The silicon content of beer and its bioavailability in healthy volunteers

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

Effect of moderate beer consumption (with and without ethanol) on osteoporosis in early postmenopausal women: Results of a pilot parallel clinical trial

Introduction

Osteoporosis is a chronic progressive bone disease characterized by low bone mineral density (BMD) and micro-architectural deterioration of bone tissue, leading to an increase in bone fragility and the risk of fractures. A well-known risk factor for bone loss is postmenopausal status. Beer may have a protective effect against osteoporosis associated with its content of silicon, polyphenols, iso-α-acids and ethanol, and its moderate consumption may therefore help to reduce bone loss in postmenopausal women.

Methods

Accordingly, a 2-year controlled clinical intervention study was conducted to evaluate if a moderate daily intake of beer with (AB) or without alcohol (NAB) could have beneficial effects on bone tissue. A total of 31 postmenopausal women were assigned to three study groups: 15 were administered AB (330 mL/day) and six, NAB (660 mL/day), whereas, the 10 in the control group refrained from consuming alcohol, NAB, and hop-related products. At baseline and subsequent assessment visits, samples of plasma and urine were taken to analyze biochemical parameters, and data on medical history, diet, and exercise were collected. BMD and the trabecular bone score (TBS) were determined by dual-energy X-ray absorptiometry. Markers of bone formation (bone alkaline phosphatase [BAP] and N-propeptide of type I collagen [PINP]) and bone resorption (N-telopeptide of type I collagen [NTX] and C-telopeptide of type I collagen [CTX]) were determined annually.

Results

Bone formation markers had increased in the AB and NAB groups compared to the control after the 2-year intervention. However, the evolution of BMD and TBS did not differ among the three groups throughout the study period.

Discussion

Therefore, according to the findings of this pilot study, moderate beer intake does not seem to have a protective effect against bone loss in early post-menopausal women.

Modifications on porous absorbable Fe-based scaffolds for bone applications: A review from corrosion and biocompatibility viewpoints

Iron (Fe) and Fe-based scaffolds have become a research frontier in absorbable materials which is inherent to their promising mechanical properties including fatigue strength and ductility. Nevertheless, their slow corrosion rate and low biocompatibility have been their major obstacles to be applied in clinical applications. Over the last decade, various modifications on porous Fe-based scaffolds have been performed to ameliorate both properties encompassing surface coating, microstructural alteration via alloying, and advanced topologically order structural design produced by additive manufacturing (AM) techniques. The recent advent of AM produces topologically ordered porous Fe-based structures with an optimized architecture having controllable pore size and strut thickness, intricate internal design, and larger exposed surface area. This undoubtedly opens up new options for controlling Fe corrosion and its structural strengths. However, the in vitro biocompatibility of the AM porous Fe still needs to be addressed considering its higher corrosion rate due to the larger exposed surface area. This review summarizes the latest progress of the modifications on porous Fe-based scaffolds with a specific focus on their responses on the corrosion behavior and biocompatibility.

Canine Silica Urolithiasis in Mexico, Associated with the Concentration of Dissolved Silica in Tap Water

Silica urolithiasis is infrequent in dogs, but in Mexico represents 12.9%. Our hypothesis is the consumption of high amounts of silicates in the diet, especially that dissolved in tap water. The objective of this study was to determine the concentrations of silica in the tap water in different geographical areas and their relationship with cases of silicate urolithiasis in dogs. From 179 cases of silicate urolithiasis, 98.9% were from dogs within a geographic area called the Trans-Mexican Volcanic Belt, which represents a cross shaft to the center of the country. Silica concentrations in tap water ranged between 3 and 76 mg/L, with a range of 27 to 76 mg/L, a mean of 49.9 ± 12 mg/L within the Trans-Mexican Volcanic Belt, and a concentration from 3 to 30 mg/L, with a mean of 16.4 ± 7 mg/L outside this area; these were significantly different (p < 0.001). These findings demonstrate that there is a geographic risk factor for silicate urolithiasis in urolith-forming dogs, related to the consumption of tap water with a high concentration of silica. Further studies are necessary to identify this same pathophysiological association in other species.

A toxicological evaluation of monomethylsilanetriol (MMST) stabilized in acacia gum, a novel silicon preparation

Monomethylsilanetriol (MMST), a silicon-containing compound, has been sold in dietary supplements. However, toxicological studies on its safety profile are not readily available. To assess the safety of MMST stabilized in acacia gum, a novel delivery form of MMST, in accordance with internationally accepted standards, the genotoxic potential and repeated-dose oral toxicity of Living Silica® Acacia Gum Stabilized Monomethylsilanetriol (formerly known as Orgono Acacia Gum Powder®), a food grade product consisting of 80 ± 10% acacia gum and 2.8% (SD ± 10%) elemental silicon from MMST, was investigated. A bacterial reverse mutation test, an in vitro mammalian chromosomal aberration test, an in vivo mammalian micronucleus test, and a 90-day repeated-dose oral toxicity study in rats were performed. No evidence of mutagenicity or genotoxic activity was observed under the applied test systems. In the 90-day study, male and female Hsd.Han Wistar rats were administered daily doses of 0, 500, 1000, and 2000 mg/kg bw/day by gavage. No mortality or treatment-related adverse effects were observed, and no target organs were identified. Therefore, the no observed adverse effects level (NOAEL) was determined as 2000 mg/kg bw/day (201 mg MMST/kg bw/day), the highest dose tested.

Sources, Bioavailability, and Safety of Silicon Derived from Foods and Other Sources Added for Nutritional Purposes in Food Supplements and Functional Foods

Silicon is a microelement that performs a number of important functions in the human body, being involved in the formation and maintenance of normal osteocartilaginous connective tissue, such as skin, hair, and nails, and having beneficial effects in the prevention of cardiovascular and neurodegenerative diseases. Natural sources of silicon include fruits, vegetables, cereals, and mineral water. European and North American diets are generally low in silicon, which correlates with a diet high in processed foods. Dietary silicon deficiency can be overcome by the consumption of high bioavailability silicon-rich foods and the use of silicon supplements. A good form of supplementation is orthosilicic acid (OSA), usually stabilized by the introduction of a methyl group, choline, or vanillin. OSA is naturally found in diatomaceous earth in the form of amorphous silica and extracts from silicon-rich plants, e.g., horsetail (Eguiseti herba L.) and nettles (Urtica dioica L.). This article presents the characteristics of the various sources of silicon and their bioavailability and safety of use, with particular reference to the sources used in functional foods and dietary supplements. There is a great need to produce functional foods containing dietary silicon, together with other scarce mineral components.

Urinary Excretion of Silicon in Men, Non-pregnant Women, and Pregnant Women: a Cross-sectional Study

Silicon is a trace element found mainly in plant-based food and proposed to be beneficial for bone health. Urinary excretion of Si has been shown to be a surrogate measure of its uptake in the gastrointestinal tract. The objective of this study was to describe and compare the levels of urinary Si excretion, and consequently Si uptake, in Swedish men, non-pregnant women, and pregnant women. No formal assessment of dietary Si intake was carried out in this study. This cross-sectional study included 89 men, 42 non-pregnant women, and 60 pregnant women. The subjects collected urine over a 24-h period and the samples were assayed for total Si using inductively coupled plasma optical emission spectrometry. The excretion levels of creatinine were used to validate the completeness of the urine sample collections. The mean 24-h urinary excretions of Si were 7.8 mg for the cohort of young men, 7.6 mg for the cohort of non-pregnant women, and 12.4 mg for the cohort of pregnant women. Creatinine excretion was similar between pregnant and non-pregnant women (10.4 vs. 10.8 mmol/day) and significantly higher in men (15.4 mmol/day). The pregnant women excreted significantly higher levels of Si than the young men and non-pregnant women, respectively (p < 0.05). The higher urinary excretion of Si by pregnant women compared with men and non-pregnant women is a novel finding possibly caused by temporary physiological changes during pregnancy such as increased gastrointestinal uptake of Si, altered bone metabolism, and increased renal excretion of Si.

Targeted healthy compounds in small and large-scale brewed beers

The determination of targeted healthy compounds in the most popular small and large-scale brewed beer sold in Italy was carried out. Nitrogen compounds, fermentable sugars, total phenolic content and antioxidant capacity, β-glucans, pyridoxine, folates and silicon were quantified. Further, amine content was determined since raw materials and brewing technology can affect their level. Significantly higher values for total phenolic content, antioxidant activity, nitrogen, folate and putrescine content were found for small scale beers. However, the statistical results were affected by the different beer styles in the small scale and large scale brewed beer groups, since the content of these components can vary between beer styles. Positive Pearson correlation was found between total phenolic content and EBC colour. Wide variations in pyridoxine, β-glucans and fermentable sugars levels were observed both for small and large scale beers, while average silicon content of two groups was similar.

Beer and its non-alcoholic compounds in health and disease

Moderate alcohol consumption has been associated with beneficial effects on human health. Specifically, consumption of red wine and beer has shown a J-shape relation with many important diseases. While a role of ethanol cannot be excluded, the high content of polyphenols in both beverages has been proposed to contribute to these effects, with beer having the advantage over wine that it is lower in alcohol. In addition to ethanol, beer contains a wide variety of compounds with known medicinal potential such as kaempferol, quercetin, tyrosol and phenolic acids, and it is the main dietary source for the flavones xanthohumol and 8-prenylnaringenin, and bitter acids such as humulones and lupulones. Clinical and pre-clinical evidence for the protective effects of moderate beer consumption against cardiovascular disease and other diseases has been accumulating since the 1990s, and the non-alcoholic compounds of beer likely exert most of the observed beneficial effects. In this review, we summarize and discuss the effects of beer consumption in health and disease as well as the clinical potential of its non-alcoholic compounds which may be promising candidates for new therapies against common chronic diseases.

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.

Alcohol intake, specific alcoholic beverages, and risk of hip fractures in postmenopausal women and men age 50 and older

BACKGROUND

Although a number of studies have examined the association between alcohol intake and hip fractures, few have considered specific alcoholic beverages separately.

OBJECTIVES

We prospectively assessed total alcohol and specific alcoholic beverage consumption and risk of hip fractures in US men and women.

METHODS

Health, lifestyle information, and hip fractures were self-reported on biennial questionnaires between 1980 and 2014 in 75,180 postmenopausal women from the Nurses' Health Study, and between 1986 and 2014 in 38,398 men aged ≥50 y from the Health Professionals Follow-Up Study. Diet was assessed approximately every 4 y with a semiquantitative FFQ. RRs were computed for hip fracture using Cox proportional hazards models, adjusting for potential confounders.

RESULTS

We ascertained 2360 incident low trauma hip fractures in women and 709 in men. Among women, RRs for low trauma hip fractures compared with nondrinkers were 0.89 (95% CI: 0.80, 0.99) for an average daily consumption of <5.0 g, 0.81 (95% CI: 0.70, 0.94) for 5.0 to <10.0 g, 0.83 (95% CI: 0.71, 0.96) for 10.0 to <20.0 g, and 0.93 (95% CI: 0.78, 1.10) for ≥20.0 g. Among men, risk declined linearly with higher alcohol consumption (P-trend = 0.002). Multivariable RR compared with nondrinkers was 0.77 (95% CI: 0.59, 1.01), 0.69 (0.49, 0.96), and 0.67 (0.48, 0.95) for an average intake of 10 g/d to <20 g/d, 20 g/d to <30 g/d, and 30.0 g/d or more, respectively. In women, the alcoholic beverage most significantly associated with hip fracture risk was red wine (RR per serving = 0.59; 95% CI: 0.45, 0.79). In men, there was no clear association with specific alcoholic beverages.

CONCLUSION

In these 2 US cohorts, low to moderate alcohol consumption, when compared with no consumption, was associated with a lower risk of hip fractures, particularly with red wine consumption among women.

The Nutritional Components of Beer and Its Relationship with Neurodegeneration and Alzheimer's Disease

The prevalence of degenerative diseases has risen in western countries. Growing evidence suggests that demenia and other cognition affectations are associated with ambient factors including specific nutrients, food ingredients or specific dietary patterns. Mediterranean diet adherence has been associated with various health benefits and decreased risk of many diseases, including neurodegenerative disorders. Beer, as part of this protective diet, contains compounds such as silicon and hops that could play a major role in preventing brain disorders. In this review, different topics regarding Mediterranean diet, beer and the consumption of their main compounds and their relation to neurological health have been addressed. Taking into account published results from our group and other studies, the hypothesis linking aluminum intoxication with dementia and/or Alzheimer’s disease and the potential role of regular beer has also been considered. Beer, in spite of its alcohol content, may have some health benefits; nonetheless, its consumption is not adequate for all subjects. Thus, this review analyzed some promising results of non-alcoholic beer on several mechanisms engaged in neurodegeneration such as inflammation, oxidation, and cholinesterase activity, and their contribution to the behavioral modifications induced by aluminum intoxication. The review ends by giving conclusions and suggesting future topics of research related to moderate beer consumption and/or the consumption of its major compounds as a potential instrument for protecting against neurodegenerative disease progression and the need to develop nutrigenetic and nutrigenomic studies in aged people and animal models.

Formation of organosilica nanoparticles with dual functional groups and simultaneous payload entrapment

A mixed organosilane system for simultaneous formation of organosilica nanoparticles has been systematically studied for loading of various compounds with a wide range of log P values. The molecule-entrapping system was understood by investigating the effects of adjusting various experimental parameters on particle formation and molecule entrapment. Particularly, rhodamine 6 G (R6G) loaded colloidal particles were prepared and characterised in detail. The results show that whereas most molecules had entrapment efficiency (EE%) in the range of 20-80%, R6G exhibited near 100% efficiency. Moreover, the colloidal system can be tuned to incorporate R6G with the extent of entrapment spanning at least 2 orders of magnitude (i.e. from 0.04 to 4 mg) and a maximum EE% of 98%. In conclusion, the study demonstrates the promise of the proposed mixed organosilane system in forming colloidal particles containing multiple functional groups with selective loading of highly hydrophobic molecules.

Association between alcohol consumption and bone mineral density in elderly Korean men and women

In this cross-sectional study based on Korean elderly men and women, heavy alcohol intake for men was related to low whole-body BMD and light alcohol intake for women was associated with high whole-body, lumbar, and total femur BMD.

PURPOSE

Alcohol is a risk factor of osteoporosis but previous studies on its effect on bone health has been controversial. The aim of this study was to evaluate the association between alcohol intake and bone mineral density in Korean elderly men and women.

METHODS

Based on the Fourth and Fifth Korean National Health and Nutrition Examination Surveys (KNHANES), 2657 men and 2080 women 50 to 79 years of age were included. Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry (DXA). Alcohol consumption was determined by self-administered questionnaires and classified into four groups according to sex: non-drinkers (0 g/day), light drinking (1-19 g/day men, 1-9 g/day women), moderate drinking (20-39 g/day men, 10-29 g/day women), and heavy drinking (≥ 40 g/day men, ≥ 20 g/day women). The adjusted mean values calculated by linear regression analysis for BMD were determined according to the amount of alcohol consumed.

RESULTS

Light drinkers had the highest whole-body BMD for both men (mean 1.164, SD 0.047-1.281) and women (mean 1.046, SD 0.912-1.180). Among men, mean whole-body BMD for heavy drinkers was significantly lower than that among light drinkers (P = 0.031). Among women, BMD for light drinkers was significantly higher in the whole body, lumbar, and total femur than that for non-drinkers (P < 0.001, P = 0.026, P = 0.040, respectively).

CONCLUSIONS

Heavy alcohol intake may be associated with lower BMD in men while light alcohol intake may associate with higher BMD among women. Future longitudinal studies investigating the effect of alcohol consumption on bone mineral density are needed to validate the findings of this study.

Silicic Acid and Beer Consumption Reverses the Metal Imbalance and the Prooxidant Status Induced by Aluminum Nitrate in Mouse Brain

BACKGROUND

Emerging evidence suggests that by affecting mineral balance, aluminum (Al) may enhance some events associated with neurodegenerative diseases.

AIM

To examine the effect of Al(NO3)3 exposure on brain Al, cooper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), silicon (Si), and zinc (Zn) levels, and the metal-change implication in brain oxidant and inflammatory status.

METHODS

Four groups of six-week-old male NMRI mice were treated for three months: i) controls, administrated with deionized water; ii) Al, which received Al(NO3)3; iii) Al+silicic acid, which were given Al(NO3)3 plus silicic acid; and iv) Al+beer, which received Al(NO3)3 plus beer.

RESULTS

Brain Al and TBARS levels and TNFα and GPx expressions increased, while Cu, Mn, and Zn levels, and catalase and CuZn-SOD expression decreased (at least, p < 0.05) in Al versus control animals. Al, Si, and TBARS levels and TNFα expression decreased (p < 0.05) in Al+silicic acid and Al+beer specimens while Cu, Mn, and Zn levels and antioxidant expression increased versus the Al group. Brain Al levels correlated negatively with those of Cu, Fe, Mn, and Zn, and catalase, CuZn-SOD, and GPx enzyme expressions but positively with Si and TBARS levels and TNFα expression. Two components of the principal component analysis (PCA) explained 71.2% of total data variance (p < 0.001). PCA connected the pro-oxidant markers with brain Al content, while brain Zn and Cu levels were closer to antioxidant enzyme expression.

CONCLUSION

Administration of Al(NO3)3 induced metal imbalance, inflammation, and antioxidant status impairment in the brain. Those effects were blocked to a significant extent by silicic acid and beer administration.

Safety of orthosilicic acid-vanillin complex (OSA-VC) as a novel food ingredient to be used in food supplements as a source of silicon and bioavailability of silicon from the source

The present scientific opinion deals with the safety of orthosilicic acid-vanillin complex (OSA-VC) as a novel food ingredient for use as a source of silicon (Si) in food supplements and with the bioavailability of Si from this source. OSA-VC is stable in liquid solution at low pH values. OSA from OSA-VC was available as revealed by the increase in plasma Si concentrations after oral ingestion in human volunteers. The toxicological data provided in support of the current application were not in accordance with the Tier 1 requirement of the 'Guidance for submission for food additive evaluations'; however, this was considered justified by the Panel given that OSA-VC at pH 6.8 dissociates into orthosilicic acid and vanillin. The daily consumption of OSA-VC at the dose recommended by the applicant would provide a supplemental intake of Si of approximately 10-18 mg Si/day which would result in an estimated total intake of roughly 30-70 mg Si/day. The maximum vanillin intake resulting from the consumption of OSA-VC would be less than 5% of the acceptable daily intake (ADI) value for vanillin of 10 mg/kg body weight (bw) per day established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 2002. The Panel concluded that there would be no safety concern with the proposed use and use level of OSA-VC as a novel food ingredient intended to be used as a source of Si in food supplements for the adult population. The Panel concluded that OSA, measured as Si, is bioavailable following ingestion of OSA-VC and appears similar to values reported in the literature for other established sources of OSA.

Use of silicon for skin and hair care: an approach of chemical forms available and efficacy

Silicon is the second most abundant element on Earth, and the third most abundant trace element in human body. It is present in water, plant and animal sources. On the skin, it is suggested that silicon is important for optimal collagen synthesis and activation of hydroxylating enzymes, improving skin strength and elasticity. Regarding hair benefits, it was suggested that a higher silicon content in the hair results in a lower rate of hair loss and increased brightness. For these beneficial effects, there is growing interest in scientific studies evaluating the efficacy and safety of using dietary supplements containing silicon. Its use aims at increasing blood levels of this element and improving the skin and its annexes appearance. There are different forms of silicon supplements available and the most important consideration to be made in order to select the best option is related to safety and bioavailability. Silicon supplements are widely used, though there is wide variation in silicon bioavailability, ranging from values below 1% up to values close to 50%, depending on the chemical form. Therefore, the aim of this study was to evaluate the scientific literature related to the different chemical forms of silicon supplements available and the limitations and recent progress in this field. According to reported studies, among the different chemical forms available, the orthosilicic acid (OSA) presents the higher bioavailability, whereas the others forms have absorption inversely proportional to the degree of polymerization. However, clinical studies evaluating safety and efficacy are still lacking.

Silicon as Versatile Player in Plant and Human Biology: Overlooked and Poorly Understood

Silicon (Si) serves as bioactive beneficial element. Si is highly abundant in soil, and occurs ubiquitously in all organisms including plants and humans. During the last three decades, nutritional significance of Si for plant and human health has received increasing attention. Plant Si plays a pivotal role in growth and development, and this beneficial effect depends usually on accumulation in plant tissues, which are then protected from various forms of biotic and abiotic stresses. Likewise, human exposure to Si imparts health benefits and essentially occurs through plant-derived food products. Si bioavailability in human diet, e.g., strengthens bones and improves immune response, as well as neuronal and connective tissue health. Despite this empiric knowledge, the essentiality of Si still remains enigmatic. Thus the link between Si availability for plant development and its profound implication for human welfare should receive attention. This review aims to provide a broad perspective on Si as important element for plant and human nutrition and to define research fields for interdisciplinary research.

Dietary Approaches for Bone Health: Lessons from the Framingham Osteoporosis Study

Osteoporosis is characterized by systemic impairment of bone mass, strength, and microarchitecture, resulting in increased risk for fragility fracture, disability, loss of independence, and even death. Adequate nutrition is important in achieving and maintaining optimal bone mass, as well as preventing this debilitating disease. It is widely accepted that adequate calcium and vitamin D intake are necessary for good bone health; however, nutritional benefits to bone go beyond these two nutrients. This review article will provide updated information on all nutrients and foods now understood to alter bone health. Specifically, this paper will focus on related research from the Framingham Osteoporosis Study, an ancillary study of the Framingham Heart Study, with data on more than 5000 adult men and women.

Digestive absorption of silicon, supplemented as orthosilicic acid-vanillin complex

SCOPE

Silicon (Si) is an abundant element on earth. It is found naturally in water in the form of orthosilicic acid (OSA), however this form is not stable under certain conditions such as in highly concentrated and non-neutral pH solutions, which lead to its polymerization and reduced bioavailability. This study aimed to assess the bioavailability of Si from OSA stabilized by vanillin (OSA-VC).

METHODS AND RESULTS

This was a single-center, double-blind, cross-over randomized controlled trial. Fourteen healthy subjects were recruited and consumed either OSA-VC or a placebo on two separate occasions. Blood and urine samples were collected during 6 h following ingestion and analyzed to determine Si absorption and excretion. Plasma Si area under the curve (0-6 h) was significantly higher after OSA-VC ingestion compared to placebo ingestion (p = 0.0002). Significantly higher urinary Si excretion was also reported over the 6-h period after OSA-VC ingestion compared to placebo (p<0.0001). Approximately 21% of ingested Si was excreted in urine during this period.

CONCLUSION

Although many studies have investigated the metabolism and bioavailability of Si supplemented in foods or as a food ingredient, this was the first to investigate and demonstrate the digestibility of OSA administered in a complex form with vanillin.

The decrease in silicon concentration of the connective tissues with age in rats is a marker of connective tissue turnover

Silicon may be important for bone and connective tissue health. Higher concentrations of silicon are suggested to be associated with bone and the connective tissues, compared with the non-connective soft tissues. Moreover, in connective tissues it has been suggested that silicon levels may decrease with age based upon analyses of human aorta. These claims, however, have not been tested under controlled conditions. Here connective and non-connective tissues were collected and analysed for silicon levels from female Sprague-Dawley rats of different ages (namely, 3, 5, 8, 12, 26 and 43 weeks; n=8-10 per age group), all maintained on the same feed source and drinking water, and kept in the same environment from weaning to adulthood. Tissues (696 samples) were digested in nitric acid and analysed by inductively coupled plasma optical emission spectrometry for total silicon content. Fasting serum samples were also collected, diluted and analysed for silicon. Higher concentrations of silicon (up to 50-fold) were found associated with bone and the connective tissues compared with the non-connective tissues. Although total silicon content increased with age in all tissues, the highest connective tissue silicon concentrations (up to 9.98 μg/g wet weight) were found in young weanling rats, decreasing thereafter with age (by 2-6 fold). Fasting serum silicon concentrations reflected the pattern of connective tissue silicon concentrations and, both measures, when compared to collagen data from a prior experiment in Sprague-Dawley rats, mirrored type I collagen turnover with age. Our findings confirm the link between silicon and connective tissues and would imply that young growing rats have proportionally higher requirements for dietary silicon than mature adults, for bone and connective tissue development, although this was not formally investigated here. However, estimation of total body silicon content suggested that actual Si requirements may be substantially lower than previously estimated which could explain why absolute silicon deficiency is difficult to achieve but, when it is achieved in young growing animals, it results in stunted growth and abnormal development of bone and other connective tissues.

Silicon: the evolution of its use in biomaterials

In the 1970s, several studies revealed the requirement for silicon in bone development, while bioactive silicate glasses simultaneously pioneered the current era of bioactive materials. Considerable research has subsequently focused on the chemistry and biological function of silicon in bone, demonstrating that the element has at least two separate effects in the extracellular matrix: (i) interacting with glycosaminoglycans and proteoglycans during their synthesis, and (ii) forming ionic substitutions in the crystal lattice structure of hydroxyapatite. In addition, the dissolution products of bioactive glass (predominantly silicic acids) have significant effects on the molecular biology of osteoblasts in vitro, regulating the expression of several genes including key osteoblastic markers, cell cycle regulators and extracellular matrix proteins. Researchers have sought to capitalize on these effects and have generated a diverse array of biomaterials, which include bioactive glasses, silicon-substituted hydroxyapatites and pure, porosified silicon, but all these materials share similarities in the mechanisms that result in their bioactivity. This review discusses the current data obtained from original research in biochemistry and biomaterials science supporting the role of silicon in bone, comparing both the biological function of the element and analysing the evolution of silicon-containing biomaterials.

Silicon balance in human volunteers; a pilot study to establish the variance in silicon excretion versus intake

Background

Accumulating evidence suggests a role for silicon in optimal connective tissue health. Further proof of its importance/essentiality may be provided by studies involving imposed depletion followed by ²⁹Si challenge to estimate metabolic balance. Prior to conducting these expensive studies, we first established the variance of estimating normal Si excretion versus intake using a single oral dose of typical dietary Si, orthosilicic acid.

Methods

Healthy volunteers were recruited from Loei Rajabhat University, separated into two matched groups (three males and three females/group) and maintained on a standardized diet for the three study days. One group ingested 500 ml water containing orthosilicic acid (28.9 mg Si) and the other group received 500 ml water alone, all on a fasted stomach. Blood samples and total urine and faeces were collected over the 48 h post-dose period and 24 h before-hand (baseline) and analysed for silicon by inductively coupled plasma optical emission spectrometry.

Results

Serum Si analysis confirmed the ready absorption of silicon from the orthosilicic acid solution. Mean total urinary and faecal Si excretions over the 24 h post-dose period accounted for 57 ± 9.5% and 39 ± 9.4% of the ingested dose, respectively. Thus in total 96.3 ± 5.8% of the ingested dose was recovered in faecal plus urinary excretions over the 24 h post-dose period.

Conclusions

We report that in healthy subjects (presumably in Si balance), the ingestion of a soluble dose of dietary Si results in the same quantity (within analytical error) being excreted within 24 h. It is currently not known if this all originated from the dose solution or if there was some exchange with the body Si pool but, given the low variance in these silicon balance data, isotopic studies are now merited.

The silicon supplement 'Monomethylsilanetriol' is safe and increases the body pool of silicon in healthy Pre-menopausal women

Background

Monomethylsilanetriol (MMST) has been used for decades as an oral silicon supplement for bone and connective tissue health, although there are no formal data on its in vivo utilisation or safety following sustained dosing.

Methods

To investigate whether MMST contributes to the body pool of silicon and, secondly, to establish its safety following 4 weeks’ supplementation in humans, twenty-two healthy pre-menopausal women (22–38 years) were recruited and supplemented with MMST at the maximum daily recommended dose (10.5 mg Si/day) for 4 weeks in a double-blind, randomised, placebo-controlled, cross-over design (i.e. 8 weeks in total). Fasting serum and urine samples were collected at baseline and at the end of the 4-week supplementation/placebo periods for analysis of total silicon by inductively coupled plasma optical emission spectrometry, MMST by proton nuclear magnetic resonance spectroscopy and full serum biochemistry. Participants also reported on, by questionnaire, their health, well-being and quality of life at 0, 4 and 8 weeks.

Results

Overall, 4-weeks supplementation with MMST significantly increased total fasting Si concentrations in serum and urine (P ≤ 0.003; paired t-test). MMST was semi-quantifiable in serum and quantifiable in urine, but only accounted for ca. 50% and 10%, respectively, of the increased total-Si concentration. There were no reported adverse effects (i.e. changes to health and well-being) or serum biochemical changes with MMST versus placebo.

Conclusions

Our data indicate that oral MMST is safe, is absorbed and undergoes sufficient metabolism in vivo to raise fasting serum silicon levels, consistent with other well absorbed forms of dietary silicon (e.g. orthosilicic acid). It thus appears to be a suitable silicon supplement.

Silicon absorption and excretion is independent of age and sex in adults

Host factors influencing the absorption and excretion of Si are poorly understood, although previous murine and human studies have suggested that age, sex and oestrogen status may affect Si metabolism and thus function. Here, serum and urine samples were collected from twenty-six healthy adults at baseline and over a 6 h period following ingestion of 17·4mg Si (orthosilicic acid) and analysed by inductively coupled plasma optical emission spectrometry. Fasting baseline serum and urinary Si concentrations were marginally higher in older adults (51-66 years old) compared with young adults (20-47 years old); however, there was no difference in the absorption of Si into serum (overall profile, rate of Si appearance, peak concentration and time to peak) between the different adult groups. The rate of elimination of Si from serum did not significantly differ with age or sex, although serum concentration at 6 h was higher in older adults and significantly correlated with age (r 0·5; P=0·01). There were, however, no significant differences in the excretion of Si into urine (a proxy for overall uptake) between the groups, averaging approximately 45 %. Oestradiol levels did not correlate with any of the above measures of Si. Thus, overall, host age and sex did not appear to markedly influence Si absorption or excretion in human adults and no correlations were found with serum oestradiol status. The marginally higher baseline and 6 h post-dose Si levels in older adults may reflect modestly impaired renal function and/or the loss of Si from connective tissues with ageing.

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.

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.

Do lifestyle choices explain the effect of alcohol on bone mineral density in women around menopause?

BACKGROUND

Moderate alcohol consumption has been shown to be positively associated with increased bone mineral density (BMD). However, other lifestyle choices have also been shown to have an effect on bone health.

OBJECTIVE

The objective was to examine the association between alcohol intake and BMD in women around menopause in the United Kingdom and to determine whether any association is independent of other lifestyle choices.

DESIGN

A cross-sectional study design was used to examine the relation between alcohol intake and BMD in a cohort of 3218 women aged 50-62 y from the Aberdeen Prospective Osteoporosis Screening Study. Women were grouped into clusters according to their lifestyle choices. ANCOVA was used to examine the effect of categorized alcohol intake on BMD adjusted for cluster of lifestyle and other baseline covariates. The ANCOVA was repeated for different types of alcoholic beverage (eg, beer, liquor, and wine) separately.

RESULTS

Three lifestyle clusters were identified and were based on different levels of the following 3 factors: smoking pack-years, fruit and vegetable intakes, and physical activity. In the lifestyle-adjusted models, women who consumed >1 drink/d of alcohol had a significantly greater femoral neck BMD (P = 0.008) and lumbar spine BMD (P = 0.007) than did those who never consumed alcohol. For separate alcoholic drinks, only beer had a positive significant effect on lumbar spine BMD after adjustment for lifestyle (P = 0.005).

CONCLUSION

Moderate alcohol intake appears to be positively associated with BMD independently of the type of lifestyle led by women around menopause.

Oral silicon supplementation: an effective therapy for preventing oral aluminum absorption and retention in mammals

Silicon is an essential element for some lower forms of life. However, it is not generally considered an essential nutrient for mammals and the mechanisms underlying its potential essentiality remain partially unknown. In recent years, a possible association between the aluminum and silicon levels in drinking water and Alzheimer's disease (AD) has been suggested. It has been reported that silicon might have a protective effect for limiting oral aluminum absorption. This review is focused primarily on the potential role of silicon in preventing oral aluminum absorption and retention in mammals. The results of a number of studies suggest that dietary silicon supplementation could be of therapeutic value for preventing chronic aluminum accumulation in the brain, and hence, be a potential therapy for AD. However, it must be noted that controversy remains about whether aluminum accumulation in the brain is a cause or a consequence of AD. It is suggested that further investigation of this issue is warranted.

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.

Silicon in beer and brewing

BACKGROUND

It has been claimed that beer is one of the richest sources of silicon in the diet; however, little is known of the relationship between silicon content and beer style and the manner in which beer is produced. The purpose of this study was to measure silicon in a diversity of beers and ascertain the grist selection and brewing factors that impact the level of silicon obtained in beer.

RESULTS

Commercial beers ranged from 6.4 to 56.5 mg L(-1) in silicon. Products derived from a grist of barley tended to contain more silicon than did those from a wheat-based grist, likely because of the high levels of silica in the retained husk layer of barley. Hops contain substantially more silicon than does grain, but quantitatively hops make a much smaller contribution than malt to the production of beer and therefore relatively less silicon in beer derives from them. During brewing the vast majority of the silicon remains with the spent grains; however, aggressive treatment during wort production in the brewhouse leads to increased extraction of silicon into wort and much of this survives into beer.

CONCLUSION

It is confirmed that beer is a very rich source of silicon.

The comparative absorption of silicon from different foods and food supplements

Dietary Si (orthosilicic acid; OSA) appears important in connective tissue health, and although the sources and intakes of Si are well established, its absorption is not. Si absorption was measured from eight high-Si-containing sources: alcohol-free beer; OSA solution (positive control); bananas; green beans; supplemental choline-stabilised OSA (ChOSA); supplemental monomethyl silanetriol (MMST); supplemental colloidal silica (CS); magnesium trisilicate British Pharmacopoeia antacid (MTBP). Two of the supplements and the antacid were pre-selected following an in vitro dissolution assay. Fasting, healthy subjects (CS, n 3; others, n > or = 5) each ingested two of the sources separated by a 1-week wash-out period. Blood and urine were collected and measured for total Si concentrations by inductively coupled plasma optical emission spectrometry. Absorption, based on urinary Si excretion, was highest for MMST and alcohol-free beer (64% of dose), followed by green beans (44%), OSA (43%), ChOSA (17%), bananas and MTBP (4%) and CS (1%). Peak serum concentrations occurred by 0.5 h for MMST and green beans, 1.5 h for OSA and alcohol-free beer, 2 h for ChOSA and CS, and 4 h for MTBP. Area under the serum curves correlated positively with urinary Si output (r 0.82; P < 0.0001). Absorption of Si from supplements and antacids was consistent with their known chemical speciation and kinetics of dissolution under simulated gastrointestinal conditions. Monomeric silicates were readily absorbed, while particulate silicates were decreasingly well absorbed with increasing polymerisation. The present results highlight the need to allow for relative absorption of Si from different foods or supplements in subsequent epidemiological and intervention studies.

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.

Moderate ingestion of alcohol is associated with acute ethanol-induced suppression of circulating CTX in a PTH-independent fashion

The "J shape" curve linking the risk of poor bone health to alcohol intake is now well recognized from epidemiological studies. Ethanol and nonethanol components of alcoholic beverages could influence bone remodeling. However, in the absence of a solid underlying mechanism, the positive association between moderate alcoholic intake and BMD remains questionable because of confounding associated social factors. The objective of this work was to characterize the short-term effects of moderate alcohol consumption on circulating bone markers, especially those involved in bone resorption. Two sequential blood-sampling studies were undertaken in fasted healthy volunteers (age, 20-47 yr) over a 6-h period using beer of different alcohol levels (<0.05-4.6%), solutions of ethanol or orthosilicic acid (two major components of beer), and water +/- calcium chloride (positive and negative controls, respectively). Study 1 (24 subjects) assessed the effects of the different solutions, whereas study 2 (26 subjects) focused on ethanol/beer dose. Using all data in a "mixed effect model," we identified the contributions of the individual components of beer, namely ethanol, energy, low-dose calcium, and high-dose orthosilicic acid, on acute bone resorption. Markers of bone formation were unchanged throughout the study for all solutions investigated. In contrast, the bone resorption marker, serum carboxy terminal telopeptide of type I collagen (CTX), was significantly reduced after ingestion of a 0.6 liters of ethanol solution (>2% ethanol; p <or= 0.01, RM-ANOVA), 0.6 liters of beer (<0.05-4.6% ethanol; p < 0.02), or a solution of calcium (180 mg calcium; p < 0.001), but only after calcium ingestion was the reduction in CTX preceded by a significant fall in serum PTH (p < 0.001). Orthosilicic acid had no acute effect. Similar reductions in CTX, from baseline, were measured in urine after ingestion of the test solutions; however, the biological variability in urine CTX was greater compared with serum CTX. Modeling indicated that the major, acute suppressive effects of moderate beer ingestion (0.6 liters) on CTX were caused by energy intake in the early phase (approximately 0-3 h) and a "nonenergy" ethanol component in the later phase (approximately 3 to >6 h). The early effect on bone resorption is well described after the intake of energy, mediated by glucagon-like peptide-2, but the late effect of moderate alcohol ingestion is novel, seems to be ethanol specific, and is mediated in a non-calcitonin- and a non-PTH-dependent fashion, thus providing a mechanism for the positive association between moderate alcohol ingestion and BMD.

Effects of beer, wine, and liquor intakes on bone mineral density in older men and women

BACKGROUND

Moderate intake of alcohol has been reported to have beneficial effects on bone. However, different classes of alcoholic beverages have not been investigated.

OBJECTIVE

Our aim was to determine the association between intake of total alcohol or individual alcoholic beverages and bone mineral density (BMD).

DESIGN

Adjusting for potential confounding factors, we examined alcohol intakes and BMD at 3 hip sites and the lumbar spine in 1182 men and in 1289 postmenopausal and 248 premenopausal women in the population-based Framingham Offspring cohort (age: 29-86 y).

RESULTS

Men were predominantly beer drinkers, and women were predominantly wine drinkers. Compared with nondrinkers, hip BMD was greater (3.4-4.5%) in men consuming 1-2 drinks/d of total alcohol or beer, whereas hip and spine BMD were significantly greater (5.0-8.3%) in postmenopausal women consuming >2 drinks/d of total alcohol or wine. Intake of >2 drinks/d of liquor in men was associated with significantly lower (3.0-5.2%) hip and spine BMD than was intake of 1-2 drinks/d of liquor in men. After adjustment for silicon intake, all intergroup differences for beer were no longer significant; differences for other alcohol sources remained significant. Power was low for premenopausal women, and the associations were not significant.

CONCLUSIONS

Moderate consumption of alcohol may be beneficial to bone in men and postmenopausal women. However, in men, high liquor intakes (>2 drinks/d) were associated with significantly lower BMD. The tendency toward stronger associations between BMD and beer or wine, relative to liquor, suggests that constituents other than ethanol may contribute to bone health. Silicon appears to mediate the association of beer, but not that of wine or liquor, with BMD. Other components need further investigation.

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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