Silicon: A neglected micronutrient essential for bone health

Bone matrix is predominantly made up of collagen, and in vitro and in animal models studies have shown that silicon is linked to glycosaminoglycans and plays an important role in the formation of cross-links between collagen and proteoglycans, determining the beneficial effects on strength, composition, and mechanical properties of bone. However, there are still no precise indications regarding a possible role of silicon on bone health in humans. Given this background, the aim of this narrative review was to consider the effectiveness of silicon dietary intake and silicon dietary supplementation (alone or with other micronutrients), in order to suggest a daily dosage of Si supplementation, on bone mineral density in humans. This review included eight eligible studies: four regarding dietary intake and four considering supplementation with silicon alone or with other nutrients. Despite the number of studies considered being low, the number of subjects studied is high (10012) and the results are interesting. Although to date the available scientific evidences are not considered valid enough to allow to establish an adequate level of Silicon intake, based on extrapolations from the data obtained with studies on animal and human models, it has been suggested that an adequate intake in order to promote beneficial effects for bone could be considered to be around 25 mg silicon/day. As for silicon dietary supplements, it has been shown that the combined treatment with orthosilicic acid (6 mg), calcium, and vitamin D has a potentially beneficial effect on femoral BMD compared to only use of calcium and vitamin D.     

Effects of boric acid supplementation on bone histomorphometry,metabolism, and biomechanical properties in aged female F-344 rats

Postmenopausal women may benefit from dietary interventions in order to increase bone strength and prevent fractures. Dietary boron (B) may be beneficial for optimal calcium metabolism and, as a consequence, optimal bone metabolism. The present study evaluated the effects of boron, in the form of boric acid, with or without 17β-estradiol (E₂) supplementation (via subcutaneous implant), in ovariectomized (OVX) aged 13-mo-old F-344 rats. Boric acid was administered by gavage at a subtoxic dose (8.7 mg B/kg/d) for 40 d. Results indicate that serum level of minerals as well as osteocalcin (a marker of bone resorption) are dependent to a greater extent on the hormonal status of the animals than on boron supplementation. Boron treatment increased the E₂-induced elevation of urinary calcium and magnesium. Bone mineral density (BMD) of the L5 vertebra and proximal femur was highest in the E₂-treated groups; no increase in BMD was conferred by boron treatment. By histomorphometry of the proximal tibial metaphysis, osteoblastic, osteoid, and eroded surfaces were significantly suppressed by E₂ treatment, but not by boron treatment. In biomechanical testing of femur and vertebra, neither E₂ nor boron treatment significantly increased bone strength. At the levels given, boron alone provided no protection against OVX-induced osteopenia. In addition, combination therapy (B + E₂) provided no additional benefits over those of 17β-estradiol treatment alone in this aged rat model.     

Vitamin D,Calcium, and Cardiovascular Mortality: A Perspective from A Plenary Lecture Given at the Annual Meeting of the American Association of Clinical Endocrinologists

ObjectiveTo examine data showing associations between serum 25-hydroxyvitamin D levels and calcium intake and cardiovascular mortality.MethodsThe articles reviewed include those published from 1992-2011 derived from search engines (PubMed, Scopus, Medscape) using the following search terms: vitamin D, calcium, cardiovascular events, cardiovascular mortality, all-cause mortality, vascular calcification, chronic kidney disease, renal stones, and hypercalci- uria. Because these articles were not weighted (graded) on the level of evidence, this review reflects my own perspective on the data and how they should be applied to clinical management.ResultsFor skeletal health, vitamin D and calcium are both needed to ensure proper skeletal growth (modeling) and repair (remodeling). Nutritional deficiencies of either vitamin D or calcium may lead to a spectrum of metabolic bone disorders. Excessive consumption of either nutrient has been linked to a variety of medical disorders, such as hypercalcemia or renal stones. There have also been associations between vitamin D or calcium intake and cardiovascular disease. However, neither of these associations have established evidence nor known causality for increasing cardiovascular risk or all-cause mortality in patients with creatinine clearances greater than 60 mL/ min. In patients with more severe chronic kidney disease, stronger data link excess calcium (or phosphorus) intake and increase in vascular calcification, but not mortality. The safe upper limit for vitamin D intake is at least 4000 IU daily and probably 10 000 IU daily; for calcium, the safe upper limit is between 2000 and 3000 mg daily.ConclusionsWhile no solid scientific evidence validates that serum vitamin D levels between 15 and 70 ng/ mL are associated with increased cardiovascular disease risk, stronger but inconsistent evidence shows an association between calcium supplementation greater than 500 mg daily and an increase in cardiovascular disease risk. Most professional societies suggest that replacement levels of these nutrients be personalized with the goal of reaching a 25-hydroxyvitamin D concentration between 30 and 50 ng/ mL and a calcium intake of 1200 mg daily. (Endocr Pract. 2011;17:798-806)     

The effect of calcium and vitamin D supplementation on osteoporotic rabbit bones studied by vibrational spectroscopy

Fourier transform infrared spectroscopy is utilized to examine the effects of increased calcium, vitamin D, and combined calcium-vitamin D supplementation on osteoporotic rabbit bones with induced inflammation. The study includes different bone sites (femur, tibia, humerus, vertebral rib) in an effort to explore possible differences among the sites. We evaluate the following parameters: mineral-to-matrix ratio, carbonate content, and non-apatitic species (labile acid phosphate and labile carbonate) contribution to bone mineral. Results show that a relatively high dose of calcium or calcium with vitamin D supplementation increases the bone mineralization index significantly. On the other hand, vitamin D alone is not as effective in promoting mineralization even with high intake. Mature B-type apatite was detected for the group with calcium supplementation similar to that of aged bone. High vitamin D intake led to increased labile species concentration revealing bone formation. This is directly associated with the suppression of pro-inflammatory cytokines linked to induced inflammation. The latter is known to adversely alter bone metabolism, contributing to the aetiopathogenesis of osteoporosis. Thus, a high intake of vitamin D under inflammation-induced osteoporosis does not promote mineralization but suppresses bone resorption and restores metabolic balance.     

Significance of Elevated Parathyroid Hormone After Parathyroidectomy

ObjectiveTo review the prevalence of parathyroid hormone elevation after parathyroidectomy for primary hyperparathyroidism and to discuss possible mechanisms.MethodsA Medline search of the English-language literature published between 1990 and 2009 was performed using the search terms “elevated PTH after parathyroidectomy.” All of the identified articles reported either prospective or retrospective studies without control groups. Studies that included patients with secondary or tertiary hyperparathyroidism were not reviewed.ResultsWithin 1 week to 5 years after parathyroidectomy, 9% to 62% of patients with a normal serum calcium concentration are reported to have an elevated parathyroid hormone concentration. No evidence suggests that postoperative normocalcemic parathyroid hormone elevation is an indication of surgical failure and recurrent hypercalcemia. Preoperative findings in patients with postoperative parathyroid hormone elevation include lower vitamin D concentration, higher concentrations of bone turnover markers, and higher parathyroid hormone concentration. Potential mechanisms for parathyroid hormone elevation in the setting of normocalcemia include vitamin D deficiency, hungry bone syndrome, and parathyroid hormone resistance. Study findings suggest a possible benefit of postoperative calcium and vitamin D supplementation, but no randomized trials have been done.ConclusionElevation of parathyroid hormone commonly occurs after parathyroidectomy for primary hyperparathyroidism, although the underlying mechanism remains unclear. (Endocr Pract. 2010;16:112-117)     

Effect of dietary boron on mineral, estrogen, and testosterone metabolism in postmenopausal women

A study was done to examine the effects of aluminum, magnesium, and boron on major mineral metabolism in postmenopausal women. This communication describes some of the effects of dietary boron on 12 women between the ages of 48 and 82 housed in a metabolic unit. A boron supplement of 3 mg/day markedly affected several indices of mineral metabolism of seven women consuming a low-magnesium diet and five women consuming a diet adequate in magnesium; the women had consumed a conventional diet supplying about 0.25 mg boron/day for 119 days. Boron supplementation markedly reduced the urinary excretion of calcium and magnesium; the depression seemed more marked when dietary magnesium was low. Boron supplementation depressed the urinary excretion of phosphorus by the low-magnesium, but not by the adequate-magnesium, women. Boron supplementation markedly elevated the serum concentrations of 17 beta-estradiol and testosterone; the elevation seemed more marked when dietary magnesium was low. Neither high dietary aluminum (1000 mg/day) nor an interaction between boron and aluminum affected the variables presented. The findings suggest that supplementation of a low-boron diet with an amount of boron commonly found in diets high in fruits and vegetables induces changes in postmenopausal women consistent with the prevention of calcium loss and bone demineralization.     

An update on magnesium and bone health

In 2009 EFSA Panel concludes that a cause and effect relationship has been established between the dietary intake of magnesium (Mg) and maintenance of normal bone. After 2009, numerous studies have been published, but no reviews have made an update on this topic. So, the aim of this narrative review was to consider the state of the art since 2009 on relationship between Mg blood levels, Mg dietary intake and Mg dietary supplementation (alone or with other micronutrients; this last topic has been considered since 1990, because it is not included in the EFSA claims) and bone health in humans. This review included 28 eligible studies: nine studies concern Mg blood, 12 studies concern Mg intake and seven studies concern Mg supplementation, alone or in combination with other nutrients. From the various studies carried out on the serum concentration of Mg and its relationship with the bone, it has been shown that lower values are related to the presence of osteoporosis, and that about 30–40% of the subjects analyzed (mainly menopausal women) have hypomagnesaemia. Various dietetic investigations have shown that many people (about 20%) constantly consume lower quantities of Mg than recommended; moreover, in this category, a lower bone mineral density and a higher fracturing risk have been found. Considering the intervention studies published to date on supplementation with Mg, most have used this mineral in the form of citrate, carbonate or oxide, with a dosage varying between 250 and 1800 mg. In all studies there was a benefit both in terms of bone mineral density and fracture risk.

     

维生素D与PTH相关性研究进展

维生素D是人体必需的一种脂溶性营养素,随着科学技术不断进步,维生素D对人类健康的作用逐渐被发现。已有研究表明,维生素D不仅与多种骨代谢相关疾病有关,并与心血管疾病、代谢综合征、感染、肿瘤、自身免疫疾病等关系密切。在骨代谢方面,维生素D的缺乏可能会导致软骨病、佝偻病、骨质疏松症,甚至会导致急性跌倒事件的发生和骨折的形成,而甲状旁腺激素(PTH)是骨代谢过程中的关键分子。本文综述了维生素D代谢过程及维生素D受体多样性及维生素D与甲状旁腺激素(PTH)相关性,以便有助于探究维生素D与骨代谢之间的关系。     

Vitamin D safety and requirements

Vitamin D an ancient secosteroid is essential for mineral homeostasis, bone remodeling, immune modulation, and energy metabolism. Recently, debates have emerged about the daily vitamin D requirements for healthy and elderly adults, the safety and efficacy of long term supplementation and the role of vitamin D deficiency in several chronic disease states. Since this molecule acts as both a vitamin and a hormone, it should not be surprising that the effects of supplementation are multi-faceted and complex. Yet despite significant progress in the last decade, our understanding of vitamin D physiology and the clinical relevance of low circulating levels of this vitamin remains incomplete. The present review provides the reader with a comprehensive and up-to-date understanding of vitamin D requirements and safety. It also raises some provocative research questions.     

The Effect of Vitamin A Supplementation on Various Elements in Elite Taekwondo Players

The present study aims to examine the effects of both physical activity and vitamin A supplementation on trace element metabolism in individuals engaged in taekwondo. The study registered seven healthy male national taekwondo players whose mean age was 21.86 ± 0.34 years and mean weight was 64.86 ± 2.72 kg. The subjects were supplemented with oral administration of 100 mg vitamin A (retinol) for 6 weeks, and concurrently, they were subjected to taekwondo training 5 days a week. Before starting the vitamin A supplementation, blood samples were taken from the subjects twice, once at rest and once after exhaustion. Similarly, at the end of the 6-week vitamin A supplementation, two blood samples were taken from the subjects, once at rest and once after exhaustion, in order to determine (by atomic emission) and compare serum cobalt, molybdenum, calcium, cadmium, chromium, copper, manganese, sodium, nickel, phosphorus, sulfur, iron, boron, and zinc (mg/L) levels. Values of boron and nickel dropped significantly after 6-week vitamin A supplementation (p < 0.001). Reduced levels of boron and nickel we obtained in the present study are believed to result from the antioxidant effect of long-term vitamin A supplementation.     

Association Between Aldosterone and Parathyroid Hormone Levels in Patients With Adrenocortical Tumors

ObjectivePatients with primary aldosteronism (PA) can present with high PTH levels and negative calcium balance, with some studies speculating that aldosterone could directly stimulate PTH secretion. Either adrenalectomy or mineralocorticoid receptor blockers could reduce PTH levels in patients with PA. The aim of this study was to assess the relationship between aldosterone levels and parathyroid hormone (PTH)-vitamin D-calcium axis in a cohort of patients with PA, compared with patients with nonsecreting adrenocortical tumors in conditions of vitamin D sufficiency.MethodsWe enrolled a series of 243 patients retrospectively, of whom 66 had PA and 177 had nonsecreting adrenal tumors, and selected those with full mineral metabolism evaluation and 25(OH) vitamin D levels >20 ng/mL at the time of initial endocrine screening. The final cohort was composed of 26 patients with PA and 39 patients, used as controls, with nonsecreting adrenal tumors. The relationships between aldosterone, PTH levels, and biochemistries of mineral metabolism were assessed.ResultsAldosterone was positively associated with PTH levels (r = 0.260, P < .05) in the whole cohort and in the PA cohort alone (r = 0.450; P = .02). In the multivariate analysis, both aldosterone concentrations and urinary calcium excretion were significantly related to PTH levels, with no effect of 25(OH) vitamin D or other parameters of bone metabolism.ConclusionPTH level is associated with aldosterone, probably independent of 25(OH) vitamin D levels and urinary calcium. Whether aldosterone interacts directly with the parathyroid glands remains to be established.     

Genistein aglycone effect on bone loss is not enhanced by supplemental calcium and vitamin D3: A dose ranging experimental study

Genistein aglycone (GEN) has a favorable effect on bone loss. We investigated the effects of GEN alone or in combination with supplemental calcium and vitamin D₃ in an animal model of bone loss to evaluate if there was additional benefit. Ovariectomized (OVX) and SHAM-OVX rats were used. OVX were divided into 12 groups and randomized to receive: GEN at 27, 54, 200, 500 or 1000 mg (human equivalent dose (HED)/day/ip injection alone or with calcium carbonate (Ca) (360 mg/kg/day/gavages) and vitamin D₃ (D₃) (50 IU/kg/day/gavages) or Ca/D₃ without GEN or untreated for 6 weeks. SHAM-OVX were randomized into 7 groups and treated with: Ca and D₃ alone or in combination with GEN (same doses as OVX), or left untreated. Bone mineral density (BMD), bone-alkaline phosphatase (b-ALP), collagen C-telopeptides (CTX), osteoprotegerin (OPG) and soluble receptor activator of NFκB ligand (sRANKL) were assessed. Femurs were excised and tested for breaking strength and histology. Uterine weight was analyzed to assess GEN's estrogenic effects on the SHAM-OVX.The most effective dose of GEN, independent of Ca/D₃ supplementation, was 54 mg/day. Higher doses yielded no further improvement in bone biomarkers, histology or strength. Only 1000 mg/day HED of genistein produced statistically significant changes in uterine weight of the SHAM-OVX. This study suggests that 54 mg/day of GEN is the threshold dose for efficacy. In addition, supplemental calcium and vitamin D₃, beyond normal dietary intake do not enhance the effects of genistein on improving measures of bone loss. This observation has implications regarding the use of calcium and vitamin D₃ supplementation.     

Effects of boron and calcium supplementation on mechanical properties of bone in rats

OBJECTIVE: The objective of this study was to consider the effects of boron (B) and calcium (Ca) supplementation on mechanical properties of bone tissues and mineral content of the selected bones in rats. METHODS: Adult male Sprague Dawley rats underwent three different treatments with boron and calcium in their drinking water, while taking diet ad libitum for 4 weeks. Rats in the three treatment groups received 2 mg B/d, 300 mg Ca/d, and a combination of 2 mg B+ 300 mg Ca/d, respectively. After the experimental period body weights were recorded and bone mechanical properties were determined on the tibiae, femurs, and fifth lumbar vertebral bones and the mineral contents of these bones was calculated as the ash percentage. RESULTS: Better measurement of bone mechanical properties were observed for boron supplementation. The stiffness of the lumbar vertebral bones tended to increase in all groups and was significant for Ca supplementation. The significant maximal load obtained for boron in all bones indicates higher strength and less strength for apparently a high level of calcium, while this negative defect in the case of lumbar vertebral bones was corrected in the presence of boron. Highest mean energy to maximal load was shown with boron supplementation, demonstrating significant values with Ca group, and lower energy for the lumbar vertebral bones in Ca group in comparison with the controls. Less deformation at the yield points was shown in Ca group. There were no significant differences in ash weights among the four groups. CONCLUSIONS: Additional and longer studies are warranted to further determine the effects of supplemental boron with different calcium levels and possibly other minerals involved in bone mechanical properties in rats.     

THE MODE OF ACTION OF VITAMIN D

1. The purpose of this review article is to re-evaluate and integrate many of the observations related to the physiological effects of vitamin D, using as a working hypothesis the concept that the vitamin may be acting analogously to a steroid hormone in terms of its ability to interact with genetic information and ultimately elicit a physiological response. Prior to this time the problem of the mechanism of action of vitamin D has primarily been approached from the point of view that the vitamin was acting as a cofactor for some specific enzymic reaction. 2. The physiological activities of vitamin D are integrated with those of parathyroid hormone to provide a homeostatic control for the regulation of primarily calcium and secondarily phosphate metabolism. It is proposed that the role of vitamin D in this homeostatic control mechanism is older and more fundamental than that of parathyroid hormone. The interaction of vitamin D on skeletal calcium metabolism may have evolved before the effects of the vitamin on intestinal calcium absorption. 3. There are several physiological defects of calcium metabolism—rickets, osteo-malacia, vitamin D-resistant rickets and idiopathic hypercalcaemia—all of which may be a consequence of an aberration in one or another of the interlocking steps of the vitamin D-dependent and calcium-dependent homeostatic control mechanism. 4. The most thoroughly established action of vitamin D in vivo is to promote or facilitate the intestinal absorption of calcium. Although the exact biochemical details of this process are not available, this may involve vitamin D-mediated synthesis of the appropriate enzyme systems or the alteration of membrane structure necessary for calcium absorption. It is not yet unequivocally established whether calcium absorption is an energy-dependent active transport process or is a passive carrier-mediated or simple diffusion process. 5. The exact action of vitamin D on bone metabolism is not as well established, but the primary effect of the vitamin is likely to mediate bone resorption. The vitamin D-dependent activities of the cell in both the intestine and bone are to absorb calcium and transfer it to the blood. 6. No direct effects of vitamin D on intestinal absorption of phosphate have been found. Furthermore the validity of a vitamin D-mediated renal reabsorption of phosphate is questioned, for the major effects of vitamin D are cation oriented. If the renal effects of vitamin D are true, it is postulated that the mechanism of action of the vitamin here on the anion, phosphate, is fundamentally different from its cation oriented mechanism. 7. There is a lag in the action of vitamin D on the vitamin mediated: (a) transport of calcium both in vivo in rats and chicks, and in vitro with everted intestinal slices; (b) the apparent increased permeability of intestinal mucosa; (c) increased levels of citric acid in serum or bone; (d) the increased incorporation of radioactive inorganic phosphorus into intestinal mucosa phospholipids. As shown by the use of radioactive vitamin D, this lag is not due to a lack of the vitamin in the target organs. 8. Whereas large, unphysiological doses of radioactive vitamin D localize in all tissues and all subcellular fractions, small physiological doses of radioactive vitamin D localize predominantly in the nucleus of the intestinal mucosa. The amount of vitamin D localized in the nucleus would appear to be too low for the vitamin to function as a cofactor, and is more indicative of an interaction on or with deoxy-ribonucleic acid. 9. Actinomycin D, an inhibitor of DNA-directed RNA synthesis, inhibits the action of vitamin D in mediating intestinal calcium absorption and bone resorption. Vitamin D also stimulates messenger-RNA synthesis in intestinal mucosa within 1/2 hr. of vitamin treatment. Vitamin D may play a crucial role, along with parathyroid hormone and calcium, in a DNA, gene-dependent, homeostatic control mechanism for cal, ium metabolism. In this system the vitamin D molecule has certain very specific structural requirements which are probably a reflection of the specificity of its receptor molecule, rather than structural requirements for a cofactor-enzyme relationship.     

Effects of dietary vitamin k levels on bone quality in broilers

This study was conducted to evaluate the effects of dietary vitamin K (menadione) on bone quality in cage-raised broilers. Three hundred and sixty male broilers were randomly allotted to one of six treatments, with six replicate pens per treatment and 10 chicks per pen. Broilers were fed one of six diets including a control diet or the control diet plus graded levels of vitamin K (0.5 mg/kg, 2 mg/kg, 8 mg/kg, 32 mg/kg and 128 mg/kg). Water and feed were provided ad libitum during the 7-week experimental period. Results indicated that vitamin K supplementation of broilers diets significantly effected bone quality and feed efficiency. The treatment containing vitamin K at 8 mg/kg improved growth performance (during weeks 6 - 7) and bone quality (during weeks 0 - 3). In our study, hydroxyapatite binding capacity of serum osteocalcin (during weeks 0 - 3), bone breaking strength, bone flexibility, bone ash weight increased linearly (P < 0.05) and bone mineral density, bone mineral content increased quadratically (P < 0.05) with increasing supplementation of vitamin K. In conclusion, to gain optimum bone quality and broiler performance, our studies suggest that the concentration of vitamin K in broilers diets should be 8 mg/kg, 2 mg/kg, and 2 mg/kg, for the starter, grower and finisher phases, respectively. Furthermore, it was shown that the starter period is an important phase for improving bone quality. In addition, this study validated the mechanism of vitamin K effects on bone quality. Vitamin K boosts the carboxylation of osteocalcin and decreases the concentration of serum undercarboxylated osteocalcin enhancing hydroxyapatite binding capacity of serum osteocalcin and improving bone quality.     

Abnormalities of Vitamin D and Calcium Metabolism after Surgical Treatment of Morbid Obesity: A Study of 136 Patients

ObjectiveTo assess the effect of bariatric surgical treatment of morbid obesity on bone mineral metabolism.MethodsWe analyzed pertinent vitamin D and calcium metabolic variables in 136 patients who had undergone a malabsorptive bariatric operation. Measurements of bone mineral density (BMD), serum 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D [1,25-(OH)₂D], parathyroid hormone (PTH), calcium, phosphorus, and alkaline phosphatase were performed. Statistical analyses assessed correlations among various factors.ResultsThe mean age (± SD) of the study group was 48.34 ± 10.28 years. Their mean weight loss was 114.55 ± 45.66 lb, and the mean duration since the bariatric surgical procedure was 54.02 ± 51.88 months. Seventeen patients (12.5%) had a T-score of -2.5 or less, and 54 patients (39.7%) had a T-score between –1.0 and –2.5. Of 119 patients in whom serum 25-OHD was measured, 40 (34%) had severe hypovitaminosis D (25-OHD < 8 ng/mL), and 50 patients (42%) had low hypovitaminosis D (serum 25-OHD 8 to 20 ng/mL). The magnitude of weight loss correlated negatively with serum 25-OHD, calcium, phosphorus, and calcium × phosphorus product values and positively with serum alkaline phosphatase level. Serum 25-OHD and calcium concentrations correlated positively with the BMD. PTH, serum 1,25-(OH)₂D, and alkaline phosphatase concentrations correlated negatively with the BMD, a reflection of the presence of secondary hyperparathyroidism, an accelerated conversion of 25-OHD to 1,25-(OH)₂D by the elevated PTH levels, and increased osteoblastic activity. The mean daily vitamin D supplementation was 6,472 ± 9,736 IU.ConclusionHypovitaminosis D and subsequent bone loss are common in patients who have undergone a bariatric surgical procedure for morbid obesity. These patients require rigorous vitamin D supplementation. (Endocr Pract. 2007;13:131-136)     

Safety of Vitamin D Replacement in Patients with Primary Hyperparathyroidism and Concomitant Vitamin D Deficiency

ObjectiveTo evaluate the safety of vitamin D replacement in patients with vitamin D deficiency and primary hyperparathyroidism.MethodsRetrospective chart review of 35 patients from our endocrine clinic, age 22 to 89 years, diagnosed with primary hyperparathyroidism and vitamin D deficiency, and treated with either 1,000 to 2,000 international units (IU) of vitamin D daily or 50,000 IU of vitamin D weekly for 5 months. Data were collected before and after treatment on serum calcium, 25-hydroxyvitamin D (25-OH D), intact parathyroid hormone (iPTH), phosphorus, alkaline phosphatase, nephrolithiasis, fractures, and osteoporosis.Results25-OH D increased significantly, from a baseline of 14.65 ± 6.57 ng/mL to 42.17 ± 12.98 ng/ mL after weekly treatment with 50,000 IU of vitamin D (P<.0001), and from 22.42 ± 5.47 ng/mL to 33.33 ± 6.39 ng/mL following daily treatment with 1,000 to 2,000 IU of vitamin D (P<.0001). Pre- and posttreatment unadjusted serum calcium remained stable in the high-dose group (10.80 ± 0.43 mg/dL vs. 10.72 ± 0.67 mg/dL; P = .47), but decreased slightly in the low-dose group (10.76 ± 0.58 mg/dL vs. 10.11 ± 0.54 mg/dL; P = .0007). After adjusting for age, sex, vitamin D, and PTH levels, the small calcium difference in the low-dose group became statistically insignificant. Treatment with either high or low doses of vitamin D did not significantly change iPTH levels. Creatinine remained stable in all patients, and no new cases of nephrolithiasis were reported.ConclusionReplacing vitamin D in mild primary hyperparathyroidism is safe, effective, and does not increase calcium to dangerous levels. (Endocr Pract. 2013;19:420-425)     

No association between the vitamin D pathway gene polymorphisms and bone biomarkers response to calcium and low dose calcitriol supplementation in postmenopausal Chinese women: a one-year prospective study

Abstract

Introduction: The aim of the study was to explore the association between the vitamin D pathway gene variations and the bone biomarkers response to calcium and low dose calcitriol supplementation in postmenopausal Chinese women.

Methods: A total of 110 healthy postmenopausal Chinese women (61.51?±?6.93?years) were enrolled. The participants were supplemented with calcium (600?mg/d) and calcitriol (0.25?μg/d), for 1?year. Four biomarkers, serum levels of beta C-terminal cross-linked telopeptides of type I collagen (β-CTX), amino-terminal propeptide of type I collagen (P1NP), parathyroid hormone (PTH) and 25-hydroxyvitamin D [25(OH)D] were measured at baseline and 12-month follow-up. Multivariate regression models were established to explore the statistical association between the change rate of the four biomarkers and 15?key genes within the vitamin D metabolic pathway.

Results: This exclusion process left 98 participants for analysis. Serum levels of P1NP, β-CTX and PTH were significantly decreased at the 12-month follow-up (all p?<?0.05). Serum 25(OH)D level had no significant change (p?>?0.05). No association was found between the vitamin D pathway gene polymorphisms and bone biomarkers response to calcium and low dose calcitriol supplementation.

Conclusions: Genetic background of postmenopausal Chinese women might not influence supplemental response of the biomarkers to calcium and low dose calcitriol.     

0～3岁婴幼儿超声骨密度现状调查及影响因素分析

目的:了解0~3岁婴幼儿的骨密度现状,并分析其相关影响因素,为婴幼儿骨密度不足的预防工作提供依据。方法:选取2016年1月-2018年10月期间于我院进行健康体检的0~3岁婴幼儿860例为研究对象。采用超声骨密度测量仪对入选婴幼儿左腿胫骨中段骨密度进行检测,并对婴幼儿的骨密度现状进行分析。采用问卷调查方式收集所有婴幼儿的性别、年龄、喂养方式、是否补充维生素D、户外活动时间等资料,并采用单因素和多因素Logistic回归分析0~3岁婴幼儿骨密度的影响因素。结果:860例婴幼儿中,骨密度正常婴幼儿336例,轻度骨密度不足婴幼儿196例,中度骨密度不足婴幼儿179例,重度骨密度不足婴幼儿149例,骨密度不足发生率为60.93%。单因素分析结果显示,不同年龄、性别、是否补充维生素D及不同户外活动时间婴幼儿之间的骨密度不足发生率比较差异有统计学意义(P0.05),而不同喂养方式婴幼儿之间的骨密度不足发生率比较差异无统计学意义(P0.05)。多因素Logistic回归分析结果显示,年龄(0~6个月,7~12个月)、性别(女)、补充维生素D(否)、户外活动时间(1 h)为0~3岁婴幼儿骨密度的危险因素(P0.05)。结论:0~3岁婴幼儿的骨密度不足发生率较高,年龄、女性、未补充维生素D、户外活动时间过少均是0~3岁婴幼儿骨密度的危险因素,可通过适量补充维生素D、增加户外活动时间以提高婴幼儿骨密度值。     

Update on nutrients involved in maintaining healthy bone

Osteoporosis is a leading cause of morbidity and mortality in the elderly and influences quality of life, as well as life expectancy. Currently, there is a growing interest among the medical scientists in search of specific nutrients and/or bioactive compounds of natural origin for the prevention of disease and maintenance of bone health. Although calcium and vitamin D have been the primary focus of nutritional prevention of osteoporosis, a recent research has clarified the importance of several additional nutrients and food constituents. Based on this review of the literature, supplementation with vitamins B, C, K, and silicon could be recommended for proper maintenance of bone health, although further clinical studies are needed. The results of studies on long-chain polyunsaturated fatty acids, potassium, magnesium, copper, selenium, and strontium are not conclusive, although studies in vitro and in animal models are interesting and promising.