Partial prevention of long-term femoral bone loss in aged ovariectomized rats supplemented with choline-stabilized orthosilicic acid

Silicon Supplementation for Bone Health: An Umbrella Review Attempting to Translate from Animals to Humans

Studies have attempted to demonstrate the benefits of silicon on bone health using a wide range of Si amounts-provided in the diet or through supplementation-and several different animal species. Previous studies in humans have also demonstrated a positive correlation between Si intake and bone health measures. The aim of the current review is to determine the effective levels of Si intake or supplementation that influence bone health to better inform future study designs and guidelines. Articles were identified using one of two search terms: "silicon AND bone" or "sodium zeolite A AND bone". Articles were included if the article was a controlled research study on the effect of Si on bone health and/or mineral metabolism and was in English. Articles were excluded if the article included human subjects, was in vitro, or studied silica grafts for bone injuries. Silicon type, group name, Si intake from diet, Si supplementation amount, animal, and age at the start were extracted when available. Dietary Si intake, Si supplementation amount, and the amount of Si standardized on a kg BW basis were calculated and presented as overall mean ± standard deviations, medians, minimums, and maximums. Studies that left out animal weights, amount of food or water consumed, or nutrient profiles of the basal diet were excluded from these calculations. Standardized Si intakes ranged from 0.003 to 863 mg/kg BW, at times vastly exceeding current human Si intake recommendations (25 mg/d). The lack of data provided by the literature made definitively determining an effective threshold of supplementation for skeletal health difficult. However, it appears that Si consistently positively influences bone and mineral metabolism by around 139 mg Si/kg BW/d, which is likely unfeasible to attain in humans and large animal species. Future studies should examine this proposed threshold more directly and standardize supplemental or dietary Si intakes to kg BW for better study replication and translation.

The effect of choline-stabilized orthosilicic acid in patients with peri-implantitis: an exploratory randomized, double-blind, placebo controlled study

Background

Choline-stabilized orthosilicic acid (CS-OSA) was previously found to stimulate bone collagen formation in osteopenia and to improve biomarkers of cartilage degradation in knee osteoarthritis. The aim of the present study was to investigate the effect of oral administration of CS-OSA on clinical symptoms of peri-implantitis and the associated bone loss.

Methods

Twenty-one patients with peri-implantitis were randomized in CS-OSA or placebo groups. After initial clinical and cone beam computed tomography (CBCT) measurements [probing pocket depth (PPD), bleeding on probing (BOP), mucosal recession (REC), distance from implant shoulder to alveolar crest (IS-AC) and distance from implant shoulder to first bone-to-implant contact (IS-BIC)], flap operations were performed at the peri-implantitis sites. All patients were instructed to use either placebo or CS-OSA capsules twice a day for 1 year. Measurements were repeated 6 and 12 months after randomization.

Results

The data of 18 patients (36 implants) were used in the per protocol analysis. PPD and BOP improved significantly (p < 0.05) compared to baseline for both groups after 6 and 12 months. However, REC significantly increased in the placebo group but not in the CS-OSA group. The change in REC over 6 and 12 months was significantly different between groups (p < 0.01). IS-BIC and IS-AC measurements remained stable in the CS-OSA group whereas in the placebo group, both parameters increased significantly after 6 and 12 months. The change in IS-BIC over 12 months was significantly different between groups (p < 0.05).

Conclusion

The results of this preliminary study suggest that CS-OSA may stabilize and even prevent further bone loss after surgical peri-implantitis treatment and support mucosal tissue healing.

Trial registration

The trial was retrospectively registered at ISRCTN registry, registration number: ISRCTN14348802, registration date: 24/06/2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01817-4.

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.

Effect of Silicon Supplementation in Diets with Different Calcium Levels on Balance of Calcium, Silicon and Magnesium, and Bone Status in Growing Female Rats

Silicon (Si) is important for the growth and development of bone and connective tissues. This study aimed to evaluate the effect of Si supplementation on the balance of calcium (Ca), Si, magnesium (Mg), and bone status in growing female rats fed diets with different Ca levels. Sixty 6-week-old female Wistar rats were divided into 6 groups and fed diets with different levels of Ca (0.1, 0.5, 1.5%) and Si (5, 500 ppm) for 10 weeks. Experimental groups were as follows: Low-Ca group (LCa; 0.1% Ca), Low-Ca with Si supplementation group (LCaSi), adequate-Ca group (ACa; 0.5% Ca), adequate-Ca with Si supplementation group (ACaSi), high-Ca group (HCa; 1.5% Ca), and high-Ca with Si supplementation group (HCaSi). Si retention significantly increased by Si supplementation and significantly decreased by high-Ca diet (1.5%). Mg retention significantly decreased by high-Ca diet. Serum Ca and Si contents were not significantly different among the 6 groups. Low-Ca diet significantly increased serum osteoclain and C-telopeptide cross-link of type 1 collagen (CTx) levels, and Si supplementation significantly decreased CTx levels in the low-Ca diet group. Bone mineral density was significantly increased along with Ca increase in the diet, but was decreased by Si supplementation in the high-Ca diet. Rats in the adequate-Ca diet group had a significant increase in strength of tibia after Si supplementation. These findings indicate that the effect of Si supplementation on bone metabolism may differ according to the Ca-intake level in growing females. Although further research is needed, when supplementing Si to improve bone health in growing females, Ca-intake level should be considered.

Relationship Between Dietary Intake and Urinary Excretion of Silicon in Free-Living Korean Adult Men and Women

Previous studies have reported that silicon (Si) has a positive effect on bone health, immune response, and cognitive health. However, basic and important studies on evaluating dietary intake and urinary excretion of Si are limited. The aim of this study was to evaluate dietary Si intake and urinary excretion according to gender and age in healthy and free-living Korean adults and to investigate the relationship between them with gender. In this cross-sectional study, anthropometric measurements, dietary assessment using a food record, and a 24-h urine collection were conducted in 80 healthy Korean adults (40 males and 40 females; groups of 8 subjects representing each decade of life [20s to 60s]) with self-selected diet. The dietary assessment and 24-h urine collection were performed twice at intervals of 3 days. Daily intake of Si was estimated using a Si database of food composition. Urinary excretion of Si was analyzed using ICP-OES. The mean dietary Si intake was 22.8 mg/day for men and 19.3 mg/day for women without significant difference according to their gender and age. Si intake was the highest from vegetables both in men and women, followed by grains, beverages, and fruits in men and by grains, fruits, and milks in women. Urinary Si excretion was significantly higher in men (9.8 mg/day) than women (9.3 mg/day), and significantly increased with age only in women. Regarding the relationship between dietary Si intake and urinary Si excretion, a significantly positive correlation was found in men, but not in women. Longitudinal and balance studies to elucidate gender differences in Si nutrition are needed.

Combined Effects of Phytoestrogen Genistein and Silicon on Ovariectomy-Induced Bone Loss in Rat

This study was performed to evaluate the effect of concomitant supplementation of genistein and silicon on bone mineral density and bone metabolism-related markers in ovariectomized rat. Three-month-old Sprague Dawley female rats were subjected to bilateral ovariectomy (OVX) or sham surgery, and then the OVX rats were randomly divided into four groups: OVX-GEN, OVX-Si, OVX-GEN-Si, and OVX. Genistein and silicon supplementation was started immediately after OVX and continued for 10 weeks. In the OVX-GEN group, 5 mg genistein per gram body weight was injected subcutaneously. The OVX-Si group was given soluble silicon daily in demineralized water (Si 20 mg/kg body weight/day). The OVX-GEN-Si group was given subcutaneous injections of 5 mg genistein per gram body weight, at the same time, given soluble silicon daily (Si 20 mg/kg body weight/day). The results showed that the genistein supplementation in the OVX rats significantly prevented the loss of uterus weight; however, the silicon supplementation showed no effect on the uterus weight loss. The lumbar spine and femur bone mineral density was significantly decreased after OVX surgery; however, this decrease was inhibited by the genistein and/or silicon, and the BMD of the lumbar spine and femur was the highest in the OVX-GEN-Si-treated group. Histomorphometric analyses showed that the supplementation of genistein and/or silicon restored bone volume and trabecular thickness of femoral trabecular bone in the OVX group. Besides, the treatment with genistein and silicon for 10 weeks increased the serum levels of calcium and phosphorus in the OVX rats; serum calcium and serum phosphorus in the OVX-GEN-Si group were higher than those in the OVX-GEN and OVX-Si group (P < 0.05). At the same time, the treatment with genistein and/or silicon decreased serum alkaline phosphatase (ALP) and osteocalcin, which were increased by ovariectomy; serum ALP and osteocalcin in the OVX-GEN-Si group were lower than those in the OVX-GEN and OVX-Si groups (P < 0.05). The results above indicate that genistein and silicon have synergistic effects on bone formation in ovariectomized rats.

A 12-week randomized, double-blind, placebo-controlled multicenter study of choline-stabilized orthosilicic acid in patients with symptomatic knee osteoarthritis

Background

The aim of this study was to assess the efficacy of choline-stabilized orthosilicic acid (ch-OSA) in patients with symptomatic knee osteoarthritis (OA).

Methods

In a multicenter, double-blind, placebo-controlled study, 211 patients with knee OA (Kellgren and Lawrence grade II or III) and moderate to moderately severe pain were randomly allocated to ch-OSA or placebo for 12 weeks. The primary outcome was the change in the WOMAC pain subscale from baseline to week 12. Secondary outcomes were changes from baseline to week 12 in WOMAC total, WOMAC stiffness, WOMAC physical function, Subject Global Assessment and levels of cartilage degradation biomarkers C-terminal telopeptide of collagen type II (CTX-II) and cartilage oligomeric matrix protein (COMP). Pre-specified subgroup analyses included the effect of gender.

Results

A total of 166 (120 women, 46 men) patients were included in the analysis (87 and 79 in the ch-OSA and placebo group, respectively). In the total study population, no differences were observed between the two treatment groups for the different outcomes but significant treatment x gender interactions were found. In men taking ch-OSA, a significant improvement in WOMAC total, WOMAC stiffness and WOMAC physical function as well as a lower increase in biomarker levels of cartilage degradation was observed, but not in women. The change in WOMAC pain showed a similar positive trend in men taking ch-OSA.

Conclusion

After 12 weeks of treatment, no effect was found of ch-OSA in the total study population on clinical parameters and biomarkers, but a gender interaction was observed. In men, ch-OSA was found effective in reducing symptoms of knee OA, which was associated with a slight but significant reduction of biomarkers that are related to cartilage degradation.

Trial registration

The study was registered retrospectively: ISRCTN88583133. Registration date: 2015-10-07.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1370-7) contains supplementary material, which is available to authorized users.

Pigmentation Effect of Rice Bran Extracted Minerals Comprising Soluble Silicic Acids

Our investigation focused on identifying melanogenesis effect of soluble minerals in rice bran ash extract (RBE) which include orthosilicic acid (OSA). Melanocytes were apparently normal in terms of morphology. It was, however, shown that they were stressed a little in the RBE and OSA added media in aspect of LDH activity. Melanin synthesis and intracellular tyrosinase activity were increased by treatment of RBE which is similar to that of OSA. The Western blotting results showed that TRP-1, tyrosinase, and MITF expression levels were 2-3 times higher in the OSA and RBE groups compared to the control group which promoted melanin synthesis through CREB phosphorylation. Moreover, histology and immunohistochemistry were shown to have similar result to that of protein expression. As a result, minerals which comprise orthosilicic acid has the potential to promote melanogenesis and both RBE and OSA have similar cell viability, protein expression, and immunostaining results, suggesting that RBE comprises specific minerals which promote melanin synthesis through increasing of MITF and CREB phosphorylation. Therefore, RBE could be used as a novel therapeutic approach to combat melanin deficiency related diseases by stimulating melanocytes via its soluble Si and mineral components.

Biological Silicon Stimulates Collagen Type 1 and Osteocalcin Synthesis in Human Osteoblast-Like Cells Through the BMP-2/Smad/RUNX2 Signaling Pathway

Silicon is essential for bone formation. A low-silicon diet leads to bone defects, and numerous animal models have demonstrated that silicon supplementation increases bone mineral density (BMD) and reduces bone fragility. However, the exact mechanism of this action has not been characterized. In this study, we aimed to determine the role of biological silicon in the induction of osteoblast differentiation and the possible underlying mechanism. We examined whether orthosilicic acid promotes collagen type 1 (COL-1) and osteocalcin synthesis through the bone morphogenetic protein-2 (BMP-2)/Smad1/5/runt-related transcription factor 2 (RUNX2) signaling pathway by investigating its effect in vitro at several concentrations on COL-1 and osteocalcin synthesis in human osteosarcoma cell lines (MG-63 and U2-OS). The expression of relevant proteins was detected by Western blotting following exposure to noggin, an inhibitor of BMP-2. In MG-63 cells, immunofluorescence methods were applied to detect changes in the expression of BMP-2, phosphorylated Smad1/5 (P-Smad1/5), and RUNX2. Furthermore, rat bone mesenchymal stem cells (BMSCs) were used to determine the effect of orthosilicic acid on osteogenic differentiation. Exposure to 10 μM orthosilicic acid markedly increased the expression of BMP-2, P-Smad1/5, RUNX2, COL-1, and osteocalcin in osteosarcoma cell lines. Enhanced ALP activity and the formation of mineralized nodules were also observed under these conditions. Furthermore, preconditioning with noggin inhibited the silicon-induced upregulation of P-Smad1/5, RUNX2, and COL-1 expression. In conclusion, the BMP-2/Smad1/5/RUNX2 signaling pathway participates in the silicon-mediated induction of COL-1 and osteocalcin synthesis, and orthosilicic acid promotes the osteogenic differentiation of rat BMSCs.

Effect of Silicon Supplementation on Bone Status in Ovariectomized Rats Under Calcium-Replete Condition

Previous studies have suggested that silicon (Si) had positive effects on bone, but such benefits from Si may be dependent on calcium status. Also, several biochemical roles of Si in osteoblastic mineralization, the regulation of gene expression related to bone matrix synthesis, and the decrease in reactive oxygen species and pro-inflammatory mediators were reported, but these effects were mostly shown in cell culture studies. Hence, we tested the effect of Si supplementation on bone status and the gene expression related to bone metabolism and inflammatory mediators in young estrogen-deficient rats under calcium-replete condition (0.5 % diet). Results showed that 15-week supplementation of both high and very high doses of Si (0.025 and 0.075 % diet, respectively) could not restore the ovariectomy (OVX)-induced decrease of bone mineral density (BMD) of vertebrae, femur, and tibia. Also, several bone biochemical markers (ALP, osteocalcin, CTx) and mRNA expression of COL-I, RANKL, IL-6, and TNF-α in femur metaphysis were not significantly changed by Si in OVX rats. However, a very high dose (0.075 %) of Si supplementation significantly increased OPG expression and decreased the ratio of RANKL/OPG in mRNA expression comparable to that of sham-control animals. Taken together, Si supplementation did not increase BMD under calcium-replete condition but the decrease in the ratio of RANKL/OPG expression to the normal level suggests the possibility of a bone health benefit of Si in estrogen deficiency-induced bone loss.

Positive association between serum silicon levels and bone mineral density in female rats following oral silicon supplementation with monomethylsilanetriol

Observational (epidemiological) studies suggest the positive association between dietary silicon intake and bone mineral density may be mediated by circulating estradiol level. Here, we report the results of a silicon supplementation study in rats that strongly support these observations and suggest an interaction between silicon and estradiol.

INTRODUCTION

Epidemiological studies report strong positive associations between dietary silicon (Si) intake and bone mineral density (BMD) in premenopausal women and indicate that the association may be mediated by estradiol. We have tested this possibility in a mixed-gender rodent intervention study.

METHODS

Tissue samples were obtained from three groups of 20-week-old Sprague Dawley rats (five males and five females per group) that had been supplemented ad libitum for 90 days in their drinking water with (i) <0.1 mg Si/L (vehicle control), (ii) 115 mg Si/L (moderate dose) or (iii) 575 mg Si/L (high dose). All rats received conventional laboratory feed, whilst supplemental Si was in the form of monomethylsilanetriol, increasing dietary Si intakes by 18 and 99 %, for the moderate- and high-dose groups, respectively.

RESULTS

Fasting serum and tissue Si concentrations were increased with Si supplementation (p < 0.05), regardless of gender. However, only for female rats was there (i) a trend for a dose-responsive increase in serum osteocalcin concentration with Si intervention and (ii) strong significant associations between serum Si concentrations and measures of bone quality (p < 0.01). Correlations were weaker or insignificant for tibia Si levels and absent for other serum or tibia elemental concentrations and bone quality measures.

CONCLUSIONS

Our findings support the epidemiological observations that dietary Si positively impacts BMD in younger females, and this may be due to a Si-estradiol interaction. Moreover, these data suggest that the Si effect is mediated systemically, rather than through its incorporation into bone.

A review of the effects of dietary silicon intake on bone homeostasis and regeneration

OBJECTIVE

Increasing evidences suggest that dietary Silicon (Si) intake, is positively correlated with bone homeostasis and regeneration, representing a potential and valid support for the prevention and improvement of bone diseases, like osteoporosis. This review, aims to provide the state of art of the studies performed until today, in order to investigate and clarify the beneficial properties and effects of silicates, on bone metabolism.

METHODS

We conducted a systematic literature search up to March 2013, using two medical databases (Pubmed and the Cochrane Library), to review the studies about Si consumption and bone metabolism.

RESULTS

We found 45 articles, but 38 were specifically focused on Si studies.

CONCLUSION

RESULTS showed a positive relationship between dietary Si intake and bone regeneration.

Update on the possible nutritional importance of silicon

Convincing evidence that silicon is a bioactive beneficial trace element continues to accumulate. The evidence, which has come from human, animal, and in vitro studies performed by several laboratories, indicate that silicon in nutritional and supra nutritional amounts promotes bone and connective tissue health, may have a modulating effect on the immune or inflammatory response, and has been associated with mental health. A plausible mechanism of action for the beneficial effects of silicon is the binding of hydroxyl groups of polyols such that it influences the formation and/or utilization of glycosaminoglycans, mucopolysaccharides, and collagen in connective tissue and bone. In addition, silicon may affect the absorption, retention or action of other mineral elements (e.g., aluminum, copper, magnesium). Based on findings from both animal and human experiments, an intake of silicon of near 25mg/d would be a reasonable suggestion for an adequate intake that would assure its nutritional benefits. Increased intakes of silicon through consuming unrefined grains, certain vegetables, and beverages and cereals made from grains should be recognized as a reasonable dietary recommendation.

Effect of water-soluble silicon supplementation on bone status and balance of calcium and magnesium in male mice

Silicon (Si) is important for the growth and development of bone and connective tissues. Several studies have reported that Si supplementation improved bone mineral density (BMD) in female ovarectomized rats. However, few studies have investigated the effects of Si supplementation on bone status and bone metabolism in male animals. The purpose of this study was to investigate the effects of Si supplementation on BMD and balance of calcium (Ca) and magnesium (Mg) in adult male mice. Si was administrated orally through demineralized water containing different contents of Si as a form of sodium metasilicate (0 %, control; 0.025 %, Si50; 0.050 %, Si100; and 0.075 %, Si150) to 9-week-old male mice for 4 weeks. Si supplementation did not alter weight gain or BMD of femur and tibia in male mice. However, a high level of Si (0.05 and 0.075 %) supplementation significantly decreased Mg retention without changing Ca retention. Serum alkaline phosphatase of Si-supplemented groups significantly decreased compared with that of the control. According to these results, short-term Si supplementation did not affect BMD but showed a possible effect on increasing the need for Mg in adult male mice.

Silicon: a review of its potential role in the prevention and treatment of postmenopausal osteoporosis

Physicians are aware of the benefits of calcium and vitamin D supplementation. However, additional nutritional components may also be important for bone health. There is a growing body of the scientific literature which recognizes that silicon plays an essential role in bone formation and maintenance. Silicon improves bone matrix quality and facilitates bone mineralization. Increased intake of bioavailable silicon has been associated with increased bone mineral density. Silicon supplementation in animals and humans has been shown to increase bone mineral density and improve bone strength. Dietary sources of bioavailable silicon include whole grains, cereals, beer, and some vegetables such as green beans. Silicon in the form of silica, or silicon dioxide (SiO2), is a common food additive but has limited intestinal absorption. More attention to this important mineral by the academic community may lead to improved nutrition, dietary supplements, and better understanding of the role of silicon in the management of postmenopausal osteoporosis.

Effects of silicon on osteoblast activity and bone mineralization of MC3T3-E1 cells

Previous studies have reported that dietary silicon (Si) intake is positively associated with bone health including bone mineral density. Although the amount of Si intake is high among trace elements in humans, how dietary Si affects bone formation at the cellular level is not well addressed. The purpose of this study was to investigate the role of Si in osteoblast activity and bone mineralization. MC3T3-E1 was cultured as mature osteoblasts and treated with sodium metasilicate (0, 1, 5, 10, 25, 50, and 100 μM) as a source of Si. After 7 days of treatment, 5 and 10 μM of sodium metasilicate significantly increased intracellular alkaline phosphatase activity (p < 0.05) when compared to the control. Additionally, all doses of sodium metasilicate (1, 5, 10, 25, 50, and 100 μM) increased mineralized nodule formation at 14 days of differentiation as evidenced by increased Alizarin Red S staining. In the analysis of gene expression, 50 μM of sodium metasilicate upregulated type I collagen (COL-I) compared to the control group. However, the increase of COL-I gene expression as a result of treatment with 1, 10, 25, and 100 μM of sodium metasilicate did not reach statistical significance. mRNA expression of insulin-like growth factor-I and receptor activator of NF-κB ligand was not significantly changed at any dose of sodium metasilicate (0, 1, 5, 10, 25, 50, and 100 μM). In light of the results, we conclude that Si has a positive effect on bone metabolism by enhancing osteoblast mineralization activity.

Biological and therapeutic effects of ortho-silicic acid and some ortho-silicic acid-releasing compounds: New perspectives for therapy

Silicon (Si) is the most abundant element present in the Earth's crust besides oxygen. However, the exact biological roles of silicon remain unknown. Moreover, the ortho-silicic acid (H4SiO4), as a major form of bioavailable silicon for both humans and animals, has not been given adequate attention so far. Silicon has already been associated with bone mineralization, collagen synthesis, skin, hair and nails health atherosclerosis, Alzheimer disease, immune system enhancement, and with some other disorders or pharmacological effects. Beside the ortho-silicic acid and its stabilized formulations such as choline chloride-stabilized ortho-silicic acid and sodium or potassium silicates (e.g. M2SiO3; M= Na,K), the most important sources that release ortho-silicic acid as a bioavailable form of silicon are: colloidal silicic acid (hydrated silica gel), silica gel (amorphous silicon dioxide), and zeolites. Although all these compounds are characterized by substantial water insolubility, they release small, but significant, equilibrium concentration of ortho-silicic acid (H4SiO4) in contact with water and physiological fluids. Even though certain pharmacological effects of these compounds might be attributed to specific structural characteristics that result in profound adsorption and absorption properties, they all exhibit similar pharmacological profiles readily comparable to ortho-silicic acid effects. The most unusual ortho-silicic acid-releasing agents are certain types of zeolites, a class of aluminosilicates with well described ion(cation)-exchange properties. Numerous biological activities of some types of zeolites documented so far might probably be attributable to the ortho-silicic acid-releasing property. In this review, we therefore discuss biological and potential therapeutic effects of ortho-silicic acid and ortho-silicic acid -releasing silicon compounds as its major natural sources.

Micronutrients-incorporated calcium phosphate particles with protective effect on osteoporotic bone tissue

BACKGROUND

Supplementation of individual micronutrient is inadequate for maintaining bone function because single micronutrient can not contribute significantly a positive remodeling balance.

OBJECTIVE

We developed the highly integrated, stably dietary multi-micronutrients with good bioavailability and low adverse effect on the improvement of bone consolidation in osteoporosis.

METHODS

The trace element-codoped calcium phosphate (teCaP) particles were prepared in the modified body fluid and carefully evaluated. Rats, aged 3 months, were ovariectomized and when 6 month intervened with the conditioned, low, moderate, and high teCaP diets.

RESULTS

The teCaP particles showed highly dissolvable in stomach juice-mimicing acidic solutions. Three months after intervention, the body weight increase showed remarkable differences among the low teCaP diet (~52 g), moderate teCaP diet (~34 g) and high teCaP diet (~23 g) group. In particular, the intake of moderate teCaP greatly improved the retention of trace elements in femural bone for better protection against the skeletal weakening, and resulted in a significant increase of bone mineral density (104.06%) in comparison with the conventional high calcium plus vitamin D3 diet (Control group).

CONCLUSIONS

These investigations improve our understanding of micronutrient retention on bone consolidation in osteoporotic bone tissue, and also provide new mild wet-chemical approach to prepare potent nutritionally effective edible complements to synergistically relieve bone degeneration and prevent osteoporosis.

Silicon: the health benefits of a metalloid

Silicon is the second most abundant element in nature behind oxygen. As a metalloid, silicon has been used in many industrial applications including use as an additive in the food and beverage industry. As a result, humans come into contact with silicon through both environmental exposures but also as a dietary component. Moreover, many forms of silicon, that is, Si bound to oxygen, are water-soluble, absorbable, and potentially bioavailable to humans presumably with biological activity. However, the specific biochemical or physiological functions of silicon, if any, are largely unknown although generally thought to exist. As a result, there is growing interest in the potential therapeutic effects of water-soluble silica on human health. For example, silicon has been suggested to exhibit roles in the structural integrity of nails, hair, and skin, overall collagen synthesis, bone mineralization, and bone health and reduced metal accumulation in Alzheimer's disease, immune system health, and reduction of the risk for atherosclerosis. Although emerging research is promising, much additional, corroborative research is needed particularly regarding speciation of health-promoting forms of silicon and its relative bioavailability. Orthosilicic acid is the major form of bioavailable silicon whereas thin fibrous crystalline asbestos is a health hazard promoting asbestosis and significant impairment of lung function and increased cancer risk. It has been proposed that relatively insoluble forms of silica can also release small but meaningful quantities of silicon into biological compartments. For example, colloidal silicic acid, silica gel, and zeolites, although relatively insoluble in water, can increase concentrations of water-soluble silica and are thought to rely on specific structural physicochemical characteristics. Collectively, the food supply contributes enough silicon in the forms aforementioned that could be absorbed and significantly improve overall human health despite the negative perception of silica as a health hazard. This review discusses the possible biological potential of the metalloid silicon as bioavailable orthosilicic acid and the potential beneficial effects on human health.

A silicon cell cycle in a bacterial model of calcium phosphate mineralogenesis

The prokaryote Corynebacterium matruchotii produces calcium phosphate (bone salt) and may serve as a convenient model for examining individual factors relevant to vertebrate calcification. A factor of current clinical uncertainty is silicon. To investigate its possible role in biomineralisation advanced optical (digital deconvolution and 3D fluorescent image rendering) and electron microscopy (EDX microanalysis and elemental mapping) were applied to calcifying microbial colonies grown in graded Si concentrations (0-60mM). Cell viability was confirmed throughout by TO-PRO-3-iodide and SYTO-9 nucleic acid staining. It was observed that calcium accumulated in dense intracellular microspherical objects (types i-iii) as nanoparticles (5 nm, type i), nanospheres (30-50 nm, type ii) and filamentous clusters (0.1-0.5 μm, type iii), with a regular transitory Si content evident. With bacterial colony development (7-28 days) the P content increased from 5 to 60%, while Si was displaced from 60 to 5%, distinguishing the phenomenon from random contamination, and with a significant relationship (p<0.001) found between calcified object number and Si supplementation (optimum 0.01mM). The Si-containing, intracellular calcified objects (also positive for Mg and negative with Lysensor blue DND-167 for acidocalcisomes) were extruded naturally in bubble-like chains to complete the cycle by coating the cell surface with discrete mineral particles. These could be harvested by lysis, French press and density fractionation when Si was confirmed in a proportion. It was concluded that the unexplained orthopaedic activity of Si may derive from its special property to facilitate calcium phosphorylation in biological systems, thereby recapitulating an ancient and conserved bacterial cycle of calcification via silicification.

Dietary silicon interacts with oestrogen to influence bone health: evidence from the Aberdeen Prospective Osteoporosis Screening Study

BACKGROUND

Silicon (Si), as Si(OH)(4), is derived mainly from plant-based foods. Dietary Si is associated with bone mineral density (BMD) in premenopausal but not postmenopausal women.

OBJECTIVE

To examine the association between Si intake and markers of bone health in middle-aged women and to test for interaction with oestrogen status.

METHODS

Femoral neck (FN) and lumbar spine (LS) BMD, urinary markers of bone resorption (free pyridinoline and deoxypyridinoline cross-links relative to creatinine, fPYD/Cr and fDPD/Cr) and serum markers of bone formation (N-terminal propeptide of type 1 collagen, P1NP) were measured in a cohort of 3198 women aged 50-62 years (n=1170 current HRT users, n=1018 never used HRT). Dietary Si, bioavailable Si and dietary confounders were estimated by food frequency questionnaire.

RESULTS

Mean FN BMD was 2% lower (p<0.005) in the lowest quartile (Q1) compared to the top quartile of energy-adjusted Si intake (Q4) (mean (SD) Q1, 16 (4.0) mg/d; Q4, 31.5 (7.3) mg/d). Energy-adjusted Si intake was associated with FN BMD for oestrogen-replete women only (late premenopausal women (r=+0.21, p=0.03); women on HRT [r=+0.09, p<0.001]). There was an interaction between oestrogen status and quartile of energy-adjusted Si intake on FN BMD, which was significant after adjustment for confounders (F=3.3, p=0.020), and stronger for bioavailable Si (F=5.0. p=0.002). Quartile of energy-adjusted dietary Si intake was negatively associated with fDPD/Cr and fPYD/Cr (p<0.001) and positively with P1NP (p<0.05).

CONCLUSIONS

This study suggests that oestrogen status is important for Si metabolism in bone health. Further work is required to elucidate the mechanism.

Subtleties of biomineralisation revealed by manipulation of the eggshell membrane

Biocalcification of collagen matrices with calcium phosphate and biosilicification of diatom frustules with amorphous silica are two discrete processes that have intrigued biologists and materials scientists for decades. Recent advancements in the understanding of the mechanisms involved in these two biomineralisation processes have resulted in the use of biomimetic strategies to replicate these processes separately using polyanionic, polycationic or zwitterionic analogues of extracellular matrix proteins to stabilise amorphous mineral precursor phases. To date, there is a lack of a universal model that enables the subtleties of these two apparently dissimilar biomineralisation processes to be studied together. Here, we utilise the eggshell membrane as a universal model for differential biomimetic calcification and silicification. By manipulating the eggshell membrane to render it permeable to stabilised mineral precursors, it is possible to introduce nanostructured calcium phosphate or silica into eggshell membrane fibre cores or mantles. We provide a model for infiltrating the two compartmental niches of a biopolymer membrane with different intrafibre minerals to obtain materials with potentially improved structure-property relationships.

Biosilica-based strategies for treatment of osteoporosis and other bone diseases

Osteoporosis is a common disease in later life, which has become a growing public health problem. This degenerative bone disease primarily affects postmenopausal women, but also men may suffer from reduced bone mineral density. The development of prophylactic treatments and medications of osteoporosis has become an urgent issue due to the increasing proportion of the elderly in the population. Apart from medical/hormonal treatments, current strategies for prophylaxis of osteoporosis are primarily based on calcium supplementation as a main constituent of bone hydroxyapatite mineral. Despite previous reports suggesting an essential role in skeletal growth and development, the significance of the trace element silicon in human bone formation has attracted major scientific interest only rather recently. The interest in silicon has been further increased by the latest discoveries in the field of biosilicification, the formation of the inorganic silica skeleton of the oldest still extant animals on Earth, the sponges, which revealed new insights in the biological function of this element. Sponges make use of silicon to build up their inorganic skeleton which consists of biogenously formed polymeric silica (biosilica). The formation of biosilica is mediated by specific enzymes, silicateins, which have been isolated, characterized, and expressed in a recombinant way. Epidemiological studies revealed that dietary silicon reduces the risk of osteoporosis and other bone diseases. Recent results allowed for the first time to understand the molecular mechanism underlying the protective effect of silicic acid/biosilica against osteoporosis. Biosilica was shown to modulate the ratio of expression of two cytokines involved in bone formation-RANKL and osteoprotegerin. Hence, biosilica has been proposed to have a potential in prophylaxis and therapy of osteoporosis and related bone diseases.

Dietary silicon intake in Belgium: Sources, availability from foods, and human serum levels

The dietary intake of silicon by using the duplicate portion sampling technique of 24 hour-meals during 7 consecutive days is estimated.Since plant-based foods are major sources of silicon the elemental content is determined in various vegetarian foodstuffs commercially available in Belgium.Mean silicon intake from the 24-hour duplicate meals consumed daily by nearly 2000 persons was 18.6 +/- 8.5 mg/day. The major food sources were unrefined grains of high fibre content, cereal products and root vegetables. For vegetarian foods rice and barley revealed high silicon levels. Very high serum concentrations in newborns and concomittant low levels in the mothers indicated a homeostatic mechanism in humans. Besides the dietary intake, serum silicon levels of various population groups support the concept of essentiality of the element. An in vitro dialysability of the element in a simulated digestion procedure is used as a surrogate of silicon uptake.Silicon was readily available from foods but this correlated inversely with the elemental content.Serum silicon levels, as a function of age, gave indication of an important role of this element. In vitro availability study proved an inverse relation with the elemental content. A preliminary in vivo experiment confirmed that bioavailability is not only determined by concentration, but especially by the type of food and species under which silicon is present.

Silicon supplementation improves the bone mineral density of calcium-deficient ovariectomized rats by reducing bone resorption

The purpose of this study was to investigate the effect of silicon (Si) supplementation on bone mineral density (BMD) and bone metabolism parameters relative to calcium (Ca) intake levels in ovariectomized rats. A total of 72 female Wistar rats (6 weeks) were ovariectomized (OVX) and divided into six groups, and Si (500 mg of Si per kilogram of feed) was or was not administered with diets containing various levels of Ca (0.1%, 0.5%, and 1.5%) for 10 weeks. The groups were as follows: (1) Ca-deficient group (0.1% Ca), (2) Ca-deficient with Si supplementation group, (3) adequate Ca group (0.5% Ca), (4) adequate Ca with Si supplementation group, (5) high Ca group (1.5% Ca), and (6) high Ca with Si supplementation group. Si supplementation significantly increased the BMD of the femur and tibia in Ca-deficient OVX rats, while no change was observed with Si supplementation in the BMD of the spine, femur, and tibia in the adequate and high Ca groups. Serum alkaline phosphatase and osteocalcin levels were not affected by Si supplementation or Ca intake levels. C-telopeptide type I collagen levels were significantly decreased as a result of Si supplementation in Ca-deficient OVX rats. In summary, Si supplementation produced positive effects on bone mineral density in Ca-deficient OVX rats by reducing bone resorption. Therefore, Si supplementation may also prove to be helpful in preventing osteoporosis in postmenopausal women whose calcium intake is insufficient.

Increased longitudinal growth in rats on a silicon-depleted diet

Silicon-deficiency studies in growing animals in the early 1970s reported stunted growth and profound defects in bone and other connective tissues. However, more recent attempts to replicate these findings have found mild alterations in bone metabolism without any adverse health effects. Thus the biological role of silicon remains unknown. Using a specifically formulated silicon-depleted diet and modern methods for silicon analysis and assessment of skeletal development, we undertook, through international collaboration between silicon researchers, an extensive study of long-term silicon depletion on skeletal development in an animal. 21-day old female Sprague-Dawley rats (n=20) were fed a silicon-depleted diet (3.2 microg Si/g feed) for 26 weeks and their growth and skeletal development were compared with identical rats (n=10) on the same diet but with silicon added as Si(OH)(4) to their drinking water (53.2 microg Si/g water); total silicon intakes were 24 times different. A third group of rats, receiving a standard rodent stock feed (322 microg Si/g feed) and tap water (5 microg Si/g water), served as a reference group for optimal growth. A series of anthropometric and bone quality measures were undertaken during and following the study. Fasting serum silicon concentrations and especially urinary silicon excretion were significantly lower in the silicon-deprived group compared to the supplemented group (P=0.03 and 0.004, respectively). Tibia and soft-tissue silicon contents did not differ between the two groups, but tibia silicon levels were significantly lower compared to the reference group (P<0.0001). Outward adverse health effects were not observed in the silicon-deprived group. However, body lengths from week 18 onwards (P<0.05) and bone lengths at necropsy (P Collapse

Key Words

• bone growth
• sprague–dawley rats
• silicon deficiency
• orthosilicic acid supplementation
• bone and soft-tissue silicon concentrations
• tibia calcium and phosphorus

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MESH Headings

• Animal Feed
• Animals
• Body Weight
• Bone Density/drug effects
• Bone Development
• Bone Remodeling
• Bone and Bones/drug effects
• Bone and Bones/metabolism
• Bone and Bones/pathology
• Chondrocytes/drug effects
• Female
• Rats
• Rats, Sprague-Dawley
• Silicon/deficiency
• Silicon/metabolism
• Tetracycline/pharmacology
• Tibia/pathology
• Tomography, X-Ray Computed/methods

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Grants

• Wellcome Trust
• MC_U105960399 Medical Research Council

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Affiliation(s)

Ravin Jugdaohsingh MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK.
Mario R Calomme
Karen Robinson
Forrest Nielsen
Simon H C Anderson
Patrick D'Haese
Piet Geusens
Nigel Loveridge
Richard P H Thompson
Jonathan J Powell

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Short-term administration of water-soluble silicon improves mineral density of the femur and tibia in ovariectomized rats

Silicon is important for the proper growth and development of bone and connective tissues. This study was designed to investigate if water-soluble silicon could be used for the treatment of postmenopausal osteoporosis. Silicon (Si 20 mg/kg body weight/day) was administrated orally to 17-week-old ovariectomized (OVX) rats for 4 weeks. Silicon did not alter weight gain in OVX rats. Silicon supplementation significantly increased the bone mineral density of the femur (p < 0.05, vs. OVX control group) and tibia in OVX rats (p < 0.05, vs. OVX control group). Serum alkaline phosphatase and osteocalcin, two bone formation biomarkers tested, were not significantly altered, but urinary calcium and phosphorous excretion tended to decrease with silicon supplementation. OVX rats with silicon supplementation showed a relatively higher serum CTx compared to the nonsupplemented OVX group (p < 0.01, vs. OVX control group). According to these results, short-term soluble silicon supplementation improved bone mineral density in OVX-induced osteoporosis.

Trace element loss in urine and effluent following traumatic injury

BACKGROUND

Few data are available to establish recommendations for trace element supplementation during critical illness. This study quantified the loss of several elements and assessed the adequacy of manganese and selenium in parenteral nutrition (PN).

METHODS

Men with traumatic injuries were grouped by renal status: adequate (POLY; n = 6), acute failure with continuous venovenous hemofiltration (CVVH; n = 2), or continuous venovenous hemodiafiltration (CVVHD; n = 4). PN supplied 300 microg/d manganese and 60 microg/d selenium. Urine and effluent (from artificial kidneys) were collected for 3 days and analyzed for boron, manganese, nickel, and silicon using inductively coupled plasma atomic emission spectrometry, and for selenium using atomic absorption spectrometry.

RESULTS

POLY manganese and selenium excretion averaged (standard deviation [SD]) 7.9 (3.3) microg/d and 103.5 (22.4) microg/d, respectively. All elements except selenium were detected in dialysate (prior to use). CVVHD effluent contained 3.5 and 7.3 times more manganese and nickel than CVVH ultrafiltrate, respectively. Loss of manganese averaged 2.6%, 21%, and 73% of PN amounts for POLY, CVVH, and CVVHD groups, respectively.

DISCUSSION

Minimal loss of manganese compared with the amount in PN suggests that excessive amounts are retained. POLY patients excreted more selenium than was in PN, indicating negative balance. POLY losses of boron and silicon were less than that published for healthy adults, reflecting less than typical intake, whereas loss during CVVH was in the normal reference range, possibly because of added intake from boron contamination of replacement fluids. All patients lost more nickel than amounts published for healthy adults.

CONCLUSIONS

Current guidelines of 60-100 microg/d of parenteral manganese may be excessive for trauma patients. The uptake of manganese and nickel from contaminants in CVVHD dialysate should be investigated.

Choline-stabilized orthosilicic acid supplementation as an adjunct to calcium/vitamin D3 stimulates markers of bone formation in osteopenic females: a randomized, placebo-controlled trial

Background

Mounting evidence supports a physiological role for silicon (Si) as orthosilicic acid (OSA, Si(OH)₄) in bone formation. The effect of oral choline-stabilized orthosilicic acid (ch-OSA) on markers of bone turnover and bone mineral density (BMD) was investigated in a double-blind placebo-controlled trial.

Methods

Over 12-months, 136 women out of 184 randomized (T-score spine < -1.5) completed the study and received, daily, 1000 mg Ca and 20 μg cholecalciferol (Vit D3) and three different ch-OSA doses (3, 6 and 12 mg Si) or placebo. Bone formation markers in serum and urinary resorption markers were measured at baseline, and after 6 and 12 months. Femoral and lumbar BMD were measured at baseline and after 12 months by DEXA.

Results

Overall, there was a trend for ch-OSA to confer some additional benefit to Ca and Vit D3 treatment, especially for markers of bone formation, but only the marker for type I collagen formation (PINP) was significant at 12 months for the 6 and 12 mg Si dose (vs. placebo) without a clear dose response effect. A trend for a dose-corresponding increase was observed in the bone resorption marker, collagen type I C-terminal telopeptide (CTX-I).

Lumbar spine BMD did not change significantly. Post-hoc subgroup analysis (baseline T-score femur < -1) however was significant for the 6 mg dose at the femoral neck (T-test). There were no ch-OSA related adverse events observed and biochemical safety parameters remained within the normal range.

Conclusion

Combined therapy of ch-OSA and Ca/Vit D3 had a potential beneficial effect on bone collagen compared to Ca/Vit D3 alone which suggests that this treatment is of potential use in osteoporosis. NTR 1029