Bone Zinc Content Research Articles

Association between bone trace elements and osteoporosis in older adults: a cross-sectional study.

Objectives:Metal micronutrients deficiency may be one of the risk factors for the development of osteoporosis. This study aimed to measure the trace element contents in human bone tissue to analyze the relationship between micronutrients and osteoporosis.Design:A cross-sectional survey was performed on data from 51 elderly patients with proximal femoral fracture.Methods:The concentrations of calcium, phosphorus, manganese, iron, copper, and zinc in bone tissue samples from 51 elderly patients with proximal femoral fracture were determined by energy-dispersive X-ray fluorescence (EDX). Subjects were divided into osteoporosis and non-osteoporosis groups according to their bone mineral density (BMD) T-score values. The difference in metal elements concentrations in bone tissue between the two groups was compared, and the role of metal elements in osteoporosis was discussed.Results:There was no statistical difference in age, sex, body mass index (BMI), serum albumin, biochemical blood indices, and bone turnover markers between the two groups. The Mann–Whitney U test was used to compare the difference in metal elements concentrations in bone tissue samples between the two groups. The results showed that manganese, copper, and zinc concentrations in the cancellous bone were significantly higher in the non-osteoporosis group than in the osteoporosis group. Multivariate logistic regression analysis indicated that high bone zinc concentration [odds ratio = 0.26, 95% confidence interval (CI) = 0.075–0.928, p = 0.038] was negatively correlated with osteoporosis.Conclusion:Manganese, copper, and zinc play an essential role in bone mineralization and metabolism. Among them, zinc may be most closely related to osteoporosis and play a key role in bone development and maintenance of bone mass. Therefore, we believe that the design of zinc-rich compounds or nutrients as a new complementary factor to increase the intake of zinc for the elderly could be able to prevent and intervene in the occurrence of osteoporosis in the early stage.

Dietary Calcium to Digestible Phosphorus Ratio for Optimal Growth Performance and Bone Mineralization in Growing and Finishing Pigs.

Simple SummaryMinimizing the use of dietary non-renewable mineral phosphates improves the sustainability of phosphorus use in growing-finishing pigs. As the phosphorus metabolism is closely linked to calcium, this experiment compared three dietary calcium to digestible phosphorus ratios within two phosphorus levels to determine the optimum levels for growth performance and bone mineralization. The lowest calcium level was insufficient for an efficient metabolic use of P, the medium level was sufficient to maximize growth performance and highest level further improved bone mineralization. The low digestible phosphorus level enabled a complete removal of supplemented mineral phosphates in the finisher period, which resulted, per pig, in a decrease of its use by 65% and a decrease of the calculated P excretion by 41%, without impaired growth performance. However, a reduced bone mineralization was observed. This study shows that there is potential to reduce the digestible phosphorus compared to practiced levels in grower–finisher pigs and shows that the optimal calcium to digestible phosphorus ratio needs to be maintained at the upper range of the actually available recommendations.Within the context of maximizing the use of dietary phosphorus, a growing-finishing pig study was conducted to determine the optimal total dietary calcium (Ca) to digestible phosphorus (dP) ratio and to verify the possibility of mineral phosphate removal during the finishing period on growth performance and mineral status. The potential for replacing chemical and mechanical bone properties by dual energy X-ray absorptiometry (DXA) measures on non-dissected feet was also verified. Three Ca to dP ratios (2.2:1, 2.5:1 and 2.8:1) within two dP levels (P+, P–) were fed during 91 days to 84 pigs. The grower and finisher P+ diets contained 3.0 and 2.4 and P– diets contained 2.5 and 1.7 g dP/kg, respectively. Growth performance and blood serum mineral content were independent of treatments, except that 2.2:1 impaired finisher feed conversion ratio compared to 2.5:1 and 2.8:1. Urinary P concentration increased by 37% in 2.2:1 compared to 2.5:1 and 2.8:1. Maximal load on bone and DXA mineral density were reduced in 2.2:1 compared to 2.8:1. Bone ash and volumetric density were reduced in 2.2:1 and 2.5:1 compared to 2.8:1. Diet P– reduced bone ash, maximal load, volumetric density and DXA bone mineral content and density. No interaction was observed between Ca and dP level. Therefore, 2.2:1 was insufficient for an efficient metabolic use of P, 2.5:1 was sufficient to maximize growth performance and 2.8:1 further improved bone mineralization. Increasing dietary Ca did not impair bone zinc content. Diets P– without supplemented mineral phosphates during the finisher period resulted, per pig, in a decrease of its use by 65% and of the calculated P excretion by 41%, without impaired growth performance. Finally, DXA data responded to dietary treatments as did labor intensive chemical and mechanical bone properties.

15. Comparison of the Effect of a Standard Inclusion Level of Inorganic Zinc to Organic Form at Lowered Level on Bone Development in Growing Male Ross Broiler Chickens

Abstract The purpose of this study was to compare the effect of a standard inclusion level of inorganic zinc to organic form at lowered level on the bone development in growing male Ross 308 chickens, assessed on the basis of mechanical, geometric, and histomorphometric parameters of limb bone, and bone zinc content, as well as hormones of somatotropic axis. A total of 80 one-day-old male Ross broiler chickens were randomly allocated to 2 groups of 40 chickens each. The control group was fed with a corn-soybean meal basal diet providing the recommended zinc amount (100 mg×kg-1) from zinc oxide, and the experimental group was supplemented with glycinate chelate providing 25% of the total requirement of the microelement recommended for Ross 308 broiler chicks. The mechanical and histomorphometric parameters and geometry of tibia were determined as well as the serum concentration of growth hormone, IGF-1, osteocalcin and leptin. The serum concentration of Zn, Cu, Ca, Mg, Fe, P and zinc bone content were determined. The results showed that birds fed with the diet supplemented with organic zinc in the amount of 25% of the recommended amount did not exhibit weight and general growth disorders and had an unchanged concentration of growth hormone, leptin, and IGF-1. The serum concentration of Zn, Cu, Ca, Mg, Fe, P did not differ between groups. The contents of zinc detected in bones in the controls and the group supplemented with the organic source did not differ as well. Although tibial mechanics and geometry remained unchanged, histomorphometry revealed a disproportionately large osteoporotic bone. The changes in tibial trabecular bone as a result of the diet supplemented with glycinate chelate only in 25% of the total requirement of the microelement recommended for Ross 308 broiler chicks seems to be insufficient for tibia development.

Comparative study on the bioavailability of chelated or inorganic zinc in diets containing tricalcium phosphate and phytate to turbot (Scophthalmus maximus)

Abstract A 2 × 6 factorial experiment was conducted to evaluate the effects of chelated (Mintrex™ Zn, Zn–M) or inorganic (ZnSO4·7H2O, Zn–S) zinc as dietary zinc sources on growth, feed utilization, tissue zinc deposition and anti-oxidative responses of turbot (Scophthalmus maximus). Semi-purified diets were made to contain tricalcium phosphate and sodium phytate at levels of 2% and 0.5%, respectively, to resemble levels in practical diets. Ten experimental diets were made by adding either Zn–S or Zn–M to the basal diet to achieve five levels of dietary zinc (15, 45, 75, 105 and 135 mg/kg diet) for each zinc source, respectively. The basal control diet and ten experimental diets were fed to groups (n = 5) of juvenile turbot (initial mean weight: 4.78 g) for 8 weeks. Results showed that the specific growth rate (SGR), feed intake (FI), feed efficiency (FE), whole body and bone zinc concentration, whole body crude lipid content, serum superoxide dismutase (SOD) activity and glutathione peroxidase (GSH-PX) activity in serum or liver of turbot were significantly improved by zinc supplementation (P 0.05). On the basis of SGR, the dietary zinc requirement of juvenile turbot was estimated to be 60.2 mg/kg, using broken-line regression analysis.

The influence of dietary zinc content on mechanical properties of chicken tibiotarsal bone

The authors evaluated the effect of diets with different Zn levels on mechanical properties of bones in 60 Ross 308 hybrid broilers, from 2 to 35 days of age, which were randomly divided in 2 groups, with 30 chickens each. The first group (Zn50) was fed a commercial basal diet with no Zn additives (zinc content - 50 mg/kg feed). The second group (Zn100) was fed the basal diet + 50 mg of Zn/kg feed. In this group the dietary Zn level was increased by adding 62.23 mg of zinc oxide (ZnO)/kg feed to starter and grower feeds. In group Zn100 compared to Zn50 the values of blood zinc level were significantly higher on days 7 and 35 (p<0.01 and p<0.05). Significant differences in bone zinc content were not detected. On days 7, 21, and 35 the selected mechanical properties of the tibiotarsus were evaluated. The results obtained in the experiment showed differences in biomechanical competence of broiler bones from group Zn50 compared to Zn100. In broilers from group Zn100, there were significantly higher values in the limit of elasticity (Re), bending strength (Rm) and fracture stress (Rl) (p<0.05 to p<0.01) of chicken bones on day 35. The mean levels (117.80 ± 19.66, 126.70 ± 32.56, 114.10 ± 19.92, respectively) were determined in broiler bones from group Zn100 compared to Zn50 (95.27 ±18.71, 100.2 ± 20.56, 80.93 ± 35.22, respectively). In group Zn100 were observed significantly increased values of the bone crosssection area (Ar) on day 35 and moment of inertia (I) on days 21 and 35 (p<0.05). The clinical examination of the locomotory system showed bone deformities of the intertarsal joint in 10% of broilers from group Zn50. Present results suggest that the determination of the weight bearing of the tibial bone evaluated by assessing of mechanical properties of bones is an indicator of the locomotory system disorders and the Zn content in feed has a direct and statistically significant effect on bone strength in broiler chickens.

Role of nutritional zinc in the prevention of osteoporosis

Zinc is known as an essential nutritional factor in the growth of the human and animals. Bone growth retardation is a common finding in various conditions associated with dietary zinc deficiency. Bone zinc content has been shown to decrease in aging, skeletal unloading, and postmenopausal conditions, suggesting its role in bone disorder. Zinc has been demonstrated to have a stimulatory effect on osteoblastic bone formation and mineralization; the metal directly activates aminoacyl-tRNA synthetase, a rate-limiting enzyme at translational process of protein synthesis, in the cells, and it stimulates cellular protein synthesis. Zinc has been shown to stimulate gene expression of the transcription factors runt-related transcription factor 2 (Runx2) that is related to differentiation into osteoblastic cells. Moreover, zinc has been shown to inhibit osteoclastic bone resorption due to inhibiting osteoclast-like cell formation from bone marrow cells and stimulating apoptotic cell death of mature osteoclasts. Zinc has a suppressive effect on the receptor activator of nuclear factor (NF)-kappaB ligand (RANKL)-induced osteoclastogenesis. Zinc transporter has been shown to express in osteoblastic and osteoclastic cells. Zinc protein is involved in transcription. The intake of dietary zinc causes an increase in bone mass. beta-Alanyl-L: -histidinato zinc (AHZ) is a zinc compound, in which zinc is chelated to beta-alanyl-L: -histidine. The stimulatory effect of AHZ on bone formation is more intensive than that of zinc sulfate. Zinc acexamate has also been shown to have a potent-anabolic effect on bone. The oral administration of AHZ or zinc acexamate has the restorative effect on bone loss under various pathophysiologic conditions including aging, skeletal unloading, aluminum bone toxicity, calcium- and vitamin D-deficiency, adjuvant arthritis, estrogen deficiency, diabetes, and fracture healing. Zinc compounds may be designed as new supplementation factor in the prevention and therapy of osteoporosis.

Yogurt protects against growth retardation in weanling rats fed diets high in phytic acid

The purpose of this study was to determine the effects of adding yogurt to animal diets that were high in phytic acid (PA) and adequate in zinc (38 μg Zn/g). The PA:Zn molar ratio was 60:1. Zinc status was determined by documenting growth and measuring the zinc concentration in bone (tibia) and plasma. For 25 days, six groups ( n=6) of Sprague–Dawley weanling rats were fed one of six AIN-76 diets. Half of the diets contained PA. Four of the diets contained yogurt with either active or heat-treated (inactive) cultures added at 25% of the diet. The diets were as follows: (a) AIN, (b) AIN with active yogurt, (c) AIN and inactive yogurt, (d) AIN with PA, (e) AIN with PA plus active yogurt and (f) AIN with PA plus inactive yogurt. Body weight, weight gain and zinc concentration in bone and plasma were measured, and food efficiency ratio was calculated. Rats fed diets with PA and yogurt had normal growth compared to the control group. Growth retardation was evident in the group fed the diet with PA and no yogurt. This group had significantly lower body weight compared to all other groups ( P<.05). Rats fed diets with PA, with or without yogurt, had significantly lower zinc concentration in bone and plasma ( P<.05). Adding yogurt to diets high in PA resulted in normal growth in weanling rats; however, zinc concentration in bone and plasma was still suboptimal.

Relative Bioavailability of Zinc in Yogurt Using Body Weight Gain, Femur Weight and Bone Zinc Content in Rats as Markers

Objective: some previous works have shown the importance of zinc in nutrition, and even evaluated different zinc sources for food supplementation with this micronutrient. The aim of this work was to evaluate zinc gluconate stabi- lized with glycine (BZ) as a zinc source for food fortification by employing yogurt as the vehicle and zinc sulfate (SZ) as the standard zinc source. Materials and methods: weaned Sprague Dawley rats were separated in 7 groups of 10 rats each, which were fed with diets according to the scheme: Group 1- 2ppm Zn; Groups 2, 3 and 4 - 9, 20 and 34 ppm Zn as SO4Zn.7H2O (SZ) and Groups 5, 6 and 7 - 9, 20 and 34 ppm Zn as zinc gluconate stabilized with glycine (BZ) during 21 days. Zinc sources were provided in a vehicle as yogurt, added in the final diet at 10%. Body weight gain, femur weight and femur zinc content were evaluated at the end of the treatments in order to determine zinc bioavailability, as previously described by others. In this way, body weight gain and femur weight were analyzed by a non linear regression according to equation: Y = Ymax (1-e (-kX) ) and femur zinc content was analyzed by a linear regression, all of them as a function of dietary zinc from each source. Results: relative zinc bioavailability of BZ was 0.95; 0.95 and 1.10 according to body weight gain, femur weight and femur zinc content, respectively. Conclusion: zinc gluconate stabilized with glycine may be considered as a suitable source of zinc for food fortification in a yogurt matrix.

Differences in zinc status between patients with osteoarthritis and osteoporosis

Zinc has been suggested to play an important role in the development of osteoporosis, whereas the influence of zinc on osteoarthritis has attracted much less attention. The aim of the study was to investigate and compare the zinc status and bone turnover, density, and biomechanical properties of osteoarthritic and osteoporotic patients. The study comprised 40 women who underwent hip replacement due to osteoarthritis or osteoporosis. Serum and urine zinc content, and bone resorption markers and serum bone formation markers were determined. The unaffected hip and the exarticulated affected femoral head underwent DEXA scanning. Bone biopsies were obtained from the femoral heads and the biomechanical properties were determined. The biopsies were ashed and the bone zinc content was ascertained. Osteoarthritic patients had significantly higher serum zinc concentrations and lower urine zinc concentrations than osteoporotic patients, whereas the bone zinc content did not differ. The zinc status was not found to be a predictor for the bone strength. In conclusion, the finding that the zinc status of osteoporotic patients is significantly different from that of osteoartritic patients is new and supports the view that osteoporosis and osteoarthritis rarely occur in the same individual.

Magnesium Supplementation did not Affect the Increasing Bone Zinc Concentration in Rats Given Excess Calcium as Carbonate

We investigated the effect of magnesium supplementation on zinc distribution in rats given excess calcium as carbonate. Rats were given a control diet (5 g/kg calcium and 0.5 g/kg magnesium), a high calcium diet (HC, 25 g/kg calcium and 0.5 g/kg magnesium) or the high calcium diet supplied with magnesium (HCM, 25 g/kg calcium and 2.5 g/kg magnesium) for 4 weeks. Calcium carbonate and magnesium oxide were used for increasing these mineral concentrations in diets. Although feed intake did not differ among the groups, the excess calcium suppressed feed efficiency, irrespective of dietary magnesium concentration. Femoral magnesium concentration was lower in the HC group than in the control and the HCM groups. Femoral zinc concentration was higher in the HC group and the HCM group than in the control group. The zinc concentration in the kidney was lower in the HC group and the HCM group than in the control group. The excess calcium did not affect zinc concentration in plasma and other tissues such as the liver, testis, and spleen, irrespective of dietary magnesium. These results suggest that the increasing bone zinc and the decreasing renal zinc do not result from magnesium insufficiency in rats given excess calcium as carbonate.

Excess calcium increases bone zinc concentration without affecting zinc absorption in rats

We examined zinc (Zn) metabolism in rats given diets containing excess calcium (Ca). Rats were given phytate-free diet containing 5 g Ca/kg (control), 12.5 g Ca/kg, or 25 g Ca/kg for 4 wk in Experiment 1. The dietary treatment did not affect Zn concentration in the plasma, testis, kidney, spleen and liver; however, Zn concentration in the femur and its cortex was significantly higher in rats given diet containing 25 g Ca/kg than in other rats. Rats were given phytate-free diet containing 5 g Ca /kg or 25 g Ca /kg for 4 wk in Experiment 2. After 12-h food deprivation, rats were given a diet extrinsically labeled by 67Zn with dysprosium as a fecal marker for 4 h. Feces were collected from 1 d before administration of the labeled diet to 5 d after administration. Excess Ca did not affect the true absorption of Zn and its endogenous excretion but increased femoral Zn. These results suggest that excess Ca improves Zn bioavailability without affecting Zn absorption when diets do not contain phytate.

Sparing effect of microbial phytase on zinc supplementation in maize–soya-bean meal diets for chickens

The experiment was conducted to evaluate the sparing effect of microbial phytase on the need for dietary zinc supplementation in chicks. A maize–soya-bean meal basal diet, containing 33 mg of zinc and 16 mg of copper per kg, supplemented with 0, 6, 12, 18, 24, 30 or 60 mg of zinc as sulphate per kg or with 250, 500, 750 or 1000 units (FTU) of microbial phytase (3-phytase from Aspergillus niger, Natuphos®) per kg was given to 1-day-old chicks for 20 days. Sixteen chicks placed in individual cages were assigned to each diet except the unsupplemented basal diet which was assigned to 32 cages. Actual range of phytase supplementation was 280 to 850 FTU per kg diet. Growth performance was not affected by microbial phytase. Chicks given the unsupplemented basal diet and the basal diet supplemented with 60 mg of zinc per kg displayed similar performance. Bone weight, bone ash, liver weight and liver dry matter were independent (P > 0.1) of zinc and phytase supplementations. Plasma, bone and liver zinc concentrations increased linearly (P < 0.001) and quadratically (P < 0.001; P < 0.001 and P < 0.05, respectively) with zinc added. Plasma zinc tended to increase linearly (P = 0.07) and bone zinc increased linearly (P < 0.01) with phytase added but no quadratic response was detected (P > 0.1). Liver zinc was unresponsive to phytase added (P > 0.1). Liver copper decreased linearly (P < 0.001) and quadratically (P < 0.01) with zinc supplementation. Mathematical functions were fitted to the responses of plasma and bone zinc to zinc and phytase added and used to calculate zinc equivalency values of phytase. The models included a linear plateau response to zinc added and a linear response to phytase added. In diets without phytase, plasma and bone zinc concentrations were maximised for a dietary zinc concentration of 55 and 51 mg/kg, respectively. Over the range of 280 to 850 FTU, 100 FTU was equivalent to 1 mg of zinc as sulphate. Consequently, in a maize–soya-bean meal chicken diet formulated to contain 60 mg zinc per kg, zinc ingested, and in turn, zinc excreted may be reduced by around 10% if the diet contains 500 FTU as Natuphos® per kg.

Assessment of dietary zinc requirement of weaned piglets fed diets with or without microbial phytase

Fifty-four pigs, weaned at 26 days of age at an average body weight of 7.74 kg were used in a 26-day experiment to assess the zinc requirement of piglets, using diets based on maize and soybean meal, with or without microbial phytase. The nine experimental diets were the basal diet containing 33 mg of zinc/kg supplemented with 10, 25, 40, 60 or 80 mg of zinc as sulphate (ZnSO(4), 7H(2)O)/kg and the basal diet supplemented with 0, 10, 25 or 40 mg of zinc as sulphate/kg and 700 units (U) of microbial phytase (Natuphos)/kg. Pigs were fed the basal diet for a 7-day adjustment period prior to the 19-day experimental period. Microbial phytase enhanced plasma alkaline phosphatase (AP) activity, plasma zinc and bone zinc concentrations. These parameters increased linearly with zinc intake, with a similar slope with and without phytase. The response of bone zinc-to-zinc added did not plateau. Without microbial phytase, plasma AP activity and zinc concentration were maximized when dietary zinc reached 86 and 92 mg/kg respectively. With microbial phytase they were maximized when dietary zinc concentration reached 54 and 49 mg/kg respectively. Accounting for a safety margin, the recommended supply of zinc for weaned piglets up to 16 kg fed maize-soybean meal diets supplemented with zinc as sulphate is thus of 100-110 mg/kg diet. This supply may be reduced by around 35 mg if the diet is supplemented with 700 U of microbial phytase.

Replacement of zinc sulphate by microbial phytase for piglets given a maize-soya-bean meal diet

AbstractForty-eight pigs, weaned at 27 days of age at an average body weight of 7·55 kg were used in a 19-day experiment to investigate the influence of microbial phytase on zinc utilization and to calculate equivalency values of zinc as sulphate for microbial phytase. Eight experimental diets were formulated: a maize-soya-bean meal basal diet containing 30 mg of zinc per kg supplemented with 10, 25, 40 or 100 mg of zinc from sulphate (ZnSO4, 7H2O) per kg or with 100, 250, 500 or 750 units (U) of microbial phytase (3- phytase from Aspergillus niger, Natuphos ®) per kg. The dietary supplies of calcium and phosphorus were adjusted accounting for the release of these elements by microbial phytase. The copper concentration in the diets was 11 mg/kg. Pigs were given the basal diet for a 7-day adjustment period prior to the 19-day experimental period. At the end of the experiment, bone ash, phosphorus and calcium concentrations as well as plasma and liver copper concentrations were independent of the diet (P&gt; 0·10). The zinc status of piglets was assessed through plasma alkaline phosphatase activity (APA) and zinc concentration, bone zinc concentration and liver zinc concentration. Plasma zinc, plasma APA and bone zinc increased linearly (P&lt; 0·001) and quadratically (P&lt; 0·01,P&lt; 0·001 andP&lt; 0·001, respectively) with zinc added. These parameters also increased linearly (P&lt; 0·001) and quadratically (P&lt; 0·05,P&lt; 0·001 andP&lt; 0·05, respectively) with phytase added. Liver zinc increased quadratically (P&lt; 0·05) with zinc added and tended to increase linearly with phytase added (P= 0·077). Linear and non-linear response equations of indicators of zinc status to zinc added and phytase added were developed and used to calculate zinc equivalency values of phytase. Non-linear models were linear plateau models for zinc added and exponential models for phytase added. Plasma APA, plasma zinc and bone zinc were maximized when zinc added reached 43, 54 and 56 mg/kg of diet, respectively. The mean function of equivalency of zinc as sulphate (Zn, mg/kg of diet) for microbial phytase (Phyt, U per kg of diet) was Zn = 49·9 − 58·3 e−0·00233Phyt. From this equation it is calculated that 250, 500, and 750 U of 3-phytase from Aspergillus niger can avoid the addition of 17, 32 and 40 mg of zinc as sulphate in a piglet diet. Zinc ingested and, in turn, zinc excreted, may be proportionately reduced by almost 0·30 by replacing 30 mg of zinc as sulphate by 500 U of phytase as Natuphos ® in a piglet maize and soya-bean meal diet formulated to contain 100 mg of zinc per kg.

Determination of Relative Bioavailability of Zinc in a Petit Suisse Cheese Using Weight Gain and Bone Zinc Content in Rats as Markers

The aim of the study was to determine the relative bioavailability of zinc gluconate stabilized with glycine in a Petit Suisse cheese from an infant dessert. Weight gain and bone zinc content were the nutritional responses evaluated for the diets of different zinc content: 2 ppm (basal) and 5, 10, and 30 ppm from zinc gluconate stabilized with glycine and zinc sulfate. Nonlinear regression analysis of the fitted curves for weight gain determined a relative zinc bioavailability of 100% for the Y<I->max ratio and 96% for Ymax/t1/2 ratio for zinc gluconate stabilized with glycine (R2=0.7996 for zinc sulfate and 0.8665 for zinc gluconate stabilized with glycine). The slope ratio analysis from linear regression of femur zinc determined a relative zinc bioavailability of 93% for zinc gluconate stabilized with glycine (R<I+>2=0.8693 for zinc sulfate and 0.8307 for zinc gluconate stabilized with glycine). Zinc gluconate stabilized with glycine has similar bioavailability as zinc sulfate in a Petit Suisse cheese nutritional matrix, with the advantage that the stabilized compound does not modify the sensorial characteristics of the fortified cheese.

Effect of phytate on element bioavailability in the second generation of rats

In this paper the relation between long term consumption of a high dose of sodium phytate and the mineral status of the organism is evaluated in rats. For this purpose, element concentrations (Ca, Mg, Fe, Zn, Mn) were determined in liver, heart, testicle, bone and urine of a second generation of Wistar rats, treated with a phytate free diet (AIN-76A) and with the same diet plus 1% phytate as sodium salt. The most significant differences were observed between bone zinc contents of male and female rats. The zinc content of rats fed a 1% phytate as sodium salt diet resulted clearly lower than that found in no-phytate treated rats. Hence, it is concluded that when up to 1% of phytate as sodium salt is consumed together with an equilibrated purified diet (free of phytate), no decrease in mineral bioavailability is observed in second generation rats, except for an indication of lower zinc availability by lower zinc concentrations in some organs, mainly bone. However, using this purified diet, the zinc concentration in bone resulted around 10 times higher than found in rats fed with a common non purified rat chow.

Bioavailability of two sources of zinc in weanling pigs

Thirty-two pigs, weaned at 28 days of age with an average body weight of 9 kg, were used in an experiment devoted to the assessment of the bioavailability of an organic Zn source (ZnOrg) compared to Zn sulfate. Pigs were fed a basal diet containing 28 mg·kg -1 of Zn supplemented with ZnSO4 or ZnOrg to provide 0, 10, 20 and 30 mg·kg -1 of supplemental Zn. In order to reduce the amount and the variability of their Zn stores, pigs were fed the basal diet for a 7-day adjustment period preceding a 19-day experimental period. Growth performance and bone bending moment were not affected by the level nor the source of zinc. On the contrary, plasma zinc concentration and alkaline phosphatase activity (P < 0.001), bone zinc concentration (P < 0.001), liver and empty body zinc concentrations (P < 0.01) as well as the amount of Zn retained estimated both by the balance tech- nique (BT) (P < 0.001) and by the comparative slaughter technique (CST) (P < 0.01) increased lin- early in response to supplemental Zn. However, the two Zn sources exhibited a similar bioavailability. Twenty-seven percent of Zn intake was retained when measured by means of the balance technique, regardless of the dietary level or zinc source. Zn retention was 54% lower when measured by means of the CST as compared to the BT. pig / zinc / bioavailability / source / indicator

Increased bone strontium levels in hemodialysis patients with osteomalacia

In this study, we report on the association between increased bone strontium levels and the presence of osteomalacia in end-stage renal failure patients treated by hemodialysis. We performed a histologic examination and determined the strontium content and strontium/calcium ratios in bone biopsies of 100 hemodialysis patients recruited from various centers all over the world. Aside from the bone strontium concentration, the bone aluminum content was assessed. The bone zinc concentration, a nonrelevant element for bone toxicity, was also measured. Bone strontium levels and bone strontium/calcium ratios were increased in subjects with osteomalacia when compared with those with the other types of renal osteodystrophy. Bone strontium and bone calcium levels correlated with each other. The slope of the linear regression curve correlating these parameters was much steeper in the osteomalacic group (Y = 2.22X - 120) as compared with the other types of renal osteodystrophy (Y = 0.52X - 5.7). Within the group of patients with osteomalacia, bone strontium levels also significantly correlated with the bone aluminum content (r = 0.72, P = 0.018). No such correlation was found for the other types of renal osteodystrophy. The bone zinc concentration of subjects with normal renal function did not differ significantly from the values noted for the various types of renal osteodystrophy taken as separate groups, nor could increased bone zinc concentrations be associated with a particular bone lesion. Our data demonstrate an association between osteomalacia and increased bone strontium concentrations in dialysis patients. Further studies are warranted to establish whether strontium plays either a primary, secondary, or contributive role in the development of the latter type of renal osteodystrophy.

Role of zinc in bone formation and bone resorption

Zinc is essential for the growth of the human and other animals. Bone growth retardation is a common finding in various conditions associated with zinc deficiency, suggesting a physiological role of zinc in the growth and mineralization of bone tissue. Bone zinc content is decreased by development with aging, skeletal unloading, and postmenopausal conditions. Zinc deficiency may play a pathophysiological role in the deterioration of bone metabolism. Zinc has been demonstrated to have a stimulatory effect on bone formation and mineralization; the metal directly activates aminoacyl-tRNA synthetase in osteoblastic cells, and it stimulates cellular protein synthesis. Moreover, zinc inhibits osteoclastic bone resorption by inhibiting osteoclast-like cell formation from marrow cells. Zinc may act on the process of bone-resorbing factors-induced protein kinase C activation, which is involved in Ca2+ signaling in osteoclastic cells. Zinc plays a role in the preservation of bone mass. AHZ is a zinc compound, in which zinc is chelated to β-alanyl-L-histidine. The stimulatory effect of AHZ on bone formation was more intensive than that of zinc sulfate. It is confirmed that bone-forming effect of AHZ is a greater than that of various bone-regulating hormones and other factors. The oral administration of AHZ has a fine restorative effect on osteopenia with various pathophysiological conditions. Zinc compound may be a new drug in the therapy of osteoporosis. J. Trace Elem. Exp. Med. 11:119–135, 1998. © 1998 Wiley-Liss, Inc.

Role of zinc in bone formation and bone resorption

Zinc is essential for the growth of the human and other animals. Bone growth retardation is a common finding in various conditions associated with zinc deficiency, suggesting a physiological role of zinc in the growth and mineralization of bone tissue. Bone zinc content is decreased by development with aging, skeletal unloading, and postmenopausal conditions. Zinc deficiency may play a pathophysiological role in the deterioration of bone metabolism. Zinc has been demonstrated to have a stimulatory effect on bone formation and mineralization; the metal directly activates aminoacyl-tRNA synthetase in osteoblastic cells, and it stimulates cellular protein synthesis. Moreover, zinc inhibits osteoclastic bone resorption by inhibiting osteoclast-like cell formation from marrow cells. Zinc may act on the process of bone-resorbing factors-induced protein kinase C activation, which is involved in Ca2+ signaling in osteoclastic cells. Zinc plays a role in the preservation of bone mass. AHZ is a zinc compound, in which zinc is chelated to β-alanyl-L-histidine. The stimulatory effect of AHZ on bone formation was more intensive than that of zinc sulfate. It is confirmed that bone-forming effect of AHZ is a greater than that of various bone-regulating hormones and other factors. The oral administration of AHZ has a fine restorative effect on osteopenia with various pathophysiological conditions. Zinc compound may be a new drug in the therapy of osteoporosis. J. Trace Elem. Exp. Med. 11:119–135, 1998. © 1998 Wiley-Liss, Inc.