Circulating amino acids are associated with bone mineral density decline and ten-year major osteoporotic fracture risk in older community-dwelling adults

Dietary patterns modify the association between body mass index and mortality in older adults

BACKGROUND

The potential modifying roles of dietary patterns in the association between body mass index (BMI) and mortality in older adults remain unclear. This study aimed to examine the stratified and combined associations of dietary patterns and BMI with all-cause, cancer and cardiovascular disease (CVD) mortality.

METHODS

This prospective cohort study included 3982 Chinese community-dwelling older adults between 2001 and 2003. A 280-item validated food frequency questionnaire was used to calculate five dietary indies: Diet Quality Index-International (DQI-I), Dietary Inflammatory Index (DII), Mediterranean Diet Score (MDS), Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet. Higher DQI-I scores indicate better overall diet quality, while higher DII scores represent a pro-inflammatory diet. Higher MDS, DASH, and MIND scores indicate greater adherence to these healthy dietary patterns. Mortality data were obtained from official records. Hazard ratios (HRs) and 95 % confidence intervals (CIs) were estimated using Cox proportional hazards models.

RESULTS

Over a median follow-up of 16.8 years, there were 1879 all-cause deaths, 561 cancer deaths, and 386 CVD deaths. The J-shaped associations between BMI with all-cause and cancer mortality were weaker in healthier dietary patterns (DQI-I, MDS, DASH, MIND ≥median or DII

CONCLUSIONS

Higher diet quality attenuated the increased risks of all-cause and cancer mortality associated with underweight or obesity in older adults. Anti-inflammatory and antioxidative diets may protect against CVD mortality associated with obesity.

Collapse

Key Words

• Body mass index
• Diet quality
• Dietary pattern
• Mortality
• Obesity
• Older adults

Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

Shu-Yi Li Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
Zhi-Hui Lu Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
Jason Leung Jockey Club Centre for Osteoporosis Care and Control, The Chinese University of Hong Kong, Hong Kong, China
Yi Su Key Laboratory of Molecular Epidemiology of Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
Blanche Yu Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China; Jockey Club Centre for Osteoporosis Care and Control, The Chinese University of Hong Kong, Hong Kong, China
Timothy Kwok Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China; Jockey Club Centre for Osteoporosis Care and Control, The Chinese University of Hong Kong, Hong Kong, China.

Collapse

Association Between Dietary Tryptophan Intake and Bone Health: A Cross-Sectional Study

The relationship between dietary tryptophan intake and the risk of low bone mineral density (LBMD) has not been thoroughly evaluated. This study aimed to examine the relationship between dietary tryptophan intake and LBMD. A total of 12,003 participants aged 50 years and older with complete data on bone mineral density (BMD) and tryptophan intake from the National Health and Nutrition Examination Survey (NHANES) 2005 to 2020 were included in this cross-sectional study. The median dietary tryptophan intake among the 12,003 participants was 1822.14 mg/day, with significantly lower levels observed in individuals with LBMD compared to those with normal bone mass (1740.45 mg/day vs. 2041.39 mg/day, p < 0.001). For every 2.7-fold increase in dietary tryptophan intake, the risk of low BMD decreases by 22%. When dietary tryptophan intake was categorized into quartiles, significantly lower risks of LBMD were observed in the third [Odds Ratio (OR) = 0.68, 95% confidence interval (CI): 0.51-0.91] and fourth (OR = 0.65, 95% CI: 0.49-0.87) quartiles compared to the reference group after multivariable adjustment. Moreover, the restricted cubic spline (RCS) results revealed a negative nonlinear relationship between dietary tryptophan intake and LBMD (p for overall < 0.001, p for nonlinear < 0.05), with this correlation remaining consistent across various population subgroups and exhibiting no significant interaction according to stratification variables. Sensitivity analyses further substantiated these findings. Overall, we found that increased dietary tryptophan intake may be associated with a lower risk of LBMD among individuals aged ≥ 50 years, highlighting the importance of optimizing tryptophan nutrition for reducing osteoporosis risk.

Serum metabolomics analyses reveal biomarkers of osteoporosis and the mechanism of Quanduzhong capsules

With the aging of the population, the prevalence of osteoporosis (OP) is rising rapidly, making it an important public health concern. Early screening and effective treatment of OP are the primary challenges facing the management of OP today. Quanduzhong capsule (QDZ) is a single preparation composed of Eucommia ulmoides Oliv., which is included in the Pharmacopoeia of the People's Republic of China. It is used to treat OP in clinical practice, but its mechanisms are unclear. This study involved 30 patients with OP, 30 healthy controls (HC), and 28 OP patients treated with QDZ to identify potential biomarkers for the early diagnosis of OP and to investigate the potential mechanism of QDZ in treating OP. The serum samples were analyzed using targeted amino acid metabolomics. Significant differences in amino acid metabolism were identified between the OP cohort and the HC group, as well as between OP patients before and after QDZ treatment. Compared with HC, the serum levels of 14 amino acids in OP patients changed significantly. Kynurenine, arginine, citrulline, methionine, and their combinations are expected to be potential biomarkers for OP diagnosis. Notably, QDZ reversed the changes in levels of 10 amino acids in the serum of OP patients and significantly impacted numerous metabolic pathways during the treatment of OP. This study focuses on screening potential biomarkers for the early detection of OP, which offers a new insight into the mechanism study of QDZ in treating OP.

Dietary inflammatory index, mediating biomarkers and incident frailty in Chinese community-dwelling older adults

OBJECTIVES

Diet can modulate systemic inflammation, while inflammation is a critical contributory factor of frailty. However, longitudinal data on the association between dietary inflammatory index (DII) and frailty are limited, and the intermediate mechanisms remain unclear. This study aimed to examine the association between DII and incident frailty and the potential mediating roles of frailty-related biomarkers.

DESIGN

Prospective cohort study.

SETTING

The Mr. OS and Ms. OS (Hong Kong) study.

PARTICIPANTS

A total of 3,035 community-dwelling men and women aged above 65 years without frailty at baseline were included.

MEASUREMENTS

DII scores were calculated using the locally validated food frequency questionnaire. Incident frailty at year four was defined using the Fried frailty phenotype. Logistic regression was used to examine the association between DII and frailty onset. Mediation analysis was used to explore the mediating roles of frailty-related biomarkers in the DII-frailty association.

RESULTS

During four years of follow-up, 208 individuals developed frailty. Compared with the lowest tertile of DII, the highest tertile was associated with an increased risk of incident frailty (OR: 1.82; 95% CI: 1.17-2.82; p = 0.008) after adjustment for relevant confounders. The DII-frailty association was significant in men but not in women. Furthermore, increasing serum homocysteine, decreasing serum folate, and reducing estimated glomerular filtration rate (eGFR) mediated 11.6%, 7.1%, and 9.6 % of the total relation between DII and frailty onset, respectively.

CONCLUSION

In this cohort study, a pro-inflammatory diet was associated with a higher risk of frailty onset, mediated by homocysteine, folate, and renal function.

Association of serum levels of phenylalanine and tyrosine with hip fractures and frailty in older adults: The cardiovascular health study

This study examined if the amino acids phenylalanine or tyrosine contribute to risk of hip fracture or frailty in older adults. We determined that neither phenylalanine nor tyrosine are important predictors of hip fracture or frailty. We suggest advice on protein intake for skeletal health consider specific amino acid composition.

PURPOSE

Protein is essential for skeletal health, but the specific amino acid compositions of protein may have differential associations with fracture risk. The aim of this study was to determine the association of serum levels of the aromatic amino acids phenylalanine and tyrosine with risk for incident hip fractures over twelve years of follow-up and cross sectional associations with frailty.

METHODS

We included 131 older men and women from the Cardiovascular Health Study (CHS) who sustained a hip fracture over twelve years of follow-up and 131 men and women without an incident hip fracture over this same period of time. 42% of this cohort were men and 95% were Caucasian. Weighted multivariable Cox hazards molecules were used to estimate the hazard ratios (HR) and 95% confidence intervals (CI) of incident hip fracture associated with a one standard deviation (SD) higher serum level of phenylalanine or tyrosine. Relative risk regression was used to determine the cross-sectional association of these amino acids with Freid's frailty index.

RESULTS

Neither serum levels of phenylalanine (HR 0.85 (95% CI 0.62-1.16) or tyrosine (HR 0.82 (95% CI 0.62-1.1) were significantly associated with incident hip fractures or cross sectionally with frailty (frail compared with prefrail/not frail) (HR 0.92 (95% CI 0.48-1.76) and HR (0.86 (95% CI 0.46-1.61) respectively.

CONCLUSION

Phenylalanine and tyrosine are not significant contributors to hip fractures or frailty in older men and women.

Serum branched-chain amino acid levels are associated with fracture risk in Japanese women

AIM

Branched-chain amino acids (BCAAs) have been shown to exert beneficial effects on muscle and bone metabolism; however, no studies to date have investigated whether BCAAs have beneficial effects on bone fractures. Herein, we aim to prospectively investigate the relationship between serum BCAA concentrations and the occurrence of vertebral fractures (VFs) in Japanese women.

METHODS

During the observation period (7.5 ± 6.1 years), 188 of 983 participants experienced VF. Kaplan-Meier analyses were conducted to examine time-dependent variations in the vertebral compression fracture occurrence rate. Patients were stratified into quartiles based on serum BCAA concentration for this analysis.

RESULTS

The analysis results indicated that the group with the lowest BCAA level developed VFs significantly earlier and with a higher frequency than the other groups (P < 0.001). A Cox proportional hazards model showed that BCAA concentration was a significant risk factor for incident fracture, even after adjusting for possible confounding factors. A series of multiple regression analyses were performed to identify factors related to serum BCAA concentration, with the results identifying levels of glycated hemoglobin (P < 0.001), adiponectin (P < 0.001), and NOx (P = 0.011) as significant factors associated with serum BCAA.

CONCLUSIONS

Overall, the present study revealed that a lower serum BCAA level was an independent risk factor for incident VF in postmenopausal women. Geriatr Gerontol Int 2024; 24: 603-608.

Discussion on protein recommendations for supporting muscle and bone health in older adults: a mini review

Muscle and bone tissues are interconnected, and both rely on an adequate protein intake. Recommendations for protein intake for older adults specifically vary across countries. The purpose of this narrative review is to discuss the existing evidence for protein recommendations for supporting muscle and bone health in older adults and to evaluate if a protein intake above the current population reference intake (PRI) for older adults would be scientifically justified. First, this review summarizes the protein recommendations from bodies setting dietary reference values, expert groups, and national health organizations. Next, relevant studies investigating the impact of protein on muscle and bone health in older adults are discussed. In addition, the importance of protein quality for muscle and bone health is addressed. Lastly, a number of research gaps are identified to further explore the added value of a protein intake above the PRI for older adults.

Gut Clostridium sporogenes-derived indole propionic acid suppresses osteoclast formation by activating pregnane X receptor

Bone homeostasis is maintained by osteoclast-mediated bone resorption and osteoblast-mediated bone formation. A dramatic decrease in estrogen levels in postmenopausal women leads to osteoclast overactivation, impaired bone homeostasis, and subsequent bone loss. Changes in the gut microbiome affect bone mineral density. However, the role of the gut microbiome in estrogen deficiency-induced bone loss and its underlying mechanism remain unknown. In this study, we found that the abundance of Clostridium sporogenes (C. spor.) and its derived metabolite, indole propionic acid (IPA), were decreased in ovariectomized (OVX) mice. In vitro assays suggested that IPA suppressed osteoclast differentiation and function. At the molecular level, IPA suppressed receptor activator of nuclear factor kappa-Β ligand (RANKL)-induced pregnane X receptor (PXR) ubiquitination and degradation, leading to increased binding of remaining PXR with P65. In vivo daily IPA administration or repeated C. spor. colonization protected against OVX-induced bone loss. To protect live bacteria from the harsh gastric environment and delay the emptying of orally administered C. spor. from the intestine, a C. spor.-encapsulated silk fibroin (SF) hydrogel system was developed, which achieved bone protection in OVX mice comparable to that achieved with repeated germ transplantation or daily IPA administration. Overall, we found that gut C. spor.-derived IPA was involved in estrogen deficiency-induced osteoclast overactivation by regulating the PXR/P65 complex. The C. spor.-encapsulated SF hydrogel system is a promising tool for combating postmenopausal osteoporosis without the disadvantages of repeated germ transplantation.

Association between amino acids and recent osteoporotic fracture: a matched incident case-control study

Context

Osteoporotic fracture is a major public health issue globally. Human research on the association between amino acids (AAs) and fracture is still lacking.

Objective

To examine the association between AAs and recent osteoporotic fractures.

Methods

This age and sex matched incident case-control study identified 44 recent x-ray confirmed fracture cases in the Second Hospital of Jilin University and 88 community-based healthy controls aged 50+ years. Plasma AAs were measured by high performance liquid chromatography coupled with mass spectrometry. After adjusting for covariates (i.e., body mass index, milk intake >1 time/week, falls and physical activity), we conducted conditional logistical regression models to test the association between AAs and fracture.

Results

Among cases there were 23 (52.3%) hip fractures and 21 (47.7%) non-hip fractures. Total, essential, and non-essential AAs were significantly lower in cases than in controls. In the multivariable conditional logistic regression models, after adjusting for covariates, each standard deviation increase in the total (odds ratio [OR]: 0.304; 95% confidence interval [CI]: 0.117-0.794), essential (OR: 0.408; 95% CI: 0.181-0.923) and non-essential AAs (OR: 0.290; 95%CI: 0.107-0.782) was negatively associated with recent fracture. These inverse associations were mainly found for hip fracture, rather than non-hip fractures. Among these AAs, lysine, alanine, arginine, glutamine, histidine and piperamide showed the significantly negative associations with fracture.

Conclusion

There was a negative relationship between AAs and recent osteoporotic fracture; such relationship appeared to be more obvious for hip fracture.

ROS/MMP-9 mediated CS degradation in BMSC inhibits citric acid metabolism participating in the dual regulation of bone remodelling

It is necessary to figure out the abnormal energy metabolites at the cellular level of postmenopausal osteoporosis (PMOP) bone microenvironment. In this study, we constructed PMOP model by ovariectomy and identified 9 differential metabolites compared with control femur by energy metabolomic. The enrichment analysis of differential metabolites revealed that tricarboxylic acid cycle, glucagon pathway and purinergic signaling pathway were the main abnormal metabolic processes. Citric acid was identified as the key metabolite by constructing compound reaction-enzyme-gene network. The functional annotation of citric acid targets identified by network pharmacological tools indicated that matrix metalloproteinase 9 (MMP-9) may be involved in regulating citric acid metabolism in the osteogenic differentiation of bone marrow mesenchymal stem cell (BMSC). Molecular docking shows that the interaction forces between MMP-9 and citric acid synthase (CS) is -638, and there are multiple groups of residues used to form hydrogen bonds. Exogenous H2O2 promotes the expression of MMP-9 in BMSC to further degrade CS resulting in a decrease in mitochondrial citric acid synthesis, which leads to the disorder of bone remodeling by two underlying mechanisms ((1) the decreased histone acetylation inhibits the osteogenic differentiation potential of BMSC; (2) the decreased bone mineralization by citric acid deposition). MMP-9-specific inhibitor (MMP-9-IN-1) could significantly improve the amount of CS in BMSC to promote cellular citric acid synthesis, and further enhance bone remodeling. These findings suggest inhibiting the degradation of CS by MMP-9 to promote the net production of citric acid in osteogenic differentiation of BMSC may be a new direction of PMOP research.

Plasma serotonin precursors and metabolite are correlated with bone mineral density and bone turnover markers in patients with postmenopausal osteoporosis

BACKGROUND

Serotonin (5-HT) precursors regulate bone remodeling. This study aims to investigate the correlation of plasma 5-HT precursors and metabolite with bone mineral density (BMD) and bone turnover markers in postmenopausal osteoporosis (PMOP) patients.

METHODS

The age, body mass index (BMI), and years since menopause (YSM) were documented for 348 postmenopausal women in normal/osteopenia/osteoporosis (OP) groups, with lumbar spine and femoral neck BMD measured. Serum bone turnover markers (PINP/β-CTX) and plasma 5-HT, 5-HT precursors (Trp/5-HTP) and metabolite (5-HIAA) were measured by ELISA. OP patients were allocated to high/low expression groups following ROC analysis of 5-HT/Trp/5-HTP/5-HIAA. The relationship of plasma 5-HT/Trp/5-HTP/5-HIAA, BMD, and bone turnover markers with PMOP was analyzed using logistic regression analysis. The correlation of plasma 5-HT/Trp/5-HTP/5-HIAA with BMD and bone turnover markers was analyzed using Pearson's correlation analysis, followed by logistic regression analysis of the relationship between plasma 5-HT/Trp/5-HTP/5-HIAA and BMD, bone turnover markers and PMOP.

RESULTS

BMI, YSM, BMD and PINP, and β-CTX levels differed among groups. Levels of plasma 5-HT precursors/metabolite were increased in OP patients. Individuals with high 5-HT precursors/metabolite levels had low BMD and high PINP/β-CTX levels. The 5-HT precursors/metabolite negatively-correlated with BMD and positively-correlated with PINP/β-CTX. BMI, YSM, BMD, and PINP/β-CTX/Trp/5-HTP/5-HT related to PMOP and were independent risk factors for OP.

CONCLUSION

Plasma 5-HT precursors and metabolite negatively-correlate with BMD and positively-correlate with PINP/β-CTX in PMOP patients. Peripheral 5-HT precursors and metabolite level may be a new direction of treatment of PMOP and bone metabolism-related disorders.

Fracture risk prediction in old Chinese people-a narrative review

With aging, the burden of osteoporotic fracture (OF) increases substantially, while China is expected to carry the greatest part in the future. The risk of fracture varies greatly across racial groups and geographic regions, and systematically organized evidence on the potential predictors for fracture risk is needed for Chinese. This review briefly introduces the epidemiology of OF and expands on the predictors and predictive tools for the risk of OF, as well as the challenges for their potential translation in the old Chinese population. There are regional differences of fracture incidence among China. The fracture incidences in Hong Kong and Taiwan have decreased in recent years, while it is still increasing in mainland China. Although the application of dual-energy X-ray absorptiometry (DXA) is limited among old Chinese in the mainland, bone mineral density (BMD) by DXA has a predictive value similar to that worldwide. Other non-DXA modalities, especially heel QUS, are helpful in assessing bone health. The fracture risk assessment tool (FRAX) has a good discrimination ability for OFs, especially the FRAX with BMD. And some clinical factors have added value to FRAX, which has been verified in old Chinese. In addition, although the application of the osteoporosis self-assessment tool for Asians (OSTA) in Chinese needs further validation, it may help identify high-risk populations in areas with limited resources. Moreover, the translation use of the muscle quality and genetic or serum biomarkers in fracture prediction needs further works. More applicable and targeted fracture risk predictors and tools are still needed for the old Chinese population.

Efficacy of the Chinese herbal medicine Jintiange capsules in the postoperative treatment of osteoporotic vertebral compression fractures: a systematic review and meta-analysis

Background

In traditional Chinese medicine, Jintiange capsules are frequently used to treat metabolic bone diseases and strengthen bones and tendons. The main component of Jintiange capsules is bionic tiger bone powder. However, the active ingredients and proteins are derived from other animal bones, with chemical profiles similar to that of natural tiger bone. This study aimed to explore the efficacy of Jintiange capsules, a Chinese herbal medicine, in the postoperative treatment of osteoporotic vertebral compression fractures (OVCFs).

Methods

In this systematic review, literature was retrieved using PubMed, the Cochrane Library, the Chinese National Knowledge Infrastructure, the Web of Science, the Wanfang Database, the Chinese Biomedical Literature Database, and the Chinese VIP Database from inception to July 2023. The primary outcome measures were the bone mineral density (BMD) and effective rate. The secondary outcome measures were the visual analog pain score (VAS), Oswestry disability index (ODI), Cobb's angle, serum osteocalcin, serum alkaline phosphatase, and adverse events. RevMan 5.4 and STATA 17.0 software were used for data analysis.

Results

We enrolled randomized controlled trials (RCTs) focusing on 1,642 patients in the meta-analysis. The meta-analysis illustrated that Jintiange capsules significantly increased the BMD of the lumbar spine (p < 0.00001), femoral neck (p = 0.0005), and whole body (p = 0.01). The subgroup analysis of Jintiange capsules combination therapy showed that the BMD of the lumbar spine and whole body was significantly improved with Jintiange capsules (p < 0.00001). The test for the overall effect showed that Jintiange capsules had a significantly higher effective rate than the control groups (p = 0.003). Additionally, the overall effect test showed that Jintiange capsules decreased the VAS and ODI (p < 0.00001) and Cobb's angle (p = 0.02), and improved serum OC and ALP (p < 0.00001) compared with the controls. Furthermore, the pooled analysis of adverse reactions showed no serious impacts on the treatment of OVCFs.

Conclusion

Jintiange capsules demonstrate high safety and efficacy in the treatment of OVCFs, including increasing BMD, the lift effect rate, serum OC levels, and pain relief, decreasing the ODI, serum ALP levels, and adverse events, and improving Cobb's angle. Additional research is required to validate the efficacy of Jintiange capsules for the postoperative treatment of OVCFs.Systematic review registration: https://www.crd.york.ac.uk/PROSPERO.

Plasma Levels of Branched Chain Amino Acids, Incident Hip Fractures, and Bone Mineral Density of the Hip and Spine

OBJECTIVE

Branched chain amino acids (BCAA) are building blocks for protein, an essential component of bone. However, the association of plasma levels of BCAA with fractures in populations outside of Hong Kong or with hip fractures in particular is not known. The purpose of these analyses was to determine the relationship of BCAA including valine, leucine, and isoleucine and total BCAA (SD of the sum of Z-scores for each BCAA) with incident hip fractures and bone mineral density (BMD) of the hip and lumbar spine in older African American and Caucasian men and women in the Cardiovascular Health Study.

DESIGN

Longitudinal analyses of association of plasma levels of BCAA with incident hip fractures and cross-sectional BMD of the hip and lumbar spine from the Cardiovascular Health Study.

SETTING

Community.

PARTICIPANTS

A total of 1850 men (38% of cohort) and women; mean age 73 years.

MAIN OUTCOME MEASURES

Incident hip fractures and cross-sectional BMD of the total hip, femoral neck, and lumbar spine.

RESULTS

In fully adjusted models, over 12 years of follow-up, we observed no significant association between incident hip fracture and plasma values of valine, leucine, isoleucine, or total BCAA per 1 SD higher of each BCAA. Plasma values of leucine but not valine, isoleucine, or total BCAA, were positively and significantly associated with BMD of the total hip (P = .03) and femoral neck (P = .02), but not the lumbar spine (P = .07).

CONCLUSIONS

Plasma levels of the BCAA leucine may be associated with higher BMD in older men and women. However, given the lack of significant association with hip fracture risk, further information is needed to determine whether BCAAs would be novel targets for osteoporosis therapies.

Low Circulating Valine Associate With High Risk of Hip Fractures

CONTEXT

Hip fractures constitute a major health concern. An adequate supply of amino acids is crucial to ensure optimal acquisition and remodeling of bone. Circulating amino acid levels have been proposed as markers of bone mineral density, but data on their ability to predict incident fractures are scarce.

OBJECTIVES

To investigate the associations between circulating amino acids and incident fractures.

METHODS

We used UK Biobank (n = 111 257; 901 hip fracture cases) as a discovery cohort and the Umeå Fracture and Osteoporosis (UFO) hip fracture study (hip fracture cases n = 2225; controls n = 2225) for replication. Associations with bone microstructure parameters were tested in a subsample of Osteoporotic Fractures in Men Sweden (n = 449).

RESULTS

Circulating valine was robustly associated with hip fractures in the UK Biobank (HR per SD increase 0.79, 95% CI 0.73-0.84), and this finding was replicated in the UFO study (combined meta-analysis including 3126 incident hip fracture cases, odds ratio per SD increase 0.84, 95% CI 0.80-0.88). Detailed bone microstructure analyses showed that high circulating valine was associated with high cortical bone area and trabecular thickness.

CONCLUSION

Low circulating valine is a robust predictor of incident hip fractures. We propose that circulating valine may add information for hip fracture prediction. Future studies are warranted to determine whether low valine is causally associated with hip fractures.

The Association of Tryptophan and Its Metabolites With Incident Hip Fractures, Mortality, and Prevalent Frailty in Older Adults: The Cardiovascular Health Study

Amino acids are the building blocks of proteins, and sufficient protein intake is important for skeletal health. We utilized stored serum from the Cardiovascular Health Study in 1992-1993 to examine the relationship between levels of the essential amino acid tryptophan (trp) and its oxidized and nonoxidized metabolites to risk for incident hip fractures and mortality over 12 years of follow-up. We included 131 persons who sustained a hip fracture during this time period and 131 without a hip fracture over these same 12 years of follow-up; 58% female and 95% White. Weighted multivariable Cox hazards models were used to estimate the hazard ratios (HR) and 95% confidence intervals (CI) of incident hip fracture associated with a one standard deviation (SD) higher trp or its metabolites exposure. Relative risk regression was used to evaluate the cross-sectional association of trp and its metabolites with frailty. Higher serum levels of trp were significantly associated with lower risk of incident hip fractures (HR = 0.75 per SD of trp (95% CI 0.57-0.99) but were not significantly associated with mortality or frailty status by Freid's frailty index. There were no statistically significant associations between any of the oxidized or nonoxidized products of trp with incident hip fractures (p ≥ 0.64), mortality (p ≥ 0.20), or cross-sectional frailty status (p ≥ 0.13) after multiple testing adjustment. Randomized clinical trials examining whether increasing trp intake is beneficial for osteoporosis are needed. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Divergent Survival Outcomes Associated with Elevated Branched-Chain Amino Acid Levels among Older Adults with or without Hypertension and Diabetes: A Validated, Prospective, Longitudinal Follow-Up Study

Branched-chain amino acids are critical metabolic intermediates that can indicate increased risk of cardiometabolic disease when levels are elevated or, alternatively, suggest sufficient mitochondrial energy metabolism and reserve in old age. The interpretation of BCAA levels can be context-dependent, and it remains unclear whether abnormal levels can inform prognosis. This prospective longitudinal study aimed to determine the interrelationship between mortality hazard and fasting serum BCAA levels among older men and women aged ≥65 years with or without hypertension and diabetes mellitus. At baseline (0Y), fasting serum BCAA concentration in 2997 community-living older men and women were measured. Approximately 14 years later (14Y), 860 study participants returned for repeat measurements. Deaths were analysed and classified into cardiovascular and non-cardiovascular causes using International Classification of Diseases codes. Survival analysis and multivariable Cox regression were performed. During a median follow-up of 17Y, 971 (78.6%) non-cardiovascular and 263 (21.4%) cardiovascular deaths occurred among 1235 (41.2%) deceased (median age, 85.8 years [IQR 81.7-89.7]). From 0Y to 14Y, BCAA levels declined in both sexes, whereas serum creatinine concentration increased (both p < 0.0001). In older adults without hypertension or diabetes mellitus, the relationship between mortality hazard and BCAA level was linear and above-median BCAA levels were associated with improved survival, whereas in the presence of cardiometabolic disease the relationship was U-shaped. Overall, adjusted Cox regression determined that each 10% increment in BCAA concentration was associated with a 7% (p = 0.0002) and 16% (p = 0.0057) reduction in mortality hazard estimated at 0Y and 14Y, respectively. Our findings suggested that abnormally high or low (dyshomeostatic) BCAA levels among older adults with hypertension and/or diabetes mellitus were associated with increased mortality, whereas in those with neither disease, increased BCAA levels was associated with improved survival, particularly in the oldest-old.

What Nutraceuticals Can Do for Duchenne Muscular Dystrophy: Lessons Learned from Amino Acid Supplementation in Mouse Models

Duchenne muscular dystrophy (DMD), the severest form of muscular dystrophy, is characterized by progressive muscle weakness with fatal outcomes most often before the fourth decade of life. Despite the recent addition of molecular treatments, DMD remains a disease without a cure, and the need persists for the development of supportive therapies aiming to help improve patients' quality of life. This review focuses on the therapeutical potential of amino acid and derivative supplements, summarizing results obtained in preclinical studies in murine disease models. Several promising compounds have emerged, with L-arginine, N-acetylcysteine, and taurine featuring among the most intensively investigated. Their beneficial effects include reduced inflammatory, oxidative, fibrotic, and necrotic damage to skeletal muscle tissues. Improvement of muscle strength and endurance have been reported; however, mild side effects have also surfaced. More explorative, placebo-controlled and long-term clinical trials would need to be conducted in order to identify amino acid formulae that are safe and of true benefit to DMD patients.

Metabolomics of Osteoporosis in Humans: A Systematic Review

PURPOSE OF REVIEW

To systematically review recent studies investigating the association between metabolites and bone mineral density (BMD) in humans.

METHODS

Using predefined keywords, we searched literature published from Jan 1, 2019 to Feb 20, 2022 in PubMed, Web of Science, Embase, and Scopus. Studies that met the predefined exclusion criteria were excluded. Among the included studies, we identified metabolites that were reported to be associated with BMD by at least three independent studies.

RECENT FINDINGS

A total of 170 studies were retrieved from the databases. After excluding studies that did not meet our predefined inclusion criteria, 16 articles were used in this review. More than 400 unique metabolites in blood were shown to be significantly associated with BMD. Of these, three metabolites were reported by ≥ 3 studies, namely valine, leucine and glycine. Glycine was consistently shown to be inversely associated with BMD, while valine was consistently observed to be positively associated with BMD. Inconsistent associations with BMD was observed for leucine. With advances in metabolomics technology, an increasing number of metabolites associated with BMD have been identified. Two of these metabolites, namely valine and glycine, were consistently associated with BMD, highlighting their potential for clinical application in osteoporosis. International collaboration with a larger population to conduct clinical studies on these metabolites is warranted. On the other hand, given that metabolomics could be affected by genetics and environmental factors, whether the inconsistent association of the metabolites with BMD is due to the interaction between metabolites and genes and/or lifestyle warrants further study.

Increased Dietary Intakes of Total Protein, Animal Protein and White Meat Protein Were Associated with Reduced Bone Loss—A Prospective Analysis Based on Guangzhou Health and Nutrition Cohort, South China

In this study, we aimed to prospectively investigate the relationships between different types of dietary protein and changes in bone mass in Chinese middle-aged and elderly people. Dietary intakes were evaluated by means of a validated food frequency questionnaire. Bone mineral density (BMD) was measured using a dual-energy bone densitometer at multiple bone sites. Multivariable regression models were applied to investigate the associations of the participants’ dietary intakes of total protein, intakes of protein from various sources, and amino acid intakes with the annualized changes in BMD during a 3-year follow-up. A total of 1987 participants aged 60.3 ± 4.9 years were included in the analyses. Multivariable linear regression results showed that dietary intakes of total protein, animal protein, and protein from white meat were positively correlated with BMD changes, with standardized coefficients (β) of 0.104, 0.073, and 0.074 at the femur neck (p < 0.01) and 0.118, 0.067, and 0.067 at the trochanter (p < 0.01), respectively. With each increase of 0.1g·kg−1·d−1 in animal protein and white meat protein intakes, the BMD losses were reduced by 5.40 and 9.24 mg/cm2 at the femur neck (p < 0.05) and 1.11 and 1.84 mg/cm2 at the trochanter (p < 0.01), respectively. Our prospective data, obtained from Chinese adults, showed that dietary total and animal protein, especially protein from white meat, could significantly reduce bone loss at the femur neck and trochanter.

Metabolomic patterns, redox-related genes and metals, and bone fragility endpoints in the Hortega Study

BACKGROUND

The potential joint influence of metabolites on bone fragility has been rarely evaluated. We assessed the association of plasma metabolic patterns with bone fragility endpoints (primarily, incident osteoporosis-related bone fractures, and, secondarily, bone mineral density BMD) in the Hortega Study participants. Redox balance plays a key role in bone metabolism. We also assessed differential associations in participant subgroups by redox-related metal exposure levels and candidate genetic variants.

MATERIAL AND METHODS

In 467 participants older than 50 years from the Hortega Study, a representative sample from a region in Spain, we estimated metabolic principal components (mPC) for 54 plasma metabolites from NMR-spectrometry. Metals biomarkers were measured in plasma by AAS and in urine by HPLC-ICPMS. Redox-related SNPs (N = 341) were measured by oligo-ligation assay.

RESULTS

The prospective association with incident bone fractures was inverse for mPC1 (non-essential and essential amino acids, including branched-chain, and bacterial co-metabolites, including isobutyrate, trimethylamines and phenylpropionate, versus fatty acids and VLDL) and mPC4 (HDL), but positive for mPC2 (essential amino acids, including aromatic, and bacterial co-metabolites, including isopropanol and methanol). Findings from BMD models were consistent. Participants with decreased selenium and increased antimony, arsenic and, suggestively, cadmium exposures showed higher mPC2-associated bone fractures risk. Genetic variants annotated to 19 genes, with the strongest evidence for NCF4, NOX4 and XDH, showed differential metabolic-related bone fractures risk.

CONCLUSIONS

Metabolic patterns reflecting amino acids, microbiota co-metabolism and lipid metabolism were associated with bone fragility endpoints. Carriers of redox-related variants may benefit from metabolic interventions to prevent the consequences of bone fragility depending on their antimony, arsenic, selenium, and, possibly, cadmium, exposure levels.

Osteoporosis and Alveolar Bone Health in Periodontitis Niche: A Predisposing Factors-Centered Review

Periodontitis is a periodontal inflammatory condition that results from disrupted periodontal host-microbe homeostasis, manifested by the destruction of tooth-supporting structures, especially inflammatory alveolar bone loss. Osteoporosis is characterized by systemic deterioration of bone mass and microarchitecture. The roles of many systemic factors have been identified in the pathogenesis of osteoporosis, including endocrine change, metabolic disorders, health-impaired behaviors and mental stress. The prevalence rate of osteoporotic fracture is in sustained elevation in the past decades. Recent studies suggest that individuals with concomitant osteoporosis are more vulnerable to periodontal impairment. Current reviews of worse periodontal status in the context of osteoporosis are limited, mainly centering on the impacts of menopausal and diabetic osteoporosis on periodontitis. Herein, this review article makes an effort to provide a comprehensive view of the relationship between osteoporosis and periodontitis, with a focus on clarifying how those risk factors in osteoporotic populations modify the alveolar bone homeostasis in the periodontitis niche.

Jin-Tian-Ge ameliorates ovariectomy-induced bone loss in rats and modulates osteoblastogenesis and osteoclastogenesis in vitro

BACKGROUND

Tiger bone, which had been one of the most famous traditional Chinese medicine for 2000 years, was originate from the skeleton of Panthera tigris L., and had the actions of anti-inflammatory, analgesic, immune-regulatory and promoting healing of bone fracture, and was used for the treatment of osteoporosis and rheumatoid arthritis. Jin-Tian-Ge (JTG), the artificial tiger bone powder, were prepared from skeletons of several farmed animals to substitute the natural tiger bone, and has been used for the treatment of osteoporosis in clinical practice. However, the characteristic and mechanism of action of JTG for the therapy of osteoporosis need to be further evidenced by using modern pharmacological methods. The aim of this work is to investigate the bone-protective effects of JTG, and explore the possible underlying mechanism.

METHODS

Ovariectomy (OVX) rats were orally administrated JTG or estradiol valerate (EV) for 12 weeks. We investigated the pharmacodynamic effects of JTG on anti-bone loss in OVX rats, and also investigated the role of JTG in promoting osteogenesis and inhibiting osteoclast differentiation.

RESULTS

JTG increased the bone mineral density (BMD), improved the bone microarchitecture and biomechanical properties in ovariectomized rast, whereas reversed the bone high turnover in OVX rats as evidenced by serum biochemical markers in OVX rats. JTG increased osteogenic differentiation of BMSCs in vitro, and up-regulated the expression of the key proteins of BMP and Wnt/β-catenin pathways. JTG also inhibited the osteoclastogenesis of BMM as evidenced by the alteration of the TRAP activity, F-actin construction and the expression of nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), c-Fos, Cathepsin K (Ctsk) and matrix metallopeptidase 9 (MMP9) of OCs induced with RANKL and LPS, reduced the expression and phosphorylation of NF-κB in OCs.

CONCLUSIONS

JTG prevented bone loss in OVX rats and increased osteogenic differentiation of BMSCs through regulation of the BMP and Wnt/β-catenin pathway, inhibited osteoclastogenesis by suppressing the NF-κB pathway, suggesting that JTG had the potentials for prevention and treatment of osteoporosis by modulating formation and differentiation of osteoblast and osteoclast.

Role of Essential Amino Acids in Age-Induced Bone Loss

Age-induced osteoporosis is a global problem. Essential amino acids (EAAs) work as an energy source and a molecular pathway modulator in bone, but their functions have not been systematically reviewed in aging bone. This study aimed to discuss the contribution of EAAs on aging bone from in vitro, in vivo, and human investigations. In aged people with osteoporosis, serum EAAs were detected changing up and down, without a well-established conclusion. The supply of EAAs in aged people either rescued or did not affect bone mineral density (BMD) and bone volume. In most signaling studies, EAAs were proven to increase bone mass. Lysine, threonine, methionine, tryptophan, and isoleucine can increase osteoblast proliferation, activation, and differentiation, and decrease osteoclast activity. Oxidized L-tryptophan promotes bone marrow stem cells (BMSCs) differentiating into osteoblasts. However, the oxidation product of tryptophan called kynurenine increases osteoclast activity, and enhances the differentiation of adipocytes from BMSCs. Taken together, in terms of bone minerals and volume, more views consider EAAs to have a positive effect on aging bone, but the function of EAAs in bone metabolism has not been fully demonstrated and more studies are needed in this area in the future.

Association of amino acid metabolites with osteoporosis, a metabolomic approach: Bushehr elderly health program

INTRODUCTION AND OBJECTIVES

Amino acids are the most frequently reported metabolites associated with low bone mineral density (BMD) in metabolomics studies. We aimed to evaluate the association between amino acid metabolic profile and bone indices in the elderly population.

METHODS

400 individuals were randomly selected from 2384 elderly men and women over 60 years participating in the second stage of the Bushehr elderly health (BEH) program, a population-based prospective cohort study that is being conducted in Bushehr, a southern province of Iran. Frozen plasma samples were used to measure 29 amino acid and derivatives metabolites using the UPLC-MS/MS-based targeted metabolomics platform. We conducted Elastic net regression analysis to detect the metabolites associated with BMD of different sites and lumbar spine trabecular bone score, and also to examine the ability of the measured metabolites to differentiate osteoporosis.

RESULTS

We adjusted the analysis for possible confounders (age, BMI, diabetes, smoking, physical activity, vitamin D level, and sex). Valine, leucine, isoleucine, and alanine in women and tryptophan in men were the most important amino acids inversely associated with osteoporosis (OR range from 0.77 to 0.89). Sarcosine, followed by tyrosine, asparagine, alpha aminobutyric acid, and ADMA in women and glutamine in men and when both women and men were considered together were the most discriminating amino acids detected in individuals with osteoporosis (OR range from 1.15 to 1.31).

CONCLUSION

We found several amino acid metabolites associated with possible bone status in elderly individuals. Further studies are required to evaluate the utility of these metabolites as clinical biomarkers for osteoporosis prediction and their effect on bone health as dietary supplements.

BCAT1 promotes osteoclast maturation by regulating branched-chain amino acid metabolism

Branched-chain aminotransferase 1 (BCAT1) transfers the amine group on branched-chain amino acids (BCAAs) to alpha-ketoglutarate. This generates glutamate along with alpha-keto acids that are eventually oxidized to provide the cell with energy. BCAT1 thus plays a critical role in sustaining BCAA concentrations and availability as an energy source. Osteoclasts have high metabolic needs during differentiation. When we assessed the levels of amino acids in bone marrow macrophages (BMMs) that were undergoing receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation, we found that the BCAA levels steadily increase during this process. In vitro analyses then showed that all three BCAAs but especially valine were needed for osteoclast maturation. Moreover, selective inhibition of BCAT1 with gabapentin significantly reduced osteoclast maturation. Expression of enzymatically dead BCAT1 also abrogated osteoclast maturation. Importantly, gabapentin inhibited lipopolysaccharide (LPS)-induced bone loss of calvaria in mice. These findings suggest that BCAT1 could serve as a therapeutic target that dampens osteoclast formation.

The Association of Circulating Amino Acids and Dietary Inflammatory Potential with Muscle Health in Chinese Community-Dwelling Older People

Amino acids (AAs) and dietary inflammatory potential play essential roles in muscle health. We examined the associations of dietary inflammatory index (DII) of habitual diet with serum AA profile, and ascertained if the associations between DII and muscle outcomes were mediated by serum AAs, in 2994 older Chinese community-dwelling men and women (mean age 72 years) in Hong Kong. Higher serum branched chain AAs (BCAAs), aromatic AAs and total glutathione (tGSH) were generally associated with better muscle status at baseline. A more pro-inflammatory diet, correlating with higher serum total homocysteine and cystathionine, was directly (90.2%) and indirectly (9.8%) through lower tGSH associated with 4-year decline in hand grip strength in men. Higher tGSH was associated with favorable 4-year changes in hand grip strength, gait speed and time needed for 5-time chair stands in men and 4-year change in muscle mass in women. Higher leucine and isoleucine were associated with decreased risk of sarcopenia in men; the associations were abolished after adjustment for BMI. In older men, perturbations in serum sulfur AAs metabolism may be biomarkers of DII related adverse muscle status, while the lower risk of sarcopenia with higher BCAAs may partly be due to preserved BMI.

The association of serum sulfur amino acids and related metabolites with incident diabetes: a prospective cohort study

AIM

Plasma total cysteine (tCys) is associated with fat mass and insulin resistance, whereas taurine is inversely related to diabetes risk. We investigated the association of serum sulfur amino acids (SAAs) and related amino acids (AAs) with incident diabetes.

METHODS

Serum AAs were measured at baseline in 2997 subjects aged ≥ 65 years. Diabetes was recorded at baseline and after 4 years. Logistic regression evaluated the association of SAAs [methionine, total homocysteine (tHcy), cystathionine, tCys, and taurine] and related metabolites [serine, total glutathione (tGSH), glutamine, and glutamic acid] with diabetes risk.

RESULTS

Among 2564 subjects without diabetes at baseline, 4.6% developed diabetes. Each SD increment in serum tCys was associated with a 68% higher risk (95% CI 1.27, 2.23) of diabetes [OR for upper vs. lower quartile 2.87 (1.39, 5.91)], after full adjustments (age, sex, other AAs, adiposity, eGFR, physical activity, blood pressure, diet and medication); equivalent ORs for cystathionine were 1.33 (1.08, 1.64) and 1.68 (0.85, 3.29). Subjects who were simultaneously in the upper tertiles of both cystathionine and tCys had a fivefold risk [OR = 5.04 (1.55, 16.32)] of diabetes compared with those in the lowest tertiles. Higher serine was independently associated with a lower risk of developing diabetes [fully adjusted OR per SD = 0.68 (0.54, 0.86)]. Glutamic acid and glutamine showed positive and negative associations, respectively, with incident diabetes in age- and sex-adjusted analysis, but only the glutamic acid association was independent of other confounders [fully adjusted OR per SD = 1.95 (1.19, 3.21); for upper quartile = 7.94 (3.04, 20.75)]. tGSH was inversely related to diabetes after adjusting for age and sex, but not other confounders. No consistent associations were observed for methionine, tHcy or taurine.

CONCLUSION

Specific SAAs and related metabolites show strong and independent associations with incident diabetes. This suggests that perturbations in the SAA metabolic pathway may be an early marker for diabetes risk.

Development of a synbiotic that protects against ovariectomy-induced trabecular bone loss

The gut microbiome has the capacity to regulate bone mass. The aim of this study was to develop a nutritional synbiotic dietary assemblage at an optimal dose to maintain bone mass in ovariectomized (Ovx) mice. We performed genomic analyses and in vitro experiments in a large collection of bacterial and fungal strains (>4,000) derived from fresh fruit and vegetables to identify candidates with the synergistic capacity to produce bone-protective short-chain fatty acids (SCFA) and vitamin K2. The candidate SBD111-A, composed of Lactiplantibacillus plantarum, Levilactobacillus brevis, Leuconostoc mesenteroides, Pseudomonas fluorescens, and Pichia kudriavzevii together with prebiotic dietary fibers, produced high levels of SCFA in vitro and protected against Ovx-induced trabecular bone loss in a dose-dependent manner in mice. Metagenomic sequencing revealed that SBD111-A changed the taxonomic composition and enriched specific pathways for synthesis of bone-protective SCFA, vitamin K2, and branched-chain amino acids in the gut microbiome.NEW & NOTEWORTHY We performed genomic analyses and in vitro experiments in a collection of bacterial and fungal strains. We identified a combination (SBD111-A) that produced high levels of SCFA in vitro and protected against ovariectomy-induced bone loss in a dose-dependent manner in mice. Metagenomic sequencing revealed that SBD111-A changed the taxonomic composition and function of the gut microbiome and enriched pathways for synthesis of bone-protective SCFA, vitamin K2, and branched-chain amino acids.

Higher fruit and vegetable variety associated with lower risk of cognitive impairment in Chinese community-dwelling older men: a 4-year cohort study

PURPOSE

Few studies have examined the variety in fruit and vegetable (FV) intake with cognitive impairment in older adults. This study examined the associations of variety in fruit, vegetable and combined FV with 4-year incident cognitive impairment in Chinese community-dwelling older adults.

METHODS

Data was derived from a cohort study among Chinese community-dwelling older adults aged ≥ 65 years in Hong Kong. At baseline, a validated food frequency questionnaire was used to assess variety in fruit, vegetable and combined FV. Cognitive impairment was defined as a Community Screening Instrument of Dementia score of < 29.5 points and/or Mini-Mental State Examination score of < 27 points. Adjusted multiple logistic regression was performed to examine the associations. Results are presented as odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Of the 1518 participants [median age: 70 years (IQR 68-74), 32.7% women] included at baseline, 300 men and 111 women were newly identified as cognitively impaired at the 4-year follow-up. In men, higher variety in vegetable (adjusted OR: 0.97, 95% CI 0.95-0.99, p = 0.029) and combined FV (adjusted OR: 0.98, 95% CI 0.96-0.98, p = 0.039) were significantly associated with a lower risk of cognitive impairment. Fruit variety was not associated with cognitive impairment. In women, there were no associations between variety in fruit, vegetable and combined FV with cognitive impairment in the adjusted model.

CONCLUSION

Independent of FV quantity, higher variety in vegetable and combined FV were associated with lower risk of cognitive impairment in Chinese community-dwelling older adults, and these associations were only observed in men.

Gut Microbiota and Serum Metabolic Signatures of High-Fat-Induced Bone Loss in Mice

Background

Accumulating evidence indicates that high-fat diet (HFD) is a controllable risk factor for osteoporosis, but the underlying mechanism remains to be elucidated. As a primary biological barrier for nutrient entry into the human body, the composition and function of gut microbiota (GM) can be altered rapidly by HFD, which may trigger abnormal bone metabolism. In the current study, we analyzed the signatures of GM and serum metabolomics in HFD-induced bone loss and explored the potential correlations of GM and serum metabolites on HFD-related bone loss.

Methods

We conducted a mouse model with HFD-induced bone loss through a 12-week diet intervention. Micro-CT, Osmium-μCT, and histological analyses were used to observe bone microstructure and bone marrow adipose tissue. Quantitative Real-Time PCR was applied to analyze gene expression related to osteogenesis, adipogenesis, and osteoclastogenesis. Enzyme-linked immunosorbent assay was used to measure the biochemical markers of bone turnover. 16s rDNA sequencing was employed to analyze the abundance of GM, and UHPLC-MS/MS was used to identify serum metabolites. Correlation analysis was performed to explore the relationships among bone phenotypes, GM, and the metabolome.

Results

HFD induced bone loss accompanied by bone marrow adipose tissue expansion and bone formation inhibition. In the HFD group, the relative abundance of Firmicutes was increased significantly, while Bacteroidetes, Actinobacteria, Epsilonbacteraeota, and Patescibacteria were decreased compared with the ND group. Association analysis showed that thirty-two bacterial genera were significantly related to bone volume per tissue volume (BV/TV). One hundred and forty-five serum metabolites were identified as differential metabolites associated with HFD intervention, which were significantly enriched in five pathways, such as purine metabolism, regulation of lipolysis in adipocyte and cGMP-PKG signaling pathway. Sixty-four diffiential metabolites were matched to the MS2 spectra; and ten of them were positively correlated with BV/TV and five were negatively correlated with BV/TV.

Conclusions

These findings indicated that the alternations of GM and serum metabolites were related to HFD-induced bone loss, which might provide new insights into explain the occurrence and development of HFD-related osteoporosis. The regulatory effects of GM and metabolites associated with HFD on bone homeostasis required further exploration.

Jintiange Capsule Alleviates Rheumatoid Arthritis and Reverses Changes of Serum Metabolic Profile in Collagen-Induced Arthritic Rats

Purpose

Jintiange capsule (JTG), an approved drug developed as a substitute for tiger bone (TB), has been clinically applied for osteoporosis therapy since 2003. The drug is composed of bionic TB powder, in which peptides and proteins are primarily enriched from other bone extracts. However, as a precious material of traditional Chinese medicine (TCM), TB has been mainly understood and used in TCM to relieve osteoporosis, rheumatoid arthritis and bone injury. Inspired by those, the purpose of this study was to investigate whether JTG also had an effect on relieving rheumatoid arthritis in collagen-induced arthritic (CIA) rats and explore potential mechanism from the perspective of serum metabolic profile changes.

Methods

JTG was analyzed using Nano LC-MS/MS and orally administered in CIA rats for 6 weeks. After administration, intervention effects of JTG on synovial inflammation, bone micro-architecture and bone metabolism were studied, and the impact of JTG on serum metabolic profiles in CIA rats was investigated by metabolomics.

Results

Nine bioactive peptides were identified in JTG. In animal treatments, JTG alleviated paw swelling (P < 0.01), arthritic severity (P < 0.01) and synovial tissue proliferation, as well as inflammatory cell infiltration of ankle joint, decreased bone loss, improved microstructure of bone in CIA rats by regulating bone absorption and formation, specifically increasing bone mineral density (BMD) (P < 0.05), bone volume fraction (BVF) (P < 0.05), trabecular number (Tb.N) (P < 0.05) and decreasing trabecular separation (Tb.Sp) (P < 0.05). Besides, serum IL-6 was down-regulated remarkably in CIA rats (P < 0.05). Furthermore, metabolomics analysis revealed that 32 metabolites were regulated significantly (P < 0.05) by comparison between CIA model and JTG in 360 mg/kg dose. The pathway analysis implied that JTG was involved in regulation of biosynthesis of phenylalanine.

Conclusion

JTG alleviates rheumatoid arthritis and reverses changes in serum metabolic profile in CIA rats.

Point your SmartPhone at the code above. If you have a QR code reader, the video abstract will appear. Or use:

https://youtu.be/fgIlcSWmw_Y

Metabolomic biomarkers of low BMD: a systematic review

Due to the metabolic nature of osteoporosis, this study was conducted to identify metabolomic studies investigating the metabolic profile of low bone mineral density (BMD) and osteoporosis. A comprehensive systematic literature search was conducted through PubMed, Web of Science, Scopus, and Embase databases up to April 08, 2020, to identify observational studies with cross-sectional or case-control designs investigating the metabolic profile of low BMD in adults using biofluid specimen via metabolomic platform. The quality assessment panel specified for the "omics"-based diagnostic research (QUADOMICS) tool was used to estimate the methodologic quality of the included studies. Ten untargeted and one targeted approach metabolomic studies investigating biomarkers in different biofluids through mass spectrometry or nuclear magnetic resonance platforms were included in the systematic review. Some metabolite panels, rather than individual metabolites, showed promising results in differentiating low BMD from normal. Candidate metabolites were of different categories including amino acids, followed by lipids and carbohydrates. Besides, certain pathways were suggested by some of the studies to be involved. This systematic review suggested that metabolic profiling could improve the diagnosis of low BMD. Despite valuable findings attained from each of these studies, there was great heterogeneity regarding the ethnicity and age of participants, samples, and the metabolomic platform. Further longitudinal studies are needed to validate the results and confirm the predictive role of metabolic profile on low BMD and fracture. It is also mandatory to address and minimize the heterogeneity in future studies by using reliable quantitative methods. Summary: Due to the metabolic nature of osteoporosis, researchers have considered metabolomic studies recently. This systematic review showed that metabolic profiling including different categories of metabolites could improve the diagnosis of low BMD. However, great heterogeneity was observed and it is mandatory to address and minimize the heterogeneity in future studies.

A 1:1 matched case-control study on dietary protein intakes and hip fracture risk in Chinese elderly men and women

The role of protein intake in bone has been controversial. Our case-control study among Chinese elderly concluded that a higher consumption of protein, even substituted for fat, is associated with lowered hip fracture risk. Differences in protein sources, amino acids composition, gender, and calcium sufficiency may explain the inconsistency.

PURPOSE

The aim of the study was to investigate the association of dietary protein intakes with hip fracture risk among Chinese elderly.

METHODS

This was a 1:1 age and sex matched cross-sectional study of case-control design among 1070 pairs of elderly Chinese people aged 55 to 80 years. Patients who were newly diagnosed (within 2-week) hip fracture by X-ray were recruited from four hospitals in Guangdong Province of China. Dietary intakes were evaluated by a validated food frequency questionnaire for total protein, protein from different sources, amino acids profiles, and estimated renal acid load in diet.

RESULTS

Daily average intakes of total protein were 58.1±27.0 (women) and 65.7±31.8 (men) g/d for cases, and 66.8±21.5 (women) and 72.1±24.4 (men) for controls (p<0.001). Multivariable regression indicated that, compared with the lowest quartile, the highest quartile of consumption of energy adjusted total protein [OR: 0.360 (0.206~0.630) for women and 0.381 (0.153~0.949) for men] and animal protein [0.326 (0.183, 0.560) for women and 0.335 (0.136~0.828) for men] was significantly associated with the lowered risk of hip fracture in a dose-response manner (all p for trend <0.05). A significant hip fracture risk reduction was observed in women with higher intakes of sulfur amino acids [OR: 0.464 (0.286~0.753)] and aromatic amino acids [0.537 (0.326~0.884)] but not in men. Subgroup analysis suggested that these associations were more evident in elderly with lower body mass index and dietary calcium intake less than 400 mg/d.

CONCLUSIONS

A higher level of protein intake, even substituted for fat, is associated with lowered hip fracture risk.

Nutrients with anabolic/anticatabolic, antioxidant, and anti-inflammatory properties: Targeting the biological mechanisms of aging to support musculoskeletal health

Old age is associated with declines in bone density and muscle mass and function, which predisposes to mobility disability, falls, and fractures. Poor nutritional status, a risk factor for several age-related pathologies, becomes prevalent in old age and contributes to the structural and functional changes of the musculoskeletal system that increases the risk of osteoporosis, sarcopenia, osteosarcopenia, and physical frailty. The biological mechanisms underpinning these pathologies often overlap and include loss of proteostasis, impaired redox functioning, and chronic low-grade inflammation. Thus, provision of nutrients with anabolic/anticatabolic, antioxidant, and anti-inflammatory properties may be an effective strategy to offset these age-related pathologies. We searched PUBMED for pre-clinical and clinical work examining the effects of nutrients with a combined effect on muscle and bone. This review summarizes recent evidence on the mechanisms of action and potential clinical use of nutrients that concomitantly improve muscle and bone health in older persons.

Serum Metabolite Profile Associated with Sex-Dependent Visceral Adiposity Index and Low Bone Mineral Density in a Mexican Population

Recent evidence shows that obesity correlates negatively with bone mass. However, traditional anthropometric measures such as body mass index could not discriminate visceral adipose tissue from subcutaneous adipose tissue. The visceral adiposity index (VAI) is a reliable sex-specified indicator of visceral adipose distribution and function. Thus, we aimed to identify metabolomic profiles associated with VAI and low bone mineral density (BMD). A total of 602 individuals from the Health Workers Cohort Study were included. Forty serum metabolites were measured using the targeted metabolomics approach, and multivariate regression models were used to test associations of metabolomic profiles with anthropometric, clinical, and biochemical parameters. The analysis showed a serum amino acid signature composed of glycine, leucine, arginine, valine, and acylcarnitines associated with high VAI and low BMD. In addition, we found a sex-dependent VAI in pathways related to primary bile acid biosynthesis, branched-chain amino acids, and the biosynthesis of pantothenate and coenzyme A (CoA). In conclusion, a metabolic profile differs by VAI and BMD status, and these changes are gender-dependent.

Serum Amino Acids Patterns and 4-Year Sarcopenia Risk in Community-Dwelling Chinese Older Adults

INTRODUCTION

Dietary protein intake and serum amino acids (AAs) are factors controlling the rate of muscle protein synthesis and catabolism. This study examined the association between serum AAs patterns and incident sarcopenia in community-dwelling older adults.

METHODS

Chinese older adults in Hong Kong aged ≥65 years attended a health check at baseline and 4-year follow-up. At baseline, fasting blood was collected to measure 17 serum AAs. Serum AAs patterns were identified using principal component analysis. Dietary protein intake was assessed using a validated food frequency questionnaire. A composite score was computed by summing the principal component score and sex-standardized protein intake. Six composite scores representing each AAs pattern were available for each participant. Sarcopenia was defined using the updated version of the Asian Working Group for Sarcopenia. Crude and adjusted multiple logistic regressions were performed to examine the associations between each of the 6 composite scores and sarcopenia over 4 years. Results are presented as odds ratio (OR) and 95% confidence interval (CI). To address multiple testing, a Bonferroni correction was applied using a corrected significance level of p < 0.008 (α 0.05/6 patterns).

RESULTS

Data of 2,610 participants (mean age 71.6 years, 45.4% men) were available. In men, serum AAs patterns characterized by high branched-chain AAs (BCAAs) (OR 0.77, 95% CI 0.69-0.87, p < 0.001) and tyrosine, tryptophan, and phenylalanine (OR 0.79, 95% CI 0.71-0.89, p < 0.001) were significantly associated with a lower risk of sarcopenia over 4-year follow-up. After adjusting for confounders, the associations were no longer significant. In women, serum AAs patterns characterized by glutamine, glutamic acid, and methionine (OR 1.28, 95% CI 1.11-1.47, p = 0.001) and arginine, taurine, and serine (OR 1.20, 95% CI 1.06-1.35, p = 0.003) were associated with a higher risk of sarcopenia. After adjusting for confounders, serum AAs pattern characterized by high BCAAs (adjusted OR 1.52, 95% CI 1.25-1.86, p < 0.001) and arginine, taurine, and serine (adjusted OR 1.30, 95% CI 1.09-1.56, p = 0.004) were significantly associated with a higher risk of sarcopenia. No association between other AAs patterns with incident sarcopenia was found.

CONCLUSIONS

In community-dwelling Chinese older adults, serum AAs patterns characterized by high BCAAs and nonessential AAs (arginine, taurine, and serine) were associated with a higher risk of sarcopenia in women. Findings may allow identifying new targets for interventions.

Network pharmacology integrated with experimental validation reveals the regulatory mechanism of plastrum testudinis in treating senile osteoporosis

ETHNOPHARMACOLOGICAL RELEVANCE

Plastrum testudinis (PT) has been used in traditional Chinese medicine to treat bone diseases such as senile osteoporosis (SOP) for thousands of years. However, the underlying mechanisms remain largely unknown.

AIM OF THE STUDY

This study aims to investigate the possible molecular mechanism of PT in the treatment of SOP using an integrated strategy of network pharmacology and experimental validation.

MATERIALS AND METHODS

The compounds of PT and its targets were identified through the BATMAN-TCM database. The SOP-related targets were retrieved from the GeneCards database. Protein-protein interaction information was obtained by inputting the intersection targets into the STRING database. Cytoscape software was used to construct a protein-protein interaction network and a PT-compound-target-SOP network. Using Cytoscape and R software, we conducted GO function and KEGG pathway enrichment analyses. We also conducted in vivo and in vitro experiments to verify the network pharmacology findings.

RESULTS

In total, 6 active compounds and 342 targets of PT were screened, of which 57 common targets were related to SOP. The GO biological process enrichment analysis identified 880 entries, mainly relating to the regulation of hormone response, the cell apoptotic process, the apoptotic signaling pathway, NF-kappaB transcription factor activity, fatty acid transportation, osteoclast differentiation, macrophage activation, and inflammatory response. The KEGG pathway enrichment analysis identified 52 entries, including 14 related signaling pathways, which mainly involved the TNF, MAPK, IL-17, AGE-RAGE, estrogen, relaxin, and other signaling pathways. Our in vivo experiments confirmed that PT alleviates SOP, while the in vitro experiments demonstrated that PT exerts a suppressive effect on osteoclast differentiation and bone resorption in a concentration-dependent manner. Furthermore, we observed that PT downregulates the expression of osteoclast-specific genes, including C-FOS, TNF, and BDNF, in the MAPK signaling pathway.

CONCLUSION

Through network pharmacology and experimental validation, this study is the first to report that PT downregulates the expression of osteoclast-specific genes, including C-FOS, TNF, and BDNF, in the MAPK signaling pathway, thus exerting a suppressive effect on osteoclast differentiation and bone resorption, which may be the molecular mechanism for PT treatment of SOP.

Gut microbiota and bone metabolism

Osteoporosis is the most common metabolic skeletal disease. It is characterized by the deterioration of the skeletal microarchitecture and bone loss, leading to ostealgia, and even bone fractures. Accumulating evidence has indicated that there is an inextricable relationship between the gut microbiota (GM) and bone homeostasis involving host-microbiota crosstalk. Any perturbation of the GM can play an initiating and reinforcing role in disrupting the bone remodeling balance during the development of osteoporosis. Although the GM is known to influence bone metabolism, the mechanisms associated with these effects remain unclear. Herein, we review the current knowledge of how the GM affects bone metabolism in health and disease, summarize the correlation between pathogen-associated molecular patterns of GM structural components and bone metabolism, and discuss the potential mechanisms underlying how GM metabolites regulate bone turnover. Deciphering the complicated relationship between the GM and bone health will provide new insights into the prevention and treatment of osteoporosis.

Evaluation of the relationship between homocysteine levels and bone mineral density in postmenopausal women

OBJECTIVE

The current study aimed to evaluate the relationship between homocysteine (Hcy) levels and bone mineral density (BMD) in postmenopausal women.

METHODS

The present, cross-sectional study included 760 postmenopausal women. The following variables were recorded: age, age at menopause, body mass index (BMI), BMD (measured by dual-energy X-ray absorptiometry [DXA] scanning and expressed as lumbar, femoral neck and total hip T-scores), smoking status, biochemical parameters (Hcy, creatinine, calcium, phosphorus, vitamin D and parathormone levels) and vitamin D supplementation.

RESULTS

The mean age of the sample population was 56.4 ± 5.77 years and the mean age at menopause was 49.9 ± 3.62 years. The mean BMI was 25.2 ± 4.49 kg/m². In the current study, a comparison of the subjects with osteoporosis, osteopenia and normal BMD revealed that the subjects in the low BMD group were significantly older (p < 0.001), had a lower age at menopause (p < 0.001) and had lower BMI (p < 0.001). There was no statistically significant difference among the groups with regard to the plasma levels of Hcy (p = 0.946). The levels of Hcy were positively correlated to the creatinine levels (r = 0.21). The present study did not observe any significant correlations between the Hcy levels and other parameters.

CONCLUSIONS

In the present study, 15.3% of the subjects had hyperhomocysteinemia and 62.11% had low BMD. The current results obtained from a group of postmenopausal women suggest that the plasma levels of Hcy are not related to BMD in the lumbar spine (L1-L4), femoral neck and total hip. In the current study, age, age at menopause and low BMI were observed to be associated with low BMD.

The Role of Osteoclast Energy Metabolism in the Occurrence and Development of Osteoporosis

In recent decades, the mechanism underlying bone metabolic disorders based on energy metabolism has been heavily researched. Bone resorption by osteoclasts plays an important role in the occurrence and development of osteoporosis. However, the mechanism underlying the osteoclast energy metabolism disorder that interferes with bone homeostasis has not been determined. Bone resorption by osteoclasts is a process that consumes large amounts of adenosine triphosphate (ATP) produced by glycolysis and oxidative phosphorylation. In addition to glucose, fatty acids and amino acids can also be used as substrates to produce energy through oxidative phosphorylation. In this review, we summarize and analyze the energy-based phenotypic changes, epigenetic regulation, and coupling with systemic energy metabolism of osteoclasts during the development and progression of osteoporosis. At the same time, we propose a hypothesis, the compensatory recovery mechanism (involving the balance between osteoclast survival and functional activation), which may provide a new approach for the treatment of osteoporosis.

Relationship Between Serum Amino Acid Levels and Bone Mineral Density: A Mendelian Randomization Study

BACKGROUND

This study aimed to explore the association between serum amino acids (AAs) levels and bone mineral density (BMD).

METHODS

We performed a two-sample Mendelian randomization (MR) analysis to analyze the associations between the levels of eight AAs and BMD values by using summary-level genome-wide association study (GWAS) data. We applied the MR Steiger filtering method and MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) global test to check for and remove single nucleotide polymorphisms (SNPs) that were horizontally pleiotropic. The associations were estimated with the inverse variance weighted (IVW), MR-Egger, weighted median and MR Robust Adjusted Profile Score (MR.RAPS) methods.

RESULTS

Our study found that genetically increased isoleucine (Ile) [IVW: effect = 0.1601, 95% confidence interval (CI) = 0.0604 ~ 0.2597, p = 0.0016] and valine (Val) levels (IVW: effect = 0.0953, 95% CI = 0.0251 ~ 0.1655, p = 0.0078) were positively associated with total body BMD (TB-BMD). The results also revealed that genetically increased tyrosine (Tyr) levels were negatively associated with TB-BMD (IVW: effect = -0.1091, 95% CI = -0.1863 ~ -0.0320, p = 0.0055).

CONCLUSIONS

In this study, associations between serum AA levels and BMD were established. These findings underscore the important role that serum AAs play in the development of osteoporosis and provide evidence that osteoporosis can be prevented and treated by the intake of certain AAs.

A Multi-Omic Analysis for Low Bone Mineral Density in Postmenopausal Women Suggests a RELATIONSHIP between Diet, Metabolites, and Microbiota

The effect of microbiota composition and its health on bone tissue is a novel field for research. However, their associations with bone mineral density (BMD) have not been established in postmenopausal women. The present study investigates the relation of diet, the microbiota composition, and the serum metabolic profile in postmenopausal women with normal-BMD or with low-BMD. Ninety-two Mexican postmenopausal women were classified into normal-BMD (n = 34) and low-BMD (n = 58). The V4 hypervariable region was sequenced using the Miseq platform. Serum vitamin D was determined by chemiluminescence immunoassay. Serum concentrations of acyl-carnitines and amino acids were determined by electrospray tandem mass spectrometry. Diet was assessed by a food frequency questionnaire. The low-BMD group had fewer observed species, higher abundance of γ-Proteobacteria, lower consumption of lycopene, and lower concentrations of leucine, valine, and tyrosine compared with the normal-BMD group. These amino acids correlated positively with the abundance of Bacteroides. Lycopene consumption positively correlated with Oscillospira and negatively correlated with Pantoea genus abundance. Finally, the intestinal microbiota of women with vitamin D deficiency was related to Erysipelotrichaceae and Veillonellaceae abundance compared to the vitamin D non-deficient group. Associations mediated by the gut microbiota between diet and circulating metabolites with low-BMD were identified.

Helicobacter pylori Related Diseases and Osteoporotic Fractures (Narrative Review)

Osteoporosis (OP) and osteoporotic fractures (OFs) are common multifactorial and heterogenic disorders of increasing incidence. Helicobacter pylori (H.p.) colonizes the stomach approximately in half of the world's population, causes gastroduodenal diseases and is prevalent in numerous extra-digestive diseases known to be associated with OP/OF. The studies regarding relationship between H.p. infection (HPI) and OP/OFs are inconsistent. The current review summarizes the relevant literature on the potential role of HPI in OP, falls and OFs and highlights the reasons for controversies in the publications. In the first section, after a brief overview of HPI biological features, we analyze the studies evaluating the association of HPI and bone status. The second part includes data on the prevalence of OP/OFs in HPI-induced gastroduodenal diseases (peptic ulcer, chronic/atrophic gastritis and cancer) and the effects of acid-suppressive drugs. In the next section, we discuss the possible contribution of HPI-associated extra-digestive diseases and medications to OP/OF, focusing on conditions affecting both bone homeostasis and predisposing to falls. In the last section, we describe clinical implications of accumulated data on HPI as a co-factor of OP/OF and present a feasible five-step algorithm for OP/OF risk assessment and management in regard to HPI, emphasizing the importance of an integrative (but differentiated) holistic approach. Increased awareness about the consequences of HPI linked to OP/OF can aid early detection and management. Further research on the HPI-OP/OF relationship is needed to close current knowledge gaps and improve clinical management of both OP/OF and HPI-related disorders.

The effect of physical activity on dose-relationship between serum 25-hydroxyvitamin D and cardiovascular health events in older adults

BACKGROUND AND AIMS

Reverse J- or U-shaped associations between serum 25-hydroxyvitamin D (25[OH]D) concentrations and cardiovascular outcomes have been reported, which need clarifications in older adults. Physical activity, correlating with both serum 25[OH]D concentration and cardiovascular health, may have an effect on the dose-relationships.

METHODS AND RESULTS

At baseline, 2790 participants aged 65 years and over, free of vitamin D supplementation use, had assays for serum 25[OH]D concentrations and health related characteristics and measurements, were followed up for cardiovascular events and death by up to 7 and 15 years, respectively. The dose-response associations of serum 25[OH]D concentrations with cardiovascular events and mortality risk were examined using Cox regression models. After adjusting for physical activity and other covariates, serum 25[OH]D concentration was non-linearly associated with cardiovascular mortality risk (U-shaped, P = 0.009). According to the Institute of Medicine categories, the HR(95% CI) of cardiovascular mortality risk separately in deficient (<25 nmol/L), inadequate (25 to < 50 nmol/L) and potentially harmful (≥125 nmol/L) level was 1.67 (0.23, 12.01), 1.66 (1.25, 2.20) and 2.21 (0.30, 16.37), respectively. The risk of 25[OH]D inadequacy for cardiovascular mortality was significantly attenuated by increased physical activity, especially leisure activity (P for trend = 0.008 and 0.021, respectively). No significant finding was observed for incident cardiovascular events.

CONCLUSION

Both lower and higher serum 25[OH]D concentrations were associated with risk of cardiovascular mortality in Chinese community-dwelling older adults. Physical activity may attenuate the cardiovascular mortality risk of vitamin D inadequacy, but its role in individuals with higher 25[OH]D concentrations remains unclear.