Vitamin C supplement use and bone mineral density in postmenopausal women

Effects of kalsis, a dietary supplement, on bone metabolism in the ovariectomized rats

We studied the ability of Kalsis, a food supplement that contains selenium, citric acid, and vitamin E, to prevent the effects of ovariectomy on bone loss. Six-month-old, Wistar female rats were studied. Groups (n = 12): SHAM: sham-operated rats; OVX: ovariectomized rats, treated with vehicle; OVX + Kalsis: ovariectomized rats treated with Kalsis (25 mg/kg/day) for 3 months. Bone mineral density (BMD) was determined by DXA in lumbar spine and femur. Computerized microtomography (μCT) in femur and serum osteocalcin (BGP), aminoterminal propeptide of procollagen I (PINP), β-isomer of carboxyterminal telopeptide of collagen I (CTX), and 5b isoenzyme of tartrate-resistant acid phosphatase (TRAP) were performed. Treatment with Kalsis prevented BMD loss in OVX group. μCT showed a decrease in BV/TV, and trabecular number, and an increase in trabecular separation in OVX rats. Kalsis administration attenuated partially bone loss observed by μCT due to ovariectomy. BGP, PINP, and the resorption index (CTX/TRAP) were increased in OVX group. Treatment with Kalsis maintained this increase. The mechanism of action of this supplement is not through a decrease in bone remodelling rate. The antioxidant action of this food supplement, due to the synergism of all its components, as a cause of its beneficial effect is suggested.

Effect of antiresorptive therapy on urinary hydroxyproline in postmenopausal osteoporosis

Osteoporosis becomes a serious health threat for older postmenopausal women by predisposing them to an increased risk of fracture. Osteoporosis and associated fractures are an important cause of morbidity and mortality. Special attention is being paid to early detection, management, and treatment of postmenopausal osteoporosis in women. Biochemical markers can enable dynamic and rapid measurement of total body skeletal metabolism and will be clinically useful in the management of postmenopausal osteoporosis women (PMO) and also for assessing the effects of antiresorptive therapy. With this view, we planned to assess osteoclastic activity by determining urinary hydroxyproline in osteoporotic women. The aim of this study is to measure urinary hydroxyproline (expressed as mg of hydroxyproline/g of creatinine) and serum ascorbic acid in postmenopausal women with osteoporosis and without osteoporosis. These biochemical parameters were determined 3 months post antiresorptive therapy (alendronate + calcium + vitamin D) in postmenopausal osteoporosis patients. 60 postmenopausal women with osteoporosis in the age group 45-60 years and 60 healthy postmenopausal women (normal bone mineral density) in the same age group were included in the study. Urinary hydroxyproline levels were significantly increased (P < 0.001) in PMO at baseline level as compared to control group. These levels were decreased significantly (P < 0.001) post therapy in PMO patients. Serum vitamin C levels were significantly decreased (P < 0.001) in PMO patients at baseline level as compared to controls. No significant change occurred of serum vitamin C level post therapy. Raised excretion of hydroxyproline at the baseline level might be due to increased degradation of collagen type I from the bone matrix in osteoporosis. Breakdown of collagen seems to be lowered as reflected by lowering of hydroxyproline excretion post antiresorptive therapy. Alteration in the concentration of this marker can be very well utilized to monitor the effectiveness of therapy. Thus simple, direct urinary assay to measure bone resorption is very useful in monitoring the therapy in PMO and may become an integral part of the management of osteoporosis.

Pharmacokinetics and safety of calcium L-threonate in healthy volunteers after single and multiple oral administrations

AIM

To evaluate the pharmacokinetics of L-threonate after single or multiple oral administrations and its safety profile in healthy Chinese volunteers.

METHODS

This was an open-label, single- and multiple-dose study. The subjects were assigned to receive a single dose, 675, 2025, or 4050 mg, of calcium L-threonate (n=12) or repeated doses of 2025 mg twice daily for 4 d (n=12). Serial plasma and urine samples were analyzed with HPLC-MS/MS. Pharmacokinetic parameters of L-threonate were calculated using non-compartmental analysis with WinNonlin software.

RESULTS

In the single dose group, C(max) reached at 2.0 h and the mean t(1/2) was approximately 2.5 h. Area under curve (AUC) and C(max) increased with dose escalation, but dose proportionality was not observed over the range of 675 to 4050 mg. AUC and C(max) in the fasted subjects were lower compared with those in the non-fasted subjects. Cumulative urinary excretion of L-threonate over 24 h represented 5.9% of the administered dose with a mean Cl/r of 0.8 L/h. In the multiple-dose study, no accumulation appeared upon repeated doses of 2025 mg twice daily for 4 d. There were no serious adverse events that occurred during this study.

CONCLUSION

Calcium L-threonate was well tolerated in healthy Chinese subjects, with no pattern of dose-related adverse events. Plasma exposure increased with dose escalation, but linear pharmacokinetics were not observed over the studied doses. L-threonate was absorbed rapidly, and its absorption was enhanced by food intake. No systemic accumulation appeared after repeated administrations.

Senescence Marker Protein 30: Functional and Structural Insights to its Unknown Physiological Function

Senescence marker protein 30 (SMP30) is a multifunctional protein involved in cellular Ca(2+) homeostasis and the biosynthesis of ascorbate in non-primate mammals. The primary structure of the protein is highly conserved among vertebrates, suggesting the existence of a significant physiological function common to all mammals, including primates. Enzymatic activities of SMP30 include aldonolactone and organophosphate hydrolysis. Protective effects against apoptosis and oxidative stress have been reported. X-ray crystallography revealed that SMP30 is a six-bladed β-propeller with structural similarity to paraoxonase 1, another protein with lactonase and organophosphate hydrolase activities. SMP30 has recently been tied to several physiological conditions including osteoporosis, liver fibrosis, diabetes, and cancer. This review aims to describe the recent advances made toward understanding the connection between molecular structure, enzymatic activity and physiological function of this highly conserved, multifaceted protein.

Effects of ovariectomy and ascorbic acid supplement on oxidative stress parameters and bone mineral density in rats

OBJECTIVES

The aim of this study is to investigate the effects of ovariectomy on bone mineral density (BMD) and oxidative state in rats, and the alterations in these effects that vitamin C supplementation may produce.

MATERIALS AND METHODS

TWENTY FEMALE WISTAR ALBINO RATS WERE RANDOMLY DIVIDED INTO THREE GROUPS: control (C, n=6); ovariectomy (O, n=7); and ovariectomy+vitamin C supplement (OV, n=7). Oxidative stress (OS) was assessed 100 days postovariectomy by measuring the activity of several enzymes, including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase, as well as the concentrations of malondialdehyde (MDA), nitric oxide (NO), and total sulfhydryl groups in plasma and bone homogenates.

RESULTS

A significant decrease in BMD was observed in O group compared with C group (p=0.015), and a significant increase was observed in OV compared with O group (p=0.003). When groups were compared with respect to parameters of OS, MDA and NO levels in bone tissue were significantly higher in O than in C (p=0.032, p=0.022) and were significantly lower in OV than in O (p=0.025, p=0.018). SOD activity was significantly higher in O than in C (p=0.032). In plasma, MDA activity was significantly higher in O than in C (p=0.022) and NO level was significantly higher in O than in C and OV (p=0.017, p=0.018).

CONCLUSIONS

Our results suggest that ovariectomy may produce osteoporosis and OS in females, and vitamin C supplementation may provide alterations regarding improvement in OS and BMD values. We assume that studies including more subjects are needed to make a decisive conclusion about OS-BMD relation.

Effect of Cistanches Herba aqueous extract on bone loss in ovariectomized rat

To assess the ability of traditional Chinese medicine Cistanches Herba extract (CHE) to prevent bone loss in the ovariectomized (OVX) rat, Cistanches Herba extract (CHE) was administered intragastrically to the rats. Female rats were anesthetized with pentobarbital sodium (40 mg kg(-1), i.p.), and their ovaries were removed bilaterally. The rats in the sham-operated group were anesthetized, laparotomized, and sutured without removing their ovaries. After 1 week of recovery from surgery, the OVX rats were randomly divided into three groups and orally treated with H(2)O (OVX group) or CHE (100 or 200 mg kg(-1) daily) for 3 months. The sham-operated group (n = 8) was orally treated with H(2)O. After 3 months, the total body bone mineral density (BMD), bone mineral content (BMC), Bone biomechanical index, blood mineral levels and blood antioxidant enzymes activities were examined in sham-operated, ovariectomized and Cistanches Herba extract treated rats. Results showed that Cistanches Herba extract treatment significantly dose-dependently enhanced bone mineral density (BMD), bone mineral content (BMC), maximum load, displacement at maximum load, stress at maximum load, load at auto break, displacement at auto break, and stress at auto break, and blood antioxidant enzymes activities, decreased blood Ca, Zn and Cu levels compared to the OVX group. This experiment demonstrates that the administration of Cistanches Herba extract to ovariectomized rats reverses bone loss and prevents osteoporosis.

Oxidative stress and bone markers in plasma of patients with long-bone fixative surgery: role of antioxidants

It is well known that bone markers (e.g. osteocalcin and alkaline phosphatase) play a significant role in healing of bone fractures, whereas oxidative stress delay such healing. The present study aimed to investigate the effect of a mixture of antioxidants (vitamins A, C, E, and selenium) on oxidative stress parameters, and the levels of bone healing markers in the plasma of male patients following fixative surgery of long bones. Antioxidant tablets (300 µg vitamin A, 10 mg vitamin E, 60 mg vitamin C, and 75 µg selenium) were administered to groups 3 and 4 (10 patients in each) for 1 and 2 weeks, respectively, in addition to the regular postoperative treatment. Groups 1 (25 patients) and 2 (10 patients) received the regular post-operative treatment consisting of intravenous (I.V.) second generation of cephalosporin 1000 mg/day for 3 days, oral diclofenac 50 mg, and paracetamol 500 mg twice daily for 15 days. Osteocalcin level and alkaline phosphatase activity as well as antioxidant enzymes superoxide dismutase (SOD), glutathione reductase (GR), as well as glutathione (GSH), and thiobarbituric acid reactive substances (TBARS) as indices of oxidative stress, were determined in the plasma of all patients after 1 or 2 weeks of long-bone fixative surgery. The results revealed that osteocalcin level and the activity of alkaline phosphatase were markedly increased in the plasma of patients who received antioxidants for 2 weeks. In addition, after 1 and/or 2 weeks, the levels of TBARS were significantly lower in the antioxidant-treated patients compared with those who did not receive antioxidants. On the other hand, the activities of SOD and GR were markedly elevated in plasma of patients who received antioxidants after 1 or 2 weeks compared with patients who received regular therapy. Moreover, the level of plasma GSH was markedly increased only after 2 weeks in patients who received antioxidants. It is concluded that administration of antioxidant vitamins A, E, and C in addition to selenium could accelerate bone healing after long-bone fixative surgery. Therefore, antioxidants should be considered in designing therapeutic protocols in post-operative bone surgery.

Vegetable and fruit intake and its relevance with serum osteocalcin and urinary deoxypyridinoline in Korean adults

The purpose of this study was to evaluate the daily vegetable and fruit intake status of Korean adults and to examine the relationship of vegetable and fruit intake with bone metabolism. The vegetable and fruit intake of 542 healthy male and female adults was analyzed. Then, by selecting 51 targets from the subjects, the relation of vegetable and fruit intake with serum calcium, osteocalcin and deoxypyridinoline (DPD) excretion in urine was examined. The total vegetable intake per day was 397.7 g and 333.5 g by men and women respectively for the age group of 20-29, 366.9 g and 309.2 g respectively for the age group of 30-49, 378.4 g and 325.9 g respectively for the age group of 50-64. Of vegetable varieties, leafy and stem vegetables displayed the highest intake. The order of major intake items of vegetables and fruits was found to be Chinese cabbage kimchi, onion, radish, cucumber, and welsh onion for the age group of 20-29, watermelon, Chinese cabbage kimchi, peach, potato, and onion for the age group of 30-49 and watermelon, Chinese cabbage kimchi, tomato, potato, and peach for the age group of 50-64. Of 51 targets, β-carotene intake displayed a significantly negative correlation with serum osteocalcin. While caloric intake as well as protein, carbohydrate, calcium, phosphorous, zinc and total food intake displayed a significantly negative correlation with DPD excretion in urine, tuber vegetable intake displayed a significantly positive correlation with DPD excretion in urine. In the future, a study will be necessary to accurately explain the relevance of vegetable and fruit intake with bone mineral density and bone metabolism. Also, efforts will be required to increase vegetable and fruit intake.

PAMM: a redox regulatory protein that modulates osteoclast differentiation

The central role of reactive oxygen species (ROS) in osteoclast differentiation and in bone homeostasis prompted us to characterize the redox regulatory system of osteoclasts. In this report, we describe the expression and functional characterization of PAMM, a CXXC motif-containing peroxiredoxin 2-like protein expressed in bone marrow monocytes on stimulation with M-CSF and RANKL. Expression of wild-type (but not C to G mutants of the CXXC domain) PAMM in HEK293 cells results in an increased GSH/GSSG ratio, indicating a shift toward a more reduced environment. Expression of PAMM in RAW264.7 monocytes protected cells from hydrogen peroxide-induced oxidative stress, indicating that PAMM regulates cellular redox status. RANKL stimulation of RAW 264.7 cells caused a decrease in the GSH/GSSG ratio (reflecting a complementary increase in ROS). In addition, RANKL-induced osteoclast formation requires phosphorylation and translocation of NF-kappaB and c-Jun. In stably transfected RAW 264.7 cells, PAMM overexpression prevented the reduction of GSH/GSSG induced by RANKL. Concurrently, PAMM expression completely abolished RANKL-induced p100 NF-kappaB and c-Jun activation, as well as osteoclast formation. We conclude that PAMM is a redox regulatory protein that modulates osteoclast differentiation in vitro. PAMM expression may affect bone resorption in vivo and help to maintain bone mass.

A review of select vitamins and minerals used by postmenopausal women

OBJECTIVES

The purpose of this review is to summarize the effectiveness of select vitamins, minerals and trace elements in postmenopausal women for their effects on bone health, cardiovascular health, breast cancer, cognition and vasomotor symptoms.

METHODS

Review of the relevant literature and results from recent clinical studies, as well as critical analyses of published systematic reviews and meta-analyses were obtained from PubMed and Cochrane Library of Reviews. Vitamin A, the B vitamins, vitamin C, calcium, vitamin D, vitamin E, vitamin K, magnesium, selenium and zinc were selected for review. In circumstances where the vitamin, mineral or trace element has not been studied for a given condition, no information was provided.

RESULTS AND DISCUSSION

All vitamins, minerals and trace elements play an important role in maintaining health and wellbeing among menopausal women. Adequate dietary intake is essential and supplementation should be considered in women with documented malabsorption syndromes or deficiencies. Based on a review of the literature, supplementation with vitamin C, D, K and calcium can also be recommended for proper maintenance of bone health. The only supplement studied for vasomotor symptoms was vitamin E and this vitamin lacked clinical support. Supplementation in healthy postmenopausal women with vitamins and minerals in diet or pill forms cannot be recommended currently for any other indications.

Ascorbate synthesis pathway: dual role of ascorbate in bone homeostasis

Using mouse gene knock-out models, we identify aldehyde reductase (EC 1.1.1.2, Akr1a4 (GR)) and aldose reductase (EC 1.1.1.21, Akr1b3 (AR)) as the enzymes responsible for conversion of D-glucuronate to L-gulonate, a key step in the ascorbate (ASC) synthesis pathway in mice. The gene knock-out (KO) mice show that the two enzymes, GR and AR, provide approximately 85 and approximately 15% of L-gulonate, respectively. GRKO/ARKO double knock-out mice are unable to synthesize ASC (>95% ASC deficit) and develop scurvy. The GRKO mice ( approximately 85% ASC deficit) develop and grow normally when fed regular mouse chow (ASC content = 0) but suffer severe osteopenia and spontaneous fractures with stresses that increase ASC requirements, such as pregnancy or castration. Castration greatly increases osteoclast numbers and activity in GRKO mice and promotes increased bone loss as compared with wild-type controls and additionally induces proliferation of immature dysplastic osteoblasts likely because of an ASC-sensitive block(s) in early differentiation. ASC and the antioxidants pycnogenol and resveratrol block osteoclast proliferation and bone loss, but only ASC feeding restores osteoblast differentiation and prevents their dysplastic proliferation. This is the first in vivo demonstration of two independent roles for ASC as an antioxidant suppressing osteoclast activity and number as well as a cofactor promoting osteoblast differentiation. Although humans have lost the ability to synthesize ASC, our mouse models suggest the mechanisms by which suboptimal ASC availability facilitates the development of osteoporosis, which has important implications for human osteoporosis.

Enhancement of calcium/vitamin d supplement efficacy by administering concomitantly three key nutrients essential to bone collagen matrix for the treatment of osteopenia in middle-aged women: a one-year follow-up

Two vitamins and proline (CB₆Pro), three nutrients essential for bone collagen, were used in combination to a 1000 mg calcium/250 IU vitamin D (Ca/D) daily supplement to treat osteopenia as a preventive measure against osteoporosis later in life. Middle-aged women not using estrogen were screened for osteopenia using the WHO criteria and divided into three groups (n = 20 each): 1) placebo healthy controls with normal bone mineral density (BMD); 2) control Ca/D-treated osteopenic patients; and 3) Ca/D + CB₆Pro-treated osteopenic patients. The three groups were comparable at baseline except for BMD. After one-year treatment, cortical diaphyseal BMD remained constant in each group, but trabecular bone loss persisted (at 5 lumbar sites) in osteopenic group 2. No further bone loss was detected in osteopenic group 3. A loss of 2% was evidenced in the placebo group at one lumbar site. Markers of bone formation (which increase in coupling to resorption) decreased significantly in both osteopenic groups. Although biomarkers of resorption did not change, hormone (PTH and 1,25(OH)₂D₃)-induced osteoclastic activity was significantly reduced. No decline in BMD occurred at any bone site in osteopenic group 3, highlighting the importance of improving the quality of bone matrix concomitantly to mineral replacement.

Effect of alpha tocopherol acetate in Walker 256/B cells-induced oxidative damage in a rat model of breast cancer skeletal metastases

The pathophysiological changes and the oxidative-antioxidative status were evaluated in the bone microenvironment of rat inoculated with Walker 256/B mammary gland carcinoma cells, and used alpha-tocopherol acetate (ATA) as a countermeasure. Walker 256/B cells were injected into the right femora of aged male rats. Animals were randomized into three groups: 12 rats were injected with saline (control group); 14 rats were injected with Walker 256/B cells (5x10(4)) in the medullar cavity (W256 group); 14 rats were inoculated with Walker 256/B cells and treated with ATA (45mg/kg BW) (W256+ATA group). After 20 days, rats were euthanized and the femurs were radiographed. Micro architectural parameters were measured by microcomputed tomography and histology. Serum, bone and bone marrow were evaluated for oxidative damage. In parallel, cell cultures were done in the presence of ATA and ROS were measured by fluorescence; apoptotic cells were determined in parallel. W256 groups had osteolytic damages with marked resorption of cortical and trabecular bone. W256+ATA animals presented marked osteosclerotic areas associated with tumor necrosis areas inside the bone cavity. Levels of lipid peroxidation and protein oxidation were found to increase in W256 rats; a significant reduction in SOD and GSH-p activities was also observed. W256+ATA group had significantly reduced oxidative damage, but not reversed back to the control levels. The present study shows that Walker 256/B cells induce skeletal metastases associated with oxidative damage in the bone microenvironment. ATA reduced the oxidative stress damage, enhanced osteosclerosis and tumor cell apoptosis both in vitro and in vivo.

Green tea and bone metabolism

Osteoporosis is a major health problem in both elderly women and men. Epidemiological evidence has shown an association between tea consumption and the prevention of age-related bone loss in elderly women and men. Ingestion of green tea and green tea bioactive compounds may be beneficial in mitigating bone loss of this population and decreasing their risk of osteoporotic fractures. This review describes the effect of green tea or its bioactive components on bone health, with an emphasis on (i) the prevalence and etiology of osteoporosis; (ii) the role of oxidative stress and antioxidants in osteoporosis; (iii) green tea composition and bioavailability; (iv) the effects of green tea and its active components on osteogenesis, osteoblastogenesis, and osteoclastogenesis from human epidemiological, animal, as well as cell culture studies; (v) possible mechanisms explaining the osteoprotective effects of green tea bioactive compounds; (vi) other bioactive components in tea that benefit bone health; and (vii) a summary and future direction of green tea and bone health research and the translational aspects. In general, tea and its bioactive components might decrease the risk of fracture by improving bone mineral density and supporting osteoblastic activities while suppressing osteoclastic activities.

Green tea polyphenols mitigate deterioration of bone microarchitecture in middle-aged female rats

Our previous study demonstrated that green tea polyphenols (GTP) benefit bone health in middle-aged female rats without (sham, SH) and with ovariectomy (OVX), because of GTP's antioxidant capacity. The current study further evaluates whether GTP can restore bone micro-structure in both gonad-intact and gonadal-hormone-deficient middle-aged female rats. A 16-week study was performed based on a 2 (SH vs. OVX)x3 (no GTP, 0.1% GTP, and 0.5% GTP in drinking water) factorial design using 14-month-old female rats (n=10/group). An additional 10 rats were euthanized at the beginning of study to provide baseline parameters. Analysis using dual-energy X-ray absorptiometry, histomorphometry, and micro-computed tomography showed that GTP supplementation resulted in (a) increased trabecular volume, thickness, number, and bone formation of proximal tibia, periosteal bone formation rate of tibia shaft, and cortical thickness and area of femur, and (b) decreased trabecular separation and bone erosion of proximal tibia, and endocortical bone eroded surface of tibia shaft. We concluded that drinking water supplemented with GTP mitigated deterioration of bone microarchitecture in both intact and ovariectomized middle-aged female rats by suppressing bone erosion, enhancing bone formation, and modulating endocortical and cancellous bone compartments, resulting in a larger net bone volume.

Nutritional determinants of bone health

Osteoporosis is a major public health problem. The aging population will require vigilant prevention, education, and treatment to maintain bone density and reduce the risk of fractures and falls. Nutritional requirements of elderly persons can have a profound effect on bone health. Calcium, vitamin D, and protein are vital nutrients for optimal bone health. Adequate calcium is essential for bone maintenance. Vitamin D research shows a link between reduced falls and fractures. Related macro- and micronutrients play an important role in bone mass integrity and quality. Adequate nutrition for older adults needs to be encouraged to promote and maintain bone health.

High vitamin C intake is associated with lower 4-year bone loss in elderly men

Vitamin C is essential for collagen formation and normal bone development. We evaluated associations of total, supplemental, and dietary vitamin C intake with bone mineral density (BMD) at the hip [femoral neck, trochanter], spine, and radial shaft and 4-y BMD change in elderly participants from the Framingham Osteoporosis Study. Energy-adjusted vitamin C intakes were estimated from the Willett FFQ in 1988-89. Mean BMD and 4-y BMD change was estimated, for men and women, by tertile/category of vitamin C intake, adjusting for covariates. We tested for interaction with smoking, calcium, and vitamin E intake. Among 334 men and 540 women, the mean age was 75 y and mean vitamin D intake was 8.25 mug/d (women) and 8.05 mug/d (men). We observed negative associations between total and supplemental vitamin C intake and trochanter-BMD among current male smokers (P-trend = 0.01). Among male nonsmokers, total vitamin C intake was positively associated with femoral neck BMD (P-trend = 0.04). Higher total vitamin C intake was associated with less femoral neck and trochanter-BMD loss in men with low calcium (all P-trend Collapse

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MESH Headings

• Aged
• Aged, 80 and over
• Ascorbic Acid/therapeutic use
• Body Mass Index
• Cohort Studies
• Dose-Response Relationship, Drug
• Female
• Fruit
• Humans
• Male
• Massachusetts
• Middle Aged
• Osteoporosis/prevention & control
• Seasons
• Vegetables

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Grants

• N01 HC025195 NHLBI NIH HHS
• R01 AR041398 NIAMS NIH HHS
• R01 AR/AG 41398 NIA NIH HHS
• N01-HC-25195 NHLBI NIH HHS

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Affiliation(s)

Shivani Sahni Dietary Assessment and Epidemiology Research Program, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111
Marian T. Hannan Institute for Aging Research, Hebrew SeniorLife and the Harvard Medical School, Boston, MA 02131
David Gagnon Department of Biostatistics, Boston University School of Public Health, Boston, MA 02118
Jeffrey Blumberg Antioxidants Research Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111
L. Adrienne Cupples Department of Biostatistics, Boston University School of Public Health, Boston, MA 02118
Douglas P. Kiel Institute for Aging Research, Hebrew SeniorLife and the Harvard Medical School, Boston, MA 02131
Katherine L. Tucker Dietary Assessment and Epidemiology Research Program, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111

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Collaborators Collapse

Protective effect of green tea polyphenols on bone loss in middle-aged female rats

Recent studies have suggested that green tea polyphenols (GTP) are promising agents for preventing bone loss in women. Findings that GTP supplementation resulted in increased urinary GTP concentrations and bone mass via an increase of antioxidant capacity and/or a decrease of oxidative stress damage suggest a significant role of GTP in bone health of women.

INTRODUCTION

Recent studies suggested that green tea polyphenols (GTP) are promising agents for preventing bone loss in women. However, the mechanism related to the possible protective role of GTP in bone loss is not well understood.

METHODS

This study evaluated bioavailability, mechanisms, bone mass, and safety of GTP in preventing bone loss in middle-aged rats without (sham, SH) and with ovariectomy (OVX). A 16-week study of 2 (SH vs. OVX) x 3 (no GTP, 0.1% GTP, and 0.5% GTP in drinking water) factorial design using 14-month-old female rats (n = 10/group) was performed. An additional 10 rats in baseline group were euthanized at the beginning of study to provide baseline parameters.

RESULTS

There was no difference in femur bone mineral density between baseline and the SH+0.5% GTP group. Ovariectomy resulted in lower values for liver glutathione peroxidase activity, serum estradiol, and bone mineral density. GTP supplementation resulted in increased urinary epigallocatechin and epicatechin concentrations, liver glutathione peroxidase activity and femur bone mineral density, decreased urinary 8-hydroxy-2'-deoxyguanosine and urinary calcium levels, but no effect on serum estradiol and blood chemistry levels.

CONCLUSION

We conclude that a bone-protective role of GTP may contribute to an increase of antioxidant capacity and/or a decrease of oxidative stress damage.

Staphylococcal enterotoxin C injection in combination with ascorbic acid promotes the differentiation of bone marrow-derived mesenchymal stem cells into osteoblasts in vitro

Staphylococcal enterotoxin C injection is established as a clinical therapy for delayed healing or disunion of bone fractures. In the present study, the effects of staphylococcal enterotoxin C injection in combination with ascorbic acid (SEC-AA) on the differentiation of bone marrow-derived mesenchymal stem cells (MSCs) and their influences on the mineralization of osteoblasts were investigated. SEC-AA treatment induced increased levels of alkaline phosphatase activity in MSCs and increased numbers of alizarin red-stained calcified nodules, indicating enhanced differentiation of MSCs into osteoblasts. The findings demonstrated that SEC-AA promoted the differentiation of MSCs into osteoblasts and accelerated the cytopoiesis of osteoblasts. Our data provide a cytological model for bone fracture therapy aimed at shortening the time required for healing and improving the clinical outcome, and also provide a theoretical basis for inducible differentiation of MSCs, mineralization of osteoblasts and reconstruction of bone tissues.

Serum carotenoid concentrations in postmenopausal women from the United States with and without osteoporosis

Antioxidant defenses may be compromised in osteoporotic women. Little is known about fruit and vegetable or carotenoid consumption among postmenopausal women. The primary carotenoids in human serum are alpha- and beta-carotene, lycopene, beta-cryptoxanthin, lutein, and zeaxanthin. This study investigated the interrelationships among serum carotenoid concentrations, fruit and vegetable intake, and osteoporosis in postmenopausal women (n = 59, 62.7 +/- 8.8 y). Bone density was assessed by dual energy x-ray absorptiometry and osteoporosis diagnosis was based upon T-scores. Serum samples (n = 53) and three-day diet records (n = 49) were analyzed. Logistic regression analyzed differences between carotenoids after adjusting for serum retinol; supplement usage; milk, yogurt, fruit, and vegetable intake; and body mass index (BMI). Pearson statistics correlated carotenoids with specific fruit or vegetable intake. Serum lycopene concentrations were lower in the osteoporosis group than controls (p = 0.03). Beta-cryptoxanthin intake was higher in the osteoporosis group (p = 0.0046). Total fruit and vegetable intakes were correlated with serum lycopene and beta-cryptoxanthin (p = 0.03, 0.006, respectively). Serum alpha-carotene concentration was associated with carrot intake, and zeaxanthin and beta-cryptoxanthin with lettuce intake. Carotenoids that may have beneficial skeletal effects are lower in women with osteoporosis. Research is needed to identify potential protective mechanisms or utilization of carotenoids during osteoporosis.

Effect of antioxidants on knee cartilage and bone in healthy, middle-aged subjects: a cross-sectional study

The aim of the present study is to examine the effect of dietary antioxidants on knee structure in a cohort of healthy, middle-aged subjects with no clinical knee osteoarthritis.

Two hundred and ninety-three healthy adults (mean age = 58.0 years, standard deviation = 5.5) without knee pain or knee injury were selected from an existing community-based cohort. The intake of antioxidant vitamins and food sources by these individuals was estimated from a food frequency questionnaire at baseline. The cartilage volume, bone area, cartilage defects and bone marrow lesions were assessed approximately 10 years later using magnetic resonance imaging.

In multivariate analyses, higher vitamin C intake was associated with a reduced risk of bone marrow lesions (odds ratio = 0.50, 95% confidence interval (CI) = 0.29–0.87, P = 0.01) and with a reduction in the tibial plateau bone area (β = -35.5, 95% CI = -68.8 to -2.3, P = 0.04). There was an inverse association between fruit intake and the tibial plateau bone area (β = -27.8, 95% CI = -54.9 to -0.7, P = 0.04) and between fruit intake and the risk of bone marrow lesions (odds ratio = 0.72, 95% CI = 0.52–0.99, P = 0.05). Neither fruit intake nor vitamin C intake was significantly associated with the cartilage volume or cartilage defects. Lutein and zeaxanthin intake was associated with a decreased risk of cartilage defects (odds ratio = 0.71, 95% CI = 0.51–0.99, P = 0.04), and vitamin E intake tended to be positively associated with the tibial plateau bone area (β = 33.7, 95% CI = -3.1 to 70.4, P = 0.07) only after adjusting for vitamin C intake. The β-cryptoxanthin intake was inversely associated with the tibial plateau bone area after adjusting for vitamin E intake (β = -33.2, 95% CI = -63.1 to -3.4, P = 0.03). Intake of vegetables and other carotenoids was not significantly associated with cartilage or bone measures.

The present study suggests a beneficial effect of fruit consumption and vitamin C intake as they are associated with a reduction in bone size and the number of bone marrow lesions, both of which are important in the pathogenesis of knee osteoarthritis. While our findings need to be confirmed by longitudinal studies, they highlight the potential of the diet to modify the risk of osteoarthritis.

Régime méditerranéen et ostéoporose

As a result of the demographic shift towards an ageing population, all industrialized countries face a growing prevalence of chronic age-related conditions, particularly osteoporosis. This multifaceted disease is defined as "a systemic skeletal disorder" characterised by low bone mass and micro-architectural deterioration of bone tissue, which results in increased bone fragility and susceptibility to fracture. Two main categories have been suggested: post-menopausal and senile osteoporosis. The prevention of osteoporosis through dietary means is especially challenging in technologically advanced societies. Indeed, within Europe, conspicuous differences are encountered in the severity of osteoporosis, the lowest incidence being reported in the Mediterranean area. The beneficial effect is attributed mainly to specific eating pattern. These food items contain a complex array of naturally occurring bioactive molecules with antioxidant, anti-inflammatory and alkalinising properties, that may contribute to the bone-sparing effect of Mediterranean diet.

Increased formation of 8-iso-prostaglandin F(2alpha) is associated with altered bone metabolism and lower bone mass in hypercholesterolaemic subjects

OBJECTIVES

To investigate the relationship of 8-iso-prostaglandin (PG) F(2alpha) levels, a reliable marker of in vivo oxidative stress and lipid peroxidation, with bone mineral density (BMD), bone turnover markers, osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) in hypercholesterolaemia.

DESIGN

Cross-sectional study.

SETTING

University hospital centre.

METHODS

Serum 8-iso-PGF(2alpha) levels were measured in 173 hypercholesterolaemic subjects and in 152 age- and sex-matched normocholesterolaemic controls. Femoral neck and lumbar spine BMD, serum bone-specific alkaline phosphatase (BAP), osteocalcin (OC), OPG and RANKL levels, as well as urinary levels of C-terminal telopeptides of type I collagen (CTX-I), were also assessed.

RESULTS

Hypercholesterolaemic subjects showed higher (P < 0.0001) serum 8-iso-PGF(2alpha) levels than controls. They also had decreased (P < 0.0001) femoral neck and lumbar spine BMD, and lower (P < 0.0001) serum BAP and OC levels. No significant differences between hypercholesterolaemic and control subjects were found when comparing urinary CTX-I levels, or serum OPG and RANKL levels. In multivariate linear regression analysis, serum 8-iso-PGF(2alpha) was the only negative predictor for femoral neck BMD and serum BAP and OC levels in hypercholesterolaemic subjects. No significant correlation (all P > 0.25) was present between serum 8-iso-PGF(2alpha) levels and urinary CTX-I levels, or serum OPG and RANKL levels, in hypercholesterolaemic subjects.

CONCLUSIONS

We found an association between increased serum 8-iso-PGF(2alpha) levels and lower bone mass and reduced serum BAP and OC concentrations in hypercholesterolaemic subjects. These results would suggest a possible role for oxidative stress in the development of lower bone mass in hypercholesterolaemia.

The role of nutrients in bone health, from A to Z

Osteoporosis is a major public health problem, affecting millions of individuals. Dietary intake is an important modifiable factor for bone health. Inadequate intake of nutrients important to bone increases the risk for bone loss and subsequent osteoporosis. The process of bone formation requires an adequate and constant supply of nutrients, such as calcium, protein, magnesium, phosphorus, vitamin D, potassium, and fluoride. However, there are several other vitamins and minerals needed for metabolic processes related to bone, including manganese, copper, boron, iron, zinc, vitamin A, vitamin K, vitamin C, and the B vitamins. Although the recommended levels of nutrients traditionally related to bone were aimed to promote bone mass and strength, the recommended levels of the other nutrients that also influence bone were set on different parameters, and may not be optimal for bone health, in view of recent epidemiological studies and clinical trials.

Effects of calcitonin, risedronate, and raloxifene on erythrocyte antioxidant enzyme activity, lipid peroxidation, and nitric oxide in postmenopausal osteoporosis

BACKGROUND

The aims of this study were to compare erythrocyte antioxidant enzyme activities, lipid peroxidation, and nitric oxide levels (NO) in women with postmenopausal osteoporosis (PMO) and non-porotic postmenopausal healthy controls and to assess the relationship between bone mineral density and these oxidant/antioxidant parameters. Additionally, in vivo effects of three different anti-osteoporotic drugs, calcitonin, risedronate and raloxifene, on the erythrocyte oxidant-antioxidant status in women with PMO were also assessed.

METHODS

Postmenopausal women aged 40-65 years and without previous diagnosis or treatment for osteoporosis and independent in activities of daily living were included. Bone mineral density was measured at the lumbar spine and proximal femur using DXA. Erythrocyte enzyme activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and lipid peroxidation end-product malondialdehyde (MDA) and nitrite/nitrate levels, by product of NO, were assessed. Fifty-nine women with PMO were included (mean age 56.7 years), 44 completed course of therapy and were analyzed. Twenty-two non-porotic healthy women (mean age 55.8 years) were included as controls.

RESULTS

Patients had significantly lower CAT and GSH-Px enzyme activity and higher levels of MDA and NO than non-porotic healthy controls. Proximal femur BMD measurements significantly correlated with NO levels. QUALEFFO scores improved in different levels with these short-term treatments. In all treatment groups, erythrocyte MDA levels significantly decreased; moreover, risedronate reduced NO levels and raloxifene enhanced CAT enzyme activity.

CONCLUSIONS

Oxidative stress plays an important role in the pathogenesis of PMO. Studied drugs had ultimate effects on reducing lipid peroxidation. Raloxifene also had potent effects in the enhancement of antioxidant defense system.

Follicle-stimulating hormone stimulates TNF production from immune cells to enhance osteoblast and osteoclast formation

Declining estrogen production after menopause causes osteoporosis in which the resorption of bone exceeds the increase in bone formation. We recently found that mice deficient in the beta-subunit of follicle-stimulating hormone (FSHbeta) are protected from bone loss despite severe estrogen deficiency. Here we show that FSHbeta-deficient mice have lowered TNFalpha levels. However, TNFalpha-deficient mice are resistant to hypogonadal bone loss despite having elevated FSH, suggesting that TNFalpha is critical to the effect of FSH on bone mass. We find that FSH directly stimulates TNFalpha production from bone marrow granulocytes and macrophages. We also explore how TNFalpha up-regulation induces bone loss. By modeling the known actions of TNFalpha, we attribute the high-turnover bone loss to an expanded osteoclast precursor pool, together with enhanced osteoblast formation. TNFalpha inhibits osteoblastogenesis in the presence of ascorbic acid in culture medium, but in its absence this effect becomes stimulatory; thus, ascorbic acid reverses the true action of TNFalpha. Likewise, ascorbic acid blunts the effects of TNFalpha in stimulating osteoclast formation. We propose that hypogonadal bone loss is caused, at least in part, by enhanced FSH secretion, which in turn increases TNFalpha production to expand the number of bone marrow osteoclast precursors. Ascorbic acid may prevent FSH-induced hypogonadal bone loss by modulating the catabolic actions of TNFalpha.

Antioxidant alpha-lipoic acid inhibits osteoclast differentiation by reducing nuclear factor-kappaB DNA binding and prevents in vivo bone resorption induced by receptor activator of nuclear factor-kappaB ligand and tumor necrosis factor-alpha

The relationship between oxidative stress and bone mineral density or osteoporosis has recently been reported. As bone loss occurring in osteoporosis and inflammatory diseases is primarily due to increases in osteoclast number, reactive oxygen species (ROS) may be relevant to osteoclast differentiation, which requires receptor activator of nuclear factor-kappaB ligand (RANKL). Tumor necrosis factor-alpha (TNF-alpha) frequently present in inflammatory conditions has a profound synergy with RANKL in osteoclastogenesis. In this study, we investigated the effects of alpha-lipoic acid (alpha-LA), a strong antioxidant clinically used for some time, on osteoclast differentiation and bone resorption. At concentrations showing no growth inhibition, alpha-LA potently suppressed osteoclastogenesis from bone marrow-derived precursor cells driven either by a high-dose RANKL alone or by a low-dose RANKL plus TNF-alpha (RANKL/TNF-alpha). alpha-LA abolished ROS elevation by RANKL or RANKL/TNF-alpha and inhibited NF-kappaB activation in osteoclast precursor cells. Specifically, alpha-LA reduced DNA binding of NF-kappaB but did not inhibit IKK activation. Furthermore, alpha-LA greatly suppressed in vivo bone loss induced by RANKL or TNF-alpha in a calvarial remodeling model. Therefore, our data provide evidence that ROS plays an important role in osteoclast differentiation through NF-kappaB regulation and the antioxidant alpha-lipoic acid has a therapeutic potential for bone erosive diseases.

Antioxidant intake and risk of osteoporotic hip fracture in Utah: an effect modified by smoking status

The role of antioxidant intake in osteoporotic hip fracture risk is uncertain and may be modified by smoking. In the Utah Study of Nutrition and Bone Health, a statewide, population-based case-control study, the authors investigated whether antioxidant intake was associated with risk of osteoporotic hip fracture and whether this association was modified by smoking status. The analyses included data on 1,215 male and female cases aged > or = 50 years who incurred a hip fracture during 1997-2001 and 1,349 age- and sex-matched controls. Diet was assessed by food frequency questionnaire. Among ever smokers, participants in the highest quintile of vitamin E intake (vs. the lowest) had a lower risk of hip fracture after adjustment for confounders (odds ratio = 0.29, 95% confidence interval (CI): 0.16, 0.52; p-trend < 0.0001). The corresponding odds ratio for beta-carotene intake was 0.39 (95% CI: 0.23, 0.68; p-trend = 0.0004), and for selenium intake it was 0.27 (95% CI: 0.12, 0.58; p-trend = 0.0003). Vitamin C intake did not have a significant graded association with hip fracture risk among ever smokers. Similar findings were obtained when an overall antioxidant intake score was used (odds ratio = 0.19, 95% CI: 0.10, 0.37; p-trend < 0.0001). No similar associations were found in never smokers. Antioxidant intake was associated with reduced risk of osteoporotic hip fracture in these elderly subjects, and the effect was strongly modified by smoking status.

Lycopene

Oxidative stress is now recognized as an important etiological factor in the causation of several chronic diseases including cancer, cardiovascular diseases, osteoporosis, and diabetes. Antioxidants play an important role in mitigating the damaging effects of oxidative stress on cells. Lycopene, a carotenoid antioxidant, has received considerable scientific interest in recent years. Epidemiological, tissue culture, and animal studies provide convincing evidence supporting the role of lycopene in the prevention of chronic diseases. Human intervention studies are now being conducted to validate epidemiological observations and to understand the mechanisms of action of lycopene in disease prevention. To obtain a better understanding of the role of lycopene in human health, this chapter reviews the most recent information pertaining to its chemistry, bioavailability, metabolism, role in the prevention of prostate cancer and cancer of other target organs, its role in cardiovascular diseases, osteoporosis, hypertension, and male infertility. A discussion of the most relevant molecular markers of cancer is also included as a guide to future researchers in this area. The chapter concludes by reviewing global intake levels of lycopene, suggested levels of intake, and future research directions.

Musculoskeletal manifestations of scurvy

Scurvy occurs in individuals who eat inadequate amounts of fresh fruit or vegetables, often because of dietary imbalances related to advanced age or homelessness. Asthenia, vascular purpura, bleeding, and gum abnormalities are the main symptoms. In 80% of cases, the manifestations of scurvy include musculoskeletal symptoms consisting of arthralgia, myalgia, hemarthrosis, and muscular hematomas. Vitamin C depletion is responsible for structural collagen alterations, defective osteoid matrix formation, and increased bone resorption. Imaging studies may show osteolysis, joint space loss, osteonecrosis, osteopenia, and/or periosteal proliferation. Trabecular and cortical osteoporosis is common. Children experience severe lower limb pain related to subperiosteal bleeding. Laboratory tests show nonspecific abnormalities including anemia and low levels of cholesterol and albumin. The finding of a serum ascorbic acid level lower than 2.5 mg/l confirms the diagnosis. Vitamin C supplementation ensures prompt resolution of the symptoms.

Ascorbic acid inhibits osteoclastogenesis of RAW264.7 cells induced by receptor activated nuclear factor kappaB ligand (RANKL) in vitro

Ascorbic acid (AA) plays a key role in the regulation of differentiation and activation of osteoclast (OCL). It was reported that AA might induce the formation of OCL in cocultures of mouse bone marrow cells and ST2 cells, but it is not clear whether AA has a direct impact on the OCL precursors. The purpose of this study was to examine the effect of AA on the differentiation of OCL precursor RAW264.7 cells, cultured with receptor-activated nuclear factor kappaB ligand (RANKL). The results showed that AA remarkably inhibited the cell proliferation at a higher concentration and RANKL alone is sufficient for osteoclastogenesis. The expression of carbonic anhydrase (CAII) mRNA and protein, the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs), and the percentage area of resorption lacunae induced by RANKL were decreased when AA was added to the cultures. The results demonstrate that AA inhibits RANKL-induced differentiation of OCL precursor cells into mature OCL and reduces the formation of bone resorption pits in vitro.

Biochanin A Stimulates Osteoblastic Differentiation and Inhibits Hydrogen Peroxide-Induced Production of Inflammatory Mediators in MC3T3-E1 Cells

Phytoestrogens are plant chemicals that are structurally analogous to estrogen and are known to affect estrogenic activity. Biochanin A, a naturally occurring isoflavone, has been identified and detected in various diets and plant species. We examined the effects of biochanin A on the differentiation of osteoblastic MC3T3-E1 cells and the production of local factors in osteoblasts. Biochanin A (1-50 microM) caused a significant elevation of cell growth, alkaline phosphatase (ALP) activity, collagen content, and osteocalcin secretion in osteoblastic MC3T3-E1 cells (p<0.05). The effect of biochanin A (10 microM) in increasing ALP activity and collagen content was completely prevented by the presence of 10(-6) M cycloheximide and 10(-6) M tamoxifen, suggesting that biochanin A's effect results from a newly synthesized protein component and might be partly involved in estrogen action. We then examined the effect of biochanin A on the H2O2-induced production of inflammatory mediators in osteoblasts. Biochanin A (1-10 microM) decreased the 0.2 mM H2O2-induced production of TNF-alpha, IL-6 and NO in osteoblasts. These results suggest that biochanin A may be useful as potential phytoestrogens, which play important physiological roles in the prevention of postmenopausal osteoporosis.

Homocysteine – a newly recognised risk factor for osteoporosis

Osteoporosis is a widespread problem, which frequently has devastating health consequences through its association with fragility fractures. The total number of fractures, and hence the cost to society, will increase dramatically over the next 50years as a result of demographic changes in the number of elderly people. Thus, prevention of osteoporosis by identifying risk factors or risk indicators, as well as the development of new treatment strategies, are major issues. Recent data suggest that homocysteine (Hcy), folate, vitamin B

Regulation of human osteoclast differentiation by thioredoxin binding protein-2 and redox-sensitive signaling

Differential expression of TBP-2 and Trx-1 occurs during osteoclastogenesis. Adenoviral overexpression of TBP-2 in osteoclast precursors inhibits Trx-1 expression, osteoclast formation, and AP-1 binding activity. TBP-2 and Trx-1 are key regulators of osteoclastogenesis.

INTRODUCTION

Thioredoxin binding protein-2 (TBP-2) negatively regulates thioredoxin-1 (Trx-1), a key endogenous modulator of cellular redox and signaling. In gene array analysis, we found that TBP-2 expression was reduced during human osteoclast differentiation compared with macrophage differentiation. Our aim was to determine the roles of TBP-2 and Trx-1 in human osteoclastogenesis and RANKL signaling.

MATERIALS AND METHODS

Osteoclasts or macrophages were generated from colony-forming unit-granulocyte macrophage (CFU-GM) precursors treated with sRANKL and macrophage-colony-stimulating factor (M-CSF), or M-CSF alone, respectively. Expression of TBP-2 and Trx-1 was quantified by real-time PCR and Western analysis. Adenoviral gene transfer was used to overexpress TBP-2 in precursors. NF-kappaB and activator protein 1 (AP-1) signaling was assessed with EMSA.

RESULTS

In the presence of sRANKL, expression of TBP-2 was decreased, whereas Trx-1 expression was increased. The antioxidant N-acetylcysteine reversed this pattern and markedly inhibited osteoclastogenesis. Adenoviral overexpression of human TBP-2 in precursors inhibited osteoclastogenesis and Trx-1 expression, inhibited sRANKL-induced DNA binding of AP-1, but enhanced sRANKL-induced DNA binding of NF-kappaB.

CONCLUSIONS

These data support significant roles for TBP-2 and the Trx system in osteoclast differentiation that are mediated by redox regulation of AP-1 transcription. A likely mechanism of stress signal induction of bone resorption is provided. Modulators of the Trx system such as antioxidants have potential as antiresorptive therapies.

Oxidative stress inhibits osteoblastic differentiation of bone cells by ERK and NF-kappaB

Signaling pathways involved in oxidative stress-induced inhibition of osteoblast differentiation are not known. We showed in this report that H(2)O(2) (0.1-0.2mM)-induced oxidative stress suppressed the osteoblastic differentiation process of primary rabbit bone marrow stromal cells (BMSC) and calvarial osteoblasts, manifested by a reduction of differentiation markers including alkaline phosphatase (ALP), type I collagen, colony-forming unit-osteoprogenitor (CFU-O) formation, and nuclear phosphorylation of Runx2. H(2)O(2) treatment stimulated phospholipase C-gamma1 (PLC-gamma1), extracellular signal-regulated kinase 1/2 (ERK1/2), and NF-kappaB signaling but inhibited p38 mitogen-activated protein kinase (MAPK) activation. In the presence of 20microM PD98059 or 50microM caffeic acid phenethyl ester (CAPE), specific inhibitor for ERKs or NF-kappaB, respectively, could significantly reverse the decrease of above-mentioned osteoblastic differentiation markers elicited by H(2)O(2) (0.1mM). Furthermore, PD98059 also suppressed H(2)O(2)-stimulated NF-kappaB signaling in this process. These data suggest that ERK and ERK-dependent NF-kappaB activation is required for oxidative stress-induced inhibition of osteoblastic differentiation in rabbit BMSC and calvarial osteoblasts.

Lycopene I--effect on osteoclasts: lycopene inhibits basal and parathyroid hormone-stimulated osteoclast formation and mineral resorption mediated by reactive oxygen species in rat bone marrow cultures

Osteoclasts have been shown to produce reactive oxygen species (ROS) that can stimulate bone resorption. We explored the hypothesis that lycopene, the antioxidant carotenoid from tomatoes, can inhibit mineral resorption by inhibiting osteoclast formation and the production of ROS. Cells from bone marrow prepared from rat femur were plated into 16-well calcium phosphate-coated Osteologic Multi-test Slides and cultured in alpha-minimal essential medium supplemented with dexamethasone, beta-glycerophosphate, and ascorbic acid. The cells were treated with varying doses of lycopene in the absence or presence of parathyroid hormone (PTH) at the start of culture and at each medium change (i.e., every 48 hours). On day 8, mineral resorption pits were quantitated. Similar, parallel experiments were carried out in 12-well plastic dishes to assess tartrate-resistant acid phosphatase (TRAP) activity. Results showed that lycopene inhibited TRAP + formation of multinucleated cells in both vehicle- and PTH-treated cultures. Osteoclasts reduced nitroblue tetrazolium (NBT) to purple-colored formazan, indicating the presence of ROS in these cells. The formazan-staining cells were decreased by treatment with 10(-5) M lycopene, indicating that lycopene inhibited the formation of ROS-secreting osteoclasts. In conclusion, we have shown that lycopene inhibits basal and PTH-stimulated osteoclastic mineral resorption and formation of TRAP + multinucleated osteoclasts, as well as the ROS produced by osteoclasts. These findings are novel and may be important in the pathogenesis, treatment, and prevention of osteoporosis.

Lycopene II--effect on osteoblasts: the carotenoid lycopene stimulates cell proliferation and alkaline phosphatase activity of SaOS-2 cells

We explored the possibility that lycopene, a carotenoid that is abundant in tomatoes, has effects on proliferation and differentiation of osteoblasts, the cells responsible for bone formation. Human osteoblast-like osteosarcoma SaOS-2 cells were cultured for 24 hours, after which varying doses of a water-dispersible microemulsion preparation of lycopene or vehicle of the same dilution were added. The cells were further cultured for 24 to 144 hours, and then the cell numbers were counted. Lycopene at 10(-6) and 10(-5) M had significant stimulatory effects on cell numbers, compared with the corresponding vehicle treatment, at all time points from 24 to 144 hours. The effects of lycopene on activity of the differentiation marker alkaline phosphatase activity in the absence or presence of dexamethasone were shown to be dependent on the stage of cell differentiation. This is the first report on the effects of lycopene on osteoblasts of human origin; the results may have important applications in the prevention of osteoporosis.

Nutritional associations with bone loss during the menopausal transition: evidence of a beneficial effect of calcium, alcohol, and fruit and vegetable nutrients and of a detrimental effect of fatty acids

BACKGROUND

The menopausal transition is characterized by rapid bone loss. Few data exist on the role of nutrition.

OBJECTIVE

The objective of the study was to ascertain which dietary factors influence perimenopausal skeletal loss.

DESIGN

A longitudinal study was conducted of 891 women aged 45-55 y at baseline and 50-59 y at follow-up 5-7 y later. Bone mineral density (BMD) was measured by using dual-energy X-ray absorptiometry at the lumbar spine and femoral neck (FN). Nutrient intakes were assessed after the baseline visit and 5 y later, by using the same food-frequency questionnaire.

RESULTS

After adjustment for energy intake and other confounders, higher intakes of calcium were correlated with change in FN BMD (ie, reduced loss) (r = 0.073, P < 0.05), and the intake of modest amounts of alcohol was associated with less lumbar spine bone loss (P < 0.01 for quartile of alcohol intake). Greater FN BMD loss was associated with increased intake of polyunsaturated fatty acids (r = -0.110, P < 0.01), monounsaturated fatty acids (r = -0.069, P < 0.05), retinol (r = -0.067; P < 0.05), and vitamin E (r = -0.110; P < 0.01). The latter 2 nutrients were highly correlated with polyunsaturated fatty acids. For premenopausal women, calcium and nutrients found in fruit and vegetables (vitamin C, magnesium, and potassium) were associated with FN BMD, and calcium, vitamin C, and magnesium were associated with change in FN BMD.

CONCLUSIONS

Although menopausal status and hormone replacement therapy use dominate women's bone health, diet may influence early postmenopausal bone loss. Fruit and vegetable intake may protect against premenopausal bone loss.

The DASH diet and sodium reduction improve markers of bone turnover and calcium metabolism in adults

Dietary strategies to prevent and treat osteoporosis focus on increased intake of calcium and vitamin D. Modification of whole dietary patterns and sodium reduction may also be effective. We examined the effects of two dietary patterns and three sodium levels on bone and calcium metabolism in a randomized feeding study. A total of 186 adults, aged 23-76 y, participated. After a 2-wk run-in period, participants were assigned randomly to diets containing three levels of sodium (50, 100 and 150 mmol/d) to be consumed for 30 d in random order. Serum osteocalcin (OC), C-terminal telopeptide of type I collagen (CTX), fasting serum parathyroid hormone (PTH), urinary sodium, potassium, calcium and cAMP were measured at baseline and at the end of each sodium period. The Dietary Approaches to Stop Hypertension (DASH) diet reduced serum OC by 8-11% and CTX by 16-18% (both P < 0.001). Urinary calcium excretion did not differ between subjects that consumed the DASH and control diets. Reducing sodium from the high to the low level significantly decreased serum OC 0.6 microg/L in subjects that consumed the DASH diet, fasting serum PTH 2.66 ng/L in control subjects and urinary calcium 0.5 mmol/24 h in both groups. There were no consistent effects of the diets or sodium levels on urinary cAMP. In conclusion, the DASH diet significantly reduced bone turnover, which if sustained may improve bone mineral status. A reduced sodium intake reduced calcium excretion in both diet groups and serum OC in the DASH group. The DASH diet and reduced sodium intake may have complementary, beneficial effects on bone health.

A crucial role for thiol antioxidants in estrogen-deficiency bone loss

The mechanisms through which estrogen prevents bone loss are uncertain. Elsewhere, estrogen exerts beneficial actions by suppression of reactive oxygen species (ROS). ROS stimulate osteoclasts, the cells that resorb bone. Thus, estrogen might prevent bone loss by enhancing oxidant defenses in bone. We found that glutathione and thioredoxin, the major thiol antioxidants, and glutathione and thioredoxin reductases, the enzymes responsible for maintaining them in a reduced state, fell substantially in rodent bone marrow after ovariectomy and were rapidly normalized by exogenous 17-beta estradiol. Moreover, administration of N-acetyl cysteine (NAC) or ascorbate, antioxidants that increase tissue glutathione levels, abolished ovariectomy-induced bone loss, while l-buthionine-(S,R)-sulphoximine (BSO), a specific inhibitor of glutathione synthesis, caused substantial bone loss. The 17-beta estradiol increased glutathione and glutathione and thioredoxin reductases in osteoclast-like cells in vitro. Furthermore, in vitro NAC prevented osteoclast formation and NF-kappaB activation. BSO and hydrogen peroxide did the opposite. Expression of TNF-alpha, a target for NF-kappaB and a cytokine strongly implicated in estrogen-deficiency bone loss, was suppressed in osteoclasts by 17-beta estradiol and NAC. These observations strongly suggest that estrogen deficiency causes bone loss by lowering thiol antioxidants in osteoclasts. This directly sensitizes osteoclasts to osteoclastogenic signals and entrains ROS-enhanced expression of cytokines that promote osteoclastic bone resorption.