Dietary (n-3) and (n-6) polyunsaturates and acetylsalicylic acid alter ex vivo PGE2 biosynthesis, tissue IGF-I levels, and bone morphometry in chicks

Omega-3 PUFAs prevent bone impairment and bone marrow adiposity in mouse model of obesity

Obesity adversely affects bone and fat metabolism in mice and humans. Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) have been shown to improve glucose metabolism and bone homeostasis in obesity. However, the impact of omega-3 PUFAs on bone marrow adipose tissue (BMAT) and bone marrow stromal cell (BMSC) metabolism has not been intensively studied yet. In the present study we demonstrated that omega-3 PUFA supplementation in high fat diet (HFD + F) improved bone parameters, mechanical properties along with decreased BMAT in obese mice when compared to the HFD group. Primary BMSCs isolated from HFD + F mice showed decreased adipocyte and higher osteoblast differentiation with lower senescent phenotype along with decreased osteoclast formation suggesting improved bone marrow microenvironment promoting bone formation in mice. Thus, our study highlights the beneficial effects of omega-3 PUFA-enriched diet on bone and cellular metabolism and its potential use in the treatment of metabolic bone diseases.

Causal effect of polyunsaturated fatty acids on bone mineral density and fracture

Background

Polyunsaturated fatty acids (PUFAs) are closely related to osteoporosis. To test their causal relationship, we conducted a Mendelian randomization (MR) analysis.

Methods

We analyzed the causal relationship between four PUFAs measures, n-3 PUFAs (n-3), n-6 PUFAs (n-6), the ratio of n-3 PUFAs to total fatty acids (n-3 pct), and the ratio of n-6 PUFAs to n-3 PUFAs (n-6 to n-3), and five measures of osteoporosis, including estimated bone mineral density (eBMD), forearm (FA) BMD, femoral neck (FN) BMD, lumbar spine (LS) BMD, and fracture, using two-sample MR analysis. In order to verify the direct effect between PUFAs and BMD, we chose interleukin-6 (IL-6), tumor necrosis factor-β (TNF-β), and bone morphogenetic proteins 7 (BMP-7), three markers or cytokines strongly related to BMD, as possible confounding factors, and analyzed the possible causal relationships between them and PUFAs or BMD by MR. Inverse variance weighting (IVW), MR-Egger, weighted and weighted median were conducted. MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) and MR-Egger regression methods were used to evaluate the potential pleiotropy of instrumental variables (IVs) and outliers were identified by MR-PRESSO. Cochran's Q statistic was used to detect the heterogeneity among IVs. Leave-one-out sensitivity analysis was used to find SNPs that have a significant impact on the results. All results were corrected by the Bonferroni correction.

Results

The IVW results showed that n-3 PUFAs (OR = 1.030, 95% CI: 1.013, 1.047, P = 0.001) and n-6 PUFAs (OR = 1.053, 95% CI: 1.034, 1.072, P < 0.001) were positively correlated with eBMD, while n-6 to n-3 (OR = 0.947, 95% CI: 0.924, 0.970, P < 0.001) were negatively correlated with eBMD. These casual relationships still existed after Bonferroni correction. There were positive effects of n-3 PUFAs on FA BMD (OR = 1.090, 95% CI: 1.011, 1.176, P = 0.025) and LS BMD (OR = 1.056, 95% CI: 1.011, 1.104, P = 0.014), n-3 pct on eBMD (OR = 1.028, 95% CI: 1.002, 1.055, P = 0.035) and FA BMD (OR = 1.090, 95% CI: 1.011, 1.174, P = 0.025), n-6 to n-3 on LS BMD (OR = 1.071, 95% CI: 1.021, 1.124, P = 0.005); negative effects of n-3 pct on fracture (OR = 0.953, 95% CI: 0.918, 0.988, P = 0.009) and n-6 to n-3 on FA BMD (OR = 0.910, 95% CI: 0.837, 0.988, P = 0.025). However, these causal effects all disappeared after Bonferroni correction (all P > 0.0025). None of IL-6, TNF-β, and BMP-7 had a causal effect on PUFA and BMD simultaneously (all P > 0.05).

Conclusion

Evidence from this MR study supports the genetically predicted causal effects of n-3, n-6, n-3 pct, and n-6 to n-3 on eBMD. In addition, n-3 not only associate with FA BMD and LS BMD through its own level and n-6 to n-3, but also link to fracture through n-3 pct.

The Effects of Different Dietary Oil Sources on Broiler Chicken Bone Mineralization

This study was designed to determine the effects of dietary hazelnut oil (HO) and sunflower oil (SO) on the mineral composition of chicken femur and tibia bones. A 40-day trial was initiated with 600 1-day-old Ross 308 chickens. Initially, the chickens were randomly divided into four main groups of 150 each according to the proportion of SO and HO supplementation in their diets: control SO (25 g/kg SO), LHO (25 g/kg HO), HHO (50 g/kg HO), and MO (50 g/kg blend of 25 g/kg SO + 25 g/kg HO). Each group was further divided into six subgroups of 25 chickens. At the end of the trial, four chickens from each of the six subgroups were randomly selected and slaughtered. Their right tibia and right femur bones were isolated and analyzed for macro (Ca, P, Mg) and trace (Fe, Cu, Mn, Zn, Cr, Co, and Se) minerals in addition to ether extract and ash. The results suggest that the diets' fat concentration and fatty acid composition significantly affected the Ca, P, Mg, Fe, Cu, Cr, and Se composition of tibia bones (p < 0.01). The ether extract and ash contents of the femur bones were increased in both HHO and MO groups (p < 0.05), while Fe and Cr compositions were lower in all femur bones, except those from SO chickens (p < 0.05). The Se content of femur bones in the LHO group was higher than the other treatment groups (p < 0.05). In conclusion, the amount of oil and fatty acid in the diet affected the accumulation of Ca, P, Mg, Fe, Cu, and Cr minerals in the tibia bone. Moreover, the amount of Cr and Fe was lower in the femur and tibia bones in the group that received the HO supplement and all groups in which the amount of oil fed was increased.

Molecular Interactions between Dietary Lipids and Bone Tissue during Aging

Age-related bone disorders such as osteoporosis or osteoarthritis are a major public health problem due to the functional disability for millions of people worldwide. Furthermore, fractures are associated with a higher degree of morbidity and mortality in the long term, which generates greater financial and health costs. As the world population becomes older, the incidence of this type of disease increases and this effect seems notably greater in those countries that present a more westernized lifestyle. Thus, increased efforts are directed toward reducing risks that need to focus not only on the prevention of bone diseases, but also on the treatment of persons already afflicted. Evidence is accumulating that dietary lipids play an important role in bone health which results relevant to develop effective interventions for prevent bone diseases or alterations, especially in the elderly segment of the population. This review focuses on evidence about the effects of dietary lipids on bone health and describes possible mechanisms to explain how lipids act on bone metabolism during aging. Little work, however, has been accomplished in humans, so this is a challenge for future research.

Omega-3 fatty acids in pathological calcification and bone health

Omega-3 fatty acids (ω-3FAs) such as Docosahexaenoic acid (DHA) and Eicosapentanoic acid (EPA), are active ingredient of fish oil, which have larger health benefits against various diseases including cardiovascular, neurodegenerative, cancers and bone diseases. Substantial studies documented a preventive role of omega-3 fatty acids in pathological calcification like vascular calcification and microcalcification in cancer tissues. In parallel, these fatty acids improve bone quality probably by preventing bone decay and augmenting bone mineralization. This study also addresses that the functions of ω-3FAs not only depend on tissue types, but also work through different molecular mechanisms for preventing pathological calcification in various tissues and improving bone health. PRACTICAL APPLICATIONS: Practical applications of the current study are to improve the knowledge about the supplementation of omega-3 fatty acids. This study infers that supplementation of omega-3 fatty acids aids in bone preservation in elder females at the risk of osteoporosis and also, on the contrary, omega-3 fatty acids interfere with pathological calcification of vascular cells and cancer cells. Omega-3 supplementation should be given to the cardiac patients because of its cardio protective role. In line with this, omega-3 supplementation should be included with chemotherapy for cancer patients as it can prevent osteoblastic potential of breast cancer patients, responsible for pathological mineralization, and blocks off target toxicities. Administration of omega-3 fatty acid with chemotherapy will not only improve survival of cancer patients, but also improve the bone quality. Thus, this study allows a better understanding on omega-3 fatty acids in combating pathological complications such as osteoporosis, vascular calcification, and breast microcalcification.

Effects of dietary organic minerals, fish oil, and hydrolyzed collagen on growth performance and tibia characteristics of broiler chickens

Nutrition is a crucial factor for growth and bone development in broiler chickens. Adjustments in dietary ingredients might affect bone development and consequently locomotion related problems. This study was designed to evaluate effects of dietary organic minerals (ORM), fish oil (FISH), and hydrolyzed collagen (COL) on growth performance and tibia characteristics of broiler chickens. A total of three hundred eighty four 1-day-old Ross 308 male broiler chickens were used in a complete randomized block design with 4 diet groups and 8 replicates per diet group. In the ORM diet, the inorganic macro and trace minerals were replaced by their organic varieties. In the FISH diet, palm oil and soybean oil were partly replaced by FISH. In the COL diet, soybean meal was partly replaced by COL. Results showed that the ORM and COL diet groups reached a higher body weight (BW) at 42 D of age than the FISH diet group, whereas the control group was in between. The feed conversion ratio between day 1 and 42 was lower in the ORM and COL diet groups than in both other diet groups. On day 28, 35, and 42, gait score (GS), Varus Valgus deformity, tibia length (TL), thickness, femoral and metatarsal head thickness (THT), mineral content (TMC), mineral density (TMD), breaking strength (TBS), stiffness (TSF), and energy to fracture (TEF) were measured (n = 3/replicate). The ORM diet group had higher TL at day 42, higher THT at day 28, higher TMC at day 42, higher TMD at day 28, 35, and 42, higher TBS at day 42, higher TSF at day 35 and 42, and higher TEF at day 42 compared to the FISH diet group, with the COL and control diet groups in between. It can be concluded that replacing dietary inorganic macro and trace minerals by their organic varieties seems to stimulate tibia dimensions, strength, and mineral content of broiler chickens. On the contrary, FISH appears to negatively affect tibia characteristics.

Long term effect of dietary lipid saturation on eggshell quality and bone characteristics of laying hens

This study investigated the long-term effect of dietary fatty acid saturation on eggshell quality and bone characteristics of laying hens at end of lay. Five isoenergetic (3,011.5 kcal AME/kg DM) and isonitrogenous (169 g CP/kg DM) diets were formulated using different lipid sources at a constant 30 g/kg inclusion level. The control, polyunsaturated omega-3 (PUFA n-3), polyunsaturated omega-6 (PUFA n-6), monounsaturated omega-9 (MUFA n-9), and saturated fatty acid (SFA) diets consisted of linseed- and fish oil (50:50 blend), fish oil, sunflower oil, high oleic acid sunflower oil, and tallow, respectively. A total of 200 individually caged Hy-Line Silver-Brown hens (20 wk of age) were randomly allocated to the 5 treatments (n = 40 replicates/treatment) and received the experimental diets for 54 wk. During weeks 58, 62, 66, 70, and 74 of age (end-of-lay period), 20 eggs/treatment per day (n = 140 eggs/treatment per week) were selected for determining eggshell quality traits. At 74 wk of age, 10 birds per treatment (n = 10 birds/treatment) were randomly selected for the determination of bone quality characteristics. Data were statistically analyzed (P < 0.05) using a fully randomized 1-way ANOVA. Dietary treatment had no effect (P > 0.05) on eggshell quality traits. The MUFA n-9 treatment with the highest unsaturated to SFA ratio (UFA: SFA) resulted in a higher (P < 0.05) femur weight (10.34 g) as well as femur- (52.99%) and tibia ash (51.07%) content than the SFA treatment. Also, the PUFA n-3 diet resulted in a higher (P < 0.05) femur weight (10.21 g), femur ash (51.82%), and percentage femur (0.57%) compared to the SFA diet. Results suggested that prolonged feeding of diets varying in FA profile had no negative effect on eggshell quality, whereas UFA: SFA and long-chain n-3 PUFA affected the bone quality (especially the femur) of hens at the end of lay.

Bone Benefits of Fish Oil Supplementation Depend on its EPA and DHA Content

The preventive effect of high-dose (9%) regular-fish oil (FO) against bone loss during aging has been demonstrated, but the effects of a low-dose (1%–4%) of a highly purified concentrated FO (CFO) has not been elucidated. The aim of this study was to determine the dose-dependent effect of a CFO against bone loss in C57BL/6 female mice during aging. Twelve-month old mice were fed with 1% and 4% CFO and 4% safflower oil (SFO) diets, including a group with a 4% regular-FO diet and a group with a lab chow diet for 12 months. Bone mineral density (BMD) was analyzed by dual-energy x-ray absorptiometry (DXA) before and after the dietary intervention. At the end of dietary intervention, bone resorption markers in serum and inflammatory markers in bone marrow and splenocytes and inflammatory signaling pathways in the bone marrow were analyzed. As compared to the 4% SFO control, 4% CFO maintained higher BMD during aging, while 1% CFO offered only a mild benefit. However, the 1% CFO fed group exhibited slightly better BMD than the 4% regular-FO fed group. BMD loss protection by CFO was accompanied by reduced levels of the bone resorption marker, TRAP, and the osteoclast-stimulating-factor, RANKL, without affecting the decoy-receptor of RANKL, osteoprotegerin (OPG). Further, CFO supplementation was associated with an increase in the production of IL-10, IL-12, and IFN-γ and a decrease in the production of TNF-α and IL-6, and the activation of NF-κB, p38 MAPK, and JNK signaling pathways. In conclusion, the supplementation of 4% CFO is very efficient in maintaining BMD during aging, whereas 1% CFO is only mildly beneficial. CFO supplementation starting at middle age may maintain better bone health during aging.

Dietary n-3 PUFA content as a modulator of the femur properties in growing pigs

The relationships between both dietary and empty body fatty acid composition and the morphometry, densitometry, geometry and biomechanical properties of the femur of growing pigs were analysed. A total of thirty-two pigs aged 115 d were divided into four groups (n 8 per group). The pigs were fed either a control diet (group C) or a diet supplemented with linseed oil (rich in α-linolenic acid (C18 : 3n-3), group L), fish oil (rich in EPA (C20 : 5n-3) and DHA (C22 : 6n-3), group F) and beef tallow (rich in SFA, group T). The diets differed in n-3 PUFA contents (0·63-18·52 g/kg) and n-6:n-3 PUFA ratios (0·91-14·51). At 165 d of age, the pigs were slaughtered and the fatty acids in the empty body were determined. Moreover, the left femur was dissected. The cortical wall thickness, cross-sectional area, cortical index, bone mineral content, bone mineral density, maximum elastic strength and maximum strength were lower (P<0·05) in the femurs of pigs from groups C and T than in those from groups F and L. Significant positive correlations were found between the densitometry, geometry and biomechanical properties of the femur and both dietary and empty body n-3 PUFA content, whereas significant negative correlations were observed between the same properties and both dietary and empty body n-6:n-3 PUFA ratio. The results of the present study suggest that in growing pigs α-linolenic acid has a similar positive effect on bone health to that of EPA and DHA.

The Essentiality of Arachidonic Acid in Infant Development

Arachidonic acid (ARA, 20:4n-6) is an n-6 polyunsaturated 20-carbon fatty acid formed by the biosynthesis from linoleic acid (LA, 18:2n-6). This review considers the essential role that ARA plays in infant development. ARA is always present in human milk at a relatively fixed level and is accumulated in tissues throughout the body where it serves several important functions. Without the provision of preformed ARA in human milk or infant formula the growing infant cannot maintain ARA levels from synthetic pathways alone that are sufficient to meet metabolic demand. During late infancy and early childhood the amount of dietary ARA provided by solid foods is low. ARA serves as a precursor to leukotrienes, prostaglandins, and thromboxanes, collectively known as eicosanoids which are important for immunity and immune response. There is strong evidence based on animal and human studies that ARA is critical for infant growth, brain development, and health. These studies also demonstrate the importance of balancing the amounts of ARA and DHA as too much DHA may suppress the benefits provided by ARA. Both ARA and DHA have been added to infant formulas and follow-on formulas for more than two decades. The amounts and ratios of ARA and DHA needed in infant formula are discussed based on an in depth review of the available scientific evidence.

Effects of linseed oil and palm oil on growth performance, tibia fatty acid and biomarkers of bone metabolism in broilers

1. This study was conducted to determine the effects of different dietary fat sources on growth performance, tibia fatty acids and biomarkers of bone metabolism in broilers. 2. One-d-old commercial Arbor Acres broilers were fed with a maize-soya bean basal diet for 42 d, supplemented with oils according to the following 5 treatments: lard (lard group); linseed oil (linseed oil group); palm oil (palm oil group); linseed oil + palm oil (60:40 or 40:60 w/w, LP-1 group and LP-2 group, respectively). 3. No significant differences in weight gain, feed intake and gain/feed ratio were observed between the lard and linseed oil groups. Birds fed on palm oil had significantly greater weight gain and feed intake than those fed on lard or linseed oil. Growth performance in LP-1 and LP-2 was significantly greater than that of single-oil groups. 4. Tibia growth and bone characteristics were not influenced by supplementation with lard, linseed oil, or palm oil alone, but broilers fed on a mixture of fats had significantly greater tibia weight and length compared to broilers fed on linseed oil. Bone mineral density in tibia was significantly increased in LP-1 and LP-2 groups. 5. Supplementation of linseed oil alone or in combination with palm oil enhanced apparent digestibility of calcium, reduced serum calcium and increased tibia calcium concentrations. Moreover, supplementation with linseed oil alone or in combination with palm oil had a positive effect on biomarkers of bone growth. 6. The combination of linseed and palm oils was beneficial for growth performance, tibia growth and biomarkers of bone metabolism.

An investigation of the association between omega 3 FA and bone mineral density among older adults: results from the National Health and Nutrition Examination Survey years 2005–2008

SUMMARY

The relation of omega 3 fatty acids (n-3 FA) with bone mineral density (BMD) was assessed among adults >60 years; NHANES data (2005-2008). The association of dietary n-3 FA with measures of hip BMD was equivocal, but n-3 FA supplement use was significantly associated with higher spine BMD - a finding that deserves further study.

INTRODUCTION

Associations between polyunsaturated fatty acids and bone mineral density are not well understood.

PURPOSE

To evaluate the cross-sectional relation between dietary omega 3 fatty acid intake (specifically docosahexaenoic acid, eicosapentaenoic acid, and octadecatetraenoic) and BMD at the hip and spine among older adults.

METHODS

Omega 3 FA intake (g/day) was assessed from two 24-h recalls using the National Health and Nutrition Examination Survey (NHANES, in 2005-2008); and omega 3 FA supplement use (yes/no) via questionnaire. Multivariable regression models were developed to explain variance in femoral neck, total femur, and lumbar spine BMD among 2,125 men and women over 60 years.

RESULTS

Mean age was 70 years. In adjusted models, dietary omega 3 FA were marginally associated with greater femoral neck BMD (p = 0.0505), but not with total femur BMD (p = 0.95) or lumbar spine BMD (p = 0.74). Omega 3 supplement use was significantly positively associated with lumbar spine BMD (p = 0.005) but not with femoral neck or total femur BMD.

CONCLUSIONS

Dietary intakes of omega 3 FA were marginally associated with femoral neck BMD; however, omega 3 supplement use was significantly associated with higher lumbar spine BMD in older adults. These results emphasize the need for assessment of total omega 3 intakes (diet and supplements) to provide a greater range of intake and a more accurate picture of the relation between omega 3 FA and BMD.

DHA is a more potent inhibitor of breast cancer metastasis to bone and related osteolysis than EPA

Breast cancer patients often develop bone metastasis evidenced by osteolytic lesions, leading to severe pain and bone fracture. Attenuation of breast cancer metastasis to bone and associated osteolysis by fish oil, rich in EPA and DHA, has been demonstrated previously. However, it was not known whether EPA and DHA differentially or similarly affect breast cancer bone metastasis and associated osteolysis. In vitro culture of parental and luciferase gene encoded MDA-MB-231 human breast cancer cell lines treated with EPA and DHA revealed that DHA inhibits proliferation and invasion of breast cancer cells more potently than EPA. Intra-cardiac injection of parental and luciferase gene encoded MDA-MB-231 cells to athymic NCr nu/nu mice demonstrated that DHA-treated mice had significantly less breast cancer cell burden in bone, and also significantly less osteolytic lesions than EPA-treated mice. In vivo cell migration assay as measured by luciferase intensity revealed that DHA attenuated cell migration specifically to the bone. Moreover, the DHA-treated group showed reduced levels of CD44 and TRAP positive area in bone compared to EPA-treated group. Breast cancer cell burden and osteolytic lesions were also examined in intra-tibially breast cancer cell injected mice and found less breast cancer cell growth and associated osteolysis in DHA-treated mice as compared to EPA-treated mice. Finally, doxorubicin-resistant MCF-7 (MCF-7dox) human breast cancer cell line was used to examine if DHA can improve sensitization of MCF-7dox cells to doxorubicin. DHA improved the inhibitory effect of doxorubicin on proliferation and invasion of MCF-7dox cells. Interestingly, drug resistance gene P-gp was also down-regulated in DHA plus doxorubicin-treated cells. In conclusion, DHA attenuates breast cancer bone metastasis and associated osteolysis more potently than EPA, possibly by inhibiting migration of breast cancer cell to the bone as well as by inhibiting osteoclastic bone resorption.

Could heterotopic ossification be prevented by varying dietary n-3/n-6 polyunsaturated fatty acid ratio: a novel perspective to its treatment?

Heterotopic ossification (HO) is a common complication following with musculoskeletal trauma and surgical procedures. It usually decreases joint mobility and eventually causes loss of joint function. Despite nonsteroidal anti-inflammatory drugs (NSAIDs), the inhibitor of cyclooxygenase(COX), have been proven to prevent HO effectively via prostaglandin E2 synthesis regulation and modulation of tissue responsiveness to pro-inflammatory signaling, HO prevention is still a matter of debate for clinicians to avoid the side effect of NSAIDs. Interestingly, it is suggested that PGE2 production and pro-inflammatory microenvironment in body could be modified by varying the ratio of the precursor fatty acids in the diet. On account of the effect of dietary (n-6)/(n-3) PUFAs ratio on both COX metabolism and pro-inflammatory cytokines mediated biological responsiveness, we hypothesized lowering dietary (n-6)/(n-3) PUFAs ratio may not only directly reduce the substrate of COX-2 and COX-2 activity, but also partially ameliorate tissue inflammatory responsiveness to cytokines correlated with HO development,exerting an inhibitory effect on PGE2 synthesis to prevent HO formation. The negative role of lowering dietary (n-6)/(n-3) PUFAs ratio on angiogenesis, cytokines-induced apoptosis, inflammatory responsiveness and osteogenesis could also contribute to its action on HO development. If our hypothesis is proved to be corrected, it could be an innovative method to treat HO.

Conjugated linoleic acid is related to bone mineral density but does not affect parathyroid hormone in men

The relationships between conjugated linoleic acid (CLA) status, bone, body composition, and the effect of CLA on calciotropic hormones are unclear. A cross-sectional study was designed to examine the association between c9, t11 CLA status in erythrocyte membranes (RBC) and body composition. This preceded a dose-response trial investigating if c9, t11 CLA affected parathyroid hormone (PTH). It was hypothesized that (1) higher c9, t11 CLA status in RBC will be associated with a lower fat and higher bone mass and that (2) PTH will be reduced by 30% after supplementation of c9, t11 CLA. Fifty-four men (age, 19-53 years) were included in the cross-sectional analysis, of which 31 were studied in the dose-response trial and randomized to 1 of 3 groups: placebo (n = 10), 1.5 g/d (n = 11), or 3.0 g/d (n = 10) of c9, t11 CLA for 16 weeks. Men with RBC c9, t11 CLA status above the median had higher whole body bone mineral density (BMD) (1.359 ± 0.024 vs 1.287 ± 0.023 g/cm(2); P = .04) and whole body lean mass (WBL) percentage (78.8% ± 0.9% vs 75.3% ± 1.0%; P = .01), whereas body mass index (24.8 ± 0.5 kg/m(2) vs 27.3 ± 0.9 kg/m(2); P = .01) and whole body fat mass percentage (17.3% ± 0.9% vs 21.3% ± 1.1%; P = .007) were lower. In regression analysis, RBC c9, t11 CLA status accounted for a significant proportion (r(2) = 0.10) of the variation in whole body BMD (P = .03). There were no time or treatment differences among any bone or biomarkers of bone metabolism including PTH. These findings indicate that RBC c9, t11 CLA status, a reflection of long-term (~4 months) dietary CLA intake, positively relates to BMD. However, c9, t11 CLA supplementation does not appear to affect PTH in healthy men.

Perinatal maternal dietary supplementation of ω3-fatty acids transiently affects bone marrow microenvironment, osteoblast and osteoclast formation, and bone mass in male offspring

It is increasingly evident that micronutrient environment experienced before birth and in infancy is important for achieving optimal bone mass by adolescence and maintaining bone health. This study determined whether maternal supplementation with ω3-polyunsaturated fatty acids (n3FA) improved offspring bone growth and adult bone mass. Female rats were fed a diet containing 0.1% (control, n = 10) or 1% (n3FA, n = 11) docosahexanoic acid (DHA) during pregnancy and lactation. Offspring were weaned onto a control rat chow diet. Tibial growth plate and metaphysis structure, osteoblast/osteoclast density and differentiation, and gene expression were assessed in offspring at 3 wk (weaning), 6 wk (adolescent), and 3 months (adult). Maternal n3FA supplementation elevated offspring plasma n3FA levels at 3 and 6 wk. Although total growth plate heights were unaffected at any age, the resting zone thickness was increased in both male and female offspring at 3 wk. In n3FA males, but not females, bone trabecular number and thickness were increased at 3 wk but not other ages. The wk 3 n3FA males also exhibited an increased bone volume, an increased osteoblast but decreased osteoclast density, and lower expression of osteoclastogenic cytokines receptor activator of nuclear factor-κB ligand, TNF-α, and IL-6. No effects were seen at 6 wk or 3 months in either sex. Thus, perinatal n3FA supplementation is associated with increased bone formation, decreased resorption, and a higher bone mass in males, but not in females, at weaning; these effects do not persist into adolescence and adulthood and are unlikely to produce lasting improvements in bone health.

[High-fat diets and body composition over two generations. An experimental study]

INTRODUCTION AND OBJECTIVE

Despite recent findings reported on the nutritional factors that induce epigenetic changes, little information is available at early ages. This study analyzed in an experimental model, over two generations, potential changes in body composition and potential expression of epigenetic changes as the result of the intake of isoenergetic diets with different fat levels.

MATERIALS AND METHODS

At weaning, Wistar female rats were divided into two groups that were fed either a control diet (fat=7% w/w) or a high-fat diet (15% w/w). Rats were mated at 70 days (M(1)) and their pups (P(1)) were the first generation; P(1) rats were mated at 70 days (M(2)) and their pups (P(2)) represented the second generation. At weaning, mothers and pups (M(1), M(2) and P(1), P(2)) were measured body weight (W) and composition (% body fat, %BF), and total skeleton bone mineral content (BMC), expressed as %BMC, using chemical and DXA methods respectively.

RESULTS

At weaning, high-fat diet groups M(2) and P(2) showed significant increases in W and %BF (p<0.05); increased %BF values were already found in the M(1) and P(1) groups (p<0.001). By contrast, %BMC significantly decreased in M(2) and P(2) rats (p<0.001).

CONCLUSION

This study demonstrates the need to review certain eating habits to avoid perpetuation of unhealthy patterns generation after generation.

Maternal supplementation with dietary arachidonic and docosahexaenoic acids during lactation elevates bone mass in weanling rat and guinea pig offspring even if born small sized

Whether post-natal long chain polyunsaturated fatty acids (LCPUFA) elevates bone mineral content (BMC) of small and normal neonates was studied using pregnant rats and guinea pigs fed a control (C) diet or low protein (LP) diet to induce small neonates followed by C or LCPUFA diets during lactation. Measurements (days 3 and 21 post-partum) included BMC and density (BMD) plus bone metabolism. In rats LP reduced birth weight but at day 21 elevated weight and whole body BMC; LCPUFA enhanced spine BMC, tibia BMC and BMD and whole body BMD. In guinea pig pups, at days 3 and 21, LP reduced weight, whole body and regional BMC and BMD whereas LCPUFA reduced day 3 osteocalcin and elevated day 21 spine BMD. LCPUFA minimized loss of whole body BMC in dams and elevated osteocalcin in sows. LCPUFA during lactation enhances bone in normal and small neonates without compromising maternal bone.

Dietary ratio of n-6 to n-3 polyunsaturated fatty acids and periodontal disease in community-based older Japanese: a 3-year follow-up study

The longitudinal relationship between dietary n-6 to n-3 PUFAs ratio and periodontal disease in 235 Japanese subjects for whom data were available for the years 2003-2006 was investigated. PUFAs intake was assessed at baseline with a brief-type self-administered diet history questionnaire. Full-mouth periodontal status, measured as the clinical attachment level (CAL), was recorded at baseline and once a year for 3 years. The number of teeth with a change in the loss of CAL ≥3 mm at any site over a year was calculated as 'periodontal disease events'. Poisson regression analysis was conducted, with dietary n-6 to n-3 PUFAs ratio as the main predictor, to estimate its influence on periodontal disease events. A high dietary n-6 to n-3 PUFAs ratio was significantly associated with greater number of periodontal disease events. The findings suggest the dietary n-6 to n-3 PUFAs ratio is associated with periodontal disease among older Japanese.

Influence of high-fat diet from differential dietary sources on bone mineral density, bone strength, and bone fatty acid composition in rats

Previous studies have suggested that high-fat diets adversely affect bone development. However, these studies included other dietary manipulations, including low calcium, folic acid, and fibre, and (or) high sucrose or cholesterol, and did not directly compare several common sources of dietary fat. Thus, the overall objective of this study was to investigate the effect of high-fat diets that differ in fat quality, representing diets high in saturated fatty acids (SFA), n-3 polyunsaturated fatty acids (PUFA), or n-6 PUFA, on femur bone mineral density (BMD), strength, and fatty acid composition. Forty-day-old male Sprague-Dawley rats were maintained for 65 days on high-fat diets (20% by weight), containing coconut oil (SFA; n = 10), flaxseed oil (n-3 PUFA; n = 10), or safflower oil (n-6 PUFA; n = 11). Chow-fed rats (n = 10), at 105 days of age, were included to represent animals on a control diet. Rats fed high-fat diets had higher body weights than the chow-fed rats (p < 0.001). Among all high-fat groups, there were no differences in femur BMD (p > 0.05) or biomechanical strength properties (p > 0.05). Femurs of groups fed either the high n-3 or high n-6 PUFA diets were stronger (as measured by peak load) than those of the chow-fed group, after adjustment for significant differences in body weight (p = 0.001). As expected, the femur fatty acid profile reflected the fatty acid composition of the diet consumed. These results suggest that high-fat diets, containing high levels of PUFA in the form of flaxseed or safflower oil, have a positive effect on bone strength when fed to male rats 6 to 15 weeks of age.

Effects of long-term supplementation with omega-3 fatty acids on longitudinal changes in bone mass and microstructure in mice

A diet rich in omega-3s has previously been suggested to prevent bone loss. However, evidence for this has been limited by short exposure to omega-3 fatty acids (FAs). We investigated whether a diet enriched in eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) for the entire adult life of mice could improve bone microstructure and strength. Thirty female mice received a diet enriched in DHA or EPA or an isocaloric control diet from 3 to 17 months of age. Changes in bone microstructure were analyzed longitudinally and biomechanical properties were analysed by a three-point bending test. Bone remodelling was evaluated by markers of bone turnover and histomorphometry. Trabecular bone volume in caudal vertebrae was improved by EPA or DHA at 8 months (+26.6% and +17.2%, respectively, compared to +3.8% in controls, P=.01), but not thereafter. Trabecular bone loss in the tibia was not prevented by omega-3 FAs (BV/TV -94%, -93% and -97% in EPA, DHA and controls, respectively). EPA improved femur cortical bone volume (+8.1%, P<.05) and thickness (+4.4%, P<.05) compared to controls. EPA, but not DHA, reduced age-related decline of osteocalcin (-70% vs. -83% in controls, P<.05). EPA and DHA increased leptin levels (7.3±0.7 and 8.5±0.5 ng ml⁻¹, respectively, compared to 4.5±0.9 ng ml⁻¹ in controls, P=.001); however, only EPA further increased IGF-1 levels (739±108 ng ml⁻¹, compared to 417±58 ng ml⁻¹ in controls, P=.04). These data suggest that long-term intake of omega-3 FA, particularly EPA, may modestly improve the structural and mechanical properties of cortical bone by an increase in leptin and IGF-1 levels, without affecting trabecular bone loss.

Conjugated linoleic acid prevents growth attenuation induced by corticosteroid administration and increases bone mineral content in young rats

Corticosteroids are a common therapy in many disease states, despite frequent and potentially serious side effects. Nutritional supplementation with conjugated linoleic acid (CLA) has been shown to increase fat-free mass, whereas supplementation with n-3 and n-6 fatty acids has been shown to increase bone mineral density (BMD). To determine whether CLA can attenuate the side effects of 8 weeks of corticosteroid administration, we randomized twenty-four 5-week-old male Sprague-Dawley rats into 1 of 4 groups: control; control + methylprednisolone (7 mg.kg-1.week-1); CLA diet (1% CLA w/w); or CLA plus methylprednisolone. Body composition, bone mineral content (BMC), and BMD were assessed with dual-energy X-ray absorptiometry at the onset and at the end of the 8-week intervention. The mechanical properties of bone were determined using 3-point femur bending at the end of the intervention. Methylprednisolone resulted in an attenuation of the increase in body mass and lean mass over the 8 weeks (p < 0.05). CLA prevented the methylprednisolone-induced attenuation of body mass and lean mass accumulation. CLA also resulted in a greater increase in BMC (p < 0.05) in the lumbar spine. The energy at failure of the isolated femurs was increased with CLA (p < 0.05). Dietary CLA prevents many of the growth- and bone-related side effects arising from 8 weeks of corticosteroid administration, results in greater increases in BMC and BMD, and can contribute to an improvement in some of the mechanical properties of bone.

Preventive effects of flaxseed and sesame oil on bone loss in ovariectomized rats

A study was designed to examine the effects of dietary flaxseed oil (FO) and sesame oil (SO) which are rich successively in n-3 and (n-9 and n-6) on biochemical parameters and histological status of bone. Sixty-four 90-day-old female wistar rats were randomly assigned to 6 groups: sham-operated rat (sham)+ control diets, ovariectomized rat (OVX) + control diets, OVX + 7% FO, OVX + 7% SO, OVX + 10% FO, OVX + 10% SO. After 4 weeks of treatments, rats were euthanized; blood and tissues were collected for analyses. Markers of bone formation which is alkaline phosphatase activity and markers of bone resorption which is tartrate resistant acid phosphatase activity were measured. Present results showed that OVX increased significantly ALP and TRAP activity and the examination of bone tissue showed disruptive and lytic bone trabeculae. Animals fed 10% FO and 10% SO of fat reduced these parameters and improved bone microarchitecture. Whereas, there was no improvement in biochemical and histological states in OVX rats that received 7% of PUFAs successively provided from FO and SO diets. In conclusion, our results are encouraging because they suggest that PUFAs intake may help to prevent osteoporosis associated with estrogens deficiency. However, further studies are needed to determine the mechanism by which a diet rich in n-3 or lignans modulate bone tissue.

Identification of inflammatory and proresolving lipid mediators in bone marrow and their lipidomic profiles with ovariectomy and omega-3 intake

Newly described lipoxygenase (LOX)-generated lipid mediators, that is, resolvins and protectins as well as lipoxins, are both anti-inflammatory and proresolving. We aimed to determine whether these lipid mediators are present in bone marrow and whether their lipidomic profiles are altered following ovariectomy or dietary supplementation with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) ethyl esters. Female rats were ovariectomised or sham-operated. Shams and one ovariectomised group received a diet devoid of omega-3 long-chain polyunsaturated fatty acids. The remaining ovariectomised rats received either 0.5 g EPA or DHA ethyl ester/kg body weight/day for 4 months. Bone marrow was analyzed using both GC to determine fatty acid composition and mediator lipidomics by LC/MS/MS profiling for the presence of LOX-pathway lipid mediators derived from arachidonic acid (AA), EPA, and DHA. LOX-derived products including lipoxins, resolvin D1, resolvin E1, and protectin D1 were identified in bone marrow by the presence of diagnostic ions in their corresponding MS-MS spectra. The proportion of AA relative to DHA and of AA-derived relative to DHA-derived mediators in bone marrow was higher in ovariectomised compared to sham-operated rats. DHA or EPA ethyl ester supplementation increased the percentage of DHA and EPA in bone marrow and increased the proportion of LOX mediators biosynthesized from DHA or EPA, respectively. Given the potent bioactivities of the lipoxins, resolvins, and protectins, the presence and changes in profile postovariectomy and with EPA and DHA ethyl ester supplementation may be of interest in bone marrow function and as a potential source of these mediators in vivo.

Varying ratios of omega-6: omega-3 fatty acids on the pre-and postmortem bone mineral density, bone ash, and bone breaking strength of laying chickens

The purpose of this study was to investigate the effects of varying ratios of n-6 to n-3 fatty acids in the diets of White Leghorn chickens on tibia bone characteristics [bone mineral density, bone mineral content (BMC), ash bone mineral content, bone morphology, and cortical thickness] and tibia bone strength parameters (ultimate force, bending stress, maximum strain, Young's modulus of elasticity, area under the curve, and moment of inertia). Seventy-five 16-wk-old female White Leghorn chickens were randomly assigned to 1 of 5 dietary ratios of n-6 to n-3 fatty acids: 47.8:1, 18.0:1, 7.6:1, 5.9:1, or 4.7:1. Corn oil was the n-6 fatty acid source, whereas flax oil provided the n-3 fatty acids. Bone density was measured on the left tibia via dual-energy x-ray absorptiometry (DXA) prior to killing and after excision. Bones were ashed in a muffle furnace at 500 degrees F. Tibia bones were broken by using a 3-point bending rig. Results showed no significant effect of diet on bone characteristics. There were no significant differences among diet groups for parameters of bone strength except cortical thickness (P < or = 0.01). Bone mineral content determined by ashing was significantly different by 9.2% (P < or = 0.0001) from BMC determined in vivo by DXA; however, there were no differences in ex vivo BMC and BMC ash, although they were highly correlated (r = 0.99, P < or = 0.0001). We concluded that there was no effect of n-3 fatty acids on tibia bone in mature White Leghorn chickens. The GE Lunar Prodigy DXA instrument significantly underestimated the in vivo BMC in chickens.

Dietary fish oil results in a greater bone mass and bone formation indices in aged ovariectomized rats

Postmenopausal bone loss and the possible progression to osteoporosis is a major health concern. Until recently, hormone replacement therapy (HRT) was the standard for preventing the development of osteoporosis and possible hip fractures following menopause. However, because of some adverse effects of HRT, new therapies, lifestyle habits, and nutritional interventions are being developed and better characterized in their ability to prevent bone loss after menopause. One such option is to increase the amount of fish oil consumed in the diet. The goal of the current research was to determine the impact of fish oil supplementation on bone mass, density, formation, and resorption in an aged ovariectomized rat model. Twelve-month-old female retired breeder Sprague-Dawley rats were fed a control (Control) or fish oil (Fish) diet. Two weeks following the introduction of the diets, the rats were either sham-operated (Sham) or bilaterally ovariectomized (OVX). Ten weeks after surgery, indices of bone mass and bone histomorphometry were measured. Bone mineral content (BMC) of the whole femur was significantly higher in the Fish/OVX than in the Control/OVX, and the differences were most pronounced in the distal and proximal ends of the femur. However, the Fish/Sham and the Control/Sham did not differ in the measures of BMC. Although the Control/OVX had significantly lower cortical area and greater endosteal perimeter compared with the Control/Sham, the differences were not significant between the Fish/Sham and the Fish/OVX. In addition, the Fish/OVX had a significantly larger percent double-labeled surface and mineral apposition rate at the endocortical surface than the Control/OVX. Our findings suggest that fish oil supplementation has a positive effect on bone metabolism and might be a possible intervention to slow the loss of bone observed following menopause.

Specific effects of gamma-linolenic, eicosapentaenoic, and docosahexaenoic ethyl esters on bone post-ovariectomy in rats

Long chain polyunsaturated fatty acids (LCPUFAs) are involved in the regulation of bone metabolism. Increased dietary consumption of n-3, and possibly some n-6, LCPUFAs may limit postmenopausal bone loss. The aim of this study was to determine the effects on bone of specific fatty acids within the n-3 and n-6 LCPUFA families in ovariectomized (OVX) rats. Rats were OVX or sham-operated and fed either a control diet (OVX and sham) or a diet supplemented with 0.5 g/kg body weight/day of gamma-linolenic (GLA), eicosapentaenoic (EPA), docosahexaenoic (DHA) ethyl esters or a mixture of all three (MIX) for 16 weeks. Bone mineral content (BMC), area, and density and plasma concentrations of insulin-like growth factor-I, vitamin D, selected biochemical markers of bone metabolism, and parathyroid hormone (PTH) were determined. The OVX-induced decrease in lumbar spine BMC was significantly attenuated by DHA but not by EPA or GLA supplementation or supplementation with a mixture of all three LCPUFAs. Endosteal circumferences of tibiae were significantly greater in DHA and EPA compared to OVX. Plasma C-terminal telopeptide of type I collagen and osteocalcin concentrations were not significantly different in the DHA group compared to OVX. Femur BMC decreased by a significantly greater amount in GLA than OVX, and final plasma PTH concentrations were significantly higher in GLA compared to all other groups. In conclusion, DHA ameliorated OVX-induced bone mineral loss. GLA exacerbated post-OVX bone mineral loss, possibly as a result of PTH-induced bone catabolism.

Feeding flaxseed oil but not secoisolariciresinol diglucoside results in higher bone mass in healthy rats and rats with kidney disease

Flaxseed's oil and lignan, secoisolariciresinol diglucoside (SDG), are implicated in attainment of health and treatment of renal injury and osteoporosis. To test for these benefits, weanling Han:SPRD-cy rats (n=171) with or without kidney disease were randomized to diets made with either corn oil or flaxseed oil and with or without SDG for 12 weeks. In females, weight was lower with the SDG diet. In males fed flaxseed oil, lean mass was higher and fat % was lower. In both sexes, fat % was lower in diseased rats. Bone mineral content (BMC) and density were higher in rats fed flaxseed oil and lower in diseased rats, additionally; BMC was lower in SDG-supplemented females. The benefit of flaxseed oil on body composition is sex specific but the effect on bone mass is not. Lastly, reduced weight due to early rat kidney disease is not due to loss of lean body mass.

Improvement of bone quality in gonad-intact middle-aged male rats by long-chain n-3 polyunsaturated fatty acid

The effect of long-chain n-3 polyunsaturated fatty acid (PUFA) on bone measurements was evaluated in gonad-intact middle-aged male rats. Seven rats were killed on day 0 of dietary intervention to determine bone parameters at baseline. Experimental rats (7/group) were fed one of the following lipid treatments (g/kg diet): 167 g safflower oil + 33 g menhaden oil (N6+N3 diet, control), 200 g safflower oil (N6 diet), or 190 menhaden oil + 10 g corn oil (N3 diet). After 20 weeks of dietary treatment, all groups had lower values for peak load and ultimate stiffness in femurs compared to baseline values. Rats fed the N3 diet had the highest values for peak load, ultimate stiffness, and Young's modulus compared with those fed the N6 and control diets. Compared to baseline, all dietary treatment groups had significantly lower values for trabecular thickness and number in proximal tibia but higher values for trabecular separation and formation rate in proximal tibia and endocortical bone formation rate in tibial shaft. Compared with the control group, rats fed the N3 diet had lower values for formation rate, osteoclast number, and eroded surface in proximal tibia but higher values for periosteal mineral apposition and formation rates in tibia shaft. These findings indicate that a diet rich in long-chain n-3 PUFA mitigate aging-induced loss of bone integrity in intact middle-aged male rats through reducing bone turnover rate by suppressing both bone formation and resorption as a result of a larger net bone volume and modulating endocortical and cancellous bone compartments.

Albumin-bound lipids induce free cytoplasmic calcium oscillations in human osteoblast-like cells

[Ca(2+)](i) oscillations were found in human osteoblast-like cells (hOB cells) exposed to high-lipid bovine serum albumin (BSA), but not when exposed to low-lipid BSA. These [Ca(2+)](i) oscillations were inhibited by heptanol and suramin, which implies that gap junctions and purinergic signalling may be important for these [Ca(2+)](i) oscillations. The high-lipid BSA preparation that was used contains arachidonic acid. [Ca(2+)](i) oscillations could be induced by low lipid albumin with arachidonic acid added. The albumin-bound lipids were also important for osteoblast growth since DNA synthesis and the total cell protein content was higher in hOB cells exposed to high-lipid BSA. The effect of arachidonic acid on hOB cell proliferation was bone-donor dependent; both stimulatory and inhibitory effects were observed. The physiological importance of albumin-bound lipids is unclear; given that albumin has only minimal contact with osteoblasts under normal conditions. Only when bone capillaries are disrupted, e.g. during a fracture, would significant amounts of albumin reach osteoblasts. Albumin-bound lipids could therefore contribute to stimulation of osteoblast proliferation during fracture healing.

Effect of fish oil on bone mineral density in aging C57BL/6 female mice

Life expectancy has increased considerably over the last century in the United States. It is expected that this longevity will be accompanied by an increase in the prevalence of osteoporosis and accompanying complications in the elderly population. Age-related loss of bone mass and bone fragility are major risk factors for osteoporosis, leading to an increased risk of fractures. Therefore, nutritional strategies and lifestyle changes that prevent age-related osteoporosis and improve the quality of life for the elderly population are urgently needed. Hence, the present study compared the effects of corn oil (CO; n-6 fatty acids; commonly present in Western diets) and fish oil (FO; n-3 fatty acids) on bone mineral density (BMD) in aging C57BL/6 female mice. After 6 months of dietary treatment, we found that 18-month-old FO-fed mice maintained higher BMD in different bone regions compared to CO-fed mice. These findings were accompanied by a decreased activity of pro-inflammatory cytokines, tumor necrosis factor-alpha and interleukin-6 in stimulated splenocytes; a nonsignificant but greater increase in bone formation markers alkaline phosphatase and osteocalcin in the serum; and lower osteoclast generation in bone marrow cell cultures in FO-fed mice. In conclusion, these findings suggest that providing n-3 fatty acids may have a beneficial effect on bone mass during aging by modulating bone formation and bone resorption factors.

Protective effect of dietary long-chain n-3 polyunsaturated fatty acids on bone loss in gonad-intact middle-aged male rats

This study evaluated the effect of a fat blend containing long-chain (LC) n-3 PUFA on bone mineral density (BMD) and bone metabolism in gonad-intact middle-aged male rats (12 months old, n 28). Seven rats were killed on day 0 of dietary intervention to determine the baseline BMD. The remaining rats (seven per group) were fed a diet with one of the following dietary lipid treatments (g/kg diet): 167 g safflower oil + 33 g menhaden oil (N6 + N3 diet, control), 200 g safflower oil (N6 diet, almost devoid of LC n-3 PUFA), or 190 g menhaden oil + 10 g corn oil (N3 diet, rich in LC n-3 PUFA) for 20 weeks. After 20 weeks, all dietary treatment groups had a lower BMD compared with the baseline reference. However, rats fed the N3 diet had the highest bone mineral content and cortical + subcortical BMD compared with those fed the N6 and control N6 + N3 diet. Compared with the control (N6 + N3) group, rats fed the N3 diet had higher values for serum insulin-like growth factor-I, parathyroid hormone, 1,25-(OH)2 vitamin D3 and bone-specific alkaline phosphatase activity, but lower bone NO production and urinary Ca, whereas rats fed the N6 diet had higher bone prostaglandin E2 production and serum pyridinoline. These findings indicate a protective action of LC n-3 PUFA on ageing-induced bone loss in gonad-intact middle-aged male rats through a modulation of local factors and systemic calcitrophic hormones.

Maternal and cord blood long-chain polyunsaturated fatty acids are predictive of bone mass at birth in healthy term-born infants

Long-chain polyunsaturated fatty acids (LC PUFA) are associated with bone mass in animals and human adults, yet no data exist for human infants. Thus, the objective of this study was to establish that LC PUFA status is associated with bone mass in healthy infants. Thirty mother-infant pairs were studied for LC PUFA status by measuring maternal and cord blood red blood cells (RBC) for arachidonic acid (AA), eicosapentaenoic acid (EPA), and DHA. Infant anthropometry and lumbar spine 1-4, femur and whole-body bone mineral content (BMC) were measured within 15 d of delivery. Maternal and infant LC PUFA were tested for their relationship to BMC using Pearson correlation and backward step-wise regression analyses. At birth, the average gestational age was 39.3+/-1.1 wk and body weight was 3433+/-430 g. Cord RBC AA was positively correlated with whole-body BMC, AA:EPA positively correlated with lumbar spine 1-4 BMC and femur BMC. Maternal RBC AA was positively correlated with whole-body BMC. After accounting for infant weight using regression, whole-body BMC was positively predicted by cord RBC AA but none of the maternal LC PUFA; lumbar spine 1-4 BMC was positively predicted by cord RBCAA:EPA ratio but negatively by maternal DHA; and femur BMC was not predicted by cord LC PUFA but was negatively predicted by maternal DHA. Imbalances among the n-6 and n-3 LC PUFA by term gestation are associated with lower bone mass, suggesting that the maternal diet should be balanced in n-6 and n-3 LC PUFA.

The effect of pre- and postmolt diets high in n-3 fatty acids and molt programs on skeletal integrity and insulin-like growth factor-I of White Leghorns

This study investigated changes in bone integrity and circulating concentrations of insulin-like growth factor-I (IGF-I) of hens subjected to 2 distinct molting regimens and fed pre- and postmolt diets high in n-3 or n-6 fatty acids. A dual-energy x-ray absorptiometer determined bone mineral density (BMD) of the tibia and humerus of 45 live hens from 62 to 76 wk of age. Densitometric scans were also conducted in excised tibia and humerus at 66, 71, and 76 wk of age. Concentrations of IGF-I were monitored using an homologous RIA at the same ages. The molting treatments consisted of 10 d of fasting + cracked corn for 7 d + pullet developer diet for 10 d or a nonfasting molt (wheat-middlings-based diet for 27 d). Five weeks prior to and after either molt treatment, birds were fed 1 of 2 diets containing dietary n-6/ n-3 fatty acids ratios of 0.6 or 8.0. At the end of the molt (71 wk of age), tibial BMD decreased 30% in fasted and 11% in nonfasted molt regimens, and the fatty acid content of the premolt diet had no effect on the decline in BMD. The BMD of the humerus also decreased during molt with the exception of hens subjected to a nonfasted molt and fed n-3 fatty acid diets in which their BMD values were similar to or greater (at 73 wk of age) than those of controls during the entire experimental period (treatment by bone by age, P < or = 0.0001). Induced molt affected circulating IGF-I concentrations (treatment by age interaction, P < or = 0.0001), and the response was the same regardless of molt regimen (fasting vs. nonfasting) or diet (n-3 vs. n-6 fatty acids). A decrease in IGF-I 54 h postmolt was noted; however, from 13 to 43 d postmolt, all molted birds had elevated IGF-I as compared with controls. In conclusion, a nonfasted molt as compared with fasted molt was less detrimental to bone mineralization; dietary n-6/n-3 fatty acid ratios in the pre- and postmolt diets had little effect on the decline of skeletal integrity during molt, and circulating IGF-I concentrations were affected by molt.

Body composition in preterm infants who are fed long-chain polyunsaturated fatty acids: a prospective, randomized, controlled trial

The objective of this study was to evaluate growth and body composition of premature infants who were fed formulas with arachidonic acid (ARA; 20:4n6) and docosahexaenoic acid (DHA; 22:6n3) to 1 y of gestation-corrected age (CA). Preterm infants (750-1800 g birth weight and <33 wk gestational age) were assigned within 72 h of first enteral feeding to one of three formulas: control (n = 22), DHA+ARA from fish/fungal oil [DHA+ARA(FF); n = 20], or DHA+ARA from egg/fish oil [DHA+ARA(EF); n = 18]. Human milk feeding was allowed on the basis of the mother's choice. Infants were fed breast milk and/or preterm formulas with or without 0.26% DHA and 0.42% ARA to term CA followed by breast milk or postdischarge preterm formulas with or without 0.16% DHA and 0.42% ARA to 12 mo CA. Body composition was measured by dual-energy x-ray absorptiometry. There were no significant differences among the three study groups at any time point in weight, length, or head circumference. Bone mineral content and bone mineral density did not differ among groups. At 12 mo CA, infants who were fed DHA+ARA-supplemented formulas had significantly greater lean body mass (p < 0.05) and significantly less fat mass (p < 0.05) than infants who were fed the unsupplemented control formula. The DHA+ARA-supplemented formulas supported normal growth and bone mineralization in premature infants who were born at <33 wk gestation. Preterm formulas that had DHA+ARA at the levels and ratios in this study and were fed to 1 y CA led to increased lean body mass and reduced fat mass by 1 y of age.

Ratio of n-6 to n-3 fatty acids and bone mineral density in older adults: the Rancho Bernardo Study

BACKGROUND

Several lines of evidence suggest that n-3 fatty acids reduce the risk of some chronic diseases, including heart disease, diabetes, and cancer. Other research, mainly in animals, also suggests a role in bone health.

OBJECTIVE

We aimed to investigate the association between the ratio of dietary n-6 to n-3 fatty acids and bone mineral density (BMD) in 1532 community-dwelling men and women aged 45-90 y.

DESIGN

Between 1988 and 1992, dietary data were obtained through self-administered food-frequency questionnaires, and BMD was measured at the hip and spine with the use of dual-energy X-ray absorptiometry. A medical history was obtained and current medication use was validated. Age- and multiple-adjusted linear regression analyses were performed.

RESULTS

There was a significant inverse association between the ratio of dietary linoleic acid to alpha-linolenic acid and BMD at the hip in 642 men, 564 women not using hormone therapy, and 326 women using hormone therapy; these results were independent of age, body mass index, and lifestyle factors. An increasing ratio of total dietary n-6 to n-3 fatty acids was also significantly and independently associated with lower BMD at the hip in all women and at the spine in women not using hormone therapy.

CONCLUSIONS

A higher ratio of n-6 to n-3 fatty acids is associated with lower BMD at the hip in both sexes. These findings suggest that the relative amounts of dietary polyunsaturated fatty acids may play a vital role in preserving skeletal integrity in older age.

(n-3) fatty acids reduce the release of prostaglandin E2 from bone but do not affect bone mass in obese (fa/fa) and lean Zucker rats

Childhood obesity is prevalent and linked to the development of Type 2 diabetes mellitus (DM) and poor bone health. Some PUFA enhance bone mass and thus may improve bone health in obese children. The study objective was to determine the effects of dietary (n-6) compared with (n-3) essential PUFA and long-chain PUFA (LCPUFA) on bone in an obese and insulin-resistant state. Male fa/fa (n = 48) and lean Zucker rats (n = 48) were fed diets containing safflower oil [SO, high (n-6) PUFA], flaxseed oil [FXO, high (n-3) PUFA], or menhaden oil [MO, high (n-3) LCPUFA] for 9 wk. Measurements included the following: femur bone area (BA), mineral content (BMC), density (BMD), morphometry and ex vivo release of prostaglandin E(2) (PGE(2)); plasma osteocalcin and C-terminal telopeptides of type I collagen. Differences among groups were detected using 2-way ANOVA. Genotype effects in the fa/fa rats included lower femoral weight, length, BA, and BMC, as well as femoral head and proximal epiphysis widths compared with the lean rats, but BMD was not affected. Femur BA, BMC, and BMD did not differ among the dietary groups, but diaphysis width was elevated in the MO group and PGE(2) release was reduced by the FXO and MO diets. No genotype x diet interactions were observed. These data indicate that the fa/fa Zucker rat is at risk for low bone mass and that dietary (n-3) FA effectively reduce PGE(2) release. Whether reduced PGE(2) will support optimal peak bone mass during childhood and conserve bone mass with aging warrants investigation.

Low levels of dietary arachidonic and docosahexaenoic acids improve bone mass in neonatal piglets, but higher levels provide no benefit

In piglets, feeding arachidonic acid (AA) and docosahexaenoic acid (DHA) in a 5:1 ratio leads to elevated bone mass, but the optimal total quantity requires clarification. We studied bone mass and modeling of piglets that were randomized to receive 1 of 4 formulas for 15 d: control formula or the same formula with various levels of AA:DHA (0.5:0.1 g, 1.0:0.2 g or 2.0:0.4 g AA:DHA/100 g of fat). Measurements included: bone area (BA), mineral content (BMC), and density (BMD) of whole body, lumbar spine, and excised femurs; biomarkers of bone modeling were plasma osteocalcin and urinary cross-linked N-telopeptides of type 1 collagen (NTx), tibial ex vivo release of prostaglandin E(2) (PGE(2)), plasma insulin-like growth factor-1 (IGF-1), and tissue fatty acids. Main effects were identified using ANOVA and post hoc Bonferroni t tests. In supplemented piglets, relations among liver fatty acid proportions and bone mass were assessed using Pearson correlations. Whole body (P = 0.028) and lumbar spine (P = 0.043) BMD were higher in the group supplemented with 0.5:0.1 g AA:DHA/100 g of fat than in controls. Tissue AA and DHA increased in proportion to diet levels. Liver eicosapentaenoic acid (EPA) correlated positively (r > or = 0.38, P < or = 0.05) with whole body and femur BMC and BMD and lumbar spine BMC. Liver AA:EPA ratio correlated negatively (r > or = -0.039, P < or = 0.05) with whole body, femur, and lumbar spine BMC plus whole body and femur BMD. Dietary 1.0:0.2 g AA:DHA/100 g reduced NTx relative to 2.0:0.4 g AA:DHA/100 g of fat (P = 0.039). The diets did not affect the other biochemical variables measured. Low levels of dietary AA:DHA (0.5:0.1 g/100 g of fat) elevate bone mass, but higher amounts are not beneficial.

Effects of long-term dietary lipids on mature bone mineral content, collagen, crosslinks, and prostaglandin E2 production in Japanese quail

This study investigated the effects of long-term dietary lipids on mature bone mineral content, collagen concentration, crosslink levels, bone marrow and ex vivo prostaglandin E2 (PGE2) biosynthesis, as well as the relationship of PGE2 production to these bone formation parameters. One-month-old male Japanese quail were given a basal diet containing 1 of 4 lipid sources: soybean oil (SBO), hydrogenated soybean oil (HSBO), chicken fat (CF), or menhaden fish oil (FO) at 50 g/kg of the diet. At 8 mo of age, lipid treatments did not affect bone length, diameter, or weight in quail. Quail fed SBO or CF had significantly lower levels of mineral content in tibial bones compared with those given FO. Bone collagen level was significantly higher in quail consuming SBO than those given HSBO or CF. Collagen crosslink concentration was markedly increased in birds provided FO or HSBO compared with those fed SBO or CF. Prostaglandin E2 biosynthesis in bone organ culture and marrow were greatly increased in quail maintained on the SBO or CF diet compared with those given the FO or HSBO diet. Prostaglandin E2 production in the bone microenvironment was negatively correlated with tibial ash and collagen crosslinks but had a positive correlation with tibial collagen levels. These results support our previous findings that long-term exposure to diets high in SBO or CF impaired mature bone mechanical properties and histological characteristics. Further, the results suggest that long-term supplementation of SBO or CF in the diet had a significant adverse effect on mature bone metabolism, and that dietary lipids altered bone metabolism, perhaps partially by controlling the production of local regulatory factor in bone.

Dietary n-6:n-3 fatty acid ratio in the perinatal period affects bone parameters in adult female rats

PUFA and their metabolites are important regulators of bone formation and resorption. The effect of PUFA on bone growth may be especially striking during the perinatal period. The aim of the present study was to investigate the effect of diets with different n-6:n-3 fatty acid (FA) ratios during the perinatal period on bone parameters in the adult offspring. During late gestation and throughout lactation, rat dams were fed an isoenergetic diet containing 70 g linseed oil (n-3 diet), soyabean oil (n-6+n-3 diet) or sunflower-seed oil (n-6 diet) per kg with n-6:n-3 FA ratios of 0.4, 9 and 216, respectively. The offspring were weaned onto an ordinary chow and followed until 30 weeks of age. Bone parameters were analysed using peripheral quantitative computerised tomography and dual-energy X-ray absorptiometry. Femur length and cortical cross-sectional bone area and bone mineral content were significantly higher in the n-6+n-3 group than in the other groups. Cortical bone thickness in the n-6+n-3 group was increased compared with the n-3 group, but most cortical bone parameters did not differ between the n-3 and n-6 groups. The results suggest that regulatory mechanisms were influenced by the n-6:n-3 FA ratio early in life and not compensated for by the introduction of an ordinary diet after weaning.

The effect of polyunsaturated fatty acids, including conjugated linoleic acid, on calcium absorption and bone metabolism and composition in young growing rats

The effect of polyunsaturated fatty acids (PUFA), in particular conjugated linoleic acid (CLA), on Ca and bone metabolism is unclear. In a 2x2 factorial design study, forty male 4-week-old rats were fed a control diet containing 70 g added fat (soyabean oil (SBO; n-6 PUFA-rich diet) or menhaden oil-safflower oil (MSO; n-3 PUFA-rich diet))/kg diet with 0 or 10 g CLA/kg for 8 weeks. Ex vivo prostaglandin E2 biosynthesis by bone organ culture was significantly higher (P<0.001) in rats consuming SBO compared with MSO, irrespective of CLA. Addition of the CLA treatment to either diet further lowered (P<0.05) ex vivo prostaglandin E2 production. Neither PUFA type nor CLA altered circulating or femoral mRNA levels of osteocalcin (a marker of bone formation) or insulin-like growth factor-I (a mediator of bone metabolism). While urinary pyridinium crosslinks levels (markers of bone resorption) were unaffected by CLA irrespective of PUFA type, they were significantly higher (P<0.05) in rats consuming SBO compared with MSO irrespective of CLA. Net fractional (%) and absolute (mg) Ca absorption were significantly (P<0.01 and P<0.05 respectively) higher in CLA-supplemented than unsupplemented animals fed on the n-3 PUFA-rich diet, whereas CLA had no effect in animals fed the n-6 PUFA-rich diet. There was no effect of CLA supplementation on bone mineral mass. In conclusion, CLA supplementation over 8 weeks appeared to enhance Ca absorption in young growing rats fed an n-3 PUFA-rich diet, but had no measurable effect on bone metabolism or bone mass over this time frame.

Effects of long-term administration of N-3 polyunsaturated fatty acids (PUFA) and selective estrogen receptor modulator (SERM) derivatives in ovariectomized (OVX) mice

We studied the beneficial effects of dietary consumption of n-3 polyunsaturated fatty acids (PUFA) and two selective estrogen receptor modulator (SERM) derivatives (SERM-I and SERM-II) and their combined effect on serum lipids, skin dermis and adipose layers, bone marrow adipogenesis, and cytokine secretion in mice. Two different ovariectomized (OVX) models were studied: treatment began immediately post-OVX in one and 3 months post-OVX in the other. Our results showed that n-3 PUFA and both SERMs decreased triglyceride levels in the serum, and that SERMs also decreased serum cholesterol levels while n-3 PUFA had no similar effect. SERMs had no effect on IL-6, IL-1 beta, or IL-10 levels, but they decreased ex vivo tumor necrosis factor (TNF-alpha). N-3 PUFA decreased secretion of non-induced IL-6 and TNF-alpha from cultured BMC and IL-1 beta levels in vivo (i.e., in bone marrow plasma), but its main effect was a significant elevation in the secretion of IL-10, a known anti-inflammatory cytokine. OVX-induced B-lymphopoiesis was not affected by LY-139481 (SERM-I) while LY-353381 (SERM-II) exhibited an estrogen-antagonistic effect in sham and OVX mice and elevated the amount of B-cells in bone marrow. Fish oil consumption prevented the elevation in B-lymphopoiesis caused by OVX, but had no curative effect on established augmented B-lymphopoiesis. This activity could be mediated via the elevation of IL-10 which was shown to suppress B-lymphopoiesis. Both SERMs and n-3 PUFA inhibited the increase in adipose tissue thickness caused by OVX in mice. Our results showed that n-3 PUFA, could prevent some of the deleterious outcomes of estrogen deficiency that were not affected by SERMs. We observed no significant beneficial effects of the combined administration of SERM-I, SERM-II, and PUFA on the studied parameters.The exact mechanism by which polyunsaturated fatty acids exert their activities is still not clear, but peroxisome proliferator-activated receptors (PPARs) might be involved in processes which are modulated by n-3 PUFA.

Dietary arachidonic acid suppresses bone turnover in contrast to low dosage exogenous prostaglandin E(2) that elevates bone formation in the piglet

This study was designed to compare the effects of dietary arachidonic acid (AA) versus prostaglandin E(2) (PGE(2)) on bone cell metabolism and bone mass. Twenty-eight piglets from 7 litters were randomized to 1 of 4 treatments for 15 days: fatty acid supplemented formula (FA: 0.8% of total fatty acids as AA and 0.1% of total fatty acids as DHA)+PGE(2) injections (0.1mg/kg/day), FA+saline injections, standard formula (STD: n-6:n-3 of 8:1) + PGE(2) injections or STD+saline injections. PGE(2) resulted in elevated osteoblast activity as indicated by plasma osteocalcin and also reduced urinary calcium excretion. Dietary FA resulted in reduced bone resorption as indicated by urinary N-telopeptide and reduced bone PGE(2). Both PGE(2) and FA treatments independently lead to elevated femur mineral content, but the combined treatment caused a reduction. Thus the mechanisms by which PGE(2) and FA lead to enhanced bone mass are distinct.

Protective role of n-3 lipids and soy protein in osteoporosis

It is well established that bone loss due to estrogen deficiency after menopause is greater in women consuming higher quantities of animal protein than in women consuming vegetable protein, particularly soy protein. Besides the dietary protein source altering bone loss, it has also been postulated recently that the source of a higher n-6/n-3 ratio in dietary oils is implicated in causing osteoporosis. Both animal and human studies have indicated that an increased intake of n-6 fatty acids from vegetable oils elevates prostaglandin E(2) levels as well as pro-inflammatory cytokines such as IL-1, IL-6 and TNF-alpha. Interestingly, it has been found that lack of estrogen also increases the production of these cytokines by immune cells and thereby activates osteoclasts during the peri-menopausal period. We speculated that the use of n-3 fatty acids and soy protein, which are known to act as anti-inflammatory and down regulate pro-inflammatory cytokines, may also protect against bone loss by decreasing osteoclast activation and bone resorption. Similar to the results of others, our ongoing studies indeed show that the bone loss in ovariectomized mice is significantly attenuated by feeding diets enriched with either fish oil or soy protein when compared to corn oil and casein-fed mice. One of the mechanisms appears to be decreasing the activation of receptor activator of NF-kappaB ligand (RANKL) on T cells, which has been found to increase osteoclast activation along with increasing pro-inflammatory cytokines in OVX mice. Since hormone replacement therapy has been found to cause adverse effects, further both animal and human studies are required with moderate soy protein and fish oil supplements in understanding the mechanisms involved in altering immune function and bone loss during menopause in women and aging in men.