Dietary protein and bone health

Bone Health in Premenopausal Women with Coeliac Disease: An Observational Study

Low bone mineral density (BMD) is common in adults with coeliac disease (CD), even in individuals adhering to a gluten-free diet (GFD). Women are more likely to have low BMD and have an increased risk of osteoporosis, so women with pre-existing low BMD related to CD are at an even higher risk. BMD assessed by dual X-ray absorptiometry (DXA) and bone quality assessed through quantitative ultrasound (QUS) were investigated in 31 premenopausal women with CD consuming a GFD, and 39 matched healthy controls from the Lower North Island, New Zealand. In addition, bone metabolism and nutrient status were assessed, and four-day diet diaries were used to estimate nutrient intake. No statistically significant differences were found in BMD assessed by DXA between the two groups at the hip, lumbar spine or forearm. However, the parameters measured by the QUS were significantly lower in CD participants. Dietary data indicated significantly lower intakes of energy, dietary fibre, magnesium and phosphorus in women with CD, likely as a result of a reduced intake of wholegrain foods, and suggested that both groups had inadequate intake of calcium. No significant differences were demonstrated in biochemical parameters. BMD and bone biomarkers indicated no differences between coeliac and healthy women in New Zealand. However, these findings suggest that QUS may be more sensitive for the coeliac population, due to the disease's affect on the trabecular bone, and warrant further research.

First Ecuadorian statement consensus for the evaluation and treatment of osteoporosis

Osteoporosis management has become more relevant as the life expectancy increases. In Ecuador, approximately 19% of adults over 65 years of age have been diagnosed with osteoporosis. There is no national consensus for the management and prevention of the disease being this proposal the first Ecuadorian consensus.

INTRODUCTION

In Ecuador, it is estimated that around 19% of adults over 65 years of age have osteoporosis. Due to the increase in life expectancy in the world population, the evaluation and management of osteoporosis has become more relevant. Currently, there is no national consensus for the management and prevention of the disease. The Ecuadorian Society of Rheumatology presented the project for the elaboration of the first Ecuadorian consensus for the management and prevention of osteoporosis.

METHODS

A panel of experts in multiple areas and extensive experience was invited to participate. The consensus was carried out using the Delphi method. Six working dimensions were created: definition and epidemiology of osteoporosis, fracture risk prediction tools, non-pharmacological treatment, pharmacological treatment, calcium and vitamin D, and glucocorticoid-induced osteoporosis.

RESULTS

The first round was held in December 2021, followed by the second round in February 2022 and the third round in March 2022. The data was shared with the specialists at the end of each round. After three rounds of work, a consensus was reached for the management and prevention of osteoporosis.

CONCLUSION

This is the first Ecuadorian consensus for the management and treatment of postmenopausal osteoporosis.

Uncovering the unique characteristics of the mandible to improve clinical approaches to mandibular regeneration

The mandible (lower jaw) bone is aesthetically responsible for shaping the lower face, physiologically in charge of the masticatory movements, and phonetically accountable for the articulation of different phonemes. Thus, pathologies that result in great damage to the mandible severely impact the lives of patients. Mandibular reconstruction techniques are mainly based on the use of flaps, most notably free vascularized fibula flaps. However, the mandible is a craniofacial bone with unique characteristics. Its morphogenesis, morphology, physiology, biomechanics, genetic profile, and osteoimmune environment are different from any other non-craniofacial bone. This fact is especially important to consider during mandibular reconstruction, as all these differences result in unique clinical traits of the mandible that can impact the results of jaw reconstructions. Furthermore, overall changes in the mandible and the flap post-reconstruction may be dissimilar, and the replacement process of the bone graft tissue during healing can take years, which in some cases can result in postsurgical complications. Therefore, the present review highlights the uniqueness of the jaw and how this factor can influence the outcome of its reconstruction while using an exemplary clinical case of pseudoarthrosis in a free vascularized fibula flap.

Effects of Dietary Protein Source and Quantity on Bone Morphology and Body Composition Following a High-Protein Weight-Loss Diet in a Rat Model for Postmenopausal Obesity

Higher protein (>30% of total energy, HP)-energy restriction (HP-ER) diets are an effective means to improve body composition and metabolic health. However, weight loss (WL) is associated with bone loss, and the impact of HP-ER diets on bone is mixed and controversial. Recent evidence suggests conflicting outcomes may stem from differences in age, hormonal status, and the predominant source of dietary protein consumed. Therefore, this study investigated the effect of four 12-week energy restriction (ER) diets varying in predominate protein source (beef, milk, soy, casein) and protein quantity (normal protein, NP 15% vs. high, 35%) on bone and body composition outcomes in 32-week-old obese, ovariectomized female rats. Overall, ER decreased body weight, bone quantity (aBMD, aBMC), bone microarchitecture, and body composition parameters. WL was greater with the NP vs. HP-beef and HP-soy diets, and muscle area decreased only with the NP diet. The HP-beef diet exacerbated WL-induced bone loss (increased trabecular separation and endocortical bone formation rates, lower bone retention and trabecular BMC, and more rod-like trabeculae) compared to the HP-soy diet. The HP-milk diet did not augment WL-induced bone loss. Results suggest that specific protein source recommendations may be needed to attenuate the adverse alterations in bone quality following an HP-ER diet in a model of postmenopausal obesity.

Protein Supplement and Enhanced Recovery After Posterior Spine Fusion Surgery: A Randomized, Double-blind, Placebo-controlled Trial

STUDY DESIGN

This was a randomized, double-blind clinical trial study.

OBJECTIVE

The objective of this study was to evaluate the effect of protein supplementation on vertebral fusion and enhanced recovery after posterior spine fusion (PSF) surgery.

SUMMARY OF BACKGROUND DATA

Nonfusion is one of the most common complications of lumbar spine surgery. It has been shown that protein plays an important role in bone repair; however, its correlation to vertebral fusion following PSF surgery is unknown.

PATIENTS AND METHODS

In this randomized, double-blind clinical trial study, the intervention group received a diet with 1.2 g of protein plus high-protein supplement (36 g whey protein), and the control group received a similar diet, except for starch as a placebo from 48 hours before to 1 month after surgery.

RESULTS

The intervention group showed a significantly higher rate of vertebral fusion compared with the control group (P=0.019). Surgical site infection and pain were significantly lower in the intervention group. A significant difference was found in the wound healing rate in favor of the intervention group. The rates of decrease in serum high-sensitivity C-reactive protein levels and increase in serum levels of insulin-like growth factor 1, albumin, total protein, and alkaline phosphatase were greater in the intervention group than in the control group (P<0.001).

CONCLUSIONS

Increased protein intake improves vertebral fusion and enhances recovery in patients undergoing PSF. This was the first study to investigate the effect of protein on fusion and healing factors; as a result, further clinical trials are needed to confirm the current results.

Application of Machine Learning to Identify Clinically Meaningful Risk Group for Osteoporosis in Individuals Under the Recommended Age for Dual-Energy X-Ray Absorptiometry

Dual-energy X-ray absorptiometry (DXA) is the gold standard for diagnosing osteoporosis; it is generally recommended in men ≥ 70 and women ≥ 65 years old. Therefore, assessment of clinical risk factors for osteoporosis is very important in individuals under the recommended age for DXA. Here, we examine the diagnostic performance of machine learning-based prediction models for osteoporosis in individuals under the recommended age for DXA examination. Data of 2210 men aged 50-69 and 1099 women aged 50-64 obtained from the Korea National Health and Nutrition Examination Survey IV-V were analyzed. Extreme gradient boosting (XGBoost) was used to find relevant clinical features and applied to three machine learning models: XGBoost, logistic regression, and a multilayer perceptron. For the prediction of osteoporosis, the XGBoost model using the top 20 features extracted from XGBoost showed the most reliable performance with area under the receiver operating characteristic curve (AUROC) of 0.73 and 0.79 in men and women, respectively. We compared the diagnostic accuracy of the Shapley additive explanation values based on a risk-score model obtained from XGBoost and conventional osteoporosis risk assessment tools for prediction of osteoporosis using optimal cut-off values for each model. We observed that a cut-off risk score of ≥ 28 in men and ≥ 47 in women was optimal to classify a positive screening for osteoporosis (an AUROC of 0.86 in men and 0.91 in women). The XGBoost-based osteoporosis-prediction model outperformed conventional risk assessment tools. Therefore, machine learning-based prediction models are a more suitable option than conventional risk assessment methods for screening osteoporosis in individuals under the recommended age for DXA examination.

Joint position statement on management of patient with osteoporosis during COVID-19 contingency from the AMMOM, CONAMEGER, FELAEN, FEMECOG, FEMECOT, and ICAAFYD

Infection by SARS-Cov-2 (COVID-19) has affected practically all the world. This joint position statement of Latin American Medical Societies provides an updated guide for the prevention, diagnosis, and treatment of osteoporotic patients in the face of possible clinical scenarios posed by the COVID-19 health crisis.

BACKGROUND

Infection by SARS-Cov-2 (COVID-19) has affected practically all the world. Characterized by high contagiousness, significative morbidity, and mortality in a segment of those infected, it has overwhelmed health services and forced to redirect resources to the emergency while impacting the attention of acute non-COVID-19 and many chronic conditions.

OBJECTIVE

The objective of this study is to provide an updated guide for the prevention, diagnosis, and treatment of osteoporotic patients in the face of possible clinical scenarios posed by the COVID-19 health crisis.

METHODS

A task force, of bone specialists with a wide range of disciplines in the field of osteoporosis and fragility fracture, was convened with the representation of several professional associations, namely, the Mexican Association of Bone and Mineral Metabolism (AMMOM), the National College of Geriatric Medicine (CONAMEGER), the Latin American Federation of Endocrinology (FELAEN), the Mexican Federation of Colleges of Obstetrics and Gynecology (FEMECOG), the Mexican Federation of Colleges of Orthopedics and Traumatology (FEMECOT), and the Institute of Applied Sciences for Physical Activity and Sports of the University of Guadalajara (ICAAFYD). Clinical evidence was collated, and an evidence report was rapidly generated and disseminated. After finding the gaps in the available evidence, a consensus opinion of experts was made. The resulting draft was reviewed and modified accordingly, in 4 rounds, by the participants.

RESULTS

The task force approved the initial guidance statements, with moderate and high consensus. These were combined, resulting in the final guidance statements on the (1) evaluation of fracture risk; (2) stratification of risk priorities; (3) indications of bone density scans and lab tests; (4) initiation and continuation of pharmacologic therapy; (5) interruptions of therapy; (6) treatment of patients with incident fracture; (7) physical therapy and fall prevention; and (8) nutritional interventions.

CONCLUSION

These guidance statements are provided to promote optimal care to patients at risk for osteoporosis and fracture, during the current COVID-19 pandemic. However, given the low level of available evidence and the rapidly evolving literature, this guidance is presented as a "living document" and future updates are anticipated.

Autophagy: A Promising Target for Age-related Osteoporosis

Autophagy is a process the primary role of which is to clear up damaged cellular components such as long-lived proteins and organelles, thus participating in the conservation of different cells. Osteoporosis associated with aging is characterized by consistent changes in bone metabolism with suppression of bone formation as well as increased bone resorption. In advanced age, not only bone mass but also bone strength decrease in both sexes, resulting in an increased incidence of fractures. Clinical and animal experiments reveal that age-related bone loss is associated with many factors such as accumulation of autophagy, increased levels of reactive oxygen species, sex hormone deficiency, and high levels of endogenous glucocorticoids. Available basic and clinical studies indicate that age-associated factors can regulate autophagy. Those factors play important roles in bone remodeling and contribute to decreased bone mass and bone strength with aging. In this review, we summarize the mechanisms involved in bone metabolism related to aging and autophagy, supplying a theory for therapeutic targets to rescue bone mass and bone strength in older people.

FGF21, not GCN2, influences bone morphology due to dietary protein restrictions

Background

Dietary protein restriction is emerging as an alternative approach to treat obesity and glucose intolerance because it markedly increases plasma fibroblast growth factor 21 (FGF21) concentrations. Similarly, dietary restriction of methionine is known to mimic metabolic effects of energy and protein restriction with FGF21 as a required mechanism. However, dietary protein has been shown to be required for normal bone growth, though there is conflicting evidence as to the influence of dietary protein restriction on bone remodeling. The purpose of the current study was to evaluate the effect of dietary protein and methionine restriction on bone in lean and obese mice, and clarify whether FGF21 and general control nonderepressible 2 (GCN2) kinase, that are part of a novel endocrine pathway implicated in the detection of protein restriction, influence the effect of dietary protein restriction on bone.

Methods

Adult wild-type (WT) or Fgf21 KO mice were fed a normal protein (18 kcal%; CON) or low protein (4 kcal%; LP) diet for 2 or 27 weeks. In addition, adult WT or Gcn2 KO mice were fed a CON or LP diet for 27 weeks. Young New Zealand obese (NZO) mice were placed on high-fat diets that provided protein at control (16 kcal%; CON), low levels (4 kcal%) in a high-carbohydrate (LP/HC) or high-fat (LP/HF) regimen, or on high-fat diets (protein, 16 kcal%) that provided methionine at control (0.86%; CON-MR) or low levels (0.17%; MR) for up to 9 weeks. Long bones from the hind limbs of these mice were collected and evaluated with micro-computed tomography (μCT) for changes in trabecular and cortical architecture and mass.

Results

In WT mice the 27-week LP diet significantly reduced cortical bone, and this effect was enhanced by deletion of Fgf21 but not Gcn2. This decrease in bone did not appear after 2 weeks on the LP diet. In addition, Fgf21 KO mice had significantly less bone than their WT counterparts. In obese NZO mice dietary protein and methionine restriction altered bone architecture. The changes were mediated by FGF21 due to methionine restriction in the presence of cystine, which did not increase plasma FGF21 levels and did not affect bone architecture.

Conclusions

This study provides direct evidence of a reduction in bone following long-term dietary protein restriction in a mouse model, effects that appear to be mediated by FGF21.

Effects of Dietary Protein Quantity on Bone Quantity following Weight Loss: A Systematic Review and Meta-analysis

Research supports the hypothesis that higher total protein intake during weight loss promotes retention of lean soft tissue, but the effect of dietary protein quantity on bone mass, a lean hard tissue, is inconsistent. The purpose of this systematic review and meta-analysis was to assess the effect of dietary protein quantity [higher protein (HP): ≥25% of energy from protein or ≥1.0 g · kg body wt-1 · d-1; normal protein (NP): <25% of energy from protein or <1.0 g · kg body wt-1 · d-1] on changes in bone mineral density (BMD) and content (BMC; total body, lumbar spine, total hip, femoral neck) following a prescribed energy restriction. We hypothesized that an HP diet would attenuate the loss of BMD/BMC following weight loss in comparison to an NP diet. Two researchers systematically and independently screened 2366 publications from PubMed, Cochrane, Scopus, CINAHL, and Web of Science Core Collection and extracted data from 34 qualified publications. Inclusion criteria included the following: 1) healthy subjects ≥19 y; 2) a prescribed energy restriction; 3) measurements of total protein intake, BMD, and BMC; and 4) an intervention duration of ≥3 mo. Data from 10 of the 34 publications with 2 groups of different total protein intakes were extracted and used to conduct a random-effects model meta-analysis. A majority of publications (59%) showed a decrease in bone quantity following active weight loss, regardless of total protein intake. Statistically, the loss of total BMD (P = 0.016; weighted mean difference: +0.006 g/cm2; 95% CI: 0, 0.011 g/cm2) and lumbar spine BMD (P = 0.019; weighted mean difference: +0.017 g/cm2; 95% CI: 0.001, 0.033 g/cm2) was attenuated with an HP versus an NP weight-loss diet. However, the clinical significance is questionable given the modest weighted mean difference and study duration. Higher total protein intake does not exacerbate but may attenuate the loss of bone quantity following weight loss.

Quantitative Ultrasound and Dual X-Ray Absorptiometry as Indicators of Bone Mineral Density in Young Women and Nutritional Factors Affecting It

Young adulthood is an important stage in the accrual of bone mass. Young women are often unaware of the need, and how to optimize modifiable risk factors, particularly intake of nutrients associated with good bone health. In this study, an accessible way to estimate osteoporosis risk, quantitative ultrasound (QUS), is compared to the gold-standard technique dual X-ray absorptiometry (DXA) in a group of 54 healthy young women (18–26 years) from Manawatu, New Zealand, and the relationship with nutrient intake is investigated. Broadband ultrasound attenuation and speed of sound (BUA, SOS) were assessed by QUS calcaneal scans and bone mineral concentration/density (BMC/BMD) were determined by DXA scans of the lumbar spine and hip (total and femoral neck). Dietary intake of energy, protein, and calcium was estimated using three-day food diaries and questionnaires. DXA mean Z-scores (>−2.0) for the hip (0.19) and spine (0.2) and QUS mean Z-scores (>−1.0) (0.41) were within the expected ranges. DXA (BMD) and QUS (BUA, SOS) measurements were strongly correlated. Median intakes of protein and calcium were 83.7 g/day and 784 mg/day, respectively. Protein intake was adequate and, whilst median calcium intake was higher than national average, it was below the Estimated Average Requirement (EAR). No significant relationship was found between dietary intake of calcium or protein and BMD or BMC. To conclude, QUS may provide a reasonable indicator of osteoporosis risk in young women but may not be an appropriate diagnostic tool. Increased calcium intake is recommended for this group, regardless of BMD.

Greater yogurt consumption is associated with increased bone mineral density and physical function in older adults

In this cohort of community dwelling older adults (>60 years), we observed significant positive associations between the frequencies of yogurt intake with measures of bone density, bone biomarkers, and indicators of physical function. Improving yogurt intakes could be a valuable health strategy for maintaining bone health in older adults.

INTRODUCTION

The associations of yogurt intakes with bone health and frailty in older adults are not well documented. The aim was to investigate the association of yogurt intakes with bone mineral density (BMD), bone biomarkers, and physical function in 4310 Irish adults from the Trinity, Ulster, Department of Agriculture aging cohort study (TUDA).

METHODS

Bone measures included total hip, femoral neck, and vertebral BMD with bone biochemical markers. Physical function measures included Timed Up and Go (TUG), Instrumental Activities of Daily Living Scale, and Physical Self-Maintenance Scale.

RESULTS

Total hip and femoral neck BMD in females were 3.1-3.9% higher among those with the highest yogurt intakes (n = 970) compared to the lowest (n = 1109; P < 0.05) as were the TUG scores (-6.7%; P = 0.013). In males, tartrate-resistant acid phosphatase (TRAP 5b) concentrations were significantly lower in those with the highest yogurt intakes (-9.5%; P < 0.0001). In females, yogurt intake was a significant positive predictor of BMD at all regions. Each unit increase in yogurt intake in females was associated with a 31% lower risk of osteopenia (OR 0.69; 95% CI 0.49-0.96; P = 0.032) and a 39% lower risk of osteoporosis (OR 0.61; 95% CI 0.42-0.89; P = 0.012) and in males, a 52% lower risk of osteoporosis (OR 0.48; 95% CI 0.24-0.96; P = 0.038).

CONCLUSION

In this cohort, higher yogurt intake was associated with increased BMD and physical function scores. These results suggest that improving yogurt intakes could be a valuable public health strategy for maintaining bone health in older adults.

The relationship between protein quantity, BMD and fractures in older adults

BACKGROUND

Previously, no large-scale literature reviews have focussed on the relationship between dietary protein and its impact on bone mineral density (BMD) and fracture risk-as measures of bone health-in older adults and its potential impact as a primary prevention tool.

AIMS

The aim of this study was to assess the impact of varying dietary protein levels on bone health.

METHODS

A literature review of trials concerning older adults' (>50 years of age) and animals' varying protein intake in the diet and its effect on BMD (human and animal) and fracture risk (human only) was carried out. Additionally, a review of dietary assessment tools used in these studies was also analysed.

RESULTS

Ten out of fourteen trials assessing BMD and dietary protein quantity in humans and 3/4 in animal trials found a positive relationship between these two parameters. Four out of seven trials investigating the relationship between dietary protein quantity and fracture risk displayed a positive, protective effect of dietary protein levels on fracture risk. Sixty-two percent of studies used the Food-Frequency Questionnaire assessment method.

DISCUSSION

Increased protein intake in the diet is beneficial to bone health and reduces morbidity and mortality. The importance of using dietary protein, along with calcium and vitamin D, as a primary preventative strategy should be stressed, given the health and cost benefits that this would deliver, with a possible need for a higher level of protein in the diet of an elderly person than what is currently recommended.

Vitamin D Status in South Asian Populations - Risks and Opportunities

Human body acquires a significant amount of vitamin D by cutaneous synthesis under the action of sunlight and less is supplied through nutritional sources. Diversified sociocultural and economic determinants have been identified that limit the dietary intake of vitamin D and enough distribution of sunlight to maintain optimal levels of 25-hydroxyvitamin D (25(OH)D). Consequently, the world has witnessed a high prevalence of hypovitaminosis D in resource-limited South Asian countries. The purpose of this review is to provide a South Asian perspective of vitamin D status, critically examining India, Pakistan, Bangladesh, and Sri Lanka, and to shed light on potential determinants (latitude and season, sunshine exposure habits, age, gender, and genetic factors) leading to hypovitaminosis D among a variety of population groups. Literature search was carried out using bibliographic databases "PubMed," "Google Scholar," and "ScienceDirect.com." Serum 25(OH)D level, 20-50 nmol/L, was mainly taken as vitamin D deficiency, and determinants of low serum 25(OH)D concentration of the population under study were also considered. The review concludes that vitamin D deficiency is highly prevalent among South Asian populations and global efforts are needed to overcome hypovitaminosis in the region. In addition, dietary diversification, supplementation and fortification of foods with vitamin D, adequate exposure to sunlight, and consumption of animal foods were suggested as viable approaches to maintain 25(OH)D levels for optimal health.

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.

Association of pasta consumption with body mass index and waist-to-hip ratio: results from Moli-sani and INHES studies

Background/Objectives:

Pasta as a traditional component of Mediterranean diet (MeD) in Italy has not been studied in detail in the management of body weight. This study aimed at evaluating the association of pasta intake with body mass index (BMI) and waist-to-hip ratio, in two large epidemiological datasets.

Subjects/Methods:

A total of 14 402 participants aged ⩾35 years randomly recruited from the general population of the Molise region (Moli-sani cohort) and 8964 participants aged >18 years from all over Italy (Italian Nutrition & HEalth Survey, INHES) were separately analyzed. The European Prospective Investigation into Cancer and Nutrition (EPIC)-food frequency questionnaire and one 24-h dietary recall were used for dietary assessment. Weight, height, waist and hip circumference were measured in Moli-sani or self-reported in INHES. Residuals methodology corrected for either total energy intake or body weight was used for the analysis of pasta intake.

Results:

Higher pasta intake was associated with better adhesion to MeD in both genders (P for both<0.001). In the Moli-sani study, after multivariable analysis, pasta-energy residuals were negatively associated with BMI in women but not in men (β-coef=−0.007, P=0.003 for women and β-coef=−0.001, P=0.58 for men). When pasta intake-body weight residuals were used, pasta intake was significantly and negatively associated with BMI in crude and multi-adjusted models (including adhesion to MeD) in both genders and Moli-sani and INHES studies (for all β-coef<0, P<0.05). In the Moli-sani study, pasta-body weight residuals were significantly and negatively associated with waist and hip circumference and waist-to-hip ratio (for all β-coef<0, P<0.05).

Conclusions:

As a traditional component of MeD, pasta consumption was negatively associated with BMI, waist circumference and waist-to-hip ratio and with a lower prevalence of overweight and obesity.

The Relationship between Metabolic Syndrome and Osteoporosis: A Review

Metabolic syndrome (MetS) and osteoporosis are two major healthcare problems worldwide. Metabolic syndrome is a constellation of medical conditions consisting of central obesity, hyperglycemia, hypertension, and dyslipidemia, in which each acts on bone tissue in different ways. The growing prevalence of MetS and osteoporosis in the population along with the controversial findings on the relationship between both conditions suggest the importance for further investigation and discussion on this topic. This review aims to assess the available evidence on the effects of each component of MetS on bone metabolism from the conventional to the contemporary. Previous studies suggested that the two conditions shared some common underlying pathways, which include regulation of calcium homeostasis, receptor activator of NF-κB ligand (RANKL)/receptor activator of the NF-κB (RANK)/osteoprotegerin (OPG) and Wnt-β-catenin signaling pathways. In conclusion, we suggest that MetS may have a potential role in developing osteoporosis and more studies are necessary to further prove this hypothesis.

In Vitro Proliferation and Anti-Apoptosis of the Papain-Generated Casein and Soy Protein Hydrolysates towards Osteoblastic Cells (hFOB1.19)

Casein and soy protein were digested by papain to three degrees of hydrolysis (DH) 7.3%–13.3%, to obtain respective six casein and soy protein hydrolysates, aiming to clarify their in vitro proliferation and anti-apoptosis towards a human osteoblastic cell line (hFOB1.19 cells). Six casein and soy protein hydrolysates at five levels (0.01–0.2 mg/mL) mostly showed proliferation as positive 17β-estradiol did, because they conferred the osteoblasts with cell viability of 100%–114% and 104%–123%, respectively. The hydrolysates of higher DH values had stronger proliferation. Casein and soy protein hydrolysates of the highest DH values altered cell cycle progression, and enhanced cell proportion of S-phase from 50.5% to 56.5% and 60.5%. The two also antagonized etoposide- and NaF-induced osteoblast apoptosis. In apoptotic prevention, apoptotic cells were decreased from 31.6% to 22.6% and 15.6% (etoposide treatment), or from 19.5% to 17.7% and 12.4% (NaF treatment), respectively. In apoptotic reversal, soy protein hydrolysate decreased apoptotic cells from 13.3% to 11.7% (etoposide treatment), or from 14.5% to 11.0% (NaF treatment), but casein hydrolysate showed no reversal effect. It is concluded that the hydrolysates of two kinds had estradiol-like action on the osteoblasts, and soy protein hydrolysates had stronger proliferation and anti-apoptosis on the osteoblasts than casein hydrolysates.

Combined effects of interaction between physical activity and nutrition on bone health in children and adolescents: a systematic review

CONTEXT

Osteoporosis is a major public health concern worldwide. Understanding the roles of diet and physical activity in ensuring adequate bone mass accrual during childhood and adolescence may help identify strategies to reduce the risk of osteoporotic fractures later in life.

OBJECTIVE

The present systematic review was conducted to provide an overview of the current knowledge of the combined effects of physical activity and diet on bone mass accrual in children and adolescents.

DATA SOURCES

Data were obtained via searches of the PubMed, EMBASE, SPORTDiscus, and ISI Web of Science databases.

STUDY SELECTION

Studies published in English and Spanish between 1887 and August 2013 were eligible for inclusion. Two investigators evaluated the studies against the inclusion and exclusion criteria. A total of 14 studies (7 cross-sectional and 7 experimental) were included in the review.

DATA EXTRACTION

The Pedro score and the Black and Down's checklist were used to evaluate the methodological quality of the experimental and the cross-sectional studies, respectively. Study characteristics were summarized in accordance with the review's PICO criteria.

DATA SYNTHESIS

Significant exercise-by-calcium interaction was detected at several different bone sites.

CONCLUSIONS

Although the results of cross-sectional studies were inconsistent, the results of randomized controlled trials showed that exercise has the potential to improve bone health under conditions of adequate calcium intake.

Protein malnutrition attenuates bone anabolic response to PTH in female rats

PTH is indicated for the treatment of severe osteoporosis. Elderly osteoporotic patients frequently suffer from protein malnutrition, which may contribute to bone loss. It is unknown whether this malnutrition may affect the response to PTH. Therefore, the aim of the present study was to assess whether an isocaloric low-protein (LP) diet may influence the bone anabolic response to intermittent PTH in 6-month-old female rats. Six-month-old female rats were either pair fed an isocaloric LP diet (2.5% casein) or a normal-protein (NP) diet (15% casein) for 2 weeks. The rats continued on their respective diet while being treated with 5- or 40-μg/kg recombinant human PTH amino-terminal fragment 1-34 (PTH-[1-34]) daily, or with vehicle for 4 weeks. At the end of this period, areal bone mineral density, bone mineral content, microstructure, and bone strength in axial compression of proximal tibia or 3-point bending for midshaft tibia tests were measured. Blood was collected for the determination of IGF-I and osteocalcin. After 4 weeks of PTH-(1-34), the dose-dependent increase of proximal tibia bone mineral density, trabecular microstructure variables, and bone strength was attenuated in rats fed a LP diet as compared with rats on a NP intake. At the level of midshaft tibia cortical bone, PTH-(1-34) exerted an anabolic effect only in the NP but not in the LP diet group. Protein malnutrition was associated with lower IGF-I levels. Protein malnutrition attenuates the bone anabolic effects of PTH-(1-34) in rats. These results suggest that a sufficient protein intake should be recommended for osteoporotic patients undergoing PTH therapy.

Protein intake and lumbar bone density: the Multi-Ethnic Study of Atherosclerosis (MESA)

Dietary protein has been shown to increase urinary Ca excretion in randomised controlled trials, and diets high in protein may have detrimental effects on bone health; however, studies examining the relationship between dietary protein and bone health have conflicting results. In the present study, we examined the relationship between dietary protein (total, animal and vegetable protein) and lumbar spine trabecular volumetric bone mineral density (vBMD) among participants enrolled in the Multi-Ethnic Study of Atherosclerosis (n 1658). Protein intake was assessed using a FFQ obtained at baseline examination (2000-2). Lumbar spine vBMD was measured using quantitative computed tomography (2002-5), on average 3 years later. Multivariable linear and robust regression techniques were used to examine the associations between dietary protein and vBMD. Sex and race/ethnicity jointly modified the association of dietary protein with vBMD (P for interaction = 0·03). Among white women, higher vegetable protein intake was associated with higher vBMD (P for trend = 0·03), after adjustment for age, BMI, physical activity, alcohol consumption, current smoking, educational level, hormone therapy use, menopause and additional dietary factors. There were no consistently significant associations for total and animal protein intakes among white women or other sex and racial/ethnic groups. In conclusion, data from the present large, multi-ethnic, population-based study suggest that a higher level of protein intake, when substituted for fat, is not associated with poor bone health. Differences in the relationship between protein source and race/ethnicity of study populations may in part explain the inconsistent findings reported previously.

Bone Mineral Density in Children From Anthropological and Clinical Sciences: A Review

Bone mineral density (BMD) is a frequent topic of discussion in the clinical literature in relation to the bone health of both adults and children. However, in archaeological and/ or anthropological studies the role of BMD is often cited as a possible factor in the poor skeletal preservation which can lead to an under-representation of juvenile skeletal remains. During skeletal development and growth throughout childhood and adolescence changes take place in both the size and shape of bones and these changes also result in the increasing of mineral content. BMD can be affected by many factors, which include, age, genetics, sexual maturation, amount of physical activity and dietary calcium. This paper aims to review the clinical and anthropological literature on BMD and discuss the numerous methods of measurement and how the availability of certain methods such as Dual-energy x-ray absorptiometry (DEXA) and quantitative computed tomography (QCT) can influence the study of bone density in archaeological skeletal collections and also the future potential for forensic anthropological studies.

Bone and mineral metabolism in patients undergoing Roux-en-Y gastric bypass

Despite effective weight reduction, the impact of bariatric surgery on bone is a major concern. Mechanisms include decreased mechanical loading, calcium and vitamin D malabsorption, deficiency in other nutrients, and alterations in fat- and gut-derived hormones. The evidence to support clinical care pathways to prevent bone loss and fractures is at this point weak.

INTRODUCTION

There is a growing concern regarding the potential deleterious impact of bariatric surgery on bone metabolism. This comprehensive review addresses this controversial topic.

METHODS

We reviewed and analyzed articles evaluating bone metabolism and mechanisms for the ensuing putative bone loss in adult patients exclusively undergoing Roux-en-Y gastric bypass (RYGB) surgery, for the period spanning 1942 till September 2012.

RESULTS

Mechanisms identified to contribute to alterations in bone metabolism after bypass surgery include: decreased mechanical loading, calcium and vitamin D malabsorption with secondary hyperparathyroidism, deficiency in other nutrients, in addition to alterations in adipokines, gonadal steroids, and gut-derived hormones favoring bone loss, with the exception of serotonin and glucagon-like peptide-1. The relative contribution of each of these hormones to changes in bone homeostasis after bypass surgery remains undefined. Bone loss reflected by a decline in bone mineral density (BMD) and an increase in bone turnover markers have been reported in many studies, limited for the most part by the exclusive use of dual energy X-ray absorptiometry. Well-designed long-term prospective trials with fractures as an outcome, and studies investigating the magnitude, reversibility, and impact of the observed metabolic changes on fracture outcomes are lacking.

CONCLUSION

Robust conclusions regarding bone loss and fracture outcome after RYGB surgery cannot be drawn at this time. Although not evidence based, baseline evaluation and sequential monitoring with measurement of BMD and calciotropic hormones seem appropriate, with adequate calcium and vitamin D replacement. Beneficial interventions remain unclear.

Milk consumption during teenage years and risk of hip fractures in older adults

IMPORTANCE

Milk consumption during adolescence is recommended to promote peak bone mass and thereby reduce fracture risk in later life. However, its role in hip fracture prevention is not established and high consumption may adversely influence risk by increasing height.

OBJECTIVES

To determine whether milk consumption during teenage years influences risk of hip fracture in older adults and to investigate the role of attained height in this association.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study over 22 years of follow-up in more than 96,000 white postmenopausal women from the Nurses' Health Study and men aged 50 years and older from the Health Professionals Follow-up Study in the United States.

EXPOSURES

Frequency of consumption of milk and other foods during ages 13 to 18 years and attained height were reported at baseline. Current diet, weight, smoking, physical activity, medication use, and other risk factors for hip fractures were reported on biennial questionnaires.

MAIN OUTCOMES AND MEASURES

Cox proportional hazards models were used to calculate relative risks (RRs) of first incidence of hip fracture from low-trauma events per glass (8 fl oz or 240 mL) of milk consumed per day during teenage years.

RESULTS

During follow-up, 1226 hip fractures were identified in women and 490 in men. After controlling for known risk factors and current milk consumption, each additional glass of milk per day during teenage years was associated with a significant 9% higher risk of hip fracture in men (RR = 1.09; 95% CI, 1.01-1.17). The association was attenuated when height was added to the model (RR = 1.06; 95% CI, 0.98-1.14). Teenage milk consumption was not associated with hip fractures in women (RR = 1.00 per glass per day; 95% CI, 0.95-1.05).

CONCLUSIONS AND RELEVANCE

Greater milk consumption during teenage years was not associated with a lower risk of hip fracture in older adults. The positive association observed in men was partially mediated through attained height.

Profiles of vitamin D insufficiency and deficiency in Japanese men and women: association with biological, environmental, and nutritional factors and coexisting disorders: the ROAD study

Assessments of serum 25-hydroxyvitamin D levels in 1,683 Japanese from a population-based cohort revealed prevalences of vitamin D insufficiency and deficiency were 81.3 and 1.2%, respectively. Vitamin D deficiency was significantly associated with female sex, examined month, current smoking, lack of regular walking, higher intact parathyroid hormone (iPTH), and poor daily vitamin D intake.

INTRODUCTION

To clarify the characteristics of subjects with vitamin D insufficiency and deficiency among men and women in the general Japanese population.

METHODS

We initiated research on osteoarthritis/osteoporosis against disability (ROAD), a large-scale population-based cohort study, in 2005-2007. Blood examination was performed to measure serum 25-hydroxyvitamin D (25D) and iPTH levels and biochemical markers of bone turnover in 1,683 participants (595 men, 1,088 women). Participants completed an interviewer-administered questionnaire, measurements of bone mineral density, and x-ray examination. Vitamin D deficiency and insufficiency were defined by serum 25D levels <10 and ≥10 but <30 ng/mL, respectively.

RESULTS

The prevalence of vitamin D insufficiency and deficiency was 81.3 and 1.2%, respectively. Multinominal logistic regression analyses using potentially confounding variables revealed vitamin D insufficiency was significantly associated with age (+1 year, relative risk ratio, 0.98; 95% confidence interval, 0.96-0.99), gender (women vs. men, 2.28; 1.59-3.30), residing areas (coastal area vs. mountainous area, 0.58; 0.41-0.81), examined month (October, November, December vs. January, 0.51; 0.34-0.76), and serum levels of iPTH (+1 pg/mL, 1.02; 1.01-1.03). Vitamin D deficiency was significantly characterised by female sex (20.5; 3.1-136.7), examined month (0.28; 0.09-0.95), current smoking habit (6.39; 1.78-23.0), lack of regular outside walking (3.96; 1.34-11.7), higher iPTH (1.02; 1.01-1.03) and poor daily vitamin D intake (+10 μg/day, 0.48; 0.24-0.93).

CONCLUSIONS

A high prevalence of vitamin D insufficiency and a low prevalence of vitamin D deficiency were found in Japanese men and women, and the characteristics of vitamin D status were clarified.

Facial development disorders due to inhibition to endochondral ossification of mandibular condyle process caused by malnutrition

OBJECTIVE

To analyze the effect of protein restriction on histomorphometric parameters of bone remodeling in mandibular condyle process and its possible influence in facial development in growing rats.

MATERIALS AND METHODS

Wistar rats weaned at the age of 21 days were assigned to one of the following groups: control (fed a regular hard diet ad libitum) and protein restricted (PR) (fed a hard diet lacking in protein ad libitum). The animals were euthanized on day 35 after the onset of the experiment. Mandibles were resected, fixed in 10% formalin, hemisected at the symphysis, and then radiographed in order to perform cephalometric studies of the condylar process length and the height of the lower alveolar process. Mandibles were then processed for light microscopy, and histomorphometric determinations were performed on histologic sections of the condylar process subchondral bone.

RESULTS

The PR group showed a significantly lower body weight than control group at the end of the experiment. The length of the condylar process was lower in the PR group; however, the diet used in this study did not affect the height of the lower alveolar process. The histomorphometric analysis showed that the PR group exhibited a statistically significant decrease in bone formation and bone volume in condylar process subchondral bone.

CONCLUSION

Protein restriction inhibits bone formation and longitudinal growth in the mandibular condylar process. This result suggest that protein restriction can alter normal facial development.

Is there an epidemic vitamin D deficiency in German orthopaedic patients?

BACKGROUND

Vitamin D plays an essential role in bone health and muscle function. Some studies have shown a widespread rate of vitamin D deficiency in the general population, but few have reported on the vitamin D status of orthopaedic patients.

QUESTIONS/PURPOSES

We investigated (1) the extent of hypovitaminosis D in orthopaedic patients, (2) seasonal variations in vitamin D levels, and (3) possible risk factors for insufficient vitamin D levels.

METHODS

Vitamin D levels in 1119 patients consecutively admitted to an orthopaedic surgery department in 2011 were measured. To investigate the correlation between climate factors and vitamin D levels, the sunshine hours for each month in 2011 were collected by Deutscher Wetterdienst (the German weather service) in the region where most tested patients lived. The prevalence of normal (> 30 ng/mL), insufficient (20-30 ng/mL), and deficient (< 20 ng/mL) 25-hydroxyvitamin D levels was determined. Univariate and multivariate analyses were used to assess risk factors for insufficient vitamin D levels.

RESULTS

Overall, 84% of patients had insufficient levels of vitamin D and 60% were vitamin D deficient. Only 15% were in the target range of 30 to 60 ng/mL. The prevalence of low vitamin D levels was greater during winter and months with fewer sunshine hours. Vitamin D levels did not vary according to age, sex, and disease. Individuals with obesity, hypertension, and osteoporosis were more likely to have low vitamin D levels compared with their healthy counterparts.

CONCLUSIONS

There is an alarmingly high rate of hypovitaminosis D and vitamin D deficiency among orthopaedic patients in this region of Germany, whose latitude (50° N) is approximately the same as those of Vancouver (49°, 15' N) and Paris (48°, 51' N). Given the well-known effects on bone metabolism and muscle health, low vitamin D levels may negatively affect patients. Screening and treating hypovitaminosis D appears to be important in this patient population.

Low protein intake magnifies detrimental effects of ovariectomy and vitamin D on bone

Protein-induced changes in bone and calcium homeostasis could potentially be greater in the elderly and in women at risk for osteoporosis. We hypothesize that a low protein intake would magnify the negative changes in bone metabolism seen in vitamin D (vitD) insufficiency and/or estrogen deficiency. The present study was undertaken to better understand how a low protein diet along with vitD insufficiency could affect bone metabolism using a rodent ovariectomized (OVX) model. Rats (n = 60) underwent ovariectomy (OVX) or sham operation. The first 15 days after surgery, all rats were fed a standard rodent diet. Thereafter, rats (n = 10/group) were fed a low protein diet (LP; 2.5 %) or a control diet (NP; 12.5 %) with 100 IU% vitD (+D; cholecalciferol) or without vitD (-D) for 45 days. The groups were as follows: SHAM + NP + D (control); SHAM + LP + D; SHAM + LP - D; OVX + NP + D; OVX + LP + D; OVX + LP - D. Body weight (BW) of control and OVX + NP + D groups increased while those feeding the LP diet, independently of vitD feedings, decreased (p < 0.05). The OVX + LP - D group presented the lowest serum Ca, phosphorus and osteocalcin levels and the highest CTX levels (p < 0.05). At the end of the study, total skeleton bone mineral content, proximal tibia bone mineral density, bone volume and trabecular number levels decreased as follows: SHAM + NP + D (controls) > SHAM + LP + D > OVX + NP + D > SHAM + LP - D > OVX + LP + D > OVX + LP - D (p < 0.05). A low protein diet negatively affected bone mass and magnified the detrimental effects of vitD and/or estrogen deficiencies.

Selective osteoblast overexpression of IGF-I in mice prevents low protein-induced deterioration of bone strength and material level properties

Protein deficiency is frequently observed in elderly osteoporotic patients. Undernutrition leads to decreased levels of IGF-I, an important factor in regulating bone homeostasis throughout life. IGF-I is produced in the liver and locally in the skeleton. We hypothesized that increasing IGF-I expression in the osteoblasts, the bone forming cells, would protect the skeleton from the negative effects of a low-protein diet. To test our hypothesis, we employed a mouse model in which IGF-I was overexpressed exclusively in osteoblasts and fed either a 15% (normal) or a 2.5% (low) protein isocaloric diet to the transgenic (TG) mice and their wild-type (WT) littermates for 8 weeks. Blood was collected for biochemical determinations and weight was monitored weekly. Bones were excised for microstructural analysis (μCT), as well as biomechanical and material level properties. Histomorphometric analysis was performed for bone formation parameters. A low protein diet decreased body weight, circulating IGF-I and osteocalcin levels regardless of genotype. Overexpression of IGF-I in the osteoblasts was, however, able to protect the negative effects of low protein diet on microstructure including tibia cortical thickness and volumetric density, and on bone strength. Overexpression of IGF-I in osteoblasts in these mice protected the vertebrae from the substantial negative effects of low protein on the material level properties as measured my nanoindentation. TG mice also had larger overall geometric properties than WT mice regardless of diet. This study provides evidence that while a low protein diet leads to decreased circulating IGF-I, altered microstructure and decreased bone strength, these negative effects can be prevented with IGF-I overexpression exclusively in bone cells.

Extrinsic mechanisms involved in age-related defective bone formation

CONTEXT

Age-related bone loss is associated with progressive changes in bone remodeling characterized by decreased bone formation relative to bone resorption. Both trabecular and periosteal bone formation decline with age in both sexes, which contributes to bone fragility and increased risk of fractures. Studies in rodents and humans revealed that, independent of sex hormone deficiency, the age-related decline in bone formation is characterized by decreased osteoblast number and lifespan and reduced bone-forming capacity of individual osteoblasts. An important clinical question is to identify the mechanisms involved in the age-related defective bone formation.

EVIDENCE ACQUISITION

The mechanisms discussed in this review are based on a PubMed search and knowledge of the authors in the field.

EVIDENCE SYNTHESIS

Available basic and clinical studies indicate that multiple mechanisms are involved in the alterations of osteoblastogenesis and the resulting decline in bone formation with aging. Notably, the age-related osteoblast dysfunctions and defective bone formation are caused by a number of extrinsic clinical factors that inhibit anabolic signaling pathways in bone. Thus, targeting these pathways can abolish age-related bone loss.

CONCLUSIONS

The identification of extrinsic mechanisms involved in osteoblast dysfunctions associated with aging improves our knowledge of age-related bone loss and provides a basis for therapeutic intervention to improve bone formation and bone mass in the aging population.

Effect of protein intake on bone and muscle mass in the elderly

The aging process is frequently characterized by an involuntary loss of muscle (sarcopenia) and bone (osteoporosis) mass. Both chronic diseases are associated with decreased metabolic rate, increased risk of falls/fracture, and, as a result, increased morbidity and loss of independence in the elderly. The quality and quantity of protein intake affects bone and muscle mass in several ways and there is evidence that increased essential amino acid or protein availability can enhance muscle protein synthesis and anabolism, as well as improve bone homeostasis in older subjects. A thorough evaluation of renal function is important, since renal function decreases with age. Finally, protein and calcium intake should be considered in the prevention or treatment of the chronic diseases osteoporosis and sarcopenia.

Comparison of the effects of dietary protein, androstenediol and forearm muscle area on radial bone variables in healthy prepubertal children

Adequate dietary habits are supposed to be one of the most important modifiable factors in osteoporosis prevention. However, the importance of specific nutrients is controversial. We examined relevant nutrients which are supposed to have an impact on bone parameters and compared their effect sizes with those of two known predictors of bone development: bone-related muscle mass and androgen levels. We analysed nutritional, hormonal and anthropometric data from 107 prepubertal children participating in the Dortmund Nutritional and Anthropometric Longitudinally Designed Study. Diaphyseal bone mineral content (BMC), cortical area (CA), periosteal circumference, strength strain index and muscle area of the non-dominant forearm were measured by peripheral quantitative computed tomography. Data on long-term nutrient intakes (e.g. protein, Ca and vitamin D) were derived from 3 d weighed dietary records. Twenty-four hour urinary excretion rates of androgen metabolites including the sex steroid androstenediol were measured using GC-MS. Of all considered nutrients, only protein showed a trend for an association with BMC (β = +0·11; P = 0·073) and CA (β = +0·11; P = 0·056) in stepwise linear regression models. None of the other considered dietary variables was associated with bone parameters. The size of the bone anabolic effect of protein was partly comparable with that of androstenediol. Even though boys gained more bone mass in comparison with girls, the protein effect did not differ between sexes. Bone-related muscle area and sex steroids have the strongest effects on prepubertal diaphyseal bone. However, dietary protein may have a similar bone anabolic influence compared with androstenediol. In children without explicit nutrient deficits, protein seems to be the most important dietary component for diaphyseal bone status.

Further decrease in glycated hemoglobin following ingestion of a LoBAG30 diet for 10 weeks compared to 5 weeks in people with untreated type 2 diabetes

BACKGROUND

We previously determined that a weight-maintenance, non-ketogenic diet containing 30% carbohydrate (CHO), 30% protein, 40% fat, (30:30:40) (LoBAG30) decreased glycated hemoglobin (%tGHb) from 10.8 to 9.1% over a 5 week period in subjects with untreated type 2 diabetes. Both the fasting glucose and postprandial glucose area were decreased. Our objective in the present 10-week study was to determine: 1) whether the above results could be maintained, or even improved (suggesting a metabolic adaptation) and 2) whether the subjects would accept the diet for this longer time period. In addition, protein balance, and a number of other blood and urine constituents were quantified at 5 and at 10 weeks on the LoBAG30 diet to address metabolic adaptation.

METHODS

Eight men with untreated type 2 diabetes were studied over a 10-week period. Blood was drawn and urine was collected over a 24 hour period at the beginning of the study with subjects ingesting a standard diet of 55% CHO, 15% protein, 30% fat, and at the end of 5 and 10 weeks following ingestion of a LoBAG30 diet.

RESULTS

Body weight was stable. Fasting glucose decreased by 19% at week 5 and 28% at week 10; 24-h total glucose area decreased by 27% at week 5 and 35% at week 10 compared to baseline. Insulin did not change. Mean %tGHb decreased by 13% at week 5, 25% at week 10, and was still decreasing linearly, indicating that a metabolic adaptation occurred. Serum NEFA, AAN, uric acid, urea, albumin, prealbumin, TSH, Total T3, free T4, B12, folate, homocysteine, creatinine, growth hormone and renin did not differ between weeks 5 and 10. IGF-1 increased modestly. Urinary glucose decreased; urinary pH and calcium were similar.

CONCLUSIONS

A LoBAG30 diet resulted in continued improvement in glycemic control. This improvement occurred without significant weight loss, with unchanged insulin and glucagon profiles, and without deterioration in serum lipids, blood pressure or kidney function. Extending the duration of time on a LoBAG30 diet from 5 to 10 weeks had little or no further effect on the hormones and metabolites measured, i.e. a metabolic equilibrium was established.

Administration of growth hormone in selectively protein-deprived rats decreases BMD and bone strength

INTRODUCTION

Isocaloric protein undernutrition is associated with decreased bone mass and decreased bone strength, together with lower IGF-I levels. It remains unclear whether administration of growth hormone (GH) corrects these alterations in bone metabolism.

MATERIALS AND METHODS

Six-month-old female rats were fed isocaloric diets containing either 2.5% or 15% casein for 2 weeks. Bovine growth hormone (bGH, 0.5 or 2.5mg/kg of body weight) or vehicle was then administered as subcutaneous injections, twice daily, to rats on either diet for 4 weeks. At the proximal tibia, analysis of bone mineral density (BMD), maximal load and histomorphometry were performed. In addition, urinary deoxypyridinoline, plasma osteocalcin and IGF-I concentrations were measured. Weight was monitored weekly.

RESULTS

bGH caused a dose-dependent increase in plasma IGF-I regardless of the dietary protein content. However, bGH dose-dependently decreased BMD and bone strength in rats fed the low-protein diet. There was no significant effect of bGH on BMD in rats fed the normal protein diet within this short-term treatment period, however bone formation as detected by histomorphometry was improved in this group but not the low-protein group. Osteoclast surface was increased in the low-protein bGH-treated animals only. Changes in bone turnover markers were detectable under both normal and low-protein diets.

CONCLUSION

These results emphasize the major importance of dietary protein intake in the bone response to short-term GH administration, and highlight the need for further investigation into the effects of GH treatment in patients with reduced protein intake.

Optimizing bone health in chronic kidney disease

Phosphocalcic metabolism disorders often complicate chronic kidney disease (CKD) and worsen as kidney function declines, with a consequence on bone structural integrity. The risk of fracture exceeds that of the normal population in both patients with pre-dialysis CKD and end-stage renal disease (ESRD). The increasing incidence of CKD, the high mortality rate induced by hip fracture, the decreased quality of life and economic burden of fragility fracture make the renal bone disorders a major problem of public health around the world. Optimizing bone health in CKD patients should be a priority. Bone biopsy is invasive. Dual-energy X-ray absorptiometry, commonly used to screen individuals at risk of fragility fracture in the general population, is not adequate to assess advanced CKD because it does not discriminate fracture status in this population. New non-invasive three-dimensional high-resolution imaging techniques, distinguishing trabecular and cortical bone, appear to be promising in the assessment of bone strength and might improve bone fracture prediction in this population. Therapeutic intervention in the chronic kidney disease-mineral and bone disorders (CKD-MBD) should begin early in the course of CKD to maintain serum concentration of biological parameters involved in mineral metabolism in the normal recommended ranges, prevent the development of parathyroid hyperplasia, prevent extra-skeletal calcifications and preserve skeletal health. In this paper, we review studies of mineral and bone disorders in patients with CKD and ESRD, the utility of current techniques to assess bone health and the preventive and therapeutic strategies for managing CKD-MBD.

Dietary protein and bone health: a systematic review and meta-analysis

BACKGROUND

There has been a resurgence of interest in the controversial relation between dietary protein and bone health.

OBJECTIVE

This article reports on the first systematic review and meta-analysis of the relation between protein and bone health in healthy human adults.

DESIGN

The MEDLINE (January 1966 to September 2007) and EMBASE (1974 to July 2008) databases were electronically searched for all relevant studies of healthy adults; studies of calcium excretion or calcium balance were excluded.

RESULTS

In cross-sectional surveys, all pooled r values for the relation between protein intake and bone mineral density (BMD) or bone mineral content at the main clinically relevant sites were significant and positive; protein intake explained 1-2% of BMD. A meta-analysis of randomized placebo-controlled trials indicated a significant positive influence of all protein supplementation on lumbar spine BMD but showed no association with relative risk of hip fractures. No significant effects were identified for soy protein or milk basic protein on lumbar spine BMD.

CONCLUSIONS

A small positive effect of protein supplementation on lumbar spine BMD in randomized placebo-controlled trials supports the positive association between protein intake and bone health found in cross-sectional surveys. However, these results were not supported by cohort study findings for hip fracture risk. Any effects found were small and had 95% CIs that were close to zero. Therefore, there is a small benefit of protein on bone health, but the benefit may not necessarily translate into reduced fracture risk in the long term.

Global vitamin D status and determinants of hypovitaminosis D

This review describes the vitamin D status in different regions of the world with the objective of understanding the scope of hypovitaminosis D and the factors related to its prevalence that may contribute to the pathogenesis of osteoporosis and fragility fractures.

INTRODUCTION

Vitamin D status has been linked to the pathogenesis of hip fractures as well as other skeletal and non-skeletal disorders. The purpose of this review is to provide a global perspective of vitamin D status across different regions of the world and to identify the common and significant determinants of hypovitaminosis D.

METHODS

Six regions of the world were reviewed-Asia, Europe, Middle East and Africa, Latin America, North America, and Oceania-through a survey of published literature.

RESULTS

The definition of vitamin D insufficiency and deficiency, as well as assay methodology for 25-hydroxyvitamin D or 25(OH)D, vary between studies. However, serum 25(OH)D levels below 75 nmol/L are prevalent in every region studied whilst levels below 25 nmol/L are most common in regions such as South Asia and the Middle East. Older age, female sex, higher latitude, winter season, darker skin pigmentation, less sunlight exposure, dietary habits, and absence of vitamin D fortification are the main factors that are significantly associated with lower 25(OH)D levels.

CONCLUSION

Reports from across the world indicate that hypovitaminosis D is widespread and is re-emerging as a major health problem globally.

[Current diagnosis and therapy of osteoporosis on the basis of "European guidance 2008"]

Osteoporosis is one of the 10 most important and widespread global diseases. In Germany alone the cost of osteoporosis runs into many billions of Euros. However, it should be noted that in the past 15 years great progress has been made both in diagnosis and in the development of new medications, and this has changed the general perception of and attitude to osteoporosis. It is now taken very seriously and recognised as a national and global disorder which is both preventable and treatable. In spite of this progress, in Europe and especially in Germany, osteoporosis remains an underdiagnosed and undertreated disease. In Germany, only about 10%-15% of patients with manifest osteoporosis are properly treated. However, in addition to national guidelines, there is now a new edition of the "European Position Paper for the Diagnosis and Management of Osteoporosis". This provides physicians treating osteoporosis patients with additional information and therefore more confidence.

Early serum IGF-I response to oral protein supplements in elderly women with a recent hip fracture

BACKGROUND & AIMS

In patients with recent hip fracture, reduced serum IGF-I in relation to protein undernutrition is frequent. Elevation of circulating IGF-I in response to a daily oral supplement of 20 g of casein was observed after 6 months. This study determined if the response to casein as compared to whey protein can be observed as early as after one week.

METHODS

45 women were randomized after recent hip fracture in 3 groups receiving a preparation of 20 g of casein, an isocaloric supplement of 20 g of whey protein or an isocaloric supplement of 15 g of whey protein combined with 5 g of essential amino acids (a.a.).

RESULTS

A similar significant elevation of serum IGF-I was already observed after 7 days for casein (+37.3 microg/L), whey (+29.4) and for whey+a.a. (+34.3). From day 7-28, no further significant rise in IGF-I was recorded.

CONCLUSION

After one week of protein supplementation, the percent increase of IGF-I was of similar magnitude to that previously observed after 6 months of protein supplementation. It suggests that in hip fracture patients, long-term effects of various protein preparations on IGF-I could be predicted from changes observed as early as 7 days after the onset of supplementation.

Zinc increases the effects of essential amino acids-whey protein supplements in frail elderly

Protein undernutrition is frequent in the elderly. It contributes to the development of osteoporosis, possibly via lower IGF-I. Dietary zinc can influence IGF-I production.

OBJECTIVES

To determine the influence of dietary zinc addition on IGF-I and bone turnover responses to essential amino acids-whey (EAA-W) protein supplements in frail elderly.

DESIGN AND SETTING

A daily oral protein supplement was given to hospitalized patients for 4 weeks. On a randomized, double-blind basis, patients received either an additional 30 mg/day of zinc or control.

PARTICIPANTS

Sixty-one hospitalized elderly aged 66.7 to 105.8, with a mini-nutritional assessment score between 17 and 24 were enrolled.

MEASUREMENTS

Activities of daily living; dietary intakes; serum IGF-I, IGF-BP3, CrossLapsTM, osteocalcin and zinc were measured before and after 1, 2 and 4 weeks of protein supplementation.

RESULTS

Serum IGF-I rapidly increased in both groups. Zinc accelerated this increase with changes of +48.2 +/- 14.3 and +22.4 +/- 4.7% (p < .05) by 1 week, in the zinc-supplemented and control groups, respectively. Zinc significantly decreased the serum bone resorption marker CrossLapsTM by already 1 week. Activities of daily living improved by +27.0 +/- 3.1 and +18.3 +/- 4.5% in zinc-supplemented and control groups, respectively.

CONCLUSION

In the elderly, zinc supplementation accelerated the serum IGF-I response to EAA-W protein by 1 week and decreased a biochemical marker of bone resorption.