Effects of vitamin D supplementation on bone turnover markers and other bone-related substances in subjects with vitamin D deficiency

Vitamin D3 suppresses Npt2c abundance and differentially modulates phosphate and calcium homeostasis in Npt2a knockout mice

Vitamin D3 is clinically used for the treatment of vitamin D3 deficiency or osteoporosis, partially because of its role in regulating phosphate (Pi) and calcium (Ca2+) homeostasis. The renal sodium-phosphate cotransporter 2a (Npt2a) plays an important role in Pi homeostasis; however, the role of vitamin D3 in hypophosphatemia has never been investigated. We administered vehicle or vitamin D3 to wild-type (WT) mice or hypophosphatemic Npt2a-/- mice. In contrast to WT mice, vitamin D3 treatment increased plasma Pi levels in Npt2a-/- mice, despite similar levels of reduced parathyroid hormone and increased fibroblast growth factor 23. Plasma Ca2+ was increased ~ twofold in both genotypes. Whereas WT mice were able to increase urinary Pi and Ca2+/creatinine ratios, in Npt2a-/- mice, Pi/creatinine was unchanged and Ca2+/creatinine drastically decreased, coinciding with the highest kidney Ca2+ content, highest plasma creatinine, and greatest amount of nephrocalcinosis. In Npt2a-/- mice, vitamin D3 treatment completely diminished Npt2c abundance, so that mice resembled Npt2a/c double knockout mice. Abundance of intestinal Npt2b and claudin-3 (tight junctions protein) were reduced in Npt2a-/- only, the latter might facilitate the increase in plasma Pi in Npt2a-/- mice. Npt2a might function as regulator between renal Ca2+ excretion and reabsorption in response to vitamin D3.

The Relationship of Low-Serum Vitamin D and Early Dental Implant Failure

The study is aimed to assess the effects of serum vitamin D levels and their relationship to early dental implant failures. A total of 174 implants in 109 patients were placed and serum vitamin D levels were noted on the day of implant placement. Implants were followed up until restoration, approximately 3-6 months later, and any implant failure was reported based on 50% or more bone loss or implant mobility. Eight individuals had an implant fail early and their vitamin D levels had a mean of 42.54 ng/mL compared with the successful patients' levels of 31.92 ng/mL. Although not statistically significant, there was no correlation between patients' low serum vitamin D levels and early implant failure.

Discordant responses of bone formation and absorption markers in Japanese infants with vitamin D deficiency: a comprehensive matched case-control study

Vitamin D deficiency during infancy has been associated with increased bone turnover rate and bone mineral loss. However, few studies have examined bone turnover markers (BTMs) for both bone formation and resorption in infants with vitamin D deficiency. Here, we analyzed serum concentrations of 25OHD, intact parathormone (iPTH), and BTMs including total alkaline phosphatase (ALP), tartrate-resistant acid phosphatase isoform 5b (TRACP-5b), and serum type I collagen N-telopeptide (NTx) as well as basic clinical characteristics of 456 infants (626 samples) aged less than 12 mo born at Saitama City Hospital, Japan (latitude 35.9° North) between January 2021 and December 2022. One hundred sixteen infants (147 samples) were classified as having vitamin D deficiency (25OHD < 12.0 ng/mL), and 340 infants (479 samples) had sufficient vitamin D levels (25OHD ≥ 12.0 ng/mL). In addition to 25OHD and ALP, both TRACP-5b and sNTx were measured in 331 infants (418 samples), while 90 infants (105 samples) had only TRACP-5b measured and 101 infants (103 samples) had only sNTx measured. Statistical comparison of 104 subjects each in the vitamin D deficiency and sufficiency groups after matching for the background characteristics revealed that the vitamin D deficiency group had significantly higher levels of ALP and iPTH compared with the sufficiency group (P = <.0001, .0012, respectively). However, no significant differences were found in TRACP-5b and NTx levels between the 2 groups (P = .19, .08, respectively). Our findings suggest discordant responses between bone formation and resorption markers in subclinical vitamin D deficiency during infancy.

Prenatal but not continued postpartum vitamin D supplementation reduces maternal bone resorption as measured by C-terminal telopeptide of type 1 collagen without effects on other biomarkers of bone metabolism

Vitamin D is a key regulator of bone mineral homeostasis and may modulate maternal bone health during pregnancy and postpartum. Using previously-collected data from the Maternal Vitamin D for Infant Growth (MDIG) trial in Dhaka, Bangladesh, we aimed to investigate the effects of prenatal and postpartum vitamin D3 supplementation on circulating biomarkers of bone formation and resorption at delivery and 6 months postpartum. MDIG trial participants were randomized to receive a prenatal;postpartum regimen of placebo or vitamin D3 (IU/week) as either 0;0 (Group A), 4200;0 (B), 16,800;0 (C), 28,000;0 (D) or 28,000;28,000 (E) from 17 to 24 weeks' gestation to 6 months postpartum. As this sub-study was not pre-planned, the study sample included MDIG participants who had data for at least 1 biomarker of interest at delivery or 6 months postpartum, with a corresponding baseline measurement (n = 690; 53 % of 1300 enrolled trial participants). Biomarkers related to bone turnover were measured in maternal venous blood samples collected at enrolment, delivery, and 6 months postpartum: osteoprotegerin (OPG), osteocalcin (OC), receptor activator nuclear factor kappa-B ligand (RANKL), fibroblast growth factor 23 (FGF23), procollagen type 1 N-terminal propeptide, (P1NP) and carboxy terminal telopeptide of type 1 collagen (CTx). Supplementation effects were expressed as percent differences between each vitamin D group and placebo with 95 % confidence intervals (95 % CI). Of 690 participants, 64 % had 25-hydroxyvitamin D concentrations (25OHD) <30 nmol/L and 94 % had 25OHD < 50 nmol/L at trial enrolment. At delivery, mean CTx concentrations were 27 % lower in group E versus placebo (95 % CI: -38, -13; P < 0.001), adjusting for enrolment concentrations. However, at 6 months postpartum, CTx concentrations were not statistically different in group E versus placebo (14 %; 95 % CI: -5.3, 37; P = 0.168), adjusting for delivery CTx concentrations. Effects on other biomarkers at delivery or postpartum were not statistically significant. In conclusion, prenatal high-dose vitamin D supplementation reduced bone resorption during pregnancy, albeit by only one biomarker, and without evidence of a sustained effect in the postpartum period. However, further evidence is needed to substantiate potential maternal bone health benefits of vitamin D in the postpartum period.

The Prognostic Significance of Vitamin D Deficiency in Korean Patients With Multiple Myeloma

BACKGROUND

Vitamin D deficiency is relatively common among patients with multiple myeloma. The prognostic significance of vitamin D deficiency in Asian patients with multiple myeloma remains unevaluated. This study aimed to assess the prognostic value of vitamin D levels in this Korean patient population.

METHODS

From September 2017 to May 2020, 98 patients were enrolled in the study. Vitamin D deficiency was defined as 25-hydroxyvitamin D level of less than 10 ng/mL.

RESULTS

Thirty-six patients (36.7%) had vitamin D deficiency. These patients had significantly lower 2-year progression-free survival rates (44.8% vs. 66.9%, P = .008) and overall survival (OS) rates (2-year OS 47.2% vs. 74.2%, P = .024) compared with those without deficiency. Furthermore, patients who received vitamin D supplementation showed a trend towards improved OS compared with those who did not, with a 2-year OS rate of 51.9% vs. 33.3% (P = .14).

CONCLUSION

These findings suggest that vitamin D levels are a significant prognostic factor in patients with multiple myeloma.

Impact of vitamin D supplementation on markers of bone turnover: Systematic review and meta-analysis of randomised controlled trials

AIM

The effects of vitamin D administration on bone turnover markers (BTMs) in adults are controversial. Thus, we carried out a meta-analysis of available randomised controlled trials (RCTs) to examine the impact of vitamin D supplementation on BTMs.

METHODS

To identify relevant RCTs, we searched the PubMed/MEDLINE, Web of Science, Scopus, Cochrane Library and Embase databases for manuscripts published up to July 2022. The present study was conducted in agreement with the PRISMA guidelines. Weighed mean difference (WMD) and 95% confidence intervals (CI) were used to calculate the magnitude of the effect of the intervention.

RESULTS

A total of 42 RCTs were included in the meta-analysis. The age of the participants enrolled in the RCTs ranged from 19.4 to 84 years. The pooled results depicted a decrease in deoxypyridinoline (DPD) concentrations (WMD: -1.58 nmol/mmol, 95% CI: -2.55, -.61, p = .001) following vitamin D supplementation. In addition, subgroup analyses demonstrated that vitamin D administration notably reduced procollagen type I N-terminal propeptide (PINP) levels in individuals aged >50 years and led to a pronounced decrease in alkaline phosphatase (ALP) values when the intervention lasted >12 weeks. No significant effect was observed on other BTMs, for example, collagen type 1 cross-linked C-telopeptide (CTX) and osteocalcin (OC) levels.

CONCLUSION

Vitamin D administration decreases DPD, PINP and ALP levels, indicating a reduced bone turnover following the intervention. Other BTMs, for example, CTX or OC values, were not affected by vitamin D prescription. Vitamin D supplementation may exert a positive effect on some important BTMs.

Scientific opinion on the tolerable upper intake level for vitamin D, including the derivation of a conversion factor for calcidiol monohydrate

Following two requests from the European Commission (EC), the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the revision of the tolerable upper intake level (UL) for vitamin D and to propose a conversion factor (CF) for calcidiol monohydrate into vitamin D3 for labelling purposes. Vitamin D refers to ergocalciferol (vitamin D2), cholecalciferol (vitamin D3), and calcidiol monohydrate. Systematic reviews of the literature were conducted to assess the relative bioavailability of calcidiol monohydrate versus vitamin D3 on serum 25(OH)D concentrations, and for priority adverse health effects of excess vitamin D intake, namely persistent hypercalcaemia/hypercalciuria and endpoints related to musculoskeletal health (i.e. falls, bone fractures, bone mass/density and indices thereof). Based on the available evidence, the Panel proposes a CF for calcidiol monohydrates of 2.5 for labelling purposes. Persistent hypercalciuria, which may be an earlier sign of excess vitamin D than persistent hypercalcaemia, is selected as the critical endpoint on which to base the UL for vitamin D. A lowest-observed-adverse-effect-level (LOAEL) of 250 μg/day is identified from two randomised controlled trials in humans, to which an uncertainty factor of 2.5 is applied to account for the absence of a no-observed-adverse-effect-level (NOAEL). A UL of 100 μg vitamin D equivalents (VDE)/day is established for adults (including pregnant and lactating women) and for adolescents aged 11-17 years, as there is no reason to believe that adolescents in the phase of rapid bone formation and growth have a lower tolerance for vitamin D compared to adults. For children aged 1-10 years, a UL of 50 μg VDE/day is established by considering their smaller body size. Based on available intake data, European populations are unlikely to exceed the UL, except for regular users of food supplements containing high doses of vitamin D.

The Level of Selected Blood Parameters in Young Soccer Players in Relation to the Concentration of 25(OH)D at the Beginning and End of Autumn

This study aimed to demonstrate the changes of selected blood parameters in relation to 25(OH)D concentration during the autumn period in young soccer players. A total of 35 participants’ results (age: 17.5 ± 0.6 years, body mass 71.3 ± 6.9 kg) were tested twice: in mid-September and in mid-December and divided into subgroups with regard to two criteria. First, according to the initial level of the 25(OH)D concentration (optimal group—ODG, suboptimal group—SDG), second, according to drops in 25(OH)D concentration (high drop group—HDG, low drop group—LDG). A significant decrease (p < 0.001) in the 25(OH)D concentration was reported in the total group (TGr) and in all subgroups. Blood parameters such as white blood cells, red blood cells, haemoglobin and haematocrit increased significantly (p < 0.05) in TGr during the analysed period of time. The analysis of changes in the lipid profile did not expose significant differences except triglycerides. The asparagine amino transferase and creatine kinase activity decreased significantly after autumn in all analysed groups. The declining level of 25(OH)D concentration should be compensated (e.g., with vitamin D supplementation) during autumn. Applied training loads could also influence the blood parameters variability in young soccer players. Regular measurements of 25(OH)D concentration are helpful in identifying potential drops and allows for the preparation of individual supplementation plans for the players.

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

Clinical risk factors for severity and prognosis of antiresorptive agent-related osteonecrosis of the jaw: a retrospective observational study

INTRODUCTION

The incidence of antiresorptive agent-related osteonecrosis of the jaw (ARONJ) is rare, and its management has not yet been established. This study aimed to investigate the predictors for advanced stage and healing of ARONJ to establish an appropriate treatment strategy.

MATERIALS AND METHODS

We retrospectively analyzed patients diagnosed with ARONJ at Kobe City Medical Center General Hospital between April 2014 and March 2020. Outcomes were defined as stage ≥ 2 ARONJ (primary) and healing of ARONJ (secondary). Multivariate logistic regression analysis was used to detect factors associated with the outcomes, and odds ratios (OR) and 95% confidence intervals (CI) were calculated.

RESULTS

This study included 143 patients (stage ≥ 2 ARONJ, 51%; healing of ARONJ, 60%). Multivariate logistic regression analysis revealed that advanced age (per year) (OR 1.037; 95% CI 1.003-1.072; p = 0.028) and serum albumin (per g/dL) (OR 0.430; 95% CI 0.213-0.869; p = 0.018) were significantly associated with stage ≥ 2 ARONJ. Furthermore, multivariate logistic regression analysis revealed that cancer (yes) (OR 0.099; 95% CI 0.029-0.339; p < 0.001), conservative surgical treatment (yes) (OR 15.42; 95% CI 5.657-42.0; p < 0.001), C-reactive protein (per mg/dL) (OR 0.599; 95% CI 0.415-0.864; p < 0.001), and vitamin D analog (yes) (OR 0.167; 95% CI 0.034-0.827; p = 0.028) were factors associated with healing.

CONCLUSION

Our findings suggest that age and hypoalbuminemia are associated with the severity of ARONJ, and cancer, high inflammation, and vitamin D analog may impair healing. In contrast, conservative surgical treatment can overcome the poor treatment outcomes associated with ARONJ.

Serum sclerostin levels in osteoporotic fracture patients

PURPOSE

Sclerostin inhibits bone formation and stimulates bone resorption. Previous studies found a positive association between bone density and serum sclerostin, but literature on sclerostin levels in osteoporotic fracture patients is scarce. The aim of the present study was to compare the serum sclerostin levels in osteoporotic and non-osteoporotic fracture patients and to assess the correlation of the sclerostin levels with bone mineral density and vitamin D status.

METHODS

In this cross-sectional study, we included patients over 50 years, with an extremity fracture after low-energy trauma treated between 2012 and 2018, with biobank samples and available bone density measurements by Dual X-ray Absorption. Osteoporosis was diagnosed according the World Health Organisation criteria. Vitamin D deficiency was defined as a 25(OH)D concentration < 30 nmol/L. After defrosting biobank samples, serum sclerostin was measured using the human SOST (sclerostin) enzyme-linked immunosorbent assay kit. We prespecified a subgroup analysis including only female patients.

RESULTS

179 patients were included of whom 139(78%) were female. In 46 patients (25.7%), osteoporosis was diagnosed. Bone mineral density was positively associated with sclerostin levels (r = 0.17, p = 0.026) and patients with osteoporosis had a significantly lower serum sclerostin compared to non-osteoporotic fracture patients (mean 41.9 pmol/L vs 48.1 pmol/L; p = 0.03). This difference remained significant after correction for potential confounders. Similar results were found in the subgroup of female patients. No association between serum sclerostin and vitamin D deficiency was found.

CONCLUSION

Osteoporotic fracture patients had lower levels of sclerostin than non-osteoporotic fracture patients. Future research should focus on the use of sclerostin as biomarker for osteoporosis in fracture patients.

Bone turnover markers as surrogates of fracture healing after intramedullary fixation of tibia and femur fractures

Aims

Bone turnover markers (BTMs) follow distinct trends after fractures and limited evidence suggests differential levels in BTMs in patients with delayed healing. The effect of vitamin D, and other factors that influence BTMs and fracture healing, is important to elucidate the use of BTMs as surrogates of fracture healing. We sought to determine whether BTMs can be used as early markers of delayed fracture healing, and the effect of vitamin D on BTM response after fracture.

Methods

A total of 102 participants aged 18 to 50 years (median 28 years (interquartile range 23 to 35)), receiving an intramedullary nail for a tibial or femoral shaft fracture, were enrolled in a randomized controlled trial comparing vitamin D₃ supplementation to placebo. Serum C-terminal telopeptide of type I collagen (CTX; bone resorption marker) and N-terminal propeptide of type I procollagen (P1NP; bone formation marker) were measured at baseline, six weeks, and 12 weeks post-injury. Clinical and radiological fracture healing was assessed at three months.

Results

CTX and P1NP concentrations peaked at six weeks in all groups. Elevated six-week CTX and P1NP were associated with radiological healing at 12 weeks post-injury (odds ratio (OR) 10.5; 95% confidence interval 2.71 to 53.5, p = 0.002). We found no association between CTX or P1NP and functional healing. Baseline serum 25(OH)D showed a weak inverse relationship with P1NP (p = 0.036) and CTX (p = 0.221) at 12 weeks, but we observed no association between vitamin D supplementation and either BTM.

Conclusion

Given the association between six-week BTM concentrations and three-month radiological fracture healing, CTX and P1NP appear to be potential surrogate markers of fracture healing.

Cite this article: Bone Joint Res 2022;11(4):239–250.

Vitamin D Supplementation for 12 Months in Older Adults Alters Regulators of Bone Metabolism but Does Not Change Wnt Signaling Pathway Markers

Vitamin D status and supplementation regulates bone metabolism and may modulate Wnt signaling. We studied the response of hormonal regulators of bone metabolism, markers of Wnt signaling and bone turnover and bone mineral density (BMD) and bone mineral content (BMC) in a randomized vitamin D intervention trial (12,000 IU, 24,000 IU, 48,000 IU/mo for 1 year; men and women aged >70 years; n = 379; ISRCTN35648481). Associations with total and free 25(OH)D concentrations were analyzed by linear regression. Baseline vitamin D status was (mean ± SD) 25(OH)D: 40.0 ± 20.1 nmol/L. Supplementation dose-dependently increased total and free 25(OH)D concentrations and decreased plasma phosphate and parathyroid hormone (PTH) (all p < 0.05). The procollagen 1 intact N-terminal (PINP)/C-terminal telopeptide (CTX) ratio, C-terminal fibroblast growth factor-23 (cFGF23), and intact FGF23 (iFGF23) significantly increased with no between-group differences, whereas Klotho was unchanged. 1,25(OH)₂D and PINP significantly increased in the 24 IU and 48,000 IU groups. Sclerostin (SOST), osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL), BMD, BMC, and CTX remained unchanged. Subgroup analyses with baseline 25(OH)D <25 nmol/L (n = 94) provided similar results. Baseline total and free 25(OH)D concentrations were positively associated with 1,25(OH)₂D, 24,25(OH)₂D (p < 0.001), vitamin D binding protein (DBP) (p < 0.05), BMD, and BMC (p < 0.05). Associations with PTH (p <0.001), cFGF23 (p < 0.01), and BAP (p < 0.05) were negative. After supplementation, total and free 25(OH)D concentrations remained positively associated only with 24,25(OH)₂D (p < 0.001) and DBP (p < 0.001) and negatively with estimated glomerular filtration rate (eGFR) (p < 0.01). PTH and SOST were significantly associated only with free 25(OH)D. There were no significant relationships with BMD and BMC after supplementation. The decrease in PTH and increase in PINP/CTX ratio suggest a protective effect of supplementation on bone metabolism, although no significant effect on BMD or pronounced changes in regulators of Wnt signaling were found. The increase in FGF23 warrants caution because of its negative association with skeletal and cardiovascular health. Associations of total and free 25(OH)D with biomarkers were similar and known positive associations between vitamin D status and BMD were confirmed. The change in associations after supplementation might suggest a threshold effect. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Substantial early changes in bone and calcium metabolism among adult pharmacoresistant epilepsy patients on a modified Atkins diet

Objective

The aim of this study was to investigate whether the modified Atkins diet (MAD), a variant of the ketogenic diet, has an impact on bone‐ and calcium (Ca) metabolism.

Methods

Two groups of adult patients with pharmacoresistant epilepsy were investigated. One, the diet group (n = 53), was treated with MAD for 12 weeks, whereas the other, the reference group (n = 28), stayed on their habitual diet in the same period. All measurements were performed before and after the 12 weeks in both groups. We assessed bone health by measuring parathyroid hormone (PTH), Ca, 25‐OH vitamin D (25‐OH vit D), 1,25‐OH vitamin D (1,25‐OH vit D), phosphate, alkaline phosphatase (ALP), and the bone turnover markers procollagen type 1 N‐terminal propeptide (P1NP) and C‐terminal telopeptide collagen type 1 (CTX‐1). In addition, we examined the changes of sex hormones (estradiol, testosterone, luteinizing hormone, follicle‐stimulating hormone), sex hormone‐binding globulin, and leptin.

Results

After 12 weeks of MAD, we found a significant reduction in PTH, Ca, CTX‐1, P1NP, 1,25‐OH vit D, and leptin. There was a significant increase in 25‐OH vit D. These changes were most pronounced among patients <37 years old, and in those patients with the highest body mass index (≥25.8 kg/m²), whereas sex and type of antiseizure medication had no impact on the results. For the reference group, the changes were nonsignificant for all the analyses. In addition, the changes in sex hormones were nonsignificant.

Significance

Twelve weeks of MAD treatment leads to significant changes in bone and Ca metabolism, with a possible negative effect on bone health as a result. A reduced level of leptin may be a triggering mechanism. The changes could be important for patients on MAD, and especially relevant for those patients who receive treatment with MAD at an early age before peak bone mass is reached.

Effects of a Lifestyle Intervention on Bone Turnover in Persons with Type 2 Diabetes: A Post Hoc Analysis of the U-TURN Trial

INTRODUCTION/PURPOSE

The increased risk of fractures with type 2 diabetes (T2D) is suggested to be caused by decreased bone turnover. Current international guidelines recommend lifestyle modifications, including exercise, as first-line treatment for T2D. The aim of this study was to investigate the effects of an exercise-based lifestyle intervention on bone turnover and bone mineral density (BMD) in persons with T2D.

METHODS

Persons with T2D were randomized to either a 12-month lifestyle intervention (n = 64) or standard care (n = 34). The lifestyle intervention included five to six weekly aerobic training sessions, half of them combined with resistance training. Serum markers of bone turnover (osteocalcin, N-terminal propeptide of type-I procollagen, reflecting bone formation, and carboxyterminal collagen I crosslinks, reflecting bone resorption) and BMD (by DXA) were measured before the intervention and at follow-up.

RESULTS

From baseline to follow-up, s-propeptide of type-I procollagen increased by 34% (95% confidence interval [CI], 17%-50%), serum-carboxyterminal collagen I crosslink by 36% (95% CI, 1%-71%), and s-osteocalcin by 31% (95% CI, 11-51%) more in the lifestyle intervention group compared with standard care. Loss of weight and fat mass were the strongest mediators of the increased bone turnover. Bone mineral density was unaffected by the intervention (ΔBMD, 0.1%; 95% CI, -1.1% to 1.2%).

CONCLUSIONS

A 12-month intensive exercise-based lifestyle intervention led to a substantial but balanced increase in bone turnover in persons with T2D. The increased bone turnover combined with a preserved BMD, despite a considerable weight loss, is likely to reflect improved bone health and warrants further studies addressing the impact of exercise on risk of fractures in persons with T2D.

Effect of Vitamin D Supplementation on Vitamin D Level and Bone Mineral Density in Patients With Cirrhosis: A Randomized Clinical Trial

INTRODUCTION

In patients with cirrhosis, highly prevalent vitamin D deficiency and low bone mineral density (BMD) increase the burden of disease, and role of vitamin D supplementation is not clear. So, our aim was to determine the effect of vitamin D supplementation on vitamin D level and BMD in patients with cirrhosis.

METHODS

Patients with cirrhosis (18-60 years) of any etiology were enrolled. We measured serum 25(OH)D, parathyroid hormone, thyroid-stimulating hormone, free T4, bone-specific alkaline phosphatase, insulin-like growth factor (IGF)-1, and health-related quality of life at entry and at 1 year; however, serum calcium was measured at 3-month interval. BMD was measured by dual-energy x-ray absorptiometry at lumbar spine and left hip neck at entry and after 1 year. Statistical analysis was performed according to intention-to-treat analysis.

RESULTS

Of 390 screened patients with cirrhosis, 164 participants (82 in each group) were randomized. There was significant increase in 25(OH)D levels in intervention group after 1 year (33.7 [24.3-45.7] ng/mL vs 23.1 [17-28.2] ng/mL; P < 0.001) when compared with placebo. The mean difference in BMD at lumbar spine and left hip neck was not significantly changed after 1 year of intervention with vitamin D between both groups. There was no significant change in both the groups in levels of calcium, thyroid-stimulating hormone, parathyroid hormone, free T4, IGF-1, and bone-specific alkaline phosphatase and quality of life.

DISCUSSION

Supplementation with vitamin D for 1 year improves vitamin D levels but did not result in improvement in BMD at lumbar spine and left hip neck in patients with cirrhosis.

Changes in Bone Turnover, Inflammatory, Oxidative Stress, and Metabolic Markers in Women Consuming Iron plus Vitamin D Supplements: a Randomized Clinical Trial

We aimed to investigate whether combination of vitamin D and iron supplementation, comparing vitamin D alone, could modify bone turnover, inflammatory, oxidative stress, and metabolic markers. Eighty-seven women with hemoglobin (Hb) ≤ 12.7 g/dL and 25OHD ≤ 29 ng/mL vitamin D deficiency/insufficiency aged 18-45 years were randomly assigned into two groups: (1) receiving either 1000 IU/day vitamin D3 plus 27 mg/day iron (D-Fe); (2) vitamin D3 plus placebo supplements (D-P), for 12 weeks. In D-Fe group, significant decrease in red blood cells (RBC) (P = 0.001) and hematocrit (Hct) (P = 0.004) and increases in mean corpuscular hemoglobin concentration (MCHC) (P = 0.001), 25OHD (P < 0.001), osteocalcin (P < 0.001), high-density cholesterol (HDL) (P = 0.041), and fasting blood sugar (FBS) (P < 0.001) were observed. D-P group showed significant decrease in RBC (P < 0.001), Hb (P < 0.001), Hct (P < 0.001), mean corpuscular volume (MCV) (P = 0.004), mean corpuscular hemoglobin (MCH) (P < 0.001), MCHC (P = 0.005), serum ferritin (P < 0.001), and low-density cholesterol (LDL) (P = 0.016) and increases of 25OHD (P < 0.001), osteocalcin (P < 0.001), C-terminal telopeptide (CTX) (P = 0.025), triglyceride (TG) (P = 0.004), FBS (P < 0.001), and interleukin-6 (IL-6) (P = 0.001) at week 12. After the intervention, the D-P group had between-group increases in mean change in the osteocalcin (P = 0.007) and IL-6 (P = 0.033), and decreases in the RBC (P < 0.001), Hb (P < 0.001), Hct (P < 0.001), and MCV (P = 0.001), compared with the D-Fe group. There were significant between-group changes in MCH (P < 0.001), MCHC (P < 0.001), ferritin (P < 0.001), and serum iron (P = 0.018). Iron-vitamin D co-supplementation does not yield added benefits for improvement of bone turnover, inflammatory, oxidative stress, and metabolic markers, whereas, vitamin D alone may have some detrimental effects on inflammatory and metabolic markers. IRCT registration number: IRCT201409082365N9.

Bone health and hyperglycemia in pediatric populations

The impact of prediabetes and diabetes on skeletal health in the context of increased risk of fragility fractures in adults has been studied recently. However, the prevalence of diabetes, overweight, and obesity have also increased in younger subjects. Current data concerning bone metabolism based on assessment of markers for bone turnover and of bone quality in diabetes patients in diverse age groups appears to be inconsistent. This review synthesizes the current data on the assessment of bone turnover based on the use of circulating bone markers recommended by international organizations; the effects of age, gender, and other factors on the interpretation of the data; and the effects of type 1 and type 2 diabetes as well as hyperglycemia on bone quality and turnover with particular emphasis on the pediatric population. Early intervention in the pediatric population is necessary to prevent the progression of metabolic disturbances that accompany prediabetes and diabetes in the context of common low vitamin D status that may interfere with bone growth.

Vitamin D supplementation after the menopause

The purpose of this review was to assess recent evidence regarding the effects of low vitamin D levels on some highly prevalent clinical conditions of postmenopausal women. We reviewed and selected recent literature regarding menopause-related conditions associated with vitamin D deficiency and interventions to manage them. Low circulating 25-hydroxyvitamin D (25(OH)D) levels related to menopause are linked to diet, lifestyle, changes in body composition, insulin sensitivity, and reduced physical activity. Vitamin D supplementation increases serum 25(OH)D levels while normalizing parathyroid hormone and bone markers, and in women with serum 25(OH)D levels below 10 ng/ml supplementation may improve bone mineral density. Low vitamin D status has been associated with the metabolic syndrome, high triglyceride levels, and low high-density lipoprotein cholesterol levels. When compared with placebo, vitamin D supplementation may lower the risk of the metabolic syndrome, hypertriglyceridemia, and hyperglycemia. There is an inverse relationship between fat mass and serum 25(OH)D levels and, therefore, the dosage of supplementation should be adjusted according to the body mass index. Although vitamin D supplementation may improve glucose metabolism in prediabetic subjects, data regarding muscle strength are conflictive. There is evidence that vitamin D over-treatment, to reach extremely high circulating 25(OH)D levels, does not result in better clinical outcomes. The identification and treatment of vitamin D deficiency in postmenopausal women may improve their general health and health outcomes. Vitamin D supplementation should preferably be based on the use of either cholecalciferol or calcifediol.

Smoking and other determinants of bone turnover

The balance between bone resorption and formation may be assessed by measurement of bone turnover markers (BTMs), like carboxyl-terminal cross-linked telopeptide of type 1 collagen (CTX-1) and procollagen type 1 amino-terminal propeptide (P1NP). Smoking has been shown to influence bone turnover and to reduce bone mass density (BMD), the exact mechanism for this is, however, not settled. In this post-hoc study including 406 subjects (mean age 51.9 years), we aimed to study the impact of smoking on bone turnover. Moreover, we wanted to assess the inter-correlation between substances regulating bone metabolism and BTMs, as well as tracking over time. BMD measurements and serum analyses of CTX-1, P1NP, osteoprotegerin (OPG), receptor activator of nuclear factor ĸB ligand (RANKL), Dickkopf-1 (DKK1), sclerostin, tumor necrosis factor-α (TNF-α), and leptin were performed. Repeated serum measurements were made in 195 subjects after four months. Adjustments were made for sex, age, body mass index (BMI), smoking status, insulin resistance, serum calcium, parathyroid hormone, 25-hydroxyvitamin D and creatinine. Smokers had higher levels of DKK1 and OPG, and lower levels of RANKL, as reflected in lower BTMs and BMD compared to non-smokers. There were strong and predominantly positive inter-correlations between BTMs and the other substances, and there was a high degree of tracking with Spearman’s rho from 0.72 to 0.92 (P < 0.001) between measurements four months apart. In conclusion, smokers exhibited higher levels of DKK1 and OPG and a lower bone turnover than did non-smokers. The strong inter-correlations between the serum parameters illustrate the coupling between bone resorption and formation and crosstalk between cells.

Multiple Sclerosis Patients Show Lower Bioavailable 25(OH)D and 1,25(OH)2D, but No Difference in Ratio of 25(OH)D/24,25(OH)2D and FGF23 Concentrations

Vitamin D (VitD) insufficiency is common in multiple sclerosis (MS). VitD has possible anti-inflammatory effects on the immune system. The ratio between VitD metabolites in MS patients and the severity of the disease are suggested to be related. However, the exact effect of the bone-derived hormone fibroblast-growth-factor-23 (FGF23) and VitD binding protein (VDBP) on this ratio is not fully elucidated yet. Therefore, the aim is to study differences in total, free, and bioavailable VD metabolites and FGF23 between MS patients and healthy controls (HCs). FGF23, vitD (25(OH)D), active vitD (1,25(OH)₂D), inactive 24,25(OH)D, and VDBP were measured in 91 MS patients and 92 HCs. Bioavailable and free concentrations were calculated. No difference in FGF23 (p = 0.65) and 25(OH)D/24.25(OH)₂D ratio (p = 0.21) between MS patients and HCs was observed. Bioavailable 25(OH)D and bioavailable 1.25(OH)₂D were lower (p < 0.01), while VDBP concentrations were higher in MS patients (p = 0.02) compared with HCs, specifically in male MS patients (p = 0.01). In conclusion, FGF23 and 25(OH)D/24.25(OH)₂D did not differ between MS patients and HCs, yet bioavailable VitD concentrations are of potential clinical relevance in MS patients. The possible immunomodulating role of VDBP and gender-related differences in the VD-FGF23 axis in MS need further study.