Healthy lifestyles are associated with better vitamin D status in community-dwelling older men: The Health In Men Study (HIMS).

OBJECTIVE: Older people are more prone to vitamin D deficiency than younger populations. Individual lifestyle factors have been associated with vitamin D status. We examined the influence of a combination of lifestyle factors on vitamin D status in older men. PARTICIPANTS AND MEASUREMENTS: In a population-based cohort study of older men (age ≥65 years), a lifestyle score was calculated from eight prudent health-related behaviours (smoking, exercise, alcohol, fish and meat consumption, adding salt, milk choices and obesity) collected via questionnaire at baseline. Blood samples were collected 5 years afterwards to measure plasma 25-hydroxyvitamin D (25OHD) levels. Associations between lifestyles and the likelihood of having plasma 25OHD levels of ≥75 versus <75 nmol/L and ≥50 versus <50 nmol/L were tested using logistic regression models. RESULTS: Of the 2717 men analysed, mean plasma 25OHD was 69.0 ± 23.5 nmol/L, with 20.7% having plasma 25OHD <50 nmol/L. Men engaging in ≥4 healthy lifestyle behaviours had 20% higher odds of plasma 25OHD ≥75 nmol/L (adjusted OR = 1.20, 95% CI: 1.01-1.45) compared to those with <4 healthy behaviours. No association was found for 25OHD ≥50 nmol/L. Higher physical activity was the only individual component significantly associated with vitamin D sufficiency (highest vs. lowest quintiles of physical activity, adjusted OR = 2.01, 95% CI: 1.47-2.74 for 25OHD ≥50 nmol/L, adjusted OR = 2.35, 95% CI: 1.81-3.06 for 25OHD ≥75 nmol/L). CONCLUSION: Multiple healthy lifestyle behaviours are associated with better vitamin D status in older men. Further work is needed to determine the effects of promoting healthy lifestyle behaviours, including physical activity, on vitamin D sufficiency.

Undercarboxylated osteocalcin and ibandronate combination ameliorates hindlimb immobilization-induced muscle wasting.

Immobilization leads to muscle wasting and insulin resistance, particularly during ageing. It has been suggested that undercarboxylated osteocalcin (ucOC) improves muscle mass and glucose metabolism. Bisphosphonates, an anti-osteoporosis treatment, might protect muscle wasting independent of ucOC. We hypothesize that the combination of ucOC and ibandronate (IBN) treatments has superior protective effects against immobilization-induced muscle wasting and insulin resistance than either treatment alone. C57BL/6J mice were hindlimb-immobilized for two weeks, with injections of vehicle, ucOC (90 ng/g daily) and/or IBN (2 µg/g weekly). Insulin/oral glucose tolerance tests (ITT/OGTT) were performed. Immediately after immobilization, muscles (extensor digitorum longus (EDL), soleus, tibialis anterior, gastrocnemius and quadriceps) were isolated and measured for muscle mass. Insulin-stimulated glucose uptake (EDL and soleus) was examined. Phosphorylation/expression of proteins in anabolic/catabolic pathways were examined in quadriceps. Primary human myotubes derived from older adult muscle biopsies were treated with ucOC and/or IBN, then signalling proteins were analysed. Combined treatment, but not individual treatments, significantly increased the muscle weight/body weight ratio in immobilized soleus (31.7%; P = 0.013) and quadriceps (20.0%; P = 0.0008) muscles, concomitant with elevated p-Akt (S473)/Akt ratio (P = 0.0047). Combined treatment also enhanced whole-body glucose tolerance (16.6%; P = 0.0011). In human myotubes, combined treatment stimulated greater activation of ERK1/2 (P = 0.0067 and 0.0072) and mTOR (P = 0.036), and led to a lesser expression of Fbx32 (P = 0.049) and MuRF1 (P = 0.048) than individual treatments. These findings suggest a potential therapeutic role for the ucOC and bisphosphonates combination in protecting against muscle wasting induced by immobilization and ageing. KEY POINTS: It has been suggested that undercarboxylated osteocalcin (ucOC) improves muscle mass and glucose metabolism. Bisphosphonates, an anti-osteoporosis treatment, might protect against muscle wasting independent of ucOC. The combination treatment of ucOC and ibandronate was shown to exert a greater therapeutic effect against immobilization-induced muscle wasting, and led to greater activation of anabolic pathway and less expression of catabolic signalling proteins in myotubes derived from older adults, compared with individual treatments. The combination treatment was found to improve whole-body glucose tolerance. Our findings suggest a potential therapeutic role for the ucOC and bisphosphonates combination in protecting against muscle wasting induced by immobilization and ageing.

Osteoglycin Across the Adult Lifespan.

CONTEXT: Osteoglycin (OGN) is a proteoglycan released from bone and muscle which has been associated with markers of metabolic health. However, it is not clear whether the levels of circulating OGN change throughout the adult lifespan or if they are associated with clinical metabolic markers or fitness. OBJECTIVE: We aimed to identify the levels of circulating OGN across the lifespan and to further explore the relationship between OGN and aerobic capacity as well as OGN's association with glucose and HOMA-IR. METHODS: 107 individuals (46 males and 61 females) aged 21-87 years were included in the study. Serum OGN levels, aerobic capacity (VO2peak), glucose, and homeostatic model assessment for insulin resistance (HOMA-IR) were assessed. T-tests were used to compare participant characteristics between sexes. Regression analyses were performed to assess the relationship between OGN and age, and OGN and fitness and metabolic markers. RESULTS: OGN displayed a nonlinear, weak "U-shaped" relationship with age across both sexes. Men had higher levels of OGN than women across the lifespan (ß = 0.23, P = .03). Age and sex explained 16% of the variance in OGN (adjusted R2 = 0.16; P < .001). Higher OGN was associated with higher VO2peak (ß = 0.02, P = .001); however, those aged <50 showed a stronger positive relationship than those aged >50. A higher OGN level was associated with a higher circulating glucose level (ß = 0.17, P < .01). No association was observed between OGN and HOMA-IR. CONCLUSION: OGN was characterized by a U-shaped curve across the lifespan which was similar between sexes. Those with a higher aerobic capacity or higher glucose concentration had higher OGN levels. Our data suggest an association between OGN and aerobic fitness and glucose regulation. Future studies should focus on exploring the potential of OGN as a biomarker for chronic disease.

Adipose Tissue Dysfunction: Impact on Bone and Osseointegration.

Bone metabolism may be adversely affected in metabolic diseases such as obesity and metabolic syndrome, which are characterised by weight gain, due to the expansion of adipose tissue deposits. As an important regulator of energy metabolism, adipose tissues synthesise and secrete several key regulatory adipokines that influence a range of metabolic functions. This narrative review outlines the evidence for the mechanisms by which adipose tissue dysfunction may alter bone metabolism prior to the development of frank hyperglycaemia and presents the emerging evidence for the impact of diet-induced expansion of adipose tissue on implant osseointegration. Successful osseointegration requires normal bone cell function, and the expansion of adipose tissue deposits results in dysregulated adipokine production favouring an increase in pro-inflammatory adipokines, contributing to the development of a chronic inflammatory state and insulin resistance. The increase in inflammatory cytokines promotes the growth and differentiation of osteoclasts indirectly through the modulation of osteoblastic RANKL production and directly by reducing osteoclast apoptosis and increased osteoclastic expression of RANK. Conversely, the suppression of osteoblastic regulatory genes results in reduced osteoblast numbers and function contributing to compromised bone turnover. Compromised osseointegration has been established in hyperglycaemia; however, as discussed in this review, it may not be the only driver of altered bone metabolism. The incidence of metabolic disease in the community is rising, patients may present for implant treatment with undiagnosed, underlying changes to bone cell metabolism due to adipose tissue dysmetabolism.

Vitamin D and Skeletal Muscle: Current Concepts From Preclinical Studies.

Muscle weakness has been recognized as a hallmark feature of vitamin D deficiency for many years. Until recently, the direct biomolecular effects of vitamin D on skeletal muscle have been unclear. Although in the past, some reservations have been raised regarding the expression of the vitamin D receptor in muscle tissue, this special issue review article outlines the clear evidence from preclinical studies for not only the expression of the receptor in muscle but also the roles of vitamin D activity in muscle development, mass, and strength. Additionally, muscle may also serve as a dynamic storage site for vitamin D, and play a central role in the maintenance of circulating 25-hydroxy vitamin D levels during periods of low sun exposure. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Nutritional intake and bone health.

Osteoporotic or fragility fractures affect one in two women and one in five men who are older than 50. These events are associated with substantial morbidity, increased mortality, and an impaired quality of life. Recommended general measures for fragility fracture prevention include a balanced diet with an optimal protein and calcium intake and vitamin D sufficiency, together with regular weight-bearing physical exercise. In this narrative Review, we discuss the role of nutrients, foods, and dietary patterns in maintaining bone health. Much of this information comes from observational studies. Bone mineral density, microstructure-estimated bone strength, and trabecular and cortical microstructure are positively associated with total protein intake. Several studies indicate that fracture risk might be lower with a higher dietary protein intake, provided that the calcium supply is sufficient. Dairy products are a valuable source of these two nutrients. Hip fracture risk appears to be lower in consumers of dairy products, particularly fermented dairy products. Consuming less than five servings per day of fruit and vegetables is associated with a higher hip fracture risk. Adherence to a Mediterranean diet or to a prudent diet is associated with a lower fracture risk. These various nutrients and dietary patterns influence gut microbiota composition or function, or both. The conclusions of this Review emphasise the importance of a balanced diet including minerals, protein, and fruit and vegetables for bone health and in the prevention of fragility fractures.

The mTORC2 Regulator Homer1 Modulates Protein Levels and Sub-Cellular Localization of the CaSR in Osteoblast-Lineage Cells.

We recently found that, in human osteoblasts, Homer1 complexes to Calcium-sensing receptor (CaSR) and mediates AKT initiation via mechanistic target of rapamycin complex (mTOR) complex 2 (mTORC2) leading to beneficial effects in osteoblasts including ß-catenin stabilization and mTOR complex 1 (mTORC1) activation. Herein we further investigated the relationship between Homer1 and CaSR and demonstrate a link between the protein levels of CaSR and Homer1 in human osteoblasts in primary culture. Thus, when siRNA was used to suppress the CaSR, we observed upregulated Homer1 levels, and when siRNA was used to suppress Homer1 we observed downregulated CaSR protein levels using immunofluorescence staining of cultured osteoblasts as well as Western blot analyses of cell protein extracts. This finding was confirmed in vivo as the bone cells from osteoblast specific CaSR-/- mice showed increased Homer1 expression compared to wild-type (wt). CaSR and Homer1 protein were both expressed in osteocytes embedded in the long bones of wt mice, and immunofluorescent studies of these cells revealed that Homer1 protein sub-cellular localization was markedly altered in the osteocytes of CaSR-/- mice compared to wt. The study identifies additional roles for Homer1 in the control of the protein level and subcellular localization of CaSR in cells of the osteoblast lineage, in addition to its established role of mTORC2 activation downstream of the receptor.

Distinct Effects of a High Fat Diet on Bone in Skeletally Mature and Developing Male C57BL/6J Mice.

Increased risks of skeletal fractures are common in patients with impaired glucose handling and type 2 diabetes mellitus (T2DM). The pathogenesis of skeletal fragility in these patients remains ill-defined as patients present with normal to high bone mineral density. With increasing cases of glucose intolerance and T2DM it is imperative that we develop an accurate rodent model for further investigation. We hypothesized that a high fat diet (60%) administered to developing male C57BL/6J mice that had not reached skeletal maturity would over represent bone microarchitectural implications, and that skeletally mature mice would better represent adult-onset glucose intolerance and the pre-diabetes phenotype. Two groups of developing (8 week) and mature (12 week) male C57BL/6J mice were placed onto either a normal chow (NC) or high fat diet (HFD) for 10 weeks. Oral glucose tolerance tests were performed throughout the study period. Long bones were excised and analysed for ex vivo biomechanical testing, micro-computed tomography, 2D histomorphometry and gene/protein expression analyses. The HFD increased fasting blood glucose and significantly reduced glucose tolerance in both age groups by week 7 of the diets. The HFD reduced biomechanical strength, both cortical and trabecular indices in the developing mice, but only affected cortical outcomes in the mature mice. Similar results were reflected in the 2D histomorphometry. Tibial gene expression revealed decreased bone formation in the HFD mice of both age groups, i.e., decreased osteocalcin expression and increased sclerostin RNA expression. In the mature mice only, while the HFD led to a non-significant reduction in runt-related transcription factor 2 (Runx2) RNA expression, this decrease became significant at the protein level in the femora. Our mature HFD mouse model more accurately represents late-onset impaired glucose tolerance/pre-T2DM cases in humans and can be used to uncover potential insights into reduced bone formation as a mechanism of skeletal fragility in these patients.

Associations of Osteocalcin Forms With Metabolic Syndrome and Its Individual Components in Older Men: The Health In Men Study.

CONTEXT: The osteoblast-derived polypeptide, osteocalcin (OC), has been associated with lower risk of type 2 diabetes and metabolic syndrome (MetS) in several epidemiological studies. Animal studies have indicated the undercarboxylated form of OC (ucOC) drives its association with metabolic outcomes. OBJECTIVE: We compared associations of ucOC and carboxylated OC (cOC) with MetS and its components in older men. METHODS: A cross-sectional analysis of 2575 men aged ≥70 years and older resident in Perth, Western Australia. ucOC was assayed using a hydroxyapatite-binding method, and cOC calculated by subtracting ucOC from total OC. Main outcome measures were MetS and its components. RESULTS: Both lower serum ucOC and cOC levels, and the proportion of cOC (%cOC) were associated with less favorable metabolic parameters (higher waist circumference, triglyceride, glucose, blood pressure, and lower high-density lipoprotein cholesterol), whereas inverse associations were found with %ucOC. Men in the lowest quintile of ucOC had higher risk of MetS compared to men in the highest quintile (Q1 ≤ 7.7 vs Q5 > 13.8 ng/mL; OR = 2.4; 95% CI, 1.8-3.2). Men in the lowest quintile of cOC had higher risk of MetS compared to those in the highest quintile (≤ 5.8 vs > 13.0 ng/mL; OR = 2.4; 95% CI, 1.8-3.2). CONCLUSION: Lower concentrations of serum ucOC or cOC were associated with less favorable metabolic parameters and a higher risk of MetS. In contrast, a lower proportion of ucOC was associated with better metabolic parameters and lower MetS risk. Further research is warranted to determine whether ucOC and cOC are suitable biomarkers for cardiometabolic risk in men.

Uncovering the Bone-Muscle Interaction and Its Implications for the Health and Function of Older Adults (the Wellderly Project): Protocol for a Randomized Controlled Crossover Trial.

BACKGROUND: Bone and muscle are closely linked anatomically, biochemically, and metabolically. Acute exercise affects both bone and muscle, implying a crosstalk between the two systems. However, how these two systems communicate is still largely unknown. We will explore the role of undercarboxylated osteocalcin (ucOC) in this crosstalk. ucOC is involved in glucose metabolism and has a potential role in muscle maintenance and metabolism. OBJECTIVE: The proposed trial will determine if circulating ucOC levels in older adults at baseline and following acute exercise are associated with parameters of muscle function and if the ucOC response to exercise varies between older adults with low muscle quality and those with normal or high muscle quality. METHODS: A total of 54 men and women aged 60 years or older with no history of diabetes and warfarin and vitamin K use will be recruited. Screening tests will be performed, including those for functional, anthropometric, and clinical presentation. On the basis of muscle quality, a combined equation of lean mass (leg appendicular skeletal muscle mass in kg) and strength (leg press; one-repetition maximum), participants will be stratified into a high or low muscle function group and randomized into the controlled crossover acute intervention. Three visits will be performed approximately 7 days apart, and acute aerobic exercise, acute resistance exercise, and a control session (rest) will be completed in any order. Our primary outcome for this study is the effect of acute exercise on ucOC in older adults with low muscle function and those with high muscle function. RESULTS: The trial is active and ongoing. Recruitment began in February 2018, and 38 participants have completed the study as of May 26, 2019. CONCLUSIONS: This study will provide novel insights into bone and muscle crosstalk in older adults, potentially identifying new clinical biomarkers and mechanistic targets for drug treatments for sarcopenia and other related musculoskeletal conditions. TRIAL REGISTRATION: Australia New Zealand Clinical Trials Registry ACTRN12618001756213; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375925. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/18777.

Higher Undercarboxylated to Total Osteocalcin Ratio Is Associated With Reduced Physical Function and Increased 15-Year Falls-Related Hospitalizations: The Perth Longitudinal Study of Aging Women.

Evidence from animal models suggests that undercarboxylated osteocalcin (ucOC) is involved in muscle mass maintenance and strength. In humans, the ucOC to total (t)OC ratio may be related to muscle strength and perhaps physical function and falls risk, but data are limited. We tested the hypothesis that ucOC and ucOC/tOC ratio are associated with muscle function (muscle strength and physical function) in older women and 15-year falls-related hospitalizations. Serum tOC and ucOC were assessed in 1261 older women (mean age 75.2 ± 2.7 years) forming the Perth Longitudinal Study of Aging Women (1998 to 2013). Timed-up-and-go (TUG) and grip strength were assessed at baseline and at 5 years. Falls-related hospitalizations (14.5-year follow-up) were captured by the Hospital Morbidity Data Collection, via the Western Australian Data Linkage System. At baseline, women with higher ucOC/tOC ratio (quartile 4) had slower TUG performance compared with quartile 1 (~0.68 seconds, p < .01). Grip strength and 5-year change of TUG and grip were not different (p > .05) between quartiles. Fear of falling limiting house, outdoor, and combined activities was significantly different across quartiles (p < .05). Higher ucOC/tOC was significantly associated with poorer TUG performance at baseline and 5-year change in performance, increased walking aid use, and fear of falling (all p < .05). Higher ucOC was related to lower grip strength at baseline (p < .05) but not 5-year change in strength. Those with the highest ucOC/tOC had greater falls-related hospitalizations (unadjusted log rank, p = .004) remaining significant after adjusting for key variables (hazard ratio [HR] = 1.31, 95% confidence interval [CI] 1.09-1.57, p = .004). We identified a large proportion of older women with high ucOC/tOC ratio who had reduced physical function, including its long-term decline and increased risk of falls-related hospitalizations. Early identification of women at higher risk can enable prevention and intervention strategies to occur, reducing risk for injurious falls. © 2020 American Society for Bone and Mineral Research (ASBMR)..

The effects of acute exercise on bone turnover markers in middle-aged and older adults: A systematic review.

BACKGROUND: Bone turnover is the cellular machinery responsible for bone integrity and strength and, in the clinical setting, it is assessed using bone turnover markers (BTMs). Acute exercise can induce mechanical stress on bone which is needed for bone remodelling, but to date, there are conflicting results in regards to the effects of varying mechanical stimuli on BTMs. OBJECTIVES: This systematic review examines the effects of acute aerobic, resistance and impact exercises on BTMs in middle and older-aged adults and examines whether the responses are determined by the exercise mode, intensity, age and sex. METHODS: We searched PubMed, SCOPUS, Web of Science and EMBASE up to 22nd April 2020. Eligibility criteria included randomised controlled trials (RCTs) and single-arm studies that included middle-aged (50 to 65 years) and older adults (>65 years) and, a single-bout, acute-exercise (aerobic, resistance, impact) intervention with measurement of BTMs. PROSPERO registration number CRD42020145359. RESULTS: Thirteen studies were included; 8 in middle-aged (n = 275, 212 women/63 men, mean age = 57.9 ± 1.5 years) and 5 in older adults (n = 93, 50 women/43 men, mean age = 68.2 ± 2.2 years). Eleven studies included aerobic exercise (AE, 7 middle-aged/4 older adults), and two included resistance exercise (RE, both middle-aged). AE significantly increased C-terminal telopeptide (CTX), alkaline phosphatase (ALP) and bone-ALP in middle-aged and older adults. AE also significantly increased total osteocalcin (tOC) in middle-aged men and Procollagen I Carboxyterminal Propeptide and Cross-Linked Carboxyterminal Telopeptide of Type I Collagen in older women. RE alone decreased ALP in older adults. In middle-aged adults, RE with impact had no effect on tOC or BALP, but significantly decreased CTX. Impact (jumping) exercise alone increased Procollagen Type 1 N Propeptide and tOC in middle-aged women. CONCLUSION: Acute exercise is an effective tool to modify BTMs, however, the response appears to be exercise modality-, intensity-, age- and sex-specific. There is further need for higher quality and larger RCTs in this area.

Association between Circulating Osteocalcin and Cardiometabolic Risk Factors following a 4-Week Leafy Green Vitamin K-Rich Diet.

BACKGROUND: Evidence suggests that lower serum undercarboxylated osteocalcin (ucOC) may be negatively associated with cardiometabolic health. We investigated whether individuals with a suppression of ucOC following an increase in dietary vitamin K1 exhibit a relative worsening of cardiometabolic risk factors. MATERIALS AND METHODS: Men (n = 20) and women (n = 10) aged 62 ± 10 years participated in a randomized, controlled, crossover study. The primary analysis involved using data obtained from participants following a high vitamin K1 diet (HK; 4-week intervention of increased leafy green vegetable intake). High and low responders were defined based on the median percent reduction (30%) in ucOC following the HK diet. Blood pressure (resting and 24 h), arterial stiffness, plasma glucose, lipid concentrations, and serum OC forms were assessed. RESULTS: Following the HK diet, ucOC and ucOC/tOC were suppressed more (p < 0.01) in high responders (41 and 29%) versus low responders (12 and 10%). The reduction in ucOC and ucOC/tOC was not associated with changes in blood pressure, arterial stiffness, plasma glucose, or lipid concentrations in the high responders (p > 0.05). DISCUSSION/CONCLUSION: Suppression of ucOC via consumption of leafy green vegetables has no negative effects on cardiometabolic health, perhaps, in part, because of cross-talk mechanisms.

Skeletal Muscle and the Maintenance of Vitamin D Status.

Vitamin D, unlike the micronutrients, vitamins A, E, and K, is largely obtained not from food, but by the action of solar ultraviolet (UV) light on its precursor, 7-dehydrocholesterol, in skin. With the decline in UV light intensity in winter, most skin production of vitamin D occurs in summer. Since no defined storage organ or tissue has been found for vitamin D, it has been assumed that an adequate vitamin D status in winter can only be maintained by oral supplementation. Skeletal muscle cells have now been shown to incorporate the vitamin D-binding protein (DBP) from blood into the cell cytoplasm where it binds to cytoplasmic actin. This intracellular DBP provides an array of specific binding sites for 25-hydroxyvitamin D (25(OH)D), which diffuses into the cell from the extracellular fluid. When intracellular DBP undergoes proteolytic breakdown, the bound 25(OH)D is then released and diffuses back into the blood. This uptake and release of 25(OH)D by muscle accounts for the very long half-life of this metabolite in the circulation. Since 25(OH)D concentration in the blood declines in winter, its cycling in and out of muscle cells appears to be upregulated. Parathyroid hormone is the most likely factor enhancing the repeated cycling of 25(OH)D between skeletal muscle and blood. This mechanism appears to have evolved to maintain an adequate vitamin D status in winter.

Osteocalcin and measures of adiposity: a systematic review and meta-analysis of observational studies.

Osteocalcin, the osteoblast-derived protein, has been shown to be modulated in patients with problematic glucose metabolism. Our systematic review and meta-analysis found that in humans, higher blood osteocalcin level is associated with lower body indices of fat. PURPOSE/INTRODUCTION: Osteocalcin (OC) was found to be inversely correlated with measures of glucose and energy metabolism, with some groups suggesting the undercarboxylated form (ucOC) to be metabolically active, although the link is not clear, especially in humans. Given obesity is a major risk factor for metabolic disorders, we aimed to assess the correlation between OC and two measures of body weight: body mass index (BMI) and percentage body fat (%BF). METHODS: MEDLINE and EMBASE were searched to identify observational studies in adult populations that reported the crude correlation coefficients (r) between OC and BMI and %BF. Pool r were obtained using random-effects models. RESULTS: Fifty-one publications were included in this analysis. Both total OC (TOC) (pooled r = - 0.151, 95% CI - 0.17, - 0.130; I2 = 52%) and ucOC (pooled r = - 0.060, 95% CI - 0.103, - 0.016; I2 = 54%) were inversely correlated with BMI. The pooled r between TOC and BMI in Caucasian-and-other-regions (r = - 0.187) were stronger than those in Asian populations (r = - 0.126; intra-group p = 0.002; R2 = 0.21). The mean/median BMI of the reported cohort was the major contributor to between-study heterogeneity in correlation between TOC/ucOC and BMI (R2 = 0.28 and 0.77, respectively). Both TOC and ucOC were also inversely correlated with %BF (TOC: pooled r = - 0.185, 95% CI - 0.257 to - 0.112; ucOC: pooled r = - 0.181, 95% CI - 0.258 to - 0.101). CONCLUSION: Higher OC and ucOC were correlated with lower BMI and %BF. The inverse correlations between TOC/ucOC and BMI appear to be affected by ethnicity and obesity status.

The effects of vitamin K-rich green leafy vegetables on bone metabolism: A 4-week randomised controlled trial in middle-aged and older individuals.

BACKGROUND: High vegetable intake is associated with beneficial effects on bone. However, the mechanisms remain uncertain. Green leafy vegetables are a rich source of vitamin K1, which is known to have large effects on osteoblasts and osteocalcin (OC) metabolism. OBJECTIVE: To examine the effects of consumption of two to three extra serves of green leafy vegetables daily on bone metabolism. METHODS: Thirty individuals (mean age 61.8 ± 9.9 years, 67% male) completed three experimental phases in a randomised controlled crossover design, each lasting four weeks, with a washout period of four weeks between phases (clinical trial registration: ACTRN12615000194561). The three experimental phases were: (i) increased dietary vitamin K1 by consuming green leafy vegetables (H-K; ~200 g/d containing 164.3 [99.5-384.7] µg/d of vitamin K1); (ii) low vitamin K1 by consuming vitamin K1-poor vegetables (L-K; ~200 g/d containing 9.4 [7.7-11.6] µg/d of vitamin K1); and (iii) control (CON) where participants consumed an energy-matched non-vegetable control. OC forms, total OC (tOC), carboxylated OC (cOC) and undercarboxylated OC (ucOC), were measured in serum pre- and post-intervention for each experimental phase using a sandwich-electrochemiluminescence immunoassay. RESULTS: Pre-intervention tOC, ucOC and ucOC:tOC levels were similar between phases (P > .05). Following H-K, but not L-K, tOC, ucOC and ucOC:tOC levels were significantly lower compared to pre-intervention levels (P ≤ .001) and compared to CON (~14%, 31% and 19%, respectively, all P < .05), while cOC remained unchanged. CONCLUSIONS: In middle-aged healthy men and women, an easily achieved increase in dietary intake of vitamin K1-rich green leafy vegetables substantially reduces serum tOC and ucOC suggesting increased entry of OC into bone matrix, where it may improve the material property of bone. In conjunction with previous epidemiological and randomised controlled trial data, these findings suggest that interventions to increase vegetable intake over extended periods should include bone end points including fracture risk.

Sleep duration is associated with vitamin D deficiency in older women living in Macao, China: A pilot cross-sectional study.

Chinese women are known to have both a high prevalence of metabolic syndrome (MetS) and vitamin D deficiency (serum 25-hydroxyvitamin D (25OHD) <50 nmol/l). Associations between sleep duration and circulating 25OHD have recently been reported but, to our knowledge, these associations have not been studied in older Chinese populations. We thus investigated whether sleep duration was associated with vitamin D status in a population from Macao, China, and whether sleep duration modified the association between MetS and vitamin D deficiency. In 207 older (>55 years) Macanese, anthropometry, blood samples and validated questionnaires, including sleep duration and cardiovascular risk factors, were simultaneously collected. On multivariable categorical analyses, those women, not men, who had short sleep duration (≤6 hours (h)) were at a 2-fold risk for vitamin D deficiency (both <50 nmol/L and <37 nmol/L; OR = 1.94, 95%CI 1.29-2.92; OR = 2.05, 95%CI 1.06-3.98, respectively) and those who had longer sleep duration (>8 h) were 3-fold more likely to have vitamin D deficiency (OR = 3.07, 95%CI 1.47-6.39; OR = 2.75, 95%CI 1.08-7.00, respectively) compared to those with normal sleep duration (6-8 h). Both women and men with MetS were 2-fold more likely to have vitamin D deficiency (women: OR = 2.04, 95%CI 1.31-3.17; OR = 2.15, 95%CI 1.11-4.17, respectively; men: OR = 2.01, 95%CI 1.23-3.28; OR = 2.04, 95%CI 1.00-4.29, respectively). Moreover, women with both short sleep duration and MetS had an increased risk of vitamin D deficiency (OR = 3.26, 95%CI 1.10-9.64). These associations were not found in those with longer sleep. Men with longer sleep and MetS had a 5-fold risk of vitamin D deficiency (OR = 5.22; 95%CI 2.70-10.12). This association was non-significant for men with shorter sleep. We conclude that both short and long sleep duration were associated with vitamin D deficiency in older Chinese women. Further research is needed in larger cohorts or with intervention studies to further examine the associations between reduced sleep, metabolic syndrome and vitamin D deficiency.

A diet high in fat and fructose adversely affects osseointegration of titanium implants in rats.

OBJECTIVES: Diet-induced metabolic dysfunction such as type 2 diabetes mellitus increases the risk of implant failure in both dental and orthopaedic settings. We hypothesised that a diet high in fat and fructose would adversely affect peri-implant bone structure and function including osseointegration. MATERIALS AND METHODS: Thirty female Sprague-Dawley rats were divided into three groups (n = 10), control group (normal chow) and two intervention groups on a high-fat (60%), high-fructose (20%; HFHF) diet. Titanium implants were placed in the proximal tibial metaphysis in all groups either before commencing the diet (dHFHF group) or 6 weeks after commencing the diet (HFHF group) and observed for an 8-week healing period. Fasting blood glucose levels (fBGLs) were measured weekly. Structural and functional features of the peri-implant bone, including bone-to-implant contact (BIC), were analysed post euthanasia using microcomputed tomography, pull-out tests, and dynamic histomorphometry. RESULTS: The fBGLs were unchanged across all groups. Peri-implant trabecular bone volume was reduced in the HFHF group compared with controls (p = .02). Percentage BIC was reduced in both HFHF group (25.42 ± 3.61) and dHFHF group (28.56 ± 4.07) compared with the control group (43.26 ± 3.58, p < .05) and reflected the lower pull-out loads required in those groups. Osteoblast activity was reduced in both intervention groups compared with the control group (p < .05). CONCLUSION: The HFHF diet compromised osseointegration regardless of whether the implant was placed before or after the onset of the diet and, despite the absence of elevated fBGLs, confirming that changes in bone cell function affected both the initiation and maintenance of osseointegration independent of blood glucose levels.

Is it reasonable to ignore vitamin D status for musculoskeletal health?

Severe vitamin D deficiency-25-hydroxyvitamin D (25OHD) concentrations below around 25-30 nmol/L-may lead to growth plate disorganization and mineralization abnormalities in children (rickets) and mineralization defects throughout the skeleton (osteomalacia) and proximal muscle weakness. Both problems are reversed with vitamin D treatment. Apart from this musculoskeletal dysfunction at very low vitamin D levels, there is apparent inconsistency in the available data about whether concentrations of 25OHD below around 50 nmol/L cause muscle function impairment and increase the risk of fracture. This narrative review provides evidence to support the contention that improving vitamin D status, up to around 50 nmol/L, plays a small causal role in optimizing bone and muscle function as well as reducing overall mortality.

Osteocalcin and its forms across the lifespan in adult men.

PURPOSE: Osteocalcin (OC), an osteoblast-specific secreted protein expressed by mature osteoblasts, is used in clinical practice and in research as a marker of bone turnover. The carboxylated (cOC) and undercarboxylated (ucOC) forms may have a different biological function but age-specific reference ranges for these components are not established. Given the different physiological roles, development of reference ranges may help to identify people at risk for bone disease. METHODS: Blood was collected in the morning after an overnight fast from 236 adult men (18 to 92 years old) free of diabetes, antiresorptive, warfarin or glucocorticoid use. Serum was analyzed for total osteocalcin (tOC) and the ucOC fraction using the hydroxyapatite binding method. cOC, ucOC/tOC and cOC/tOC ratios were calculated. Reference intervals were established by polynomial quantile regression analysis. RESULTS: The normal ranges for young men (≤30 years) were: tOC 17.9-56.8 ng/mL, ucOC 7.1-22.0 ng/mL, cOC 8.51-40.3 ng/mL (2.5th to 97.5th quantiles). Aging was associated with a "U" shaped pattern for tOC, cOC and ucOC levels. ucOC/tOC ratio was higher, while cOC/tOC ratio was lower in men of advanced age. Age explained ∼31%, while body mass index explained ∼4%, of the variance in the ratios. CONCLUSIONS: We have defined normal reference ranges for the OC forms in Australian men and demonstrated that the OC ratios may be better measures, than the absolute values, to identify the age-related changes on OC in men. These ratios may be incorporated into future research and clinical trials, and their associations with prediction of events, such as fracture or diabetes risk, should be determined.