Pros and cons of fatty acids in bone biology

Association of serum fatty acids with bone health in rural elderly population in Qingdao, China: A cross-sectional study

As a type of macronutrient, fatty acids (FA) play significant roles in the bone health of elderly people. However, the specific association between different types of FA and bone health is not fully understood, especially in rural elderly populations. To address this gap, a study was conducted in rural areas of Qingdao, China. Participants aged 65 and older were randomly recruited from 11 rural villages in Licha town, Qingdao City. The levels of serum FA in their serum were measured to investigate the associations between FA and bone mass. The results showed that levels of saturated fatty acids (SFA), n-3 polyunsaturated fatty acids (n-3 PUFA), and n-6 polyunsaturated fatty acids (n-6 PUFA) were all significantly associated with bone mass. Specifically, higher levels of SFA were positively correlated with low bone mass (LBM), while PUFA levels were inversely correlated with LBM. Furthermore, the odds ratio (OR) for LBM exhibited a significant nonlinear dose-response relationship (pnonlinearity = 0.1989) with SFA levels, and a significant nonlinear dose-dependent relationship was also observed with the levels of n-3PUFA and n-6PUFA (pnonlinearity = 0.6183, 0.5808, respectively), indicating that increasing dietary PUFA intake appropriately and controlling SFA intake may benefit the bone health of elderly individuals in rural areas.

Grape seed extract prevents oestrogen deficiency-induced bone loss by modulating the gut microbiota and metabolites

Proanthocyanidin-rich grape seed extract (GSE) has been shown to have the potential to protect bones, although the underlying mechanism remains unknown. The current study aims to explore GSE's preventive and therapeutic impact on bone loss induced by oestrogen deficiency and the underlying mechanism through the gut microbiota (GM) and metabolomic responses. In oestrogen-deficient ovariectomized (OVX) mice, GSE ameliorated bone loss by inhibiting the expansion of bone marrow adipose tissue (BMAT), restoring BMAT lipolysis and promoting bone formation. GSE regulated OVX-induced GM dysbiosis by reducing the abundance of opportunistic pathogenic bacteria, such as Alistipes, Turicibacter and Romboutsia, while elevating the abundance of beneficial bacteria, such as Bifidobacterium. The modified GM primarily impacted lipid and amino acid metabolism. Furthermore, the serum metabolites of GSE exhibited a significant enrichment in lipid metabolism. In summary, GSE shows potential as a functional food for preventing oestrogen deficiency-induced bone loss by modulating GM and metabolite-mediated lipid metabolism.

Recent Advance in Regulatory Effect of GRP120 on Bone Metabolism

The link between fatty acids and bone metabolism is complex and can be direct and indirect. This link has been reported in different types of bone cells and various stages of bone metabolism. G-protein coupled receptor 120 (GPR120), also called free fatty acid receptor 4 (FFAR4), is a member of the recently discovered G protein-coupled receptor family that can interact with both long-chain saturated fatty acids (C14-C18) and long-chain unsaturated fatty acids (C16-C22). Research shows that GPR120 regulates processes in different types of bone cells, directly or indirectly affecting bone metabolism. Our research reviewed the literature on the effects of GPR120 on bone marrow mesenchymal stem cells (BMMSCs), osteoblasts, osteoclasts, and chondrocytes, focusing on the research findings regarding the mechanism by which GPR120 alters specific bone metabolic diseases-osteoporosis and osteoarthritis. The data reviewed here provide a basis for clinical and basic research into the role of GPR120 on bone metabolic diseases.

Changes in Bone Marrow Fatty Acids Early after Ovariectomy-Induced Osteoporosis in Rats and Potential Functions

The aim of this study was to investigate the changes in bone marrow fatty acids early after ovariectomy-induced osteoporosis in rats, and explore the potential function of the bone marrow fatty acids. Ninety-six female Sprague Dawley rats (12 weeks) were randomly divided into an ovariectomized (OVX) group and Sham group (N = 48/group) and received ovariectomy or Sham surgery, respectively. After 3, 5, 7,14, 21 and 28 days, eight rats in each group were sacrificed to detect the composition of bone marrow fatty acids by means of gas chromatography-mass spectrometry and evaluate the trabecular bone microarchitecture by means of microCT. Bone marrow rinsing fluid and serum were collected for the detection of nitric oxide synthase/nitric oxide (NOS/NO) and bone metabolism related parameters, respectively. Our results demonstrated that the bone microstructure was damaged significantly from 14 days after OVX surgery onwards. Sample clustering and group separation were observed between the OVX group and Sham group 3 and 14 days after surgery, which suggested the role of bone marrow fatty acids in the early stage of postmenopausal osteoporosis. Palmitoleate, myristate and arachidonate were found to play an important role in classification between the OVX group and Sham group on the 3rd day after surgery (VIP > 1, p < 0.05). Palmitoleate, myristate, alpha linolenate, stearate and eicosenoate were found to play an important role in classification between the OVX group and Sham group on the 14th day after surgery (VIP > 1, p < 0.05). The levels of myristate, palmitoleate, alpha linolenate and eicosenoate were significantly decreased in the OVX group, while the levels of arachidonate and stearate were significantly increased in OVX group (p < 0.05). Additionally, myristate, palmitoleate, alpha linoleate and eicosenoate were negatively correlated with C-terminal telopeptide of type 1 collagen (CTX-1, a bone resorption marker), while arachidonate was negative correlated with osteocalcin (OCN, a bone formation marker) (p < 0.05). A significant correlation was also found between eicosenoate and NOS (p < 0.05). Profound bone marrow fatty acids changes have taken place in the early stage of post-menopausal osteoporosis. They may affect bone formation though affecting the differentiation and function of osteoclasts or osteoblasts, respectively. The NOS/NO system may mediate the influence of eicosenoate on bone formation.

The Impact of Hempseed Consumption on Bone Parameters and Body Composition in Growing Female C57BL/6 Mice

Optimizing peak bone mass is critical to healthy aging. Beyond the established roles of dietary minerals and protein on bone integrity, fatty acids and polyphenols modify bone structure. This study investigated the effect of a diet containing hempseeds (HS), which are rich in polyunsaturated fatty acids and polyphenols, on bone mineral density, bone cell populations and body composition. Groups (n = 8 each) of female C57BL/6 mice were fed one of three diets (15% HS by weight; 5% HS; 0% HS (control)) from age 5 to 30 weeks. In vivo whole-body composition and bone mineral density and content were measured every 4 weeks using dual-energy X-ray absorptiometry. Ex vivo humeri cell populations in the epiphyseal plate region were determined by sectioning the bone longitudinally, mounting the sections on slides and staining with tartrate-resistant acid phosphatase and alkaline phosphatase stain to identify osteoclasts and osteoblasts, respectively. Mixed models with repeated measures across experimental weeks showed that neither body weight nor body weight gain across weeks differed among groups yet mice fed the 15% HS diet consumed significantly more food and more kilocalories per g body weight gained than those fed the 5% HS and control diets (p < 0.0001). Across weeks, fat mass was significantly higher in the 5% HS versus the control group (p = 0.02). At the end point, whole-body bone mineral content was significantly higher in the control compared to the 5% HS group (p = 0.02). Humeri from both HS groups displayed significantly lower osteoblast densities compared to the control group (p < 0.0001). No relationship was seen between osteoblast density and body composition measurements. These data invite closer examination of bone cell activity and microarchitecture to determine the effect of habitual HS consumption on bone integrity.

Targeting adipocytic discoidin domain receptor 2 impedes fat gain while increasing bone mass

Obesity is closely associated with low-bone-mass disorder. Discoidin domain receptor 2 (DDR2) plays essential roles in skeletal metabolism, and is probably involved in fat metabolism. To test the potential role of DDR2 in fat and fat-bone crosstalk, Ddr2 conditional knockout mice (Ddr2^Adipo) were generated in which Ddr2 gene is exclusively deleted in adipocytes by Adipoq Cre. We found that Ddr2^Adipo mice are protected from fat gain on high-fat diet, with significantly decreased adipocyte size. Ddr2^Adipo mice exhibit significantly increased bone mass and mechanical properties, with enhanced osteoblastogenesis and osteoclastogenesis. Marrow adipocyte is diminished in the bone marrow of Ddr2^Adipo mice, due to activation of lipolysis. Fatty acid in the bone marrow was reduced in Ddr2^Adipo mice. RNA-Seq analysis identified adenylate cyclase 5 (Adcy5) as downstream molecule of Ddr2. Mechanically, adipocytic Ddr2 modulates Adcy5-cAMP-PKA signaling, and Ddr2 deficiency stimulates lipolysis and supplies fatty acid for oxidation in osteoblasts, leading to the enhanced osteoblast differentiation and bone mass. Treatment of Adcy5 specific inhibitor abolishes the increased bone mass gain in Ddr2^Adipo mice. These observations establish, for the first time, that Ddr2 plays an essential role in the crosstalk between fat and bone. Targeting adipocytic Ddr2 may be a potential strategy for treating obesity and pathological bone loss simultaneously.

Gut Microbiota Feature of Senile Osteoporosis by Shallow Shotgun Sequencing Using Aged Rats Model

Senile osteoporosis is defined as an age-related bone metabolic disorder, which is characterized by bone loss and decreased bone fragility. Gut microbiota (GM) could regulate the bone metabolic process and be closely related to senile osteoporosis. Several genus-level GM were found to increase in osteoporotic animals and patients. However, to reveal the pathogenic bacteria in senile osteoporosis, further studies are still needed to investigate the complete characteristics of bacteria species. In the present study, the rats were equally divided into two groups: the control group (Con, 6-month-old) and the osteoporosis group (OP, 22-month-old). Fecal samples were freshly collected to conduct the shallow shotgun sequencing. Then, we compared the species numbers, microbial diversity, GM composition at genus and species-level, and functional metabolic pathways in the two groups. The results showed that the species number was lower in the OP group (1272) than in the control group (1413), and 1002 GM species were shared between the two groups. The OP group had the decreased α diversity compared with the control group. As for β diversity, The PCA revealed that samples in the two groups had distinguishable ecological distance in each coordinate. At the species level, Bacteroide coprocola (B. coprocola), Acinetobacter baumannii (A. baumannii), Parabacteroides distasonis (P. distasonis), and Prevotella copri (P. copri) were higher in the OP group, while Corynebacterium stationis (C. stationis), Akkermansia muciniphila (A. muciniphila), and Alistipes indistinctus (A. indistinctus) were decreased. Moreover, functional metabolic analysis revealed that metabolic pathways of fatty acid biosynthesis, valine/isoleucine biosynthesis, GABA biosynthesis, and ubiquinone biosynthesis were enriched in the senile osteoporotic rats. In conclusion, GM at the species level in senile osteoporotic rats was significantly altered in structure, composition, and function. The altered GM structure, increased GM species such as P. copri, and decreased GM species such as A. muciniphila might be linked with the development of senile osteoporosis.

Polyunsaturated Fatty Acids Level and Bone Mineral Density: A Two-Sample Mendelian Randomization Study

BACKGROUND

This Mendelian randomization (MR) study aimed to explore the causal relationship between polyunsaturated fatty acids (PUFAs) and bone mineral density (BMD).

METHODS

We conducted a two-sample MR analysis to figure out if there is any causal effect of PUFAs on BMD through the summary data from the genome-wide association study (GWAS). Relationships were evaluated through inverse variance weighted (IVW), MR-Egger, weighted median, and maximum likelihood methods. The MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) test was performed to detect the horizontal pleiotropy.

RESULTS

Our findings revealed that omega-6 fatty acids were negatively related to the TB-BMD (beta-estimate: -0.0515; 95% confidence interval [CI]: -0.0911 to -0.0119; standard error [SE]: 0.0201; p-value: 0.0106). The reverse direction MR analysis showed that TB-BMD was linked to the omega-6 FAs (beta-estimate: -0.0699; 95% CI: -0.1304 to -0.0095; SE: 0.0308; p-value: 0.0265). No statistically significant correlations between PUFAs and BMD were observed after adjusting the interactions between metabolites.

CONCLUSION

This two-sample MR analyses produced strong and new genomic evidence that there was a causal relationship between omega-6 FAs and BMD. Further investigations are still required to elucidate the potential mechanism.

Pro-Osteogenic Properties of Violina pumpkin (Cucurbita moschata) Leaf Extracts: Data from In Vitro Human Primary Cell Cultures

Traditional medicines rely mainly on use of plant extracts to mitigate or treat a wide range of disorders, including those that affect skeletal homeostasis. In this study, we investigated for the first time the potential pro-osteogenic effects of hexane, acetone and methanol extracts of the leaves of Cucurbita moschata, a very popular pumpkin cultivar in Western countries. We found that in Cucurbita moschata leaves, there are acetone-extractable substances—in particular, fatty acids such as 13-OH-9Z,11E,15E-octadecatrienoic acid (PU-13OH-FA), which is capable of both stimulating the function of human primary osteoblasts, which are responsible for bone formation, and inhibiting the differentiation of human osteoclasts, which are responsible for bone resorption. This dual effect was monitored by analyzing Runx2 expression, deposition of mineralized matrix, ALP activity, TRAP and actin ring staining respectively. This study suggests that bioactive chemicals from Cucurbita moschata leaves are potentially suitable as therapeutics for managing metabolic bone disorders such as osteoporosis and rheumatoid arthritis, and promoting tissue healing and functional recovery after bone fractures. The data we obtained increase knowledge on the biological activities of Cucurbita moschata, and in particular underline the potential benefits of consuming leaves which are a part of the plant currently little considered in the Western world.

Phytochemical Profiling in Conjunction with In Vitro and In Silico Studies to Identify Human α-Amylase Inhibitors in Leucaena leucocephala (Lam.) De Wit for the Treatment of Diabetes Mellitus

Bioactive constituents from natural sources are of great interest as alternatives to synthetic compounds for the treatment of various diseases, including diabetes mellitus. In the present study, phytochemicals present in Leucaena leucocephala (Lam.) De Wit leaves were identified by gas chromatography-mass spectrometry and further examined by qualitative and quantitative methods. α-Amylase enzyme activity assays were performed and revealed that L. leucocephala (Lam.) De Wit leaf extract inhibited enzyme activity in a dose-dependent manner, with efficacy similar to that of the standard α-amylase inhibitor acarbose. To determine which phytochemicals were involved in α-amylase enzyme inhibition, in silico virtual screening of the absorption, distribution, metabolism, excretion, and toxicity properties was performed and pharmacophore dynamics were assessed. We identified hexadecenoic acid and oleic acid ((Z)-octadec-9-enoic acid) as α-amylase inhibitors. The binding stability of α-amylase to those two fatty acids was confirmed in silico by molecular docking and a molecular dynamics simulation performed for 100 ns. Together, our findings indicate that L. leucocephala (Lam.) De Wit-derived hexadecanoic acid and oleic acid are natural product-based antidiabetic compounds that can potentially be used to manage diabetes mellitus.

Osteoprotective effects of kefir fortified with omega-3 and vitamin C in ovariectomized rats

Nutritional interventions can be valuable for the prevention of postmenopausal osteoporosis. This study aimed to investigate the effects of kefir fortified with omega-3 and vitamin C on the bone and uterus parameters of ovariectomized rats. Seventy-seven female Sprague-Dawley rats were ovariectomized or sham-operated. The ovariectomized rats were assigned to six groups and received 1 ml/day of distilled water (OVX group), milk, kefir, kefir fortified with omega-3 (kefir+ω3), kefir fortified with vitamin C (kefir+vit-C) or kefir fortified with omega-3 and vitamin C (kefir+ω3+vit-C) for 12 weeks. The sham group also received 1ml/day of distilled water. Subsequently, bone mineral content (BMC) and bone mineral density (BMD) of various bones were assessed. Femurs and uteri were harvested for bone ash analysis and histopathological examinations, respectively. Sera were analyzed for carboxy-terminal cross-linked telopeptide of type 1 collagen, procollagen type 1 amino-terminal propeptide, calcium, phosphorous, tumor necrosis factor-α (TNF-α) and total antioxidant capacity levels. Ovariectomy resulted in significant reduction in bone density (P<0.05). Kefir+ω3+vit-C significantly improved BMC of lumbar spine (0.699±0.027 g compared with 0.580±0.018 in the OVX group), and kefir, kefir+vit-C and kefir+ω3+vit-C significantly increased BMD of tibia (0.118±0.003 g/cm², 0.119±0.001 and 0.120±0.004 compared with 0.102±0.005 in the OVX group). Moreover, ovariectomy markedly elevated TNF-α level, which was significantly reversed by kefir+ω3+vit-C. Significant atrophy of the uterus was observed following ovariectomy, although the uterus parameters did not change by any of the interventions. In conclusion, kefir fortified with omega-3 and vitamin C may have protective effects against bone loss through suppressing inflammation.

Antioxidant Supplementation Does Not Affect Bone Turnover Markers During 60 Days of 6° Head-Down Tilt Bed Rest: Results from an Exploratory Randomized Controlled Trial

BACKGROUND

Immobilization and related oxidative stress are associated with bone loss. Antioxidants like polyphenols, omega-3 fatty acids, vitamins, and micronutrients may mitigate these negative effects on bone metabolism through scavenging of free radicals.

OBJECTIVES

We hypothesized that antioxidant supplementation during 60 days of 6° head-down tilt bed rest (HDBR) would reduce bone resorption and increase bone formation compared to nonsupplemented controls.

METHODS

This exploratory randomized, controlled, single-blind intervention study conducted in a parallel design included 20 healthy male volunteers (age, 34 ± 8 years; weight, 74 ± 6 kg). The study consisted of a 14-day adaptation phase [baseline data collection (BDC)], followed by 60 days of HDBR and a 14-day recovery period (R). In the antioxidant group, volunteers received an antioxidant cocktail (741 mg/d polyphenols, 2.1 g/d omega-3 fatty acids, 168 mg/d vitamin E, and 80 μg/d selenium) with their daily meals. In the control group, volunteers received no supplement. Based on their body weight, all volunteers received an individually tailored and strictly controlled diet, consistent with DRIs. We analyzed biomarkers of calcium homeostasis, bone formation, and bone resorption during BDC, HDBR, and R, as well as for 30 days after the end of HDBR. Data were analyzed by linear mixed models.

RESULTS

The antioxidant supplement did not affect serum calcium, parathyroid hormone, urinary C-telopeptide of type I collagen (CTX), urinary N-telopeptide of type I collagen, serum β-C-telopeptide of type I collagen (β-CTX), bone alkaline phosphatase, aminoterminal propeptide of type I collagen, osteocalcin, or urinary calcium excretion. In both groups, typical bed rest-related changes were observed.

CONCLUSIONS

Supplementation of an antioxidant cocktail to a diet matching the DRIs did not affect bone resorption or formation during 60 days of HDBR in healthy young men. This trial was registered at clinicaltrials.gov as NCT03594799.

Omics Profiling of S2P Mutant Fibroblasts as a Mean to Unravel the Pathomechanism and Molecular Signatures of X-Linked MBTPS2 Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is an inherited skeletal dysplasia characterized by low bone density, bone fragility and recurrent fractures. The characterization of its heterogeneous genetic basis has allowed the identification of novel players in bone development. In 2016, we described the first X-linked recessive form of OI caused by hemizygous MBTPS2 missense variants resulting in moderate to severe phenotypes. MBTPS2 encodes site-2 protease (S2P), which activates transcription factors involved in bone (OASIS) and cartilage development (BBF2H7), ER stress response (ATF6) and lipid metabolism (SREBP) via regulated intramembrane proteolysis. In times of ER stress or sterol deficiency, the aforementioned transcription factors are sequentially cleaved by site-1 protease (S1P) and S2P. Their N-terminal fragments shuttle to the nucleus to activate gene transcription. Intriguingly, missense mutations at other positions of MBTPS2 cause the dermatological spectrum condition Ichthyosis Follicularis, Atrichia and Photophobia (IFAP) and Keratosis Follicularis Spinulosa Decalvans (KFSD) without clinical overlap with OI despite the proximity of some of the pathogenic variants. To understand how single amino acid substitutions in S2P can lead to non-overlapping phenotypes, we aimed to compare the molecular features of MBTPS2-OI and MBTPS2-IFAP/KFSD, with the ultimate goal to unravel the pathomechanisms underlying MBTPS2-OI. RNA-sequencing-based transcriptome profiling of primary skin fibroblasts from healthy controls (n = 4), MBTPS2-OI (n = 3), and MBTPS2-IFAP/KFSD (n = 2) patients was performed to identify genes that are differentially expressed in MBTPS2-OI and MBTPS2-IFAP/KFSD individuals compared to controls. We observed that SREBP-dependent genes are more downregulated in OI than in IFAP/KFSD. This is coupled to alterations in the relative abundance of fatty acids in MBTPS2-OI fibroblasts in vitro, while no consistent alterations in the sterol profile were observed. Few OASIS-dependent genes are suppressed in MBTPS2-OI, while BBF2H7- and ATF6-dependent genes are comparable between OI and IFAP/KFSD patients and control fibroblasts. Importantly, we identified genes involved in cartilage physiology that are differentially expressed in MBTPS2-OI but not in MBTPS2-IFAP/KFSD fibroblasts. In conclusion, our data provide clues to how pathogenic MBTPS2 mutations cause skeletal deformities via altered fatty acid metabolism or cartilage development that may affect bone development, mineralization and endochondral ossification.

Effect of n-3 PUFA on extracellular matrix protein turnover in patients with psoriatic arthritis: a randomized, double-blind, placebo-controlled trial

Psoriatic arthritis (PsA) is a chronic inflammatory disease characterized by involvement of skin, axial and peripheral skeleton. An altered balance between extracellular matrix (ECM) formation and breakdown is a key event in PsA, and changes in ECM protein metabolites may provide insight to tissue changes. Dietary fish oils (n-3 PUFA) might affect the inflammation driven tissue turnover. The aim was to evaluate ECM metabolites in patients with PsA compared to healthy individuals and investigate the effects of n-3 PUFA. The 24-week randomized, double-blind, placebo-controlled trial of PUFA included 142 patients with PsA. Fifty-seven healthy individuals were included for comparison. This study is a sub-study investigating biomarkers of tissue remodelling as secondary outcomes. Serum samples at baseline and 24 weeks and healthy individuals were obtained, while a panel of ECM metabolites reflecting bone and soft tissue turnover were measured by ELISAs: PRO-C1, PRO-C3, PRO-C4, C1M, C3M, C4M, CTX-I and Osteocalcin (OC). C1M, PRO-C3, PRO-C4 and C4M was found to be elevated in PsA patients compared to the healthy individuals (from 56 to 792%, all p < 0.0001), where no differences were found for OC, CTX-I, PRO-C1 and C3M. PRO-C3 was increased by 7% in patients receiving n-3 PUFA after 24 weeks compared to baseline levels (p = 0.002). None of the other biomarkers was changed with n-3 PUFA treatment. This indicates that tissue turnover is increased in PsA patients compared to healthy individuals, while n-3 PUFA treatment for 24 weeks did not have an effect on tissue turnover. Trial registration NCT01818804. Registered 27 March 2013–Completed 18 February 2016. https://clinicaltrials.gov/ct2/show/NCT01818804?term=NCT01818804&rank=1

Medium-chain α-monoglycerides improves productive performance and egg quality in aged hens associated with gut microbiota modulation

The present study aimed to evaluate the effects of medium-chain α-monoglycerides (MG) on productive performance, egg quality, serum biochemical indices, and gut microbiota in laying hens. A total of 252 40-wk-old Hy-Line Brown laying hens were randomly allotted into two groups (21 hens per replicate, 6 replicates per group) and fed with a basal diet (CON group) or a basal diet containing 300 mg/kg of MG (MG300 group). The eggs laid were recorded daily on a replicate basis, and egg quality was measured at 48, 56, and 64 wk of age. At the end of this trial, three randomly selected hens from each replicate were slaughtered, and the serum and cecal digesta were collected for analysis of serum biochemical indices and sex hormones and gut microbiota composition determination. The results revealed that the laying rate was significantly (P < 0.05) increased in the MG300 group, and the feed conversion ratio was decreased (P < 0.01) during 40–64 wk of age. The eggshell strength at 56 wk of age and eggshell thickness at 56 and 64 wk of age were significantly (P < 0.05) increased in the MG300 group. In addition, dietary MG significantly (P < 0.05) increased levels of serum follicle-stimulating hormone, luteinizing hormone, estradiol, glucose, Ca, serum total cholesterol, triglycerides, and high-density lipoprotein cholesterol, but decreased the lipopolysaccharide level. Notably, MG supplementation increased (P < 0.05) the relative abundance of genera Lachnospiraceae_NK4A136_group, Romboutsia, Syntrophomonas, Victivallis, Ruminiclostridium_6, and Family_XIII_UCG_001 (P < 0.01) and simultaneously decreased the abundances of Proteobacteria, Faecalibacterium, Alistipes, Cerasicoccus, Schlegelella, and Treponema_2. Spearman's correlation analysis indicated that the differentiated genera were significantly associated with the serum biochemical indices and sex hormone. In summary, the present study revealed that dietary supplementation with MG can improve productive performance and egg quality by modulating gut microbiota, suggested that MG may act as an efficient feed supplement in aged hens.

High-Throughput Metabolomics Discovers Metabolic Biomarkers and Pathways to Evaluating the Efficacy and Exploring Potential Mechanisms of Osthole Against Osteoporosis Based on UPLC/Q-TOF-MS Coupled With Multivariate Data Analysis

Postmenopausal osteoporosis (PMOP) is the most common metabolic bone illness among the elderly especially in postmenopausal women resulting from a reduction in bone mineral density, but there is no effective drug at present. The study was aimed at evaluating efficacy of osthole against osteoporosis using high-throughput metabolomics method. The blood samples for illustrating the pathological mechanism of PMOP and exploring the efficacy of osthole treatment (ST) were collected to perform metabolites and metabolic profiles and pathways analysis using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) and pattern recognition methods. In addition, backbone weight, the bone density, and some vital biochemical indexes were also detected. A total of 28 metabolites were identified as biomarkers for ovariectomized-osteoporosis model, and ST could significantly regulate 19 of them including lysine, linoleic acid, 3-hydroxybutyric acid, prostaglandin F2a, taurocholic acid, LysoPC(15:0), l-carnitine, glucose, arginine, citric acid, corticosterone, ornithine, tryptophan, arachidonic acid, Cer(d18:0/18:0), glutamine, uric acid, 8-HETE, estriol, which mainly related with 13 metabolic pathways, such as linoleic acid metabolism, starch, and sucrose metabolism, arachidonic acid metabolism, alanine, aspartate and glutamate metabolism, arginine and proline metabolism, citrate cycle (TCA cycle), and arginine biosynthesis. The ovariectomized model (OVX) rats display a significant decrease bone density, TGF-β1, NO, and NOS level, and a significant increase bone weight, IL-6, TNF-α, and Ca 2+ level. These parameters in the ST rats were evidently improved as compared to the OVX group. ST effectively mitigated ovariectomy-induced osteoporosis in rats by affecting endogenous metabolite-related metabolic mechanism and showed the natural alternative with potential for the treatment of PMOP.

Therapeutic potentials and modulatory mechanisms of fatty acids in bone

Bone metabolism is a lifelong process that includes bone formation and resorption. Osteoblasts and osteoclasts are the predominant cell types associated with bone metabolism, which is facilitated by other cells such as bone marrow mesenchymal stem cells (BMMSCs), osteocytes and chondrocytes. As an important component in our daily diet, fatty acids are mainly categorized as long-chain fatty acids including polyunsaturated fatty acids (LCPUFAs), monounsaturated fatty acids (LCMUFAs), saturated fatty acids (LCSFAs), medium-/short-chain fatty acids (MCFAs/SCFAs) as well as their metabolites. Fatty acids are closely associated with bone metabolism and associated bone disorders. In this review, we summarized the important roles and potential therapeutic implications of fatty acids in multiple bone disorders, reviewed the diverse range of critical effects displayed by fatty acids on bone metabolism, and elucidated their modulatory roles and mechanisms on specific bone cell types. The evidence supporting close implications of fatty acids in bone metabolism and disorders suggests fatty acids as potential therapeutic and nutritional agents for the treatment and prevention of metabolic bone diseases.

The effects of dietary fatty acids on bone, hematopoietic marrow and marrow adipose tissue in a murine model of senile osteoporosis

Purpose: Marrow adipose tissue (MAT) expansion and associated lipotoxicity are important drivers of age-related bone loss and hematopoietic bone marrow (HBM) atrophy. Fish oil and borage oil (rich in ω3 fatty acids) can partially prevent aged-related bone loss in SAMP8 mice. However, whether preservation of bone mass in this progeria model is associated with MAT volumes remains unknown.

Results: MAT volume fraction (MAT%) showed a negative association with hematopoietic bone marrow (HBM%;r=-0.836, p<0.001) and bone (bone%;r=-0.344, p=0.013) volume fractions.

Adjusting for multiple comparisons, bone% was higher and MAT% was lower in Fish oil (FO)-supplemented groups vs. controls (p<0.001). HBM% did not differ significantly between the four groups. However, in the group supplemented with FO, HBM comprised higher fractions and MAT constituted lower fractions of total marrow vs. controls (p<0.001).

Conclusion: Feeding FO-enriched diet prevented age-related bone and HBM loss, by reducing MAT expansion. Our results further emphasize on the role(s) of MAT expansion in bone and HBM atrophy.

Methods: SAMP8 mice (n>9 /group) were allocated into 4 categories and fed a control ration, FO-, sunflower oil (SFO)- and borage oil-enriched diets for lifetime. Femurs were scanned using microcomputed tomography (μCT) and bone, MAT, and HBM volumes were determined using an image analysis software.

Induction of Osteogenic MC3T3-E1 Cell Differentiation by Nacre and Flesh Lipids of Tunisian Pinctada radiata

The flesh of the Pinctada radiata pearl oyster from coastal Tunisia is considered as a high source of n-3 and n-6 and its shell nacre layer is a promising osteogenic biomaterial. Fatty acid (FA) analysis showed that the major components found in total FA (TFA) were 14:0, 16:0, and 18:0 saturated FA (SFA); 16:1, 18:1, and 20:1 monoenoic FA; 20:4n-6 (ARA), 22:5n-3 (DPA). Characteristically high levels of 20:5n-3 (EPA) and 22:6n-3 (DHA) (6.53-89.75 mg/100 g TFA) polyunsaturated FA (PUFA) were found, respectively, in the TFA of nacre and flesh. Evaluated the effects in vitro of lipids extracted from nacre (Ln) and from flesh (Lc) of P. radiata on growth and the differentiation of osteoblasts. Cytotoxicity tests (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide [MTT] and lactic acid dehydrogenase c [LDH]) demonstrated that both extracts are nontoxic. Alizarin Red staining was used in an osteoblast differentiation model using the osteoblast MC3T3-E1 cell line. It showed that the FA of both extracts induced osteoblast differentiation leading to mineralization. Reverse transcription-polymerase chain reaction (RT-PCR) showed a significantly higher expression of osteocalcin (Bglap) and runt-related transcription (Runx2) in MC3T3-E1 cells in the presence of Ln. No difference of osteopontin (Spp1) and Collagen type I (Col1a1) genes compared to the control was observed. In conclusion, these results supported, obtained from our in vitro experimental model used, the interest/potential of lipids extracted from nacre and P. radiata flesh to stimulate bone formation.

Early Postnatal Changes of Bone Turnover Biomarkers in Very Low-Birth-Weight Neonates-The Effect of Two Parenteral Lipid Emulsions with Different Polyunsaturated Fatty Acid Content: A Randomized Double-Blind Study

BACKGROUND

ω-3 polyunsaturated fatty acids (n-3 PUFAs) are reported to have beneficial effect on bone mineral density. This study aimed to evaluate early changes of bone turnover biomarkers in very low-birth-weight (VLBW) neonates and the effect of 2 parenteral lipid emulsions (PLEs) with different PUFA composition.

METHODS

This is a randomized double-blind study with parallel design. VLBW neonates (n = 66) receiving parenteral nutrition (PN)>70% of daily energy requirements for >14 days were assigned into 2 groups that were prescribed soybean oil-based (n = 35) and n-3-enriched PLE (n = 31), respectively. Osteoprotegerin (OPG), soluble receptor activator of nuclear factor-kB ligand (sRANKL), osteocalcin (OC), interleukin-6 (enzyme-linked immunoblot assay kits), Ca, and P plasma levels were assessed before PLE implementation (T1) and on day 20 of life (T2).

RESULTS

In the total population, sRANKL and OC significantly increased, whereas OPG and the OPG/sRANKL ratio decreased from T1 to T2. Within each group, T1-to-T2 changes of OC were significant in both groups, whereas those of OPG/sRANKL were significant only in the soybean-based group. Multiple regressions showed an independent effect of group allocation on OPG change. Significant associations were observed between PN duration and sRANKL change (negatively), n-6/n-3 and OC changes (positively), and OPG and sRANKL changes (positively).

CONCLUSIONS

A high bone-turnover rate in VLBW neonates with predominance of bone resorption is confirmed. The lower rate of OPG/sRANKL reduction in the n-3-enriched PLE group indicates that n-3 PUFA-enriched PLEs may help to attenuate early bone loss in VLBW neonates.

Chocolate and chocolate constituents influence bone health and osteoporosis risk

Bone loss resulting in increased risk for osteoporosis is a major health issue worldwide. Chocolate is a rich source of antioxidant and antiinflammatory flavonoids and dietary minerals with the potential to benefit bone health. However, other chocolate constituents such as cocoa butter, sugar, and methylxanthines may be detrimental to bone. Human studies investigating the role of chocolate consumption on serum bone markers and bone mineral density (BMD) have been inconsistent. A contributing factor is likely the different composition and thereby the nutrient and bioactive content among chocolate types. White and milk chocolate are high in sugar and low in flavonoids and most minerals. Dark chocolate (45-85% cocoa solids) is high in flavonoids, most minerals, and low in sugar with ≥70% cocoa solids resulting in higher fat and methylxanthine content. The aim of this review was to examine the relationship between chocolate consumption and its constiuents, including flavonoid content, on bone health and osteoporosis risk. Studies showed postmenopausal women had no bone effects at moderate chocolate intakes, whereas adolescents consuming chocolate had greater longitudinal bone growth. Based on flavonoid and mineral content, unsweetened cocoa powder appeared to be the best option followed by dark chocolate with higher cocoa content in terms of supporting and preserving bone health. Determining dietary recommendations for chocolate consumption relative to bone health is important because of the growing popularity of chocolate, particularly dark chocolate, and an expected increase in consumption owing to suggestions of health benefits against various degenerative diseases.

Impacts of Psychological Stress on Osteoporosis: Clinical Implications and Treatment Interactions

The significant biochemical and physiological effects of psychological stress are beginning to be recognized as exacerbating common diseases, including osteoporosis. This review discusses the current evidence for psychological stress-associated mental health disorders as risk factors for osteoporosis, the mechanisms that may link these conditions, and potential implications for treatment. Traditional, alternative, and adjunctive therapies are discussed. This review is not intended to provide therapeutic recommendations, but, rather, the goal of this review is to delineate potential interactions of psychological stress and osteoporosis and to highlight potential multi-system implications of pharmacological interventions. Review of the current literature identifies several potentially overlapping mechanistic pathways that may be of interest (e.g., glucocorticoid signaling, insulin-like growth factor signaling, serotonin signaling) for further basic and clinical research. Current literature also supports the potential for cross-effects of therapeutics for osteoporosis and mental health disorders. While studies examining a direct link between osteoporosis and chronic psychological stress are limited, the studies reviewed herein suggest that a multi-factorial, personalized approach should be considered for improved patient outcomes in populations experiencing psychological stress, particularly those at high-risk for development of osteoporosis.

Increased Body Weight and Fat Mass After Subchronic GIP Receptor Antagonist, but Not GLP-2 Receptor Antagonist, Administration in Rats

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-2 (GLP-2) are hormones secreted from the enteroendocrine cells after a meal. They exert their actions through activation of G protein-coupled receptors (R), the GIPR and GLP-2R, respectively. Both have been reported to influence metabolism. The purpose of the study was to investigate the role of the hormones in the regulation of lipid and bone homeostasis by subchronic treatment with novel GIPR and GLP-2R antagonists. Rats were injected once daily with vehicle, GIPR, or GLP-2R antagonists for 3 weeks. Body weight, food intake, body composition, plasma lipoprotein lipase (LPL), adipokines, triglycerides and the marker of bone resorption carboxy-terminal collagen crosslinks (CTX), were examined. In rats, subchronic treatment with GIPR antagonist, rat GIP (3-30)NH₂, did not modify food intake and bone resorption, but significantly increased body weight, body fat mass, triglycerides, LPL, and leptin levels compared with vehicle treated rats. Subchronic (Pro3)GIP (a partial GIPR agonist), GLP-2(11-33), and GLP-2(3-33) (GLP-2R antagonists) treatment did not affect any parameter. The present results would be consistent with a role for GIP, but not GLP-2, in the maintenance of lipid homeostasis in rats, while neither GIPR nor GLP-2R antagonism appeared to influence bone resorption in rats.

Higher Dairy Intakes Are Associated with Higher Bone Mineral Density among Adults with Sufficient Vitamin D Status: Results from the Boston Puerto Rican Osteoporosis Study

Background

Dairy foods have been shown to improve bone mineral density (BMD) in non-Hispanic whites. Puerto Rican adults have a higher prevalence of osteoporosis and vitamin D deficiency than non-Hispanic whites. However, there is little understanding of lifestyle influences on bone in this population.

Objective

The aim of this study was to examine associations of dairy intakes with BMD among adults from the Boston Puerto Rican Osteoporosis Study with and without adequate serum vitamin D status.

Methods

A total of 904 participants in this cross-sectional analysis provided dietary intakes with a culturally tailored food-frequency questionnaire. Dairy food groups were calculated [total dairy, modified dairy (without cream or dairy desserts), fluid dairy (milk + yogurt), cheese, yogurt, and cream and desserts]. BMD (grams per centimeter squared) was measured using dual-energy X-ray absorptiometry. Vitamin D status was defined as sufficient (serum 25-hydroxyvitamin D [25(OH)D] ≥20 ng/mL) or insufficient (<20 ng/mL). General linear models were used to examine associations between dairy intake and BMD, stratified by vitamin D status.

Results

Of the total sample, 73% were women, of whom 87% were postmenopausal. Mean ± SD age was 60.0 ± 7.6 y and mean ± SD body mass index (kg/m2) was 32.3 ± 6.6. Mean serum 25(OH)D (range: 4-48 ng/mL) was 14.3 ± 3.6 ng/mL in insufficient individuals and 26.0 ± 5.5 ng/mL in sufficient individuals. In the full sample, higher intakes of modified dairy foods (β = 0.0015, P = 0.02) and milk (β = 0.0018, P = 0.04) were associated with higher femoral neck (FN) BMD. Among those who were vitamin D sufficient, higher intakes of total dairy (P = 0.03-0.07), fluid dairy (P = 0.01-0.05), and milk (P = 0.02-0.09) were significantly related to higher FN and lumbar spine BMD, respectively. Among vitamin D-insufficient participants, dairy intakes were not associated with BMD (P-range = 0.11-0.94).

Conclusions

Dairy food intakes were associated with higher BMD among adults, particularly those with sufficient vitamin D status. Future studies should confirm findings longitudinally and assess culturally acceptable lifestyle interventions to improve bone health among Hispanic adults. This trial was registered at clinicaltrials.gov as NCT01231958.

Endogenous Production of n-3 Polyunsaturated Fatty Acids Promotes Fracture Healing in Mice

Bone fracture is a global healthcare issue for high rates of delayed healing and nonunions. Although n-3 polyunsaturated fatty acid (PUFA) is considered as a beneficial factor for bone metabolism, only few studies till date focused on the effects of n-3 PUFAs on fracture healing. In this study, we investigated the effect of endogenous n-3 PUFAs on fracture healing by measuring femur fracture repair in both fat-1 transgenic mice and WT mice. Proximal femoral fracture model was established in fat-1 transgenic mice and WT mice, respectively, and then the fracture was analyzed by using X-ray, micro-computed tomography (micro-CT), and histological assessment at 7, 14, 21, 28, and 35 days after fixation. The results showed that compared with WT mice, fat-1 mice exhibited acceleration in fracture healing through radiographic and histological analysis (18–21 days versus 21–28 days postfracture). Meanwhile, X-ray and micro-CT analysis that showed better remodeling callus formation were in the fat-1 group compared to WT group. Furthermore, histological analysis revealed that endogenous n-3 PUFAs promoted local endochondral ossification and accelerated the remodeling of calcified calluses after fracture. In conclusion, the present study indicated that endogenously produced n-3 PUFAs promote fracture healing process and accelerate bone remodeling in mice, and supplementation of n-3 PUFAs was positively associated with fracture healing.

GPR40 mediates potential positive effects of a saturated fatty acid enriched diet on bone

SCOPE

The stimulation of the free fatty acid receptor G-protein coupled receptor (GPR) 40 by GW9508 prevents bone loss by inhibiting osteoclast activity, both in vitro and in vivo. Here, we questioned whether the stimulation of the GPR40 receptor by dietary fatty acids may lead to the same beneficial effect on bone.

METHODS AND RESULTS

We investigated (i) the impact of a fatty acid enriched diet (high-fat diet [HFD]) on bone health in C57/BL6 female mice depending on (ii) the estrogen status (ovariectomy) and (iii) the genotype (GPR40^+/+ or GPR40^-/- ). Bone mineral density (BMD), body composition, weight, inflammation and bone remodeling parameters were monitored. HFD decreased BMD in HFD-SH-GPR40^+/+ mice but OVX failed to further impact BMD in HFD-OVX-GPR40^+/+ mice, while additional bone loss was observed in HFD-OVX-GPR40^-/- animals. These data suggest that when stimulated by fatty acid enriched diets GPR40 contributes to counteract ovariectomy-induced bone alteration. The sparing effect is supported by the modulation of both the osteoprotegerin/receptor activator of nuclear factor kappa-B ligand (OPG/RANKL) ratio in blood stream and the expression level of inflammatory markers in adipose tissues. Bone preservation by GPR40 stimulation is dependent on the presence of long-chain saturated fatty acids.

CONCLUSION

GPR40 contributes to counter ovariectomy-induced bone loss in a context of saturated fatty acid enrichment.

Vegetarian, Gluten-Free, and Energy Restricted Diets in Female Athletes

Female athletes who follow a diet that fails to meet energy and nutrient needs are at risk for musculoskeletal injuries, menstrual disturbances, and poor sports performance. Common nutritional concerns for the female athlete include low energy availability (EA) (i.e., energy intake from food remaining for metabolic processes after accounting for energy expended during exercise) and inadequate dietary intakes (i.e., not meeting sports nutrition guidelines) of carbohydrates, protein, essential fatty acids (EFAs), B-vitamins, calcium, iron, and vitamin D. Low EA and the associated nutrient deficiencies are more common in athletes who compete in weight-sensitive sports (i.e., aesthetic, gravitational, and weight category sports) because low body fat and mass confer a competitive advantage. Other athletes at risk for energy and nutrient deficits include athletes following a vegetarian or gluten-free diet (GFD). Careful dietary planning can help an athlete meet energy and nutrient needs. This review covers the nutrition issues associated with low EA and special diets (i.e., vegetarian and GFD) and describes strategies to help female athletes meet their energy and nutrient needs.