovascular; GI = gastrointestinal; IOM = Institute of Medicine; PTH = parathyroid hormone; RCT = randomized controlled trial; αTF = α-tocopherol; ucOC = undercarboxylated osteocalcin; VKA = vitamin K antagonist; WHI = Women's Health Initiative.

Dairy products and bone health: how strong is the scientific evidence?

The relevance of dairy produce for the diminishment of osteoporotic risk is still a matter of scientific debate due to the outcome of a few single observational studies. This review will address the most robust point estimate on the role of dairy products, as reported in systematic reviews and meta-analyses on randomised controlled trials in the case of bone mineralisation or prospective studies in the case of fracture risk. Plain dairy products or those fortified with Ca and/or vitamin D improve total body bone mineral content (BMC) by 45-50 g over 1 year when the daily baseline Ca intake is lower than 750 mg in Caucasians and Chinese girls. In Caucasian and Chinese women, Ca from (fortified) dairy products increases bone mineral density (BMD) by 0·7-1·8 % over 2 years dependent on the site of measurement. Despite the results on BMC, there are currently no studies that have investigated the potential of dairy products to reduce fracture risk in children. In adult Caucasian women, daily intake of 200-250 ml of milk is associated with a reduction in fracture risk of 5 % or higher. In conclusion, the role of dairy products for BMC or BMD has been sufficiently established in Chinese and Caucasian girls and women. In Caucasian women, drinking milk also reduces fracture risk. More research on the role of dairy products within the context of bone health-promoting diets is needed in specific ethnicities, other than Chinese and Caucasians, and in men.

Pitfalls in interpreting interventional studies for osteoporosis

After adulthood, changes in the skeleton are slow and takes years for accruing or losing any appreciable amount of bone mass. Proper interpretation of studies that evaluate the effect of nutrients (like calcium, vitamin D) and anti-resorptive agents (like bisphosphonates) on bone mass is important so that the true effect of the agent is measured correctly. In this report, we are highlighting two issues of utmost importance for correctly interpreting interventional studies for osteoporosis. One issue is the bone remodelling transient (BRT). It refers to a transient change in bone mineral density (BMD) by any agent that reduces remodeling space temporarily. This change is, however, not sustained for a long period and can be misinterpreted as a true gain in bone mass. The second issue is difference between calcium balance and bone balance. Calcium balance is the difference between the amount of calcium ingested in a day and the amount of calcium lost in that day. Recommendations for dietary calcium intake are based on calcium balance studies that presume calcium balance as an equivalent for bone balance. However, these are two different entities and need to be distinguished. Dietary calcium requirements should be established by bone balance studies using bone densitometry, not by calcium balance studies.

Whey Protein Supplementation and Higher Total Protein Intake Do Not Influence Bone Quantity in Overweight and Obese Adults Following a 36-Week Exercise and Diet Intervention

BACKGROUND

Controversy exists concerning the effects of higher total protein intake (TPro) on bone health, which may be associated with reduced bone mineral density (BMD). However, whey protein (WP) may induce bone formation because of its basic component, milk basic protein.

OBJECTIVE

This study assessed the effects of WP supplementation, TPro, and change in TPro (postsupplementation - presupplementation) on BMD and bone mineral content (BMC; total body, lumbar spine, total femur, and femoral neck) in overweight and class I obese middle-aged adults following an exercise intervention.

METHODS

This analysis used data from a double-blind, randomized, placebo-controlled 36-wk WP supplementation trial, wherein participants consumed a 1.7-MJ (400-kcal) supplement (0, 20, 40, or 60 g WP/d) along with their otherwise unrestricted diet while participating in a resistance and aerobic exercise intervention (3 d/wk). TPro was the summation of WP and habitual dietary intakes (4-d food record). Statistical analyses for WP were based on group and bone data [n = 186, 108 women; mean ± SD age: 49 ± 8 y; body mass index (BMI; in kg/m²): 30.1 ± 2.8], whereas TPro was based on dietary and bone data (n = 113, 70 women; age 50 ± 8 y; BMI 30.1 ± 2.9).

RESULTS

WP supplementation, regardless of dose, did not influence BMD or BMC following the intervention. By using a multiple linear regression model, TPro (expressed as g/d or g · kg^-1 · d^-1) and change in TPro (expressed as g/d) were not associated with responses over time in total or regional BMD or BMC. By using a cluster analysis approach [<1.0 (n = 41), 1.0-1.2 (n = 28), and ≥1.2 g · kg^-1 · d^-1 (n = 44)], TPro was also not associated with responses in total or regional BMD or BMC over time.

CONCLUSION

WP supplementation and total dietary protein intake did not negatively or beneficially influence bone quantity in overweight and obese adults during a 9-mo exercise intervention. This trial was registered at clinicaltrials.gov as NCT00812409.

The effects of spinal cord injury on bone loss and dysregulation of the calcium/parathyroid hormone loop in mice

Objective

To map the progression of osteoporosis following spinal cord injury in mice in specific areas and analyze changes in parathyroid hormone (PTH) and ion levels which could be responsible for overall bone loss.

Summary of background data

Spinal cord injury rapidly induces severe bone loss compared to other conditions, yet the cause of this bone loss has not been identified. Studies suggest the bone loss after injury is not solely due to disuse.

Methods

To quantify bone loss we weighed individual bones and measured bone mineral density using dual energy X-ray absorptiometry at acute (1 week) and chronic (4 week) time points following a T9 contusion. An ELISA was used to measure blood PTH levels at 1 and 4 weeks after injury. Calcium and phosphate levels were also analyzed at 4 weeks following injury at the University of Miami pathology core.

Results

We observed a significant decrease in bone mineral density in hind limbs after an acute injury, and found this bone loss to progress over time. Furthermore, following chronic injury a decrease in bone mineral density is also observed in bones above the level of injury and in the total bone mineral density. We observed a significant decrease in parathyroid hormone levels in injured mice at the chronic time point, but not at the acute time point which suggests this could be involved in the global bone loss following injury. We also observed a significant increase in serum calcium levels following injury which could account for the imbalance of PTH levels.

Bone's Material Constituents and their Contribution to Bone Strength in Health, Disease, and Treatment

Type 1 collagen matrix volume, its degree of completeness of its mineralization, the extent of collagen crosslinking and water content, and the non-collagenous proteins like osteopontin and osteocalcin comprise the main constituents of bone's material composition. Each influences material strength and change in different ways during advancing age, health, disease, and drug therapy. These traits are not quantifiable using bone densitometry and their plurality is better captured by the term bone 'qualities' than 'quality'. These qualities are the subject of this manuscript.

Risedronate slows or partly reverses cortical and trabecular microarchitectural deterioration in postmenopausal women

During early menopause, steady-state bone remodeling is perturbed; the number of basic multicellular units (BMUs) excavating cavities upon the endosteal surface exceeds the number (generated before menopause) concurrently refilling. Later in menopause, steady-state is restored; the many BMUs generated in early menopause refill as similarly large numbers of BMUs concurrently excavate new cavities. We hypothesized that risedronate reduces the number of cavities excavated. However, in younger postmenopausal women, the fewer cavities excavated will still exceed the fewer BMUs now refilling, so net porosity increases, but less than in controls. In older postmenopausal women, the fewer cavities excavated during treatment will be less than the many (generated during early menopause) now refilling, so net porosity decreases and trabecular volumetric bone mineral density (vBMD) increases. We recruited 324 postmenopausal women in two similarly designed double-blind placebo-controlled studies that included 161 younger (Group 1, ≤ 55 years) and 163 older (Group 2, ≥ 55 years) women randomized 2:1 to risedronate 35 mg/week or placebo. High-resolution peripheral computed tomography was used to image the distal radius and tibia. Cortical porosity was quantified using the StrAx1.0 software. Risedronate reduced serum carboxyterminal cross-linking telopeptide of type 1 bone collagen (CTX-1) and serum amino-terminal propeptide of type 1 procollagen (P1NP) by ∼50%. In the younger group, distal radius compact-appearing cortex porosity increased by 4.2% ± 1.6% (p = 0.01) in controls. This was prevented by risedronate. Trabecular vBMD decreased by 3.6% ± 1.4% (p = 0.02) in controls and decreased by 1.6% ± 0.6% (p = 0.005) in the risedronate-treated group. In the older group, changes did not achieve significance apart from a reduction in compact-appearing cortex porosity in the risedronate-treated group (0.9% ± 0.4%, p = 0.047). No between-group differences reached significance. Results were comparable at the distal tibia. Between-group differences were significant for compact-appearing cortex porosity (p = 0.005). Risedronate slows microstructural deterioration in younger and partly reverses it in older postmenopausal women, features likely to contribute to antifracture efficacy.

Diet-induced weight loss: the effect of dietary protein on bone

High-protein (>30% of energy from protein or >1.2 g/kg/day) and moderately high-protein (22% to 29% of energy from protein or 1.0 to 1.2 g/kg/day) diets are popular for weight loss, but the effect of dietary protein on bone during weight loss is not well understood. Protein may help preserve bone mass during weight loss by stimulating insulin-like growth factor 1, a potent bone anabolism stimulator, and increasing intestinal calcium absorption. Protein-induced acidity is considered to have minimal effect on bone resorption in adults with normal kidney function. Both the quantity and predominant source of protein influence changes in bone with diet-induced weight loss. Higher-protein, high-dairy diets may help attenuate bone loss during weight loss.

Impact of intra- and extra-osseous soft tissue composition on changes in bone mineral density with weight loss and regain

Recent studies report a significant gain in bone mineral density (BMD) after diet-induced weight loss. This might be explained by a measurement artefact. We therefore investigated the impact of intra- and extra-osseous soft tissue composition on bone measurements by dual X-ray absorptiometry (DXA) in a longitudinal study of diet-induced weight loss and regain in 55 women and 17 men (19-46 years, BMI 28.2-46.8 kg/m(2)). Total and regional BMD were measured before and after 12.7 ± 2.2 week diet-induced weight loss and 6 months after significant weight regain (≥30%). Hydration of fat free mass (FFM) was assessed by a 3-compartment model. Skeletal muscle (SM) mass, extra-osseous adipose tissue, and bone marrow were measured by whole body magnetic resonance imaging (MRI). Mean weight loss was -9.2 ± 4.4 kg (P < 0.001) and was followed by weight regain in a subgroup of 24 subjects (+6.3 ± 2.9 kg; P < 0.001). With weight loss, bone marrow and extra-osseous adipose tissue decreased whereas BMD increased at the total body, lumbar spine, and the legs (women only) but decreased at the pelvis (men only, all P < 0.05). The decrease in BMD(pelvis) correlated with the loss in visceral adipose tissue (VAT) (P < 0.05). Increases in BMD(legs) were reversed after weight regain and inversely correlated with BMD(legs) decreases. No other associations between changes in BMD and intra- or extra-osseous soft tissue composition were found. In conclusion, changes in extra-osseous soft tissue composition had a minor contribution to changes in BMD with weight loss and decreases in bone marrow adipose tissue (BMAT) were not related to changes in BMD.

Protein intake, weight loss, and bone mineral density in postmenopausal women

BACKGROUND

Higher protein diets are promoted for effective weight loss. Striated tissues in omnivorous diets contain high-quality protein, but limited data exist regarding their effects on bone.

METHODS

To examine the effects of energy restriction-induced weight loss with higher protein omnivorous diets versus lower protein vegetarian diets on bone mineral density in overweight postmenopausal women, two randomized controlled feeding studies were conducted. In Study 1, 28 women consumed 750 kcal/day energy deficit diets with 18% energy from protein via lacto-ovo vegetarian sources (normal protein, n = 15) or 30% energy from protein with 40% of protein from lean pork (higher protein, n = 13, omnivorous) for 12 weeks. In Study 2, 54 women consumed their habitual diet (control, n = 11) or 1,250 kcal/day diets with 16% energy from nonmeat protein sources (n = 14) or 26% energy from protein, including chicken (n = 15) or beef (n = 14) for 9 weeks.

RESULTS

Study 1: With weight loss (normal protein -11.2%, higher protein -10.1%), bone mineral density was not significantly changed in normal protein (-0.003 ± 0.003 g/cm(2), -0.3%) but decreased in higher protein (-0.0167 ± 0.004 g/cm(2), -1. 4%, group-by-time p < .05). Study 2: The control, nonmeat, chicken, and beef groups lost 1.5%, 7.7%, 10.4%, and 8.1% weight and 0.0%, 0.4%, 1.1%, and 1.4% bone mineral density, respectively. The change of bone mineral density was significant for chicken and beef compared with the control (group-by-time, p < .05). Markers of calcium metabolism and bone homeostasis in blood and urine were not changed over time or differentially affected by diet.

CONCLUSION

Consumption of higher protein omnivorous diets promoted decreased bone mineral density after weight loss in overweight postmenopausal women.

Three-month weight reduction does not compromise bone strength in obese premenopausal women

Weight loss is claimed to cause bone loss. This prospective 12-month study evaluated effects of 3-month group-based weight loss with VLED on body composition, bone mass and strength (DXA and pQCT), muscle performance and biomarkers of bone turnover. The assessments were done at baseline and at 3 and 12 months. Sixty-two women of the recruited 75 obese (BMI>30) premenopausal women who completed the study were divided into 3 groups based on the tertiles of weight loss at 3 months. The group means of weight losses were 15.5% (Large), 10.5% (Medium) and 5.9% (Low). Statistical analyses were based on analysis of covariance. Bone turnover increased during the weight reduction period in all groups but practically returned to baseline during the weight maintenance phase. In general, mean bone changes remained marginal (approximately +/-1%) and the amount of weight reduction was not associated with bone loss. The only notable change was the 4% decline in bending strength at the distal radius. These results indicate that in obese premenopausal women, 3-month weight reduction resulted in increased bone turnover but was not deleterious for bone mass or strength at 3 months or after 9-month weight maintenance.

Nutrition and Bone: It is More than Calcium and Vitamin D

Unlike pharmacological agents that are taken for proscribed periods of time, food and nutrient intakes have the possibility of affecting bone health over the entire lifespan. While deficiencies or excesses of individual nutrients have been shown to affect bone, it is likely that individual foods or dietary patterns have important effects related to skeletal health. While biochemical mechanisms exist to relate a deficiency of vitamin K to altered bone metabolism, clinical trials related to supplementation of this nutrient have been confusing. It is likely that these disparate results are related to the fact that interactions of nutrients have not been considered or the possibility that suboptimal nutrient status is a marker of poor nutritional status. Vitamin A excess has been postulated to be related to high fracture risk; however, it is likely that retinol is not the best marker for the proposed interaction. Altering whole food patterns, such as the Dietary Approaches to Stop Hypertension diet, have demonstrated beneficial effects on bone metabolism. Individuals who select some vegetarian patterns may need to consider supplementation with nutrients such as calcium and protein. Future studies should center on whole food and dietary patterns and their relationship to bone metabolism and fracture risk.

Influence of exercise mode and osteogenic index on bone biomarker responses during short-term physical training

Prescribing exercise based on intensity, frequency, and duration of loading may maximize osteogenic responses in bone, but a model of the osteogenic potential of exercise has not been established in humans. In rodents, an osteogenic index (OI) has been used to predict the osteogenic potential of exercise. The current study sought to determine whether aerobic, resistance, or combined aerobic and resistance exercise programs conducted over eight weeks and compared to a control group could produce changes in biochemical markers of bone turnover indicative of bone formation. We further sought to determine whether an OI could be calculated for each of these programs that would reflect observed biochemical changes. We collected serum biomarkers [bone-specific alkaline phosphatase (BAP), osteocalcin, tartrate-resistant acid phosphatase (TRAP), C-terminal telopeptide fragment of type I collagen (CTx), deoxypyridinoline (DPD), 25-hydroxy vitamin D (25(OH)D), and parathyroid hormone (PTH)] in 56 women (20.3+/-1.8 years) before, during and after eight weeks of training. We also measured bone mineral density (BMD) at regional areas of interest using DXA and pQCT. Biomarkers of bone formation (BAP and osteocalcin) increased in the Resistance and Combined groups (p<0.05), while biomarkers of bone resorption (TRAP and DPD) decreased and increased, respectively, after training (p<0.05) in all groups. Small changes in volumetric and areal BMD (p<0.05) were observed in the distal tibia in the Aerobic and Combined groups, respectively. Mean weekly OIs were 16.0+/-1.9, 20.6+/-2.2, and 36.9+/-5.2 for the Resistance, Aerobic, and Combined groups, respectively. The calculated osteogenic potential of our programs did not correlate with the observed changes in biomarkers of bone turnover. The results of the present study demonstrate that participation in an eight week physical training program that incorporates a resistance component by previously inactive young women results in alterations in biomarkers of bone remodeling indicative of increased formation without substantial alterations in markers of resorption.

Effect of long-term intervention of soy isoflavones on bone mineral density in women: a meta-analysis of randomized controlled trials

INTRODUCTION

A number of RCTs have examined the role of soy isoflavones on bone mineral density (BMD) and yielded inconsistent results. This meta-analyses aims to assess the overall effect of soy isoflavones on BMD.

METHODS

We searched for all articles published in English from January 1990 to March, 2008. We included RCTs of soy isoflavone supplementation in women of at least one year duration. The main outcomes were BMD changes from baseline at the lumbar spine, total hip and femoral neck.

RESULTS

We identified 10 eligible RCTs containing 896 women. A mean dose of 87 mg soy isoflavones for at least one year did not significantly affect BMD changes. The mean (95%CI) differences in BMD changes (in mg/cm(2)/year) were 4.1 (-1.6, 9.8) (0.4%) at the lumbar spine, -1.5 (-7.2, 4.3) (-0.3%) at the femoral neck under random-effects model, and 2.5 (-0.5, 5.4) (0.2%) at the total hip by fix-effects model, respectively. Similar results were obtained in subgroup analyses by isoflavone sources (soy protein vs. isoflavone extract), ethnic differences (Asian vs. Western). Larger dose (>or=80 mg/d), but not lower dose (<80 mg/d), of isoflavone intervention tended to have a weak beneficial effect on spine BMD (p=0.08 vs. p=0.94).

CONCLUSIONS

Soy isoflavone supplementation is unlikely to have significant favorable on BMD at the lumbar spine and hip in women.

Inhibition of bone turnover by milk intake in postmenopausal women

Increased postmenopausal bone turnover leads to bone loss and fragility fracture risk. In the absence of osteoporosis, risk preventive measures, particularly those modifying nutritional lifestyle, are appropriate. We tested the hypothesis that milk supplementation affects bone turnover related to biochemical markers in a direction that, in the long term, may be expected to reduce postmenopausal bone loss. Thirty healthy postmenopausal women aged 59·3 (sd3·3) years were enrolled in a prospective crossover trial of 16 weeks. After a 4-week period of adaptation with diet providing 600 mg calcium plus 300 mg ingested as 250 ml semi-skimmed milk, participants were maintained during 6 weeks under the same 600 mg calcium diet and randomized to receive either 500 ml semi-skimmed milk, thus providing a total of 1200 mg calcium, or no milk supplement. In the next 6 weeks they were switched to the alternative regimen. At the end of the each period, i.e. after 4, 10 and 16 weeks, blood and urinary samples were collected. The changes in blood variables between the periods of 6 weeks without and with milk supplementation were: for parathyroid hormone, − 3·2 pg/ml (P = 0·0054); for crosslinked telopeptide of type I collagen, − 624 pg/ml (P < 0·0001); for propeptide of type I procollagen, − 5·5 ng/ml (P = 0·0092); for osteocalcin, − 2·8 ng/ml (P = 0·0014). In conclusion, a 6-week period of milk supplementation induced a decrease in several biochemical variables compatible with diminished bone turnover mediated by reduction in parathyroid hormone secretion. This nutritional approach to postmenopausal alteration in bone metabolism may be a valuable measure in the primary prevention of osteoporosis.

Non-crystalline and crystalline rheumatic disorders in chronic kidney disease

Rheumatic syndromes are cause for morbidity in patients with end-stage renal disease. Recent advances in understanding the role of tissue remodeling have provided insight into the pathogenic mechanisms responsible for some of these manifestations. Here, we survey recent and clinically relevant advances in translational research that impact our understanding of rheumatic syndromes seen in patients with significant renal disease. The management of acute and chronic crystalline arthropathies in chronic kidney disease and hemodialysis patients is discussed.

The remodeling transient and the calcium economy

The remodeling transient describes a change in bone mass that lasts one remodeling cycle following an intervention that disturbs the calcium economy. We demonstrated the transient in a study of the response of bone density to calcium/vitamin D3 supplementation and show the hazards of misinterpretation if the transient is not considered.

INTRODUCTION

The remodeling transient describes a change in bone mass that lasts for one remodeling cycle following an intervention that disturbs the calcium economy.

METHODS

We report an intervention with calcium and vitamin D supplementation in 208 postmenopausal African-American women where the remodeling transient was considered a priori in the study design. Both groups (calcium alone vs. calcium + 20 microg (800 IU) vitamin D3) were ensured a calcium intake in excess of 1200 mg/day.

RESULTS

There were no differences between the two groups in changes in BMD over time. These BMD changes were therefore interpreted to reflect increased calcium intake in both groups but not any influence of vitamin D. A transient increase in bone mineral density was observed during the first year of study, followed by a decline. The remodeling period was estimated at about 9 months, which is similar to histomorphometric estimates.

CONCLUSION

It is problematic to draw conclusions concerning interventions that influence the calcium economy without considering the remodeling transient in study design. Studies of agents that effect bone remodeling must be carried out for at least two remodeling cycles and appropriate techniques must be used in data analysis.

Premenopausal overweight women do not lose bone during moderate weight loss with adequate or higher calcium intake

BACKGROUND

Weight loss is associated with bone loss, but this has not been examined in overweight premenopausal women.

OBJECTIVE

The aim of this study was to assess whether overweight premenopausal women lose bone with moderate weight loss at recommended or higher than recommended calcium intakes.

DESIGN

Overweight premenopausal women [n = 44; x (+/-SD) age: 38 +/- 6.4 y; body mass index (BMI): 27.7 +/- 2.1 kg/m(2)] were randomly assigned to either a normal (1 g/d) or high (1.8 g/d) calcium intake during 6 mo of energy restriction [weight loss (WL) groups] or were recruited for weight maintenance at 1 g Ca/d intake. Regional bone mineral density and content were measured by dual-energy X-ray absorptiometry, and markers of bone turnover were measured before and after weight loss. True fractional calcium absorption (TFCA) was measured at baseline and during caloric restriction by using a dual-stable calcium isotope method.

RESULTS

The WL groups lost 7.2 +/- 3.3% of initial body weight. No significant decrease in BMD or rise in bone turnover was observed with weight loss at normal or high calcium intake. The group that consumed high calcium showed a strong relation (r = 0.71) between increased femoral neck bone mineral density and increased serum 25-hydroxyvitamin D. No significant effect of weight loss on TFCA was observed, and the total calcium absorbed was adequate at 238 +/- 81 and 310 +/- 91 mg/d for the normal- and high-calcium WL groups, respectively.

CONCLUSION

Overweight premenopausal women do not lose bone during weight loss at the recommended calcium intake, which may be explained by sufficient amounts of absorbed calcium.

Calcium absorption in postmenopausal Chinese women: a randomized crossover intervention study

The Ca intake and food sources of Chinese postmenopausal women are quite different from those of their Western counterparts. But, little information on Ca metabolism is available in Chinese populations. We determined true fractional calcium absorption (TFCA), true Ca absorption(= TFCA x Ca intake, Va), urinary Ca excretion (Vu,) and the difference between Va and Vu, (Va-u), in response to three dietary Ca intake levels. Twenty-one healthy postmenopausal Chinese women aged 49-64 years were recruited for this randomized crossover trial from a general community, Guangzhou, China. Subjects were randomly assigned to receive 0, 500 and 1000 mg Ca/d for 5 weeks separated by 2-week washout periods. TFCA using Ca stable isotopes, total urinary Ca excretion and Ca intake were determined after 4 weeks of adaptation. Mean values for total Ca intake (Vi) of the three phases were 391 (SD 197), 880 (SD 130) and 1382 (SD 160) mg/d. On usual diet, TFCA, Vu, Va, and Va-u were 0.57 (SD 0.12), 175 (SD 59) mg/d, 216 (SD 98) mg/d and 41 (SD 99) mg/d, respectively. With the supplementations of 500 and 1000 mg Ca/d, TFCAsignificantly decreased to 0.52 (SD 0.12) and 0.43 (SD 0.13) (P<0.001); whereas urinary Ca (P=0.003), Va and Va-u increased significantly (P< 0.001). Using a mixed-effects nonlinear regression model, it was estimated that Va-u was approaching a plateau when mean Ca intake reached 1300 mg/d. In conclusion, the present findings suggest postmenopausal Chinese women have high Ca absorption efficiency and a mean Ca intake of about 1300 mg/d is required to maximize the Va-u.

Diet, nutrition and the prevention of osteoporosis

Objective:

To review the evidence on diet and nutrition relating to osteoporosis and provide recommendations for preventing osteoporosis, in particular, osteopototic fracture.

Approach:

Firstly, to review the definition, diagnosis and epidemiology of osteoporosis, to discuss the difficulties in using bone mineral density to define osteoporosis risk in a world-wide context and to propose that fragility fracture should be considered as the disease endpoint. Secondly, to provide an overview of the scientific data, the strengths and weaknesses of the evidence and the conceptual difficulties in interpreting studies linking diet, nutrition and osteoporosis. The following were considered: calcium, vitamin D, phosphorus, magnesium, protein and fluorine. Other potential dietary influences on bone health were also discussed, including vitamins, trace elements, electrolytes, acid–base balance, phyto-oestrogens, vegetarianism and lactose intolerance.

Conclusions:

There is insufficient knowledge linking bone mineral status, growth rates or bone turnover in children and adolescents to long-term benefits in old age for these indices to be used as markers of osteoporotic disease risk. For adults, the evidence of a link between intakes of any dietary component and fracture risk is not sufficiently secure to make firm recommendations, with the exception of calcium and vitamin D. For other aspects of the diet, accumulating evidence suggests that current healthy-eating advice to decrease sodium intake, to increase potassium intake, and to consume more fresh fruits and vegetables is unlikely to be detrimental to bone health and may be beneficial.

Nutrition and bone growth and development

The growth and development of the human skeleton requires an adequate supply of many different nutritional factors. Classical nutrient deficiencies are associated with stunting (e.g. energy, protein, Zn), rickets (e.g. vitamin D) and other bone abnormalities (e.g. Cu, Zn, vitamin C). In recent years there has been interest in the role nutrition may play in bone growth at intakes above those required to prevent classical deficiencies, particularly in relation to optimising peak bone mass and minimising osteoporosis risk. There is evidence to suggest that peak bone mass and later fracture risk are influenced by the pattern of growth in childhood and by nutritional exposures in utero, in infancy and during childhood and adolescence. Of the individual nutrients, particular attention has been paid to Ca, vitamin D, protein and P. There has also been interest in several food groups, particularly dairy products, fruit and vegetables and foods contributing to acid-base balance. However, it is not possible at the present time to define dietary reference values using bone health as a criterion, and the question of what type of diet constitutes the best support for optimal bone growth and development remains open. Prudent recommendations (Department of Health, 1998; World Health Organization/Food and Agriculture Organization, 2003) are the same as those for adults, i.e. to consume a Ca intake close to the reference nutrient intake, optimise vitamin D status through adequate summer sunshine exposure (and diet supplementation where appropriate), be physically active, have a body weight in the healthy range, restrict salt intake and consume plenty of fruit and vegetables.

Effects of calcium supplementation on bone density in healthy children: meta-analysis of randomised controlled trials

OBJECTIVES

To assess the effectiveness of calcium supplementation for improving bone mineral density in healthy children and to determine if any effect is modified by other factors and persists after supplementation stops.

DESIGN

Meta-analysis.

DATA SOURCES

Electronic bibliographic databases, hand searching of conference proceedings, and contacting authors for unpublished data.

REVIEW METHODS

We included randomised placebo controlled trials of calcium supplementation in healthy children that lasted at least three months and had bone outcomes measured after at least six months of follow-up. Two reviewers independently extracted data and assessed quality. Meta-analyses predominantly used fixed effects models with outcomes given as standardised mean differences.

RESULTS

We included 19 studies involving 2859 children. Calcium supplementation had no effect on bone mineral density at the femoral neck or lumbar spine. There was a small effect on total body bone mineral content (standardised mean difference 0.14, 95% confidence interval 0.01 to 0.27) and upper limb bone mineral density (0.14, 0.04 to 0.24). This effect persisted after the end of supplementation only at the upper limb (0.14, 0.01 to 0.28). There was no evidence that sex, baseline calcium intake, pubertal stage, ethnicity, or level of physical activity modified the effect.

CONCLUSIONS

The small effect of calcium supplementation on bone mineral density in the upper limb is unlikely to reduce the risk of fracture, either in childhood or later life, to a degree of major public health importance.

Bone, body weight, and weight reduction: what are the concerns?

Of the U.S. population, 65% is either overweight or obese, and weight loss is recommended to reduce co-morbid conditions. However, bone mobilization and loss may also occur with weight loss. The risk for bone loss depends on initial body weight, age, gender, physical activity, and conditions of dieting such as the extent of energy restriction and specific levels of nutrient intake. Older populations are more prone to bone loss with weight loss; in women, this is due at least in part to a reduced dietary Ca intake and/or efficiency of absorption. Potential hormonal mechanisms regulating bone loss during weight loss are discussed, including decreases in estrogen, leptin, glucagon-like peptide-2, growth hormone, and insulin-like growth factor-1, or an increase in cortisol. In contrast, the rise in adiponectin and ghrelin with weight reduction should not be detrimental to bone. Combining energy restriction with exercise does not necessarily prevent bone loss, but may attenuate loss as was shown with additional Ca intake or osteoporosis medications. Future controlled weight loss trials should be designed to further address mechanisms influencing the density and quality of bone sites vulnerable to fracture, in the prevention of osteoporosis.

Randomized, placebo-controlled, calcium supplementation study in pregnant Gambian women: effects on breast-milk calcium concentrations and infant birth weight, growth, and bone mineral accretion in the first year of life

BACKGROUND

Growth and bone mineral accretion in Gambian infants are poorer than those in Western populations. The calcium intake of Gambian women is low, typically 300-400 mg Ca/d, and they have low breast-milk calcium concentrations, which result in low calcium intakes for their breastfed infants. A low maternal calcium supply in pregnancy may limit fetal mineral accretion and breast-milk calcium concentrations and thereby affect infant growth and bone mineral accretion.

OBJECTIVE

We investigated the effects of calcium supplementation in Gambian women during pregnancy on breast-milk calcium concentrations and infant birth weight, growth, and bone mineral accretion.

DESIGN

A randomized, double-blind, placebo-controlled supplementation study was conducted in 125 Gambian women who received 1500 mg Ca/d (as calcium carbonate) or placebo from 20 wk of gestation until delivery. Infant birth weight and gestational age were recorded. Breast milk was collected, and infant anthropometric and bone measurements were performed at 2, 13, and 52 wk after delivery. Infant bone mineral status was assessed by using single-photon absorptiometry of the radius and whole-body dual-energy X-ray absorptiometry.

RESULTS

Compliance with the supplement was high. No significant differences were detected between the groups in breast-milk calcium concentration, infant birth weight, or growth or bone mineral status during the first year of life. A slower rate of increase in infant whole-body bone mineral content and bone area was found in the supplement group than in the placebo group (group x time interaction: P = 0.03 and 0.02, respectively).

CONCLUSION

Calcium supplementation of pregnant Gambian women had no significant benefit for breast-milk calcium concentrations or infant birth weight, growth, or bone mineral status in the first year of life.

The effect on behavior and bone mineral density of individualized bone mineral density feedback and educational interventions in premenopausal women: a randomized controlled trial [NCT00273260]

BACKGROUND

Limited information is available on ways to influence osteoporosis risk in premenopausal women. This study tested four hypotheses regarding the effects of individualized bone density (BMD) feedback and different educational interventions on osteoporosis preventive behavior and BMD in pre-menopausal women, namely: that women are more likely to change calcium intake and physical activity if their BMD is low; that group education will be more efficacious at changing behavior than an information leaflet; that BMD feedback and group education have independent effects on behavior and BMD; and, that women who improve their physical activity or calcium intake will have a change in bone mass over 2 years that is better than those who do not alter their behavior.

METHODS

We performed a 2-year randomized controlled trial of BMD feedback according to T-score and either an osteoporosis information leaflet or small group education in a population-based random sample of 470 healthy women aged 25-44 years (response rate 64%). Main outcome measures were dietary calcium intake, calcium supplement use, smoking behavior, physical activity, endurance fitness, lower limb strength and BMD. We used paired t-tests, one-way ANOVA and linear regression techniques for data analysis.

RESULTS

Women who had feedback of low BMD had a greater increase in femoral neck BMD than those with normal BMD (1.6% p.a. vs. 0.7% p.a., p = 0.0001), but there was no difference in lumbar spine BMD change between these groups (0.1% p.a. vs. 0.08% p.a., p = 0.9). Both educational interventions had similar increases in femoral neck BMD (Leaflet = +1.0% p.a., Osteoporosis self-management course = + 1.3% p.a., p = 0.4). Femoral neck BMD change was only significantly associated with starting calcium supplements (1.3 % p.a, 95%CI +0.49, +2.17) and persistent self-reported change in physical activity levels (0.7% p.a., 95%CI +0.22, +1.22).

CONCLUSION

Individualized BMD feedback combined with a minimal educational intervention is effective at increasing hip but not spine bone density in premenopausal women. The changes in behavior through which this was mediated are potentially important in the prevention of other diseases, thus measuring BMD at a young age may have substantial public health benefits, particularly if these changes are sustained.

A randomized controlled trial of vitamin D3 supplementation in African American women

BACKGROUND

We conducted a randomized, placebo-controlled, double-blind trial to test the hypothesis that vitamin D(3) supplementation would prevent bone loss in calcium-replete, African American postmenopausal women.

METHODS

Two hundred eight healthy black postmenopausal women, 50 to 75 years of age, were assigned to receive either placebo or 20 microg/d (800 IU) of vitamin D(3). Calcium supplements were provided to ensure a total calcium intake of 1200 to 1500 mg/d. After 2 years, the vitamin D(3) dose was increased to 50 microg/d (2000 IU) in the active group, and the study continued for an additional year. Bone mineral density (BMD) was measured every 6 months. Markers of bone turnover, vitamin D metabolites, and parathyroid hormone (PTH) levels were measured in serum.

RESULTS

There were no significant differences in BMD between the active and control groups throughout the study. There was also no relationship between serum 25-hydroxyvitamin D levels attained and rates of bone loss. There was an increase in BMD of the total body, hip, and radius at 1 year in both groups. Over the 3 years, BMD declined at these sites by 0.26% to 0.55% per year. The BMD of the lumbar spine increased slightly in the placebo and active groups. There were no persistent changes in serum PTH levels or the markers of bone turnover, although there was a transient decline in PTH in both groups at 3 months. No significant adverse events were attributed to vitamin D supplementation.

CONCLUSIONS

There was no observed effect of vitamin D(3) supplementation on bone loss or bone turnover markers in calcium-replete, postmenopausal African American women. Further studies are needed to determine if these findings are applicable to women of other ethnic groups.

Calcium Supplementation during Childhood: Long-term Effects on Bone Mineralization

Calcium supplementation has been shown to increase bone mineralization in children and adolescents. However, catch-up mineralization later in puberty appears likely if intake is consistent with usual average intakes in the United States. Ultimately, individualized risk assessment will be developed based on genetic and lifestyle factors that can be used to guide optimal calcium intake during childhood.

Caloric restriction and calcium's effect on bone metabolism and body composition in overweight and obese premenopausal women

Obesity results in numerous preventable deaths and comorbidities. Unfortunately, a reduction of body weight has been correlated with a reduction in bone mass, the reasons for which have not been fully elucidated. The importance of maximizing peak bone mass during premenopausal years is well known. Most studies demonstrate a positive relationship between calcium intake and bone mass. However, during caloric restriction, which is commonly used for weight loss, calcium intake has shown mixed results. Calcium from dairy sources has received additional attention, beyond its importance to bone, for its role in regulating body weight and composition. Dairy foods are perceived as high fat, and therefore, are generally minimized or avoided during caloric restriction. The current calcium intake for premenopausal women is significantly below recommendations, and even if met during caloric restriction, may not be adequate. This review underscores the need for maintaining at least adequate intake levels of calcium, if not more, during weight loss regimens to minimize potential long-term detrimental effects on bone metabolism.

Effects of isoflavone supplements on bone metabolic markers and climacteric symptoms in Japanese women

A double-blind, placebo-controlled crossover study on the effects of 40~mg/d isoflavone supplements was carried out by 58 climacteric Japanese women. A questionnaire and an interview concerning climacteric symptoms, health status, dietary and exercise habit, and medical history were carried out, and the physical check-up and biochemical tests including sex-hormone analysis were made at baseline and after 4 and 8 weeks of treatment. Urinary isoflavones were separately measured from the frozen samples. Isoflavone treatment did not cause any adverse effects on anthropometric measures or blood chemistry. Urinary deoxypyridinoline, a marker of bone resorption decreased significantly with isoflavone treatment. This tendency was remarkable among equol producers. Plasma osteocalcin and bone mineral density did not change by the four-weeks treatment. As for climacteric symptoms, hot flash decreased significantly. Systolic and diastolic blood pressure of hypertensive participants decreased significantly after isoflavone treatment compared with baseline and the placebo treatment. Isoflavone supplementation offers benefits to reduce effectively on bone resorption enhanced by menopause. The treatment also showed an improvement of climacteric hot flash and hypertension. Equol producers showed better results.

Interaction of science, consumer practices and policy: calcium and bone health as a case study

Data to support a relationship between calcium and bone health are a major part of the body of evidence that underlie calcium-related policy in the United States. Examples of these policies include dietary intake recommendations, health claims for calcium and osteoporosis on food labels and an objective to improve calcium intake of the U.S. population in Healthy People 2010. Median calcium intakes among females fall below recommended levels after childhood even when supplemental calcium intakes are included. This is a concern in light of data that support a positive relationship between calcium and bone health. Most of the studies on the calcium-bone relationship have focused on older women, and several have used fracture as the endpoint; a meta-analysis of their results suggests that increased calcium intake is associated with approximately 30% decrease in fracture risk. Studies in children, adolescents and premenopausal women have focused on the relationship between calcium and bone mineral density rather than fracture; most of these also support a positive relationship between calcium intake and skeletal health although some data gaps remain. Calcium appears to be a threshold nutrient (e.g., intakes above a certain level do not result in further benefit to bone). The effect of increased calcium intake on bone density does not appear to persist unless the higher intakes are sustained. There are certain conditions, such as lactation, during which calcium intake does not appear to influence bone. Other factors that may influence the effect of calcium on bone include bone-specific genotypes and physical activity.

Dietary calcium and vitamin D intake in relation to osteoporotic fracture risk

The etiologic role of dietary calcium and vitamin D intake in primary prevention of osteoporotic fractures is uncertain, despite considerable research efforts. With the aim to examine these associations with an improved precision, we used data from a large population-based prospective cohort study in central Sweden. We estimated nutrient intake from a self-administered food-frequency questionnaire filled in by 60,689 women, aged 40-74 years at baseline during 1987-1990. During follow-up, we observed 3986 women with a fracture at any site and 1535 with a hip fracture. Rate ratio of fractures (RR) and 95% CI were estimated using Cox proportional hazards models. We found no dose-response association between dietary calcium intake and fracture risk. The age-adjusted RR of hip fracture was 1.01 (95% CI 0.96-1.06) per 300 mg calcium/day and the corresponding risk of any osteoporotic fracture was 0.99 (95% CI 0.96-1.03). Furthermore, women with an estimated calcium intake below 400 mg/day and those with a calcium intake higher than 1200 mg/day both had a similar age-adjusted hip fracture risk as those with intermediate calcium intakes: RR 1.07 (95% CI 0.92-1.24) and RR 1.00 (95% CI 0.79-1.27), respectively. Vitamin D intake was not associated with fracture risk. Furthermore, women in the highest quintiles compared to the lowest quintiles of both calcium and vitamin D intake had an age-adjusted RR of 1.02 for all fractures (95% CI 0.88-1.17). Dietary calcium or vitamin D intakes estimated at middle and older age do not seem to be of major importance for the primary prevention of osteoporotic fractures in women.

Mandibular bone remodeling under a choline-deficient diet: a histomorphometric study in rats

BACKGROUND

A deficiency of lipotropic factors in the rat induces renal, hepatic, and/or hematic damage. The aim of the present study was to evaluate the effect of a choline-deficient diet and refeeding on mandibular bone remodeling.

METHODS

Fifty Wistar rats were divided into 5 groups: group 1 (G1): control diet for 15 days; group 2 (G2): choline-deficient diet for 15 days; group 3 (G3): control diet for 30 days; group 4 (G4): choline-deficient diet for 30 days; and group 5 (G5): choline-deficient diet for 15 days and control diet for 15 days. All animals were sacrificed by ether overdose. The mandibles were resected, radiographed, decalcified, processed, and embedded in paraffin. Bucco-lingually oriented sections were obtained at the level of the interradicular bone of the medial roots of the left first molar, and stained with hematoxylin and eosin (H & E). Bone tissue density and bone remodeling were determined histomorphometrically. Body weight, food intake, hematocrit, and hemoglobinemia were also recorded.

RESULTS

Microscopic observation revealed that osteogenesis was lower in rats fed a choline-deficient diet, at both 15 and 30 days, and that this decrease did not revert with a control diet. Histomorphometric evaluation showed 37% and 27% reduction in bone tissue density at 15 and 30 days, respectively, and a 30% decrease in bone formation at 30 days, compared to controls.

CONCLUSION

In this experimental model, a choline-deficient diet led to altered bone remodeling as observed by a marked reduction in osteogenesis.

Effect of a calcium and exercise intervention on the bone mineral status of 16-18-y-old adolescent girls

BACKGROUND

Osteoporosis may be prevented or delayed by maximizing peak bone mass through diet modification and physical activity during adolescence.

OBJECTIVE

We studied whether increases in calcium intake and physical activity effectively increase the bone mineral status of adolescent girls aged 16-18 y.

DESIGN

We conducted a 15.5-mo study of calcium supplementation (1000 mg Ca/d as carbonate) in 144 adolescent girls aged 17.3 +/- 0.3 y ( +/- SD). The subjects were randomly allocated to an exercise (three 45-min exercise-to-music classes/wk during term time) or nonexercise group. Dual-energy X-ray absorptiometry of the whole body, spine, forearm, and hip was performed before and after intervention.

RESULTS

The mean (+/- SD) percentage of subjects compliant with supplement taking was 70 +/- 27% and with exercise class attendance was 36 +/- 25%. Baseline calcium intake was 938 +/- 411 mg/d. Calcium supplementation significantly increased size-adjusted bone mineral content. The effect was stronger in subjects with good compliance (percentage difference +/- SE): whole body, 0.8 +/- 0.3% (P < or = 0.01); lumbar spine, 1.9 +/- 0.5% (P < or = 0.001); ultradistal radius, 1.3 +/- 0.6% (P < or = 0.05); total hip, 2.7 +/- 0.6% (P < or = 0.001); femoral neck, 2.2 +/- 0.7% (P < or = 0.001); trochanter, 4.8 +/- 0.9% (P < or = 0.001). Attendance at > 50% of the exercise sessions was significant at the total hip (1.4 +/- 0.7%; P < or = 0.05) and trochanter (2.6 +/- 1.2%; P < or = 0.05).

CONCLUSIONS

Calcium supplementation and exercise enhanced bone mineral status in adolescent girls. Whether this is a lasting benefit, leading to the optimization of peak bone mass and a reduction in fracture risk, needs to be determined.