Effects of dietary nutrients and food groups on bone loss from the proximal femur in men and women in the 7th and 8th decades of age

Vitamin A - discovery, metabolism, receptor signaling and effects on bone mass and fracture susceptibility

The first evidence of the existence of vitamin A was the observation 1881 that a substance present in small amounts in milk was necessary for normal development and life. It was not until more than 100 years later that it was understood that vitamin A acts as a hormone through nuclear receptors. Unlike classical hormones, vitamin A cannot be synthesized by the body but needs to be supplied by the food as retinyl esters in animal products and ß-carotene in vegetables and fruits. Globally, vitamin A deficiency is a huge health problem, but in the industrialized world excess of vitamin A has been suggested to be a risk factor for secondary osteoporosis and enhanced susceptibility to fractures. Preclinical studies unequivocally have shown that increased amounts of vitamin A cause decreased cortical bone mass and weaker bones due to enhanced periosteal bone resorption. Initial clinical studies demonstrated a negative association between intake of vitamin A, as well as serum levels of vitamin A, and bone mass and fracture susceptibility. In some studies, these observations have been confirmed, but in other studies no such associations have been observed. One meta-analysis found that both low and high serum levels of vitamin A were associated with increased relative risk of hip fractures. Another meta-analysis also found that low levels of serum vitamin A increased the risk for hip fracture but could not find any association with high serum levels of vitamin A and hip fracture. It is apparent that more clinical studies, including large numbers of incident fractures, are needed to determine which levels of vitamin A that are harmful or beneficial for bone mass and fracture. It is the aim of the present review to describe how vitamin A was discovered and how vitamin A is absorbed, metabolized and is acting as a ligand for nuclear receptors. The effects by vitamin A in preclinical studies are summarized and the clinical investigations studying the effect by vitamin A on bone mass and fracture susceptibility are discussed in detail.

Associations of the Dietary Magnesium Intake and Magnesium Depletion Score With Osteoporosis Among American Adults: Data From the National Health and Nutrition Examination Survey

Objectives

The study aimed to explore the associations between dietary magnesium (Mg) intake and magnesium depletion score (MDS) among American adults with osteoporosis.

Methods

The continuous data from the National Health and Nutrition Examination Survey 2005–2006, 2007–2008, 2009–2010, 2013–2014, and 2017–2018 were merged to ensure a large and representative sample and a total of 14,566 participants were enrolled for the analysis. The weighted multivariate linear regression model was performed to assess the linear relationship between dietary Mg intake and osteoporosis. Further, the non-linear relationship was also characterized by smooth curve fitting (SCF) and weighted generalized additive model (GAM). In addition, the odds ratios (ORs) and 95% confidence intervals (95% CIs) for associations between the MDS and osteoporosis were assessed by weighted logistic regression models.

Results

After adjusting all covariates, the weighted multivariable linear regression models demonstrated that the dietary Mg intake negatively correlated with osteoporosis, especially in participants aged 55 years or older. In addition, the non-linear relationship characterized by SCF and weighted GAM showed that the dietary Mg intake presented an L-shaped association with osteoporosis among females aged 55 years or older. Moreover, the weighted logistic regression model demonstrated that compared with MDS 0, the OR between MDS ≥3 and osteoporosis was 2.987 (95% CI 1.904, 4.686) in the male-middle intake group. Moreover, compared with MDS 0, the ORs between MDS ≥3 and osteoporosis was 5.666 (95% CI 3.188, 10.069) in the female-low intake group and 1.691 (95% CI 1.394, 2.051) in the female-middle intake group.

Conclusion

The present study indicated that in people with a daily intake of Mg level below the recommended daily intake (RDI), the dietary Mg intake and Mg bioavailability represented by MDS have a negative correlation with osteoporosis. According to the results, the combination of MDS and dietary Mg intake may be more comprehensive and rigorous in screening the population with osteoporosis. Therefore, early monitoring and interventions for osteoporosis may be necessary for those with insufficient dietary Mg intake or high MDS scores.

Impact of magnesium on bone health in older adults: A systematic review and meta-analysis

BACKGROUND

Magnesium plays a key role in bone health and may, therefore, represent an interesting nutrient for the prevention of bone loss and osteoporosis. The aim of this systematic review and meta-analysis was to investigate the impact of magnesium intake from any source on bone mineral density (BMD), bone mineral content (BMC), bone turnover markers, and fracture risk in older adults.

METHODS

A systematic search was conducted using Embase, Medline Ovid and Cochrane Central from database inception to October 2020. All studies that related magnesium intake with bone health outcomes among adults aged ≥60 years were included. Two investigators independently conducted abstract and full-text screenings, data extractions, and risk of bias assessments. Authors were contacted for missing data.

RESULTS

Once 787 records were screened, six cohort studies, one case-control study and five cross-sectional studies were included. Qualitative evaluation demonstrated a positive trend between higher magnesium intake and higher hip and femoral neck BMD. Meta-analysis of four studies showed a significant positive association between magnesium intake and hip BMD (pooled beta: 0.03, 95% CI: 0.01-0.06, p < 0.05).

CONCLUSIONS

This systematic review indicates that a higher magnesium intake may support an increase in hip and femoral neck BMD. Due to limited research no associations with BMD at other sites or fractures were found. There is a need for properly designed cohort studies to determine the association between magnesium intake and bone health in older adults. Next, large and long-term randomized controlled trials in older adults are needed to determine whether an increase in magnesium (supplementation) intake can improve bone health. The combination of several bone nutrients (calcium, vitamin D, protein, magnesium and potentially more) may be needed for the most optimal effect on bone health and to delay or prevent the development of osteoporosis.

Increasing Vegetable Intake Decreases Urinary Acidity and Bone Resorption Marker in Overweight and Obese Adults: An 8-Week Randomized Controlled Trial

BACKGROUND

Controlled intervention trials are needed to confirm a positive association from epidemiological studies between vegetable consumption and bone health.

OBJECTIVE

We investigated whether providing vegetables at the Dietary Guidelines for Americans (DGA) recommended amount affects excretion of acid and calcium in urine and bone turnover markers in serum in adults with low vegetable intake.

METHODS

In total, 102 adults (19 males and 83 females, age 18-65 y, BMI ≥25 kg/m2) consuming ≤1 serving of vegetables (128 g raw leafy or 64 g cooked vegetables) per d were recruited in a 2-arm, parallel, randomized, controlled, and community-based 8-wk feeding intervention trial. The 2 arms included a vegetable intervention (VI) during which participants received extra vegetables (∼270 g/d) and an attention control (CON) group that conducted only the testing visits. Measurements included nutrient intake, plasma carotenoids, and bone-related markers in serum and urine. Differences between CON and VI at week 8 were tested using the ANCOVA with baseline values as a covariate.

RESULTS

Compared with CON, carotenoid intake (mean ± SD) was higher (6.4 ± 3.4 compared with 2.0 ± 1.2 mg/d) (P < 0.01) and dietary potential renal acid load was lower (20 ± 13 compared with 3.4 ± 14 mEq/d) (P < 0.01) in VI. Compared with CON at week 8, urine titratable acid and Mg were 24 and 26% lower, respectively, while urine pH was 3% greater (P < 0.05) and serum C-terminal telopeptide of type I collagen (CTX) was 19% lower in VI. There were no group differences in serum concentrations of propeptide of type 1 procollagen and tartrate-resistant acid phosphatase or urinary excretion of deoxypyridinoline and CTX.

CONCLUSIONS

Consumption of vegetables at the DGA-recommended amount by adults with low vegetable intake potentially benefits bone health. This trial was registered at clinicaltrials.gov as NCT02585102.

Sufficient Plasma Vitamin C Is Related to Greater Bone Mineral Density among Postmenopausal Women from the Boston Puerto Rican Health Study

BACKGROUND

Vitamin C may benefit bone as an antioxidant.

OBJECTIVES

This cross-sectional study evaluated associations between dietary, supplemental, and plasma vitamin C with bone mineral density (BMD) among Puerto Rican adults.

METHODS

Diet was assessed by food-frequency questionnaire (n = 902); plasma vitamin C, measured in fasting blood (n = 809), was categorized as sufficient (≥50 μmol/L), insufficient (20-49 μmol/L), or low (<20 μmol/L). Associations between vitamin C and BMD (measured by DXA) were tested, with false discovery rate correction for multiple comparisons, and interactions by smoking, sex, and estrogen status. Least-squares mean BMDs were compared across tertiles of diet and plasma vitamin C.

RESULTS

Participants' mean age was 59 ± 7 y (range: 46-78 y), 72% were women, mean dietary vitamin C was 95 ± 62 mg/d, and plasma vitamin C ranged from 1.7 to 125 μmol/L. No associations were observed between dietary vitamin C and BMD (P-value range: 0.48-0.96). BMD did not differ by vitamin C supplement use (P-value range: 0.07-0.29). Total femur BMD was higher (P = 0.04) among plasma vitamin C-sufficient participants (mean: 1.06; 95% CI: 1.035, 1.076 g/cm2) compared with low plasma vitamin C participants (1.026; 0.999, 1.052 g/cm2) in adjusted models. Findings at the trochanter were similar (P = 0.04). Postmenopausal women without estrogen therapy, with sufficient plasma vitamin C, showed greater total femur BMD (1.004 ± 0.014 g/cm2) compared to those with low plasma vitamin C (0.955 ± 0.017 g/cm2; P = 0.001). Similar findings were observed at the trochanter (P < 0.001). No significant associations were observed among premenopausal women or those with estrogen therapy or men. Interactions with smoking status were not significant.

CONCLUSIONS

Dietary vitamin C was not associated with BMD. Low plasma vitamin C, compared with sufficiency, was associated with lower hip BMD, particularly among postmenopausal women without estrogen therapy. Future research is needed to determine whether vitamin C status is associated with change in BMD or reduction in fracture risk.

Oxidative Stress and Osteoporosis

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Oxidative stress has been implicated as a causative factor in many disease states, possibly including the diminished bone mineral density in osteoporosis.

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Understanding the effects of oxidative stress on the development of osteoporosis may lead to further research improving preventative and therapeutic measures that can combat this important contributor to morbidity and mortality worldwide.

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A diet rich in whole plant foods with high antioxidant content along with antioxidant-preserving lifestyle changes may improve bone mineral density and reduce the risk of fragility-related fractures. While it is not explicitly clear if antioxidant activity is the effector of this change, the current evidence supports this possibility.

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Supplementation with isolated antioxidants may also provide some osteoprotective benefits, but whole plant food-derived antioxidants potentially have more overall benefits. Larger-scale clinical trials are needed to give credence to definitive clinical recommendations.

Evidence of a Positive Link between Consumption and Supplementation of Ascorbic Acid and Bone Mineral Density

In animal models it has been shown that ascorbic acid (AA) is an essential cofactor for the hydroxylation of proline in collagen synthesis. However, there are still no precise indications regarding the role of AA in maintaining bone health in humans, so the aim of this narrative review was to consider state of the art on correlation between bone mineral density (BMD), AA dietary intake and AA blood levels, and on the effectiveness of AA supplement in humans. This review included 25 eligible studies. Fifteen studies evaluated correlations between AA intake and BMD: eight studies demonstrated a positive correlation between AA dietary intake and BMD in 9664 menopausal women and one significant interaction between effects of AA intake and hormone therapy. These data were also confirmed starting from adolescence (14,566 subjects). Considering studies on AA blood concentration and BMD, there are four (337 patients) that confirm a positive correlation. Regarding studies on supplementation, there were six (2671 subjects), of which one was carried out with AA supplementation exclusively in 994 postmenopausal women with a daily average dose of 745 mg (average period: 12.4 years). BMD values were found to be approximately 3% higher in women who took supplements.

Diet-derived fruit and vegetable metabolites show sex-specific inverse relationships to osteoporosis status

BACKGROUND

The impact of nutrition on the metabolic profile of osteoporosis (OS) is unknown.

OBJECTIVE

Identify biochemical factors driving the association of fruit and vegetable (FV) intakes with OS prevalence using an untargeted metabolomics approach.

DESIGN

Cross-sectional dietary, anthropometric and plasma metabolite data were examined from the Boston Puerto Rican Osteoporosis Study, n = 600 (46-79 yr).

METHODS

Bone mineral density was assessed by DXA. OS was defined by clinical standards. A culturally adapted FFQ assessed usual dietary intake. Principal components analysis (PCA) of 42 FV items created 6 factors. Metabolomic profiles derived from plasma samples were assessed on a commercial platform. Differences in levels of 525 plasma metabolites between disease groups (OS vs no-OS) were compared using logistic regression; and associations with FV intakes by multivariable linear regression, adjusted for covariates. Metabolites significantly associated with OS status or with total FV intake were analyzed for enrichment in various biological pathways using Mbrole 2.0, MetaboAnalyst, and Reactome, using FDR correction of P-values. Correlation coefficients were calculated as Spearman's rho rank correlations, followed by hierarchical clustering of the resulting correlation coefficients using PCA FV factors and sex-specific sets of OS-associated metabolites.

RESULTS

High FV intake was inversely related to OS prevalence (Odds Ratio = 0.73; 95% CI = 0.57, 0.94; P = 0.01). Several biological processes affiliated with the FV-associating metabolites, including caffeine metabolism, carnitines and fatty acids, and glycerophospholipids. Important processes identified with OS-associated metabolites were steroid hormone biosynthesis in women and branched-chain amino acid metabolism in men. Factors derived from PCA were correlated with the OS-associated metabolites, with high intake of dark leafy greens and berries/melons appearing protective in both sexes.

CONCLUSIONS

These data warrant investigation into whether increasing intakes of dark leafy greens, berries and melons causally affect bone turnover and BMD among middle-aged and older adults at risk for osteoporosis via sex-specific metabolic pathways, and how gene-diet interactions alter these sex-specific metabolomic-osteoporosis links. ClinicalTrials.gov Identifier: NCT01231958.

Role of Vitamin C in Osteoporosis Development and Treatment-A Literature Review

Osteoporosis and associated low energy fractures are a significant clinical problem, especially in the elderly population. The occurrence of a hip fracture is associated with significant mortality and a high risk of disability. For this, apart from the treatment of osteoporosis, effective prevention of both the development of the disease and related fractures is extremely important. One aspect of osteoporosis prevention is proper dietary calcium intake and normal vitamin D3 levels. However, there is some evidence for a potential role of vitamin C in osteoporosis and fracture prevention, too. This review aims to summarize the current knowledge about the role of vitamin C in osteoporosis development, prevention and treatment. The PubMed/Medline search on the role of vitamin C in bone metabolism database was performed for articles between 2000 and May 2020. Reports from in vitro and animal studies seem promising. Epidemiological studies also indicate the positive effect of high vitamin C content in the daily diet on bone mineral density. Despite promising observations, there are still few observational and intervention studies and their results do not allow for unequivocal determination of the benefits of high daily intake of vitamin C or its long-term supplementation.

Fruit and vegetable intake and bones: A systematic review and meta-analysis

BACKGROUND

Although intake of fruits and vegetables seemed to have a protective effect on bone metabolism, its effect on fractures remains uncertain.

METHODS

A systematic review of randomized controlled trials (RCTs) and cohort studies (PROSPERO: CRD42016041462) was performed. RCTs and cohort studies that evaluated the combined intake of fruits and vegetables in men and women aged over 50 years were included. We considered fractures as a primary outcome measure. Changes in bone markers were considered as secondary outcomes. The search strategy included the following descriptors: fruit, vegetables, vegetable products, bone and bones, bone fractures, postmenopausal osteoporosis, and osteoporosis. PubMed, Embase, and Cochrane Library were the databases used. The appraisal of the studies was performed by two independent reviewers, and discussed and agreed upon by both examiners. The data extracted from the RCTs and cohort studies were summarized separately. The risks of fractures were combined across studies using random models. Bone resorption marker (CTx) was summarized with standardized mean differences. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) method was used to evaluate the strength of recommendations.

RESULTS

Of the 1,192 studies screened, 13 articles were included in the systematic review and 10 were included in the pooled analysis (6 cohort studies and 4 RCTs). The six cohort studies included in the meta-analysis included a population of 225,062. The pooled hazard ratio (HR) (95% confidence interval (CI)) of the hip in five studies was 0.92 (0.87, 0.98). Its heterogeneity was moderate (I2 = 55.7%, p = 0.060), GRADE (⊕⊕⊕O). Two cohort studies evaluated the risk of any fracture; the HR was 0.90 (95% CI: 0.86-0.96), with aheterogeneity of 24.9% (p = 0.249, GRADE (⊕⊕⊕O)). There was no association between the bone resorption marker CTx and 3 months of fruit and vegetable intake evaluated by four RCTs, GRADE (⊕⊕O O).

CONCLUSION

There was an association between the increase of at least one serving of fruits and vegetables per day and decreases in the risk of fractures. The level of evidence for this association is moderate.

Impact of vitamin C on teriparatide treatment in the improvement of bone mineral density, strength, and quality in vitamin C-deficient rats

Age-related decreases in serum levels of vitamin C (VC) may negatively affect the efficacy of anti-osteoporotic pharmacotherapy. The purpose of this study was to evaluate the effects of VC and teriparatide (TPTD) on bone mineral density (BMD), strength, and quality in VC-deficient osteogenic disorder Shionogi (ODS) rats. Six-month-old female ODS rats were divided into an untreated ODS control group, a VC group, a TPTD group, and a VC + TPTD group, based on the administration of VC and TPTD (n = 10 each). VC was given as 2.0 mg/ml supplemented water. TPTD was administered subcutaneously once a week at 30 µg/kg body weight. After 12 weeks of treatment, BMDs of the femur and lumbar spine, bone strengths of the femoral diaphysis and metaphysis, and cancellous bone quality of proximal tibiae as estimated by Fourier transform infrared spectroscopy (FTIR) were compared between groups. Compared to the ODS control group, the VC group showed significantly higher total femoral BMD, but the TPTD group showed significantly higher femoral and lumbar spinal BMD, maximum load of femoral metaphysis, and hydroxyapatite (HA) crystallinity by FTIR (p < 0.05). In addition to the increases shown in the TPTD group, the VC + TPTD group also showed significantly higher stiffness of the femoral diaphysis and breaking energy of the femoral metaphysis compared to the ODS control group (p < 0.05). These results indicated that TPTD alone increased cancellous/cortical BMD and cancellous bone strength with improvement of HA crystallinity in ODS rats, but addition of VC supplementation further improved cortical bone strength.

Vitamin C intake in relation to bone mineral density and risk of hip fracture and osteoporosis: a systematic review and meta-analysis of observational studies

We aimed to systematically review available data on the association between vitamin C intake and bone mineral density (BMD), as well as risk of fractures and osteoporosis, and to summarise this information through a meta-analysis. Previous studies on vitamin C intake in relation to BMD and risk of fracture and osteoporosis were selected through searching PubMed, Scopus, ISI Web of Science and Google Scholar databases before February 2017, using MeSH and text words. To pool data, either a fixed-effects model or a random-effects model was used, and for assessing heterogeneity, Cochran's Q and I 2 tests were used. Subgroup analysis was applied to define possible sources of heterogeneity. Greater dietary vitamin C intake was positively associated with BMD at femoral neck (pooled r 0·18; 0·06, 0·30) and lumbar spine (pooled r 0·14; 95 % CI 0·06, 0·22); however, significant between-study heterogeneity was found at femoral neck: I 2=87·6 %, P heterogeneity<0·001. In addition, we found a non-significant association between dietary vitamin C intake and the risk of hip fracture (overall relative risk=0·74; 95 % CI 0·51, 1·08). Significant between-study heterogeneity was found (I 2=79·1 %, P heterogeneity<0·001), and subgroup analysis indicated that study design, sex and age were the main sources of heterogeneity. Greater dietary vitamin C intake was associated with a 33 % lower risk of osteoporosis (overall relative risk=0·67; 95 % CI 0·47, 0·94). Greater dietary vitamin C intake was associated with a lower risk of hip fracture and osteoporosis, as well as higher BMD, at femoral neck and lumbar spine.

Dietary vitamin C intake and the risk of hip fracture: a dose-response meta-analysis

The meta-analysis suggested that dietary vitamin C was statistically inversely associated with the risk of hip fracture (overall OR = 0.73, 95% CI = 0.55-0.97, I ² = 69.1%) and with the increase of 50 mg/day vitamin C intake, the risk of hip fracture will reduce by 5% (OR = 0.95, 95% CI 0.91-1.00, P = 0.05).

INTRODUCTION

Previous studies had inconsistent findings regarding the association between vitamin C intake and the risk of hip fracture. Therefore, we conducted a meta-analysis to evaluate the association of dietary vitamin C intake and the risk of hip fracture.

METHODS

Relevant studies were identified by searching PubMed, Embase, and Web of Science up to December 2016. Additional articles were identified from reviewing the reference lists of relevant articles. The summary relative risks (RRs) or odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by random effects model. Funnel plot and Egger's test were used to test publication bias.

RESULTS

The total six articles containing 7908 controls and 2899 cases of hip fracture were included in this meta-analysis. By comparing the highest versus the lowest categories of vitamin C intake, we found that dietary vitamin C was statistically correlated with the risk of hip fracture [overall OR = 0.73, 95% CI = 0.55-0.97, I ² = 69.1%]. A linear dose-response association showed that the increase with vitamin C intake of 50 mg/day statistically reduced by 5% (OR = 0.95, 95% CI 0.91-1.00, P = 0.05) the risk of hip fracture.

CONCLUSIONS

In conclusion, the results of current meta-analysis strongly support that increasing dietary vitamin C intake can decrease the risk of hip fracture. In order to verify the association of vitamin C intake and hip fracture risk, further well-designed largely randomized controlled trials (RCTs) are needed.

Dietary Magnesium May Be Protective for Aging of Bone and Skeletal Muscle in Middle and Younger Older Age Men and Women: Cross-Sectional Findings from the UK Biobank Cohort

Although fragility fractures, osteoporosis, sarcopenia, and frailty are becoming more prevalent in our aging society the treatment options are limited and preventative strategies are needed. Despite magnesium being integral to bone and muscle physiology, the relationship between dietary magnesium and skeletal muscle and bone health has not been investigated concurrently to date. We analysed cross-sectional associations between dietary magnesium and skeletal muscle mass (as fat free mass—FFM), grip strength, and bone density (BMD) in 156,575 men and women aged 39–72 years from the UK Biobank cohort. FFM was measured with bioelectrical impedance and was expressed as the percentage of body weight (FFM%) or as divided by body mass index (FFM_BMI). Adjusted mean grip strength, FFM%, FFM_BMI, and BMD were calculated according to quintiles of dietary magnesium, while correcting for covariates. Significant inter-quintile differences across intakes of magnesium existed in men and women, respectively, of 1.1% and 2.4% for grip strength, 3.0% and 3.6% for FFM%, 5.1% and 5.5% for FFM_BMI, and 2.9% and 0.9% for BMD. These associations are as great or greater than annual measured losses of these musculoskeletal outcomes, indicating potential clinical significance. Our study suggests that dietary magnesium may play a role in musculoskeletal health and has relevance for population prevention strategies for sarcopenia, osteoporosis, and fractures.

Vegetable and Fruit Intake and Fracture-Related Hospitalisations: A Prospective Study of Older Women

The importance of vegetable and fruit intakes for the prevention of fracture in older women is not well understood. Few studies have explored vegetable and fruit intakes separately, or the associations of specific types of vegetables and fruits with fracture hospitalisations. The objective of this study was to examine the associations of vegetable and fruit intakes, separately, and specific types of vegetables and fruits with fracture-related hospitalisations in a prospective cohort of women aged ≥70 years. Vegetable and fruit intakes were assessed at baseline (1998) in 1468 women using a food frequency questionnaire. The incidence of fracture-related hospitalisations over 14.5 years of follow-up was determined using the Hospital Morbidity Data Collection, linked via the Western Australian Data Linkage System. Fractures were identified in 415 (28.3%) women, of which 158 (10.8%) were hip fractures. Higher intakes of vegetables, but not fruits, were associated with lower fracture incidence. In multivariable-adjusted models for vegetable types, cruciferous and allium vegetables were inversely associated with all fractures, with a hazard ratio (HR) (95% confidence interval) of 0.72 (0.54, 0.95) and 0.66 (0.49, 0.88), respectively, for the highest vs. lowest quartiles. Increasing vegetable intake, with an emphasis on cruciferous and allium vegetables, may prevent fractures in older postmenopausal women.

Greater Intake of Fruit and Vegetables Is Associated with Greater Bone Mineral Density and Lower Osteoporosis Risk in Middle-Aged and Elderly Adults

Objective

A few studies have suggested that the consumption of fruit and vegetables (FV) may benefit bone health, but limited data are available in Asian subjects. We examined the association between FV intake and bone mineral density (BMD) and osteoporosis in Chinese adults.

Methods

This population-based cross-sectional study involved 2083 women and 1006 men aged 40–75 years in Guangzhou, China. Habitual dietary data was collected from a 79-item food frequency questionnaire by face-to-face interviews. The BMD was measured for the whole body (WB), lumbar spine (LS), total hip (TH) and femur neck (FN) with dual-energy X-ray absorptiometry.

Results

After adjustment for potential covariates, we observed dose-dependent associations between total FV intake and BMD and osteoporosis risk. The mean BMD was higher in tertile 3 vs. tertile 1 by 1.33% (TH) and 1.31% (FN) for FV, and 1.10% (WB), 1.57% (TH), and 2.05% (FN) for fruit (all P-trends < 0.05). Significant beneficial associations with BMD at some sites were also found in most fruit categories but not in total vegetables or their subgroups. The odds ratios (95% confidence interval) of osteoporosis (T-score ≤ −2.5) in tertile 3 (vs. 1) were 0.73 (0.58–0.92), 0.37 (0.22–0.60), and 0.71 (0.52–0.97) for FV; 0.82 (0.66–1.03), 0.48 (0.30–0.77) and 0.89 (0.61–1.12) for fruit; and 0.80 (0.64–1.01), 0.57 (0.35–0.92) and 0.76 (0.55–1.05) for vegetables at the LS, TH, and FN, respectively. The favorable association between FV intake and the occurrence of osteoporosis was evident only in subjects with lower BMI (<24.0 kg/m², P-trends < 0.05).

Conclusions

Greater intake of FV was independently associated with a higher BMD and a lower presence of osteoporosis in middle-aged and elderly Chinese subjects with lower BMI. Fruit tended to have more contribution to the favorable association than vegetables.

Bone Degeneration and Its Recovery in SMP30/GNL-Knockout Mice

Senescence marker protein-30 (SMP30) decreases androgen-independently with aging and is a lactone-hydrolyzing enzyme gluconolactonase (GNL) that is involved in vitamin C biosynthesis. In the present study, bone properties of SMP30/GNL knockout (KO) mice with deficiency in vitamin C synthesis were investigated to reveal the effects of SMP30/GNL and exogenous vitamin C supplementation on bone formation. Mineral content (BMC) and mineral density (BMD) of the mandible and femur of SMP30/GNL KO and wild-type mice at 2 and 3 months of age with or without vitamin C supplementation were measured by dual-energy X-ray absorptiometry. Body and bone weight of both age groups decreased and became significantly lower than those of wild-type mice. The bones of SMP30/GNL KO mice were rough and porous, with BMC and BMD significantly below wild-type. Oral supplementation with vitamin C eliminated differences in body weight, bone weight, BMC, and BMD between SMP30/GNL KO and wild-type mice at each age. These results indicate that bone degeneration in SMP30/GNL KO mice was caused by lack of vitamin C, and that this mouse strain is an appropriate model for bone metabolism in humans, which have no ability to synthesize vitamin C.

Dietary magnesium intake, bone mineral density and risk of fracture: a systematic review and meta-analysis

Dietary magnesium intake has been related to osteoporosis and risk of fractures in earlier studies; however, findings were conflicting. This meta-analysis indicated that high magnesium intake was not associated with increased risk of fracture; however, a positive marginally significant correlation was found between magnesium intake and bone mineral density (BMD) in total hip as well as in femoral neck. Although there is some evidence on the association between magnesium intake, BMD and fractures, no previous study has summarized findings in this regard. We aimed to systematically review the current evidence on this association and to perform a meta-analysis of observational studies. We searched MEDLINE, Scopus, EMBASE and Google Scholar up to January 2015 for studies that examined the relationship between magnesium intake and BMD or fracture. Studies that had reported correlation coefficients between magnesium intake and BMD or those that reported odds ratios (ORs) or relative risks (RRs) for risk of fracture in different sites were included. In total, 12 studies were included in the meta-analysis. We found that high intakes of magnesium were not significantly associated with risk of total hip fracture (summary effect size 1.92; 95 % CI 0.81, 4.55) or total fractures (1.01; 0.94-1.07). Combining four effect sizes, a positive marginally significant correlation was observed between magnesium intake and total BMD (pooled r 0.16; 95 % CI 0.001, 032). Based on nine effect sizes, we found a marginally significant association between magnesium intake and femoral neck BMD (0.14; 0.001, 0.28). However, no significant correlation was found between magnesium intake and BMD in lumbar spine (0.09; -0.01, 0.19). We found that high intakes of magnesium were not associated with increased risk of hip and total fractures. There was a positive marginally significant correlation between magnesium intake and BMD in femoral neck and total hip. No significant correlations were observed between magnesium intake and BMD in lumbar spine.

The role of vitamin A and retinoic acid receptor signaling in post-natal maintenance of bone

Vitamin A and retinoid derivatives are recognized as morphogens that govern body patterning and skeletogenesis, producing profound defects when in excess. In post-natal bone, both high and low levels of vitamin A are associated with poor bone heath and elevated risk of fractures. Despite this, the precise mechanism of how retinoids induce post-natal bone changes remains elusive. Numerous studies have been performed to discover how retinoids induce these changes, revealing a complex morphogenic regulation of bone through interplay of different cell types. This review will discuss the direct and indirect effects of retinoids on mediators of bone turnover focusing on differentiation and activity of osteoblasts and osteoclasts and explains why some discrepancies in this field have arisen. Importantly, the overall effect of retinoids on the skeleton is highly site-specific, likely due to differential regulation of osteoblasts and osteoclasts at trabecular vs. cortical periosteal and endosteal bone surfaces. Further investigation is required to discover the direct gene targets of retinoic acid receptors (RARs) and molecular mechanisms through which these changes occur. A clear role for RARs in regulating bone is now accepted and the therapeutic potential of retinoids in treating bone diseases has been established.

Cross-sectional and prospective associations between dietary and plasma vitamin C, heel bone ultrasound, and fracture risk in men and women in the European Prospective Investigation into Cancer in Norfolk cohort

BACKGROUND

Vitamin C sufficiency may help prevent osteoporosis and fractures by mediating osteoclastogenesis, osteoblastogenesis, and bone collagen synthesis.

OBJECTIVE

We determined whether dietary intakes and plasma concentrations of vitamin C were associated with a heel ultrasound and hip and spine fracture risks in older men and women.

DESIGN

Participants were recruited from the European Prospective Investigation into Cancer in Norfolk study with 7-d diet diary estimates of vitamin C intake and plasma concentrations. A random subset (4000 of 25,639 subjects) was available for the cross-sectional (ultrasound) study of broadband ultrasound attenuation (BUA) and velocity of sound (VOS), which were determined during the second health examination. The prospective (fracture) study was a case-cohort sample of all participants with a fracture up to March 2009 and the random subset (n = 5319). ANCOVA-determined associations between quintiles of vitamin C intake and plasma status with adjusted BUA and VOS and adjusted Prentice-weighted Cox proportional HRs were calculated for fracture risk.

RESULTS

Women were 58% of the population (39-79 y old), and the median follow-up was 12.6 y (range: 0-16 y). Positive associations across all quintiles of vitamin C intake but not plasma status were significant for VOS in men (β = 2.47 m/s, P = 0.008) and BUA in women (β = 0.82 dB/MHz, P = 0.004). Vitamin C intake was not associated with fracture risk, but there was an inverse association with plasma concentrations in men, with quintile 4 having significantly lower risks of hip fractures (HR: 0.35; 95% CI: 0.16, 0.80) and spine fractures (HR: 0.26; 95% CI: 0.10, 0.69) than quintile 1.

CONCLUSIONS

Higher vitamin C intake was significantly associated with higher heel ultrasound measures in men and women, and higher plasma vitamin C concentrations were significantly associated with reduced fracture risk in men only. Our findings that vitamin C intake and status were inconsistently associated with bone health variables suggest that additional research is warranted.

The Roles and Mechanisms of Actions of Vitamin C in Bone: New Developments

Vitamin C is an important antioxidant and cofactor that is involved in the regulation of development, function, and maintenance of several cell types in the body. Deficiencies in vitamin C can lead to conditions such as scurvy, which, among other ailments, causes gingivia, bone pain, and impaired wound healing. This review examines the functional importance of vitamin C as it relates to the development and maintenance of bone tissues. Analysis of several epidemiological studies and genetic mouse models regarding the effect of vitamin C shows a positive effect on bone health. Overall, vitamin C exerts a positive effect on trabecular bone formation by influencing expression of bone matrix genes in osteoblasts. Recent studies on the molecular pathway for vitamin C actions that include direct effects of vitamin C on transcriptional regulation of target genes by influencing the activity of transcription factors and by epigenetic modification of key genes involved in skeletal development and maintenance are discussed. With an understanding of mechanisms involved in the uptake and metabolism of vitamin C and knowledge of precise molecular pathways for vitamin C actions in bone cells, it is possible that novel therapeutic strategies can be developed or existing therapies can be modified for the treatment of osteoporotic fractures.

Favorable effect of dietary vitamin C on bone mineral density in postmenopausal women (KNHANES IV, 2009): discrepancies regarding skeletal sites, age, and vitamin D status

Dietary vitamin C intake showed significant positive associations with BMD in postmenopausal women, especially with vitamin D deficiency.

INTRODUCTION

Although there is a positive role of vitamin C in osteoblastogenesis, debate remains about the contribution of vitamin C to bone mineral density (BMD) in humans.

METHODS

Data were derived from the Fourth Korean National Health and Nutrition Examination Survey. Dietary information was assessed using a 24-h dietary recall questionnaire. BMD was measured by dual-energy X-ray absorptiometry at the lumbar and hip.

RESULTS

A total of 1,196 postmenopausal women aged 50 years and older were stratified into tertiles by daily dietary vitamin C intake. After adjusting for traditional confounders, dietary vitamin C intake tertile was significantly positively associated with BMD at all sites (R = 0.513 for lumbar spine (LS) and R = 0.657 for femoral neck (FN), P < 0.05 for each). The subjects with osteoporosis had significantly lower dietary vitamin C intake than did subjects without osteoporosis (74.4 ± 66.2 vs 94.1 ± 78.6 mg/day for LS and 65.5 ± 56.6 vs 94.3 ± 79.2 mg/day for FN, respectively, P < 0.001). The multiple-adjusted odds ratio for osteoporosis for dietary vitamin C <100 mg/day was 1.790 (95 % CI 1.333-2.405, P < 0.001). However, the significant association between vitamin C intake and BMD was only observed in subjects with vitamin D deficiency and aged 50-59 years or >70 years.

CONCLUSION

Dietary vitamin C intake was positively associated with BMD in postmenopausal women, and inadequate vitamin C intake could increase the risk of osteoporosis.

Rates of and risk factors for trabecular and cortical BMD loss in middle-aged and elderly African-ancestry men

Low trabecular (Tb) and cortical (Ct) volumetric BMD (vBMD) are related to increased fracture risk, but little is known about the patterns and correlates of Tb and Ct vBMD loss with aging. We examined the rates of change in total, Tb.vBMD, and Ct.vBMD at the radius and tibia, and identified factors associated with vBMD loss among 1569 men of African descent aged 40 years and older. Quantitative computed tomography was used to measure vBMD 6 years apart. The annualized rate of loss in Tb.vBMD was significant at the radius (-0.047%/yr, p = 0.016) but not at the tibia. At the radius, a significant loss of Tb.vBMD was observed in men aged 40 to 49 years that appeared to be attenuated and not statistically significant among older age men. In contrast, the decline in Ct.vBMD was similar at both skeletal sites (-0.254 to -0.264%/yr, p < 0.0001) and was consistent across all age groups. Positive associations were found for vBMD changes with body weight (all but radius Ct.vBMD) and diabetes (Ct.vBMD only), whereas negative associations were found with hypertension (all but radius Tb.vBMD), smoking (Ct.vBMD only), and androgen deprivation therapy (cortical vBMD only). Trabecular and cortical vBMD loss appears to follow different patterns among middle- and older-aged men of African ancestry. Factors associated with the decline in vBMD also varied by compartment and anatomical site. Additional studies are needed to better understand the physiological mechanisms underlying early BMD loss among African-ancestry men.

Building healthy bones throughout life: an evidence-informed strategy to prevent osteoporosis in Australia

Osteoporosis imposes a tremendous burden on Australia: 1.2 million Australians have osteoporosis and 6.3 million have osteopenia. In the 2007–08 financial year, 82 000 Australians suffered fragility fractures, of which > 17 000 were hip fractures. In the 2000–01 financial year, direct costs were estimated at $1.9 billion per year and an additional $5.6 billion on indirect costs. Osteoporosis was designated a National Health Priority Area in 2002; however, implementation of national plans has not yet matched the rhetoric in terms of urgency. Building healthy bones throughout life, the Osteoporosis Australia strategy to prevent osteoporosis throughout the life cycle, presents an evidence-informed set of recommendations for consumers, health care professionals and policymakers. The strategy was adopted by consensus at the Osteoporosis Australia Summit in Sydney, 20 October 2011. Primary objectives throughout the life cycle are: to maximise peak bone mass during childhood and adolescence to prevent premature bone loss and improve or maintain muscle mass, strength and functional capacity in healthy adults to prevent and treat osteoporosis in order to minimise the risk of suffering fragility fractures, and reduce falls risk, in older people. The recommendations focus on three affordable and important interventions — to ensure people have adequate calcium intake, vitamin D levels and appropriate physical activity throughout their lives. Recommendations relevant to all stages of life include: daily dietary calcium intakes should be consistent with Australian and New Zealand guidelines serum levels of vitamin D in the general population should be above 50nmol/L in winter or early spring for optimal bone health regular weight-bearing physical activity, muscle strengthening exercises and challenging balance/mobility activities should be conducted in a safe environment.

Retinoid receptors in bone and their role in bone remodeling

Vitamin A (retinol) is a necessary and important constituent of the body which is provided by food intake of retinyl esters and carotenoids. Vitamin A is known best for being important for vision, but in addition to the eye, vitamin A is necessary in numerous other organs in the body, including the skeleton. Vitamin A is converted to an active compound, all-trans-retinoic acid (ATRA), which is responsible for most of its biological actions. ATRA binds to intracellular nuclear receptors called retinoic acid receptors (RARα, RARβ, RARγ). RARs and closely related retinoid X receptors (RXRα, RXRβ, RXRγ) form heterodimers which bind to DNA and function as ligand-activated transcription factors. It has been known for many years that hypervitaminosis A promotes skeleton fragility by increasing osteoclast formation and decreasing cortical bone mass. Some epidemiological studies have suggested that increased intake of vitamin A and increased serum levels of retinoids may decrease bone mineral density and increase fracture rate, but the literature on this is not conclusive. The current review summarizes how vitamin A is taken up by the intestine, metabolized, stored in the liver, and processed to ATRA. ATRA's effects on formation and activity of osteoclasts and osteoblasts are outlined, and a summary of clinical data pertaining to vitamin A and bone is presented.

Is there a role for vitamin C in preventing osteoporosis and fractures? A review of the potential underlying mechanisms and current epidemiological evidence

Osteoporosis and related fractures are a major global health issue, but there are few preventative strategies. Previously reported associations between higher intakes of fruits and vegetables and skeletal health have been suggested to be partly attributable to vitamin C. To date, there is some evidence for a potential role of vitamin C in osteoporosis and fracture prevention but an overall consensus of published studies has not yet been drawn. The present review aims to provide a summary of the proposed underlying mechanisms of vitamin C on bone and reviews the current evidence in the literature, examining a potential link between vitamin C intake and status with osteoporosis and fractures. The Bradford Hill criteria were used to assess reported associations. Recent animal studies have provided insights into the involvement of vitamin C in osteoclastogenesis and osteoblastogenesis, and its role as a mediator of bone matrix deposition, affecting both the quantity and quality of bone collagen. Observational studies have provided some evidence for this in the general population, showing positive associations between dietary vitamin C intake and supplements and higher bone mineral density or reduced fracture risk. However, previous intervention studies were not sufficiently well designed to evaluate these associations. Epidemiological data are particularly limited for vitamin C status and for fracture risk and good-quality randomised controlled trials are needed to confirm previous epidemiological findings. The present review also highlights that associations between vitamin C and bone health may be non-linear and further research is needed to ascertain optimal intakes for osteoporosis and fracture prevention.

Dietary protein's and dietary acid load's influence on bone health

A variety of genetic, mechano-response-related, endocrine-metabolic, and nutritional determinants impact bone health. Among the nutritional influences, protein intake and dietary acid load are two of the factors most controversially discussed. Although in the past high protein intake was often assumed to exert a primarily detrimental impact on bone mass and skeletal health, the majority of recent studies indicates the opposite and suggests a bone-anabolic influence. Studies examining the influence of alkalizing diets or alkalizing supplement provision on skeletal outcomes are less consistent, which raises doubts about the role of acid-base status in bone health. The present review critically evaluates relevant key issues such as acid-base terminology, influencing factors of intestinal calcium absorption, calcium balance, the endocrine-metabolic milieu related to metabolic acidosis, and some methodological aspects of dietary exposure and bone outcome examinations. It becomes apparent that for an adequate identification and characterization of either dietary acid load's or protein's impact on bone, the combined assessment of both nutritional influences is necessary.

Bone nutrients for vegetarians

The process of bone mineralization and resorption is complex and is affected by numerous factors, including dietary constituents. Although some dietary factors involved in bone health, such as calcium and vitamin D, are typically associated with dairy products, plant-based sources of these nutrients also supply other key nutrients involved in bone maintenance. Some research suggests that vegetarian diets, especially vegan diets, are associated with lower bone mineral density (BMD), but this does not appear to be clinically significant. Vegan diets are not associated with an increased fracture risk if calcium intake is adequate. Dietary factors in plant-based diets that support the development and maintenance of bone mass include calcium, vitamin D, protein, potassium, and soy isoflavones. Other factors present in plant-based diets such as oxalic acid and phytic acid can potentially interfere with absorption and retention of calcium and thereby have a negative effect on BMD. Impaired vitamin B-12 status also negatively affects BMD. The role of protein in calcium balance is multifaceted. Overall, calcium and protein intakes in accord with Dietary Reference Intakes are recommended for vegetarians, including vegans. Fortified foods are often helpful in meeting recommendations for calcium and vitamin D. Plant-based diets can provide adequate amounts of key nutrients for bone health.

Protective effects of dietary carotenoids on risk of hip fracture in men: the Singapore Chinese Health Study

Experimental and epidemiologic data suggest that carotenoids in vegetables and fruits may benefit bone health due to their antioxidant properties. The relationship between dietary total and specific carotenoids, as well as vegetables and fruits, and risk of hip fracture was examined among Chinese in Singapore. We used data from the Singapore Chinese Health Study, a prospective cohort of 63,257 men and women who were of ages 45 to 74 years between 1993 and 1998. At recruitment, subjects were interviewed on lifestyle factors and medical history. Usual diet was measured using a validated food frequency questionnaire. During a mean follow-up of 9.9 years, we identified 1630 hip fracture incident cases. Among men, consumption of vegetables was associated with lower hip fracture risk. Similarly, dietary total carotenoids and specific carotenoids, α-carotene, β-carotene, and lutein/zeaxanthin were inversely associated with hip fracture risk. Compared to men in the lowest quartile of nutrient density, men in the highest quartile had statistically significant 26% to 39% risk reduction (all p for trend <0.05). When stratified by body mass index (BMI), the greatest protective effects of total vegetables and carotenoids were found in men with BMI <20 kg/m(2) (p for trend ≤0.004). There was no association between dietary carotenoids or vegetables/fruits and hip fracture risk among women. This study suggests that adequate intake of vegetables may reduce risk of osteoporotic fractures among elderly men and that the antioxidant effects of carotenoids may counteract the mechanism of osteoporosis related to leanness.

Vitamin a metabolism, action, and role in skeletal homeostasis

Vitamin A (retinol) is ingested as either retinyl esters or carotenoids and metabolized to active compounds such as 11-cis-retinal, which is important for vision, and all-trans-retinoic acid, which is the primary mediator of biological actions of vitamin A. All-trans-retinoic acid binds to retinoic acid receptors (RARs), which heterodimerize with retinoid X receptors. RAR-retinoid X receptor heterodimers function as transcription factors, binding RAR-responsive elements in promoters of different genes. Numerous cellular functions, including bone cell functions, are mediated by vitamin A; however, it has long been recognized that increased levels of vitamin A can have deleterious effects on bone, resulting in increased skeletal fragility. Bone mass is dependent on the balance between bone resorption and bone formation. A decrease in bone mass may be caused by either an excess of resorption or decreased bone formation. Early studies indicated that the primary skeletal effect of vitamin A was to increase bone resorption, but later studies have shown that vitamin A can not only stimulate the formation of bone-resorbing osteoclasts but also inhibit their formation. Effects of vitamin A on bone formation have not been studied in as great a detail and are not as well characterized as effects on bone resorption. Several epidemiological studies have shown an association between vitamin A, decreased bone mass, and osteoporotic fractures, but the data are not conclusive because other studies have found no associations, and some studies have suggested that vitamin A primarily promotes skeletal health. In this presentation, we have summarized how vitamin A is absorbed and metabolized and how it functions intracellularly. Vitamin A deficiency and excess are introduced, and detailed descriptions of clinical and preclinical studies of the effects of vitamin A on the skeleton are presented.

Greater intake of fruit and vegetables is associated with a lower risk of osteoporotic hip fractures in elderly Chinese: a 1:1 matched case-control study

In this case-control study, we examined the relationship between the consumption of fruit and vegetables and risk of hip fractures in 646 pairs of incident cases and controls in elderly Chinese. We found that greater consumption of both fruit and vegetables in men and vegetables in women was associated with a lower risk of osteoporotic hip fractures in elderly Chinese.

INTRODUCTION

The association between fruit and vegetable consumption and the risk of osteoporotic fractures remains controversial due to limited published evidence. The purpose of this study was to determine whether consuming fruits and vegetables has a protective effect against hip fractures.

METHODS

Between January 2008 and December 2012, 646 (162 males, 484 females) incident cases (70.9 ± 6.8 years) of hip fractures were enrolled from five hospitals, with 646 sex- and age-matched (±3 years) controls (70.7 ± 6.8 years) from hospitals or the community. Face-to-face interviews were conducted to assess habitual dietary intakes using a 79-item food frequency questionnaire and various covariates by structured questionnaires.

RESULTS

Multivariate conditional logistic regression analyses showed dose-dependent inverse correlations between the intake of total fruit (p-trend = 0.014), total vegetables (p-trend <0.001), fruits and vegetables combined (p-trend < 0.001) and the risk of hip fractures after adjustment for sociodemographic characteristics, dietary factors and other potential confounders. The adjusted odds ratios (95% confidence interval) for hip fractures in the top quartiles (vs. the lowest quartiles) for the intake of fruits, vegetables and the combination of fruits and vegetables were 0.53 (0.32-0.87), 0.37 (0.23-0.60) and 0.25 (0.15-0.41), respectively. Stratified analyses showed that the benefits remained significant in males (p = 0.001) but not in females (p = 0.210) (p-interaction 0.045). Among the subcategories of fruits and vegetables, similar associations were observed for all subgroups except light-coloured fruits.

CONCLUSIONS

Our findings suggest that greater consumption of both fruits and vegetables in men and vegetables in women may decrease the risk of osteoporotic hip fractures in elderly Chinese.

Predictors of the rate of BMD loss in older men: findings from the CHAMP study

Though bone loss tends to accelerate with age there are modifiable factors that may influence the rate of bone loss even in very old men.

INTRODUCTION

The aim of this 2-year longitudinal study was to examine potential predictors of change in total hip bone mineral density (BMD) in older men.

METHODS

The Concord Health and Ageing in Men Project is a population-based study in Sydney, Australia. For this study, 1,122 men aged 70-97 years had baseline and follow-up measures of total hip BMD measured with dual X-ray absorptiometry. Data about mobility, muscle strength, balance, medication use, cognition, medical history and lifestyle factors were collected using questionnaires and clinical assessments. Serum 25-hydroxyvitamin D [25(OH)D] was also measured. Multivariate linear regression models were used to assess relationships between baseline predictors and change in BMD.

RESULTS

Over a mean of 2.2 years, there was a mean annualised loss of total hip BMD of 0.006 g/cm(2)/year (0.6 %) and hip BMC of 0.14 g/year (0.3 %). Annual BMD loss accelerated with increasing age, from 0.4 % in men aged between 70 and 75 years, to 1.2 % in men aged 85+ years. In multivariate regression models, predictors of faster BMD loss were anti-androgen, thiazolidinedione and loop-diuretic medications, kidney disease, poor dynamic balance, larger hip bone area, older age and lower serum 25(OH)D. Factors associated with attenuated bone loss were walking for exercise and use of beta-blocker medications. Change in BMD was not associated with baseline BMD, smoking, alcohol consumption, BMI, frailty, or osteoarthritis.

CONCLUSION

There was considerable variation in the rate of hip bone loss in older men. Walking, better balance and beta blockers may attenuate the acceleration of BMD loss that occurs with age.

Skeletal effects of nutrients and nutraceuticals, beyond calcium and vitamin D

There is a need to understand the role of nutrition, beyond calcium and vitamin D, in the treatment and prevention of osteoporosis in adults. Results regarding soy compounds on bone density and bone turnover are inconclusive perhaps due to differences in dose and composition or in study population characteristics. The skeletal benefit of black cohosh and red clover are unknown. Dehydroepiandrosterone (DHEA) use may benefit elderly individuals with low serum dehydroepiandrosterone-sulfate levels, but even in this group, there are inconsistent benefits to bone density (BMD). Higher fruit and vegetable intakes may relate to higher BMD. The skeletal benefit of flavonoids, carotenoids, omega-3-fatty acids, and vitamins A, C, E and K are limited to observational data or a few clinical trials, in some cases investigating pharmacologic doses. Given limited data, it would be better to get these nutrients from fruits and vegetables. Potassium bicarbonate may improve calcium homeostasis but with little impact on bone loss. High homocysteine may relate to fracture risk, but the skeletal benefit of each B vitamin is unclear. Magnesium supplementation is likely only required in persons with low magnesium levels. Data are very limited for the role of nutritional levels of boron, strontium, silicon and phosphorus in bone health. A nutrient rich diet with adequate fruits and vegetables will generally meet skeletal needs in healthy individuals. For most healthy adults, supplementation with nutrients other than calcium and vitamin D may not be required, except in those with chronic disease and the frail elderly.

Bone mineral density, polyphenols and caffeine: a reassessment

Several studies have shown beneficial associations between tea consumption and bone mineral density (BMD) and fracture risk. Current investigations into potential mechanisms of benefit are focused upon the F and polyphenol components of tea. However, previous studies have pointed towards caffeine consumption as a potential risk factor for low BMD and high fracture risk. Tea, therefore, represents an interesting paradox as a mildly caffeinated beverage that may enhance bone health. Fruit and vegetable intake has also been associated with BMD, and it is now apparent that several fruit and vegetable components, including polyphenols, may contribute positively to bone health. Evidence surrounding the function(s) of polyphenol-rich foods in bone health is examined, along with more recent studies challenging the relevance of caffeine consumption to in vivo Ca balance. Plant foods rich in polyphenols such as tea, fruit and vegetables, as significant factors in a healthy diet and lifestyle, may have positive roles in bone health, and the negative role of caffeine may have been overestimated. The present review covers evidence of dietary mediation in positive and negative aspects of bone health, in particular the roles of tea, fruit and vegetables, and of caffeine, flavonoids and polyphenols as components of these foods. Since the deleterious effects of caffeine appear to have been overstated, especially in respect of the positive effects of flavonoids, it is concluded that a reassessment of the role of caffeinated beverages may be necessary.

Critical review: vegetables and fruit in the prevention of chronic diseases

BACKGROUND

Vegetables and fruit provide a significant part of human nutrition, as they are important sources of nutrients, dietary fibre, and phytochemicals. However, it is uncertain whether the risk of certain chronic diseases can be reduced by increased consumption of vegetables or fruit by the general public, and what strength of evidence has to be allocated to such an association.

METHODS

Therefore, a comprehensive analysis of the studies available in the literature and the respective study results has been performed and evaluated regarding obesity, type 2 diabetes mellitus, hypertension, coronary heart disease (CHD), stroke, cancer, chronic inflammatory bowel disease (IBD), rheumatoid arthritis (RA), chronic obstructive pulmonary disease (COPD), asthma, osteoporosis, eye diseases, and dementia. For judgement, the strength of evidence for a risk association, the level of evidence, and the number of studies were considered, the quality of the studies and their estimated relevance based on study design and size.

RESULTS

For hypertension, CHD, and stroke, there is convincing evidence that increasing the consumption of vegetables and fruit reduces the risk of disease. There is probable evidence that the risk of cancer in general is inversely associated with the consumption of vegetables and fruit. In addition, there is possible evidence that an increased consumption of vegetables and fruit may prevent body weight gain. As overweight is the most important risk factor for type 2 diabetes mellitus, an increased consumption of vegetables and fruit therefore might indirectly reduces the incidence of type 2 diabetes mellitus. Independent of overweight, there is probable evidence that there is no influence of increased consumption on the risk of type 2 diabetes mellitus. There is possible evidence that increasing the consumption of vegetables and fruit lowers the risk of certain eye diseases, dementia and the risk of osteoporosis. Likewise, current data on asthma, COPD, and RA indicate that an increase in vegetable and fruit consumption may contribute to the prevention of these diseases. For IBD, glaucoma, and diabetic retinopathy, there was insufficient evidence regarding an association with the consumption of vegetables and fruit.

CONCLUSIONS

This critical review on the associations between the intake of vegetables and fruit and the risk of several chronic diseases shows that a high daily intake of these foods promotes health. Therefore, from a scientific point of view, national campaigns to increase vegetable and fruit consumption are justified. The promotion of vegetable and fruit consumption by nutrition and health policies is a preferable strategy to decrease the burden of several chronic diseases in Western societies.

Habitual flavonoid intakes are positively associated with bone mineral density in women

Dietary flavonoids exert bone-protective effects in animal models, but there is limited information on the effect of different flavonoid subclasses on bone health in humans. The aim of this observational study was to examine the association between habitual intake of flavonoid subclasses with bone mineral density (BMD) in a cohort of female twins. A total of 3160 women from the TwinsUK adult twin registry participated in the study. Habitual intakes of flavonoids and subclasses (flavanones, anthocyanins, flavan-3-ols, polymers, flavonols, and flavones) were calculated from semiquantitative food frequency questionnaires using an updated and extended U.S. Department of Agriculture (USDA) database. Bone density was measured using dual-energy X-ray absorptiometry. In multivariate analyses, total flavonoid intake was positively associated with higher BMD at the spine but not at the hip. For the subclasses, the magnitude of effect was greatest for anthocyanins, with a 0.034 g/cm(2) (3.4%) and 0.029 g/cm(2) (3.1%) higher BMD at the spine and hip, respectively, for women in the highest intake quintile compared to those in the lowest. Participants in the top quintile of flavone intake had a higher BMD at both sites; 0.021 g/cm(2) (spine) and 0.026 g/cm(2) (hip). At the spine, a greater intake of flavonols and polymers was associated with a higher BMD (0.021 and 0.024 g/cm(2) , respectively), whereas a higher flavanone intake was positively associated with hip BMD (0.008 g/cm(2) ). In conclusion, total flavonoid intake was positively associated with BMD, with effects observed for anthocyanins and flavones at both the hip and spine, supporting a role for flavonoids present in plant-based foods on bone health. .

Dietary patterns in relation to bone mineral density among menopausal Iranian women

The association of dietary patterns and bone health is not yet well known, and findings from the rare previous studies conducted on this issue are contradictory. We assessed the dietary patterns in relation to bone mineral density (BMD) in a sample of menopausal Iranian women. In this cross-sectional study, 160 menopausal women aged 50-85 were studied and their femoral neck and lumbar spine BMDs were measured by dual-energy X-ray absorptiometry. Dietary intakes were assessed with a validated 168-item food frequency questionnaire, and dietary patterns were identified by a principal component factor analysis method. Overall, six dietary patterns emerged, two of which had a significant association with BMD. After adjusting for potential confounders, women who had higher scores for the first (high in high-fat dairy products, organ meats, red or processed meats and nonrefined cereals) and the second (high in French fries, mayonnaise, sweets and desserts and vegetable oils) dietary patterns we identified were more likely to have BMD below the median in the lumbar spine (odds ratio 2.29; 95 % confidence interval 1.05-4.96; p = 0.04) and the femoral neck (odds ratio 2.83, 95 % confidence interval 1.31-6.09; p < 0.01), respectively, compared to women with lower scores. Dietary patterns abundant in foods with high content of saturated fatty acids (similar to factor 1) or with low density of nutrients (similar to factor 2) are detrimental to bone health in menopausal Iranian women. These findings highlight the importance of proper food selection for maintaining bone health.

Fruit and vegetable intake and bone mass in Chinese adolescents, young and postmenopausal women

OBJECTIVE

Previous studies showed an inconsistent association of fruit and vegetable consumption with bone health. We assessed the associations in Chinese adolescents, young and postmenopausal women.

DESIGN

A cross-sectional study conducted in China during July 2009 to May 2010.

SETTING

Bone mineral density (BMD) and content (BMC) at the whole body, lumbar spine and left hip were measured with dual-energy X-ray absorptiometry. Dietary intakes were assessed using an FFQ. All these values were separately standardized into Z-scores in each population subgroup.

SUBJECTS

One hundred and ten boys and 112 girls (11-14 years), 371 young women (20-34 years, postpartum within 2 weeks) and 333 postmenopausal women (50-70 years).

RESULTS

After adjustment for potential covariates, analysis of covariance showed a significantly positive association between fruit intake and BMD and BMC in all participants combined (P-trend: < 0.001 to 0.002). BMD Z-score increased by 0.25 (or 2.1 % of the mean), 0.22 (3.5 %), 0.23 (3.0 %) and 0.25 (3.5 %), and BMC Z-score increased by 0.33 (5.7 %), 0.25 (5.8 %), 0.34 (5.9 %) and 0.29 (4.7 %), at the total body, lumbar spine, total hip and femoral neck in participants belonging to the top tertile compared with the bottom tertile of fruit intake (all P < 0.05), respectively. There was no significant association between vegetable intake and bone mass at all bone sites studied except for total body BMD (P = 0.030). Relatively more pronounced effects were observed in boys and postmenopausal women.

CONCLUSION

Our findings add to the existing evidence that fruits and vegetables may have a bone sparing effect.

Fruit and vegetable intake and bone health in women aged 45 years and over: a systematic review

High fruit and vegetable intake may be associated with improved bone status among women aged ≥ 45 years. This is the first systematic review that specifically assessed this association and identified research gaps. The benefits of fruit and vegetables (F&V) on bone health remain unclear. Further studies are needed.

INTRODUCTION

F&V have several components that are beneficial to bones. Some studies report that high F&V intake is associated with improved bone status in middle aged and aged women; however, findings are inconsistent. The objective was to systematically review observational and interventional studies that investigated the effects of F&V intake on incidence of osteoporotic fractures, bone mineral density (BMD), and bone turnover markers (BTM) in women aged ≥ 45 years and to identify potential research gaps.

METHODS

Electronic databases were searched, and peer-reviewed manuscripts published in English, with F&V intake as a main dietary exposure, were included. Data selection, extraction, and evaluation of risk of bias were performed independently by two reviewers.

RESULTS

Eight studies were included. One cohort study reported cross-sectional as well as longitudinal data. There was significant between-study heterogeneity in design, definition, and amount of F&V intake, outcomes, analyses, and reporting of results. Two studies had low, two had moderate, and four had high risk of bias. Among reports with low or moderate risk of bias, two cross-sectional analyses reported positive associations between F&V intake and BMD of the forearm, lumbar spine, or total hip, whereas one randomized controlled trial and two prospective cohort analyses reported no effects. One trial reported no associations between F&V and BTM.

CONCLUSIONS

Based on limited evidence, the benefits of F&V on bone health remain unclear for women aged ≥ 45 years. Further studies with low risk of bias are needed.

Causal assessment of dietary acid load and bone disease: a systematic review & meta-analysis applying Hill's epidemiologic criteria for causality

Background

Modern diets have been suggested to increase systemic acid load and net acid excretion. In response, alkaline diets and products are marketed to avoid or counteract this acid, help the body regulate its pH to prevent and cure disease. The objective of this systematic review was to evaluate causal relationships between dietary acid load and osteoporosis using Hill's criteria.

Methods

Systematic review and meta-analysis. We systematically searched published literature for randomized intervention trials, prospective cohort studies, and meta-analyses of the acid-ash or acid-base diet hypothesis with bone-related outcomes, in which the diet acid load was altered, or an alkaline diet or alkaline salts were provided, to healthy human adults. Cellular mechanism studies were also systematically examined.

Results

Fifty-five of 238 studies met the inclusion criteria: 22 randomized interventions, 2 meta-analyses, and 11 prospective observational studies of bone health outcomes including: urine calcium excretion, calcium balance or retention, changes of bone mineral density, or fractures, among healthy adults in which acid and/or alkaline intakes were manipulated or observed through foods or supplements; and 19 in vitro cell studies which examined the hypothesized mechanism. Urine calcium excretion rates were consistent with osteoporosis development; however calcium balance studies did not demonstrate loss of whole body calcium with higher net acid excretion. Several weaknesses regarding the acid-ash hypothesis were uncovered: No intervention studies provided direct evidence of osteoporosis progression (fragility fractures, or bone strength as measured using biopsy). The supporting prospective cohort studies were not controlled regarding important osteoporosis risk factors including: weight loss during follow-up, family history of osteoporosis, baseline bone mineral density, and estrogen status. No study revealed a biologic mechanism functioning at physiological pH. Finally, randomized studies did not provide evidence for an adverse role of phosphate, milk, and grain foods in osteoporosis.

Conclusions

A causal association between dietary acid load and osteoporotic bone disease is not supported by evidence and there is no evidence that an alkaline diet is protective of bone health.

Cortical and trabecular bone, bone mineral density, and resistance to ex vivo fracture are not altered in response to life-long vitamin A supplementation in aging rats

High vitamin A (VA) intakes have been correlated with increased risk of bone fracture. Over 50% of the U.S. adult population reports use of dietary supplements, which can result in VA intakes > 200% of the RDA. In this study, 2 experiments were designed to determine the effect of dietary VA on cortical and trabecular bone properties and resistance to ex vivo fracture. In Expt. 1, we investigated whether orally administered VA accumulates in bone. Seven-week-old rats were treated daily with VA (6 mg/d for 14 d). Total retinol increased in both the tibia and femur (P < 0.01). In Expt. 2, we conducted a longitudinal study in which rats were fed 1 of 3 levels of dietary VA (marginal, adequate, and supplemented, equal to 0.35, 4, and 50 μg retinol/g diet, respectively) from weaning until the ages of 2-3 mo (young), 8-10 mo (middle-age), and 18-20 mo (old). Tibial trabecular and cortical bone structure, bone mineral density, and resistance to fracture were measured using micro-computed tomography and material testing system analysis, respectively. The VA-marginal diet affected measures of cortical bone dimension, suggesting bone remodeling was altered. VA supplementation increased medullary area and decreased cortical thickness in young rats (P < 0.05), but these changes were not present during aging. VA supplementation did not affect resistance to fracture or bone mineral content in old rats. From these results, we conclude that VA-marginal status affects trabecular bone more than cortical bone, and VA supplementation at a moderate level over the lifetime is unlikely to increase the risk of age-related bone fracture in rats.

Effects of food groups and dietary nutrients on bone loss in elderly Chinese population

OBJECTIVE

To examine the effects of food groups and dietary nutrients on bone loss in elderly Chinese population.

DESIGN

Prospective cohort study.

SETTING

A longitudinal study started at 2001 in Hong Kong.

PARTICIPANTS

1225 Chinese men and 992 women aged 65 years and over in the community.

METHODS

Daily intake of food groups and dietary nutrients at baseline was assessed by a food frequency questionnaire. Nutrient intake was adjusted for energy intake by residual method. Linear regression was used to examine the association of BMD change and food group or energy-adjusted nutrient intake with adjustment for demographic, anthropometric, lifestyle factors, and daily energy intake (for food group only).

RESULTS

Higher fish intake was associated with smaller bone loss in hip (B=-0.611, p=0.004) and femoral neck (B=-0.724, p=0.040) in men. None of the food groups were associated with bone loss in both measured sites in women. For men, lower intake of protein (B=-0.012, p=0.003), phosphorus (B=-0.0008, p=0.001), sodium (B=-0.0002, p=0.023) and isoflavone (B=-1.084, p=0.030) was associated with greater BMD loss in hip, whereas lower intake of protein (B=-0.018, p=0.006) and sodium (B=-0.0004, p=0.018) was associated with greater BMD loss in femoral neck. However, these significant associations disappeared after further adjustment for energy-adjusted calcium and vitamin D intakes. None of the nutrients were associated with BMD loss in both measured sites in women.

CONCLUSIONS

Greater fish intake may help to reduce bone loss in this sample of elderly Chinese men. The significant association between various nutrients and bone loss in elderly Chinese men was likely due to the influence of dietary calcium and vitamin D intakes. The role of food groups and dietary nutrients on bone health in this sample of elderly Chinese women seems to be minimal.

Age-related decline in bone density among ethnically diverse older men

We compared rates of BMD decline in older men of diverse ethnic background. The rate of bone loss was statistically equivalent between men of African and Caucasian descent.

INTRODUCTION

Race differences in peak bone mineral density (BMD) are well established, but the magnitude of bone loss among non-white men has not been well characterized. Our objective was to compare and contrast the rates of decline in BMD with aging among older men of different race/ethnic groups.

METHODS

The rate of decline in hip BMD was measured by dual-energy X-ray absorptiometry (Hologic QDR-4500 W) with an average follow-up of 4.6 years in 3,869 Caucasian, 138 African American, 145 Asian, and 334 Afro-Caribbean men aged ≥ 65 years (Mean ages: 73 ± 5, 70 ± 4, 72 ± 5, 71 ± 5 years, respectively).

RESULTS

The annual rate of decline in BMD at the femoral neck was -0.32%, -0.42%, -0.09%, and -0.44%/year for Caucasian, African American, Asian, and Afro-Caribbean men, respectively (p < 0.05 for Caucasian versus Asian). Although men of African ancestry have higher peak BMD than Caucasians, rates of decline in BMD with aging appear to be statistically equivalent in our study. In contrast, Asian men experienced a slower rate of decline in BMD compared with Caucasians and African Americans.

CONCLUSION

More studies are needed to better define the natural history of and factors associated with bone loss among non-white men.

Risk factors for bone loss in the hip of 75-year-old women: a 4-year follow-up study

Risk factors for bone loss among the elderly are largely unknown. The objective of the study was to examine longitudinal bone loss in the hip in one-hundred and sixty-two 75-year-old women. Bone mineral density (BMD, g/cm(2)) was measured with dual X-ray absorptiometry (DXA) at baseline and after 4 years. The relationship between changes in BMD during follow-up and the following factors; baseline BMD, baseline weight, weight change, baseline lean and fat body mass (measured with DXA), serum values of biochemical markers and hormones, nutritional and lifestyle factors according to a questionnaire was assessed. The annual mean (SD) change in femoral neck BMD was -0.31% (1.38) in total trochanter -0.35% (1.15) and total hip -0.34% (1.10) and did not differ significantly between measurement sites. Bisphosphonate users had a 2.9%, 1.7% and 1.9% mean adjusted increase in femoral neck, total trochanter and total hip BMD respectively, different from none-users (p<0.05). Subjects with more than three weekly physical activity sessions had less femoral neck bone loss than less active women (p<0.05). The proportion of the variance in BMD changes explained by multivariate models (R(2)) was 12-13%. Women gaining weight had less loss of BMD than those losing weight in the trochanter and the total hip (p<0.001), and in the femoral neck (p=0.055). Elderly women should be advised to maintain their body weight and participate in physical activity. Despite the large number of variables examined in this study, bone loss occurring with increased age is not thoroughly explained.

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.