Omega-3 fatty acids modulate ATPases involved in duodenal Ca absorption

Female rats consuming an iron and omega-3 fatty acid deficient diet preconception require combined iron and omega-3 fatty acid supplementation for the prevention of bone impairments in offspring

We previously showed in rats that pre- and postnatal deficiencies in iron and omega-3 (n-3) fatty acids can impair bone development, with additive and potentially irreversible effects when combined. This study aimed to investigate, in female rats consuming a combined iron and n-3 fatty acid deficient (ID + n-3 FAD) diet preconception, whether supplementation with iron and docosahexaenoic/eicosapentaenoic acid (DHA/EPA), alone and in combination, can prevent bone impairments in offspring. Using a 2 × 2 factorial design, female Wistar rats consuming an ID + n-3 FAD diet preconception were randomised to receive an: 1) iron supplemented (Fe + n-3 FAD), 2) DHA/EPA supplemented (ID + DHA/EPA), 3) Fe + DHA/EPA, or 4) ID + n-3 FAD diet from gestational day 10 throughout pregnancy and lactation. Post-weaning, offspring (n = 24/group; male:female = 1:1) remained on the respective experimental diets for three weeks until postnatal day 42-45. Offspring born to female rats consuming a control diet preconception and an Fe+DHA/EPA diet throughout pregnancy and lactation served as non-deficient reference group (Control+Fe+DHA/EPA). Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry and bone strength using three-point bending tests. Only offspring in the Fe+DHA/EPA group had significantly higher spine and femur BMD, and higher femur stiffness than offspring in the ID + n-3 FAD group, and had similar spine BMD and femur stiffness as the Control + Fe + DHA/EPA group. Offspring in the Fe + DHA/EPA group further had significantly higher femur strength (ultimate load) than the other experimental groups, and a similar femur strength as the Control + Fe + DHA/EPA group. This study shows that only combined iron and DHA/EPA supplementation can prevent bone impairments in offspring of female rats consuming an iron and n-3 FA deficient diet preconception.

Relationship between dietary characteristics and heel quantitative ultrasound parameters in postmenopausal women from the OsteoLaus cohort

The role of dietary patterns in the development of osteoporosis is unclear. The heel quantitative ultrasound (QUS) is a potential alternative to Dual X-Ray Absorptiometry. Nutrients, foods, dietary patterns and compliance to dietary guidelines were compared between the lowest and the highest tertiles of QUS parameters [Broadband Ultrasound Attenuation (BUA), Speed of Sound (SOS), Stiffness Index (SI)], using data from the OsteoLaus cohort. Participants in the highest tertiles of QUS parameters (385 for BUA, 397 for SOS, 386 for SI) were younger, of higher body weight, and had less major osteoporotic fractures. Women in the highest tertiles of SI and BUA consumed more fat (35.1 ± 0.4 vs 33.9 ± 0.4 and 34.9 ± 0.4 vs 33.8 ± 0.4 gr/day for SI and BUA, respectively, p < 0.05), and complied less frequently with dairy intake guidelines [odds ratio (95% confidence interval): 0.70 (0.53-0.92) and 0.72 (0.55-0.95) for SI and BUA, respectively, p < 0.05] than women in the lowest tertile. No differences were found regarding dietary patterns, healthy dietary scores, or compliance to dietary guidelines. Postmenopausal women in the highest QUS tertiles were younger, of higher weight and BMI, consumed more monounsaturated fatty acids and less dairy and calcium than women in the lowest tertiles. No differences were found between QUS tertiles regarding dietary patterns.

The effects of maternal fish oil supplementation rich in n-3 PUFA on offspring-broiler growth performance, body composition and bone microstructure

This study evaluated the effects of maternal fish oil supplementation rich in n-3 PUFA on the performance and bone health of offspring broilers at embryonic development stage and at market age. Ross 708 broiler breeder hens were fed standard diets containing either 2.3% soybean oil (SO) or fish oil (FO) for 28 days. Their fertilized eggs were collected and hatched. For a pre-hatch study, left tibia samples were collected at 18 days of incubation. For a post-hatch study, a total of 240 male chicks from each maternal treatment were randomly selected and assigned to 12 floor pens and provided with the same broiler diets. At 42 days of age, growth performance, body composition, bone microstructure, and expression of key bone marrow osteogenic and adipogenic genes were evaluated. One-way ANOVA was performed, and means were compared by student’s t-test. Maternal use of FO in breeder hen diet increased bone mineral content (p < 0.01), bone tissue volume (p < 0.05), and bone surface area (p < 0.05), but decreased total porosity volume (p < 0.01) during the embryonic development period. The FO group showed higher body weight gain and feed intake at the finisher stage than the SO group. Body composition analyses by dual-energy X-ray absorptiometry showed that the FO group had higher fat percentage and higher fat mass at day 1, but higher lean mass and total body mass at market age. The decreased expression of key adipogenic genes in the FO group suggested that prenatal FO supplementation in breeder hen diet suppressed adipogenesis in offspring bone marrow. Furthermore, no major differences were observed in expression of osteogenesis marker genes, microstructure change in trabecular bone, or bone mineral density. However, a significant higher close pores/open pores ratio suggested an improvement on bone health of the FO group. Thus, this study indicates that maternal fish oil diet rich in n-3 PUFA could have a favorable impact on fat mass and skeletal integrity in broiler offspring.

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.

The Influence of Obesity, Ovariectomy, and Greenshell Mussel Supplementation on Bone Mineral Density in Rats

Obesity is considered to impair long-term health by disturbing multiple physiological functions. However, it remains a controversial issue as to whether obesity has beneficial or detrimental effects on bone health in postmenopausal women. The aims of this study were to investigate the relationships between obesity and bone mineral density (BMD) under conditions of ovarian hormone deficiency in an animal model and to evaluate the potential health benefits of Greenshell mussel (GSM) on bone health. A total of 144 adult female Sprague-Dawley rats were fed from age 12 weeks on one of four diets (normal [ND]; ND + GSM; high fat/high sugar [HF/HS]; HF/HS + GSM; n = 36 per diet). At age 20 weeks, after a dual-energy X-ray absorptiometry (DXA) scan, 12 of the rats on each diet underwent ovariectomy (OVX) and the remaining rats were left intact. Twelve of the intact rats in each diet group were culled at age 26 weeks (short-term cohort). The remaining rats were culled at age 48 weeks (long-term cohort). Rats were DXA scanned before cull, then various fat pads were dissected. The results revealed that HF/HS rats and OVX rats dramatically increased body weight and fat deposition in correlation with leptin. In the long-term cohort, vertebral spine BMD rapidly declined after OVX. At termination, the OVX rats had decreased plasma bone turnover markers of CTX-1 and TRAP when compared with sham rats. Significantly higher BMD was found in OVX rats fed the HF/HS diet compared with ND, but this difference was not recapitulated in intact rats. BMD of right femur was significantly increased 5% to 10% by GSM in the short-term cohort. The data demonstrated that obesity can be beneficial by increasing BMD in OVX rats, and this may extrapolate to postmenopausal women as adipocyte-produced estrogen may slightly compensate for the reduction in ovarian hormones. Finally, the data showed that GSM may be beneficial to bone health by increasing BMD accrual. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Marine n-3 Polyunsaturated Fatty Acids and Bone Mineral Density in Kidney Transplant Recipients: A Randomized, Placebo-Controlled Trial

Kidney transplant recipients are at high risk of progressive bone loss and low-energy fractures in the years following transplantation. Marine n-3 polyunsaturated fatty acids (n-3 PUFA) supplementation may have beneficial effects on bone strength. The Omega-3 fatty acids in Renal Transplantation (ORENTRA) trial was an investigator initiated, randomized, placebo-controlled trial investigating the effects of marine n-3 PUFA supplementation after kidney transplantation. Effects of supplementation on bone mineral density (BMD) and calcium metabolism were pre-defined secondary endpoints. Adult kidney transplant recipients (n = 132) were randomized to 2.6 g marine n-3 PUFA supplement or olive oil (control) from 8 to 52 weeks post-transplant. Dual energy X-ray absorptiometry was performed to assess changes in bone mineral density of hip, spine, and forearm, as well as trabecular bone score (TBS) of the lumbar spine. Student's t test was used to assess between-group differences. There were no differences in ΔBMD between the two groups (intervention vs. control) at lumbar spine (-0.020 ± 0.08 vs. -0.007 ± 0.07 g/cm², p = 0.34), total hip (0.001 ± 0.03 vs. -0.005 ± 0.04, p = 0.38), or other skeletal sites in the intention-to-treat analyses. There was no difference in the change in TBS score (0.001 ± 0.096 vs. 0.009 ± 0.102, p = 0.62). Finally, no effect on biochemical parameters of mineral metabolism was seen. Results were similar when analyzed per protocol. In conclusion, we found no significant effect of 44 weeks of supplementation with 2.6 g of marine n-3 PUFA on BMD in kidney transplant recipients.

Camelina Oil Supplementation Improves Bone Parameters in Ovariectomized Rats

The aim of the present study was to determine the effect of administration of Camelina sativa oil (CO) as a source of polyunsaturated fatty acids (PUFA) on bone parameters in ovariectomized rats (OVX). Overall, 40 10-week-old healthy female Wistar rats were divided into 4 groups with 10 animals in each. Rats in the control group (SHO) were subjected to a sham operation, whereas experimental rats (OVX) were ovariectomized. After a 7-day recovery period, the SHO the rats received orally 1 mL of physiological saline for the next 6 weeks. The OVX rats received orally 1 mL of physiological saline (OVX-PhS), 5 g/kg BW (OVX-CO5), or 9 g/kg BW (OVX-CO9) of camelina oil. The use of camelina oil had a significant effect on body weight, lean mass, and fat mass. The camelina oil administration suppressed the decrease in the values of some densitometric, tomographic, and mechanical parameters of femur caused by estrogen deficiency. The CO treatment increased significantly the serum level of osteocalcin and decreased the serum level of C-terminal telopeptide of type I collagen in the OVX rats. In conclusion, camelina oil exerts a positive osteotropic effect by inhibiting ovariectomy-induced adverse changes in bones. Camelina oil supplementation can be used as an efficient method for improving bone health in a disturbed state. However, further research must be carried out on other animal species supplemented with the oil.

Plasma Fatty Acids and Quantitative Ultrasound, DXA and pQCT Derived Parameters in Postmenopausal Spanish Women

Different factors may contribute to the development of osteopenia or osteoporosis. Fatty acids are key nutrients for health, and a number of studies have reported an association between bone mineral density (BMD) and fatty acid intake. We aimed to investigate the relationships between serum levels of different fatty acids and bone parameters determined by quantitative bone ultrasound (QUS), peripheral quantitative computed tomography (pQCT), and dual-energy X-ray absorptiometry (DXA) in a sample of Spanish postmenopausal women. We enrolled a total of 301 postmenopausal women (median age 59 years; interquartile range (IQR) 7) in this study. All participants underwent full densitometric screening, including calcaneal quantitative ultrasound (QUS), peripheral quantitative computed tomography (pQCT), and dual-energy X-ray absorptiometry (DXA), as well as plasma fatty acid measurement. After adjustment for potential confounders, plasma n-3 polyunsaturated fatty acid (PUFA) levels correlated with BMD in the spine (r = 0.150; p = 0.014) and femoral neck (r = 0.143; p = 0.019). By multiple linear regression, an independent statistically significant positive relationship was observed between BMD in the spine and BMI (β = 0.288; p = 0.001) as well as total plasma n-3 PUFAs (β = 0.155; p = 0.009). The plasma n-3 PUFA level was also a significant and positive predictor of BMD at the femoral neck (β = 0.146; p = 0.009). Independent risk factors for low BMD (T-score ≤ 1) were determined by logistic regression analysis, and a relatively high level of plasma n-3 PUFAs (OR = 0.751; 95% CI 0.587-0.960, p = 0.022) was identified as a protective factor against low bone mass. In this single-center sample of Spanish postmenopausal women, we reported a significant positive and statistically independent association between BMD and plasma levels of n-3 PUFAs.

Effects of Greenshell Mussel (Perna canaliculus) Intake on Pathological Markers of Multiple Phenotypes of Osteoarthritis in Rats

The prevalence of metabolic osteoarthritis has been increasing worldwide, particularly among women. The aim of this study was to investigate the effects of the New Zealand greenshell mussel (Perna canaliculus; GSM) on osteoarthritis (OA) prevention in a rat model. One-hundred-and-eight female rats aged 12 weeks were divided into four test groups, containing 24 rats each, plus an additional control group. Each test group received one of the four experimental diets: normal control diet (ND), normal control diet supplemented with GSM (ND + GSM), high fat/high sugar diet (HFHS), or high fat/high sugar diet supplemented GSM (HFHS + GSM), for 36 weeks (end of the study). After 8 weeks on experimental diets, half of each group was subjected to ovariectomy (OVX) and the remaining half received a sham operation (ovaries left intact). The study evaluated body composition, bone mass, plasma cytokines, adipokines, HbA1c, CTX-II, and knee joint’s histopathology. HFHS diet and OVX significantly induced body weight gain and leptin production. OVX rats lost bone mineral density but increased adiponectin, HbA1C, and MCP-1. The OVX rats fed HFHS showed the highest Mankin scores. Importantly, inclusion of GSM reduced these pathological features. In conclusion, GSM might be beneficial in halting the progression of OA.

The Relationship Between Omega-3, Omega-6 and Total Polyunsaturated Fat and Musculoskeletal Health and Functional Status in Adults: A Systematic Review and Meta-analysis of RCTs

We conducted a systematic review and meta-analysis to assess the effects of increasing dietary omega-3, omega-6 and mixed polyunsaturated fatty acids (PUFA) on musculoskeletal health, functional status, sarcopenia and risk of fractures. We searched Medline, Embase, The Cochrane library, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) databases for Randomised Controlled Trials (RCTs) of adults evaluating the effects of higher versus lower oral omega-3, omega-6 or mixed PUFA for ≥ 6 months on musculoskeletal and functional outcomes. We included 28 RCTs (7288 participants, 31 comparisons), 23 reported effects of omega-3, one of omega-6 and four of mixed total PUFA. Participants and doses were heterogeneous. Six omega-3 trials were judged at low summary risk of bias. We found low-quality evidence that increasing omega-3 increased lumbar spine BMD by 2.6% (0.03 g/cm², 95% CI - 0.02 to 0.07, 463 participants). There was also the suggestion of an increase in femoral neck BMD (of 4.1%), but the evidence was of very low quality. There may be little or no effect of omega-3 on functional outcomes and bone mass; effects on other outcomes were unclear. Only one study reported on effects of omega-6 with very limited data. Increasing total PUFA had little or no effect on BMD or indices of fat-free (skeletal) muscle mass (low-quality evidence); no data were available on fractures, BMD or functional status and data on bone turnover markers were limited. Trials assessing effects of increasing omega-3, omega-6 and total PUFA on functional status, bone and skeletal muscle strength are limited with data lacking or of low quality. Whilst there is an indication that omega-3 may improve BMD, high-quality RCTs are needed to confirm this and effects on other musculoskeletal outcomes.

Calcitonin and Omega-3 Fatty Acids Exhibit Antagonistic and Non-Additive Effects in Experimental Diabetes

Because optimising therapy for the management of diabetes mellitus remains challenging, the study investigated the effects of salmon calcitonin (Sct) and/or omega-3 fatty acids (N-3 - eicosapentaenoic acid and docosahexaenoic acid-3:2), compared to metformin, on selected biochemical parameters in male Wistar rats, in an experimental model of diabetes. Forty rats were used for this study. They were divided into eight groups of five rats each, which included: Normal control; Diabetic (D) control; D + N-3; D + low dose Sct (Sct. Lw); D + high dose Sct (Sct. Hi); D + N-3 + Sct.Lw; D + N-3 + Sct.Hi; and D + metformin. Diabetes was induced in overnight fasted rats by the administration of streptozotocin (65 mg/kg b.w., i.p.), 15 min after the administration of nicotinamide (110 mg/kg b.w., i.p.). Nine days later, Sct was administered at 2.5 and 5.0 IU/kg b.w./day (i.m.), while N-3 and metformin were administered at 200 and 180 mg/kg b.w./day (p.o.) respectively, for four weeks. Sct, N-3, and metformin significantly reduced total cholesterol, LDL-C, cortisol, c-telopeptide of type 1 collagen, and collagen type 2 alpha-1. The combined administration of Sct and N-3 had more favorable effects on triglyceride and HDL-C than either monotherapy. Unlike metformin and Sct. Hi, N-3 significantly reduced alkaline phosphatase activity. Moreover, N-3 significantly suppressed the hypocalcaemic, hyperglycaemic, and insulin resistance provoking actions of Sct. Furthermore, N-3 contradicted the hepatic glycogen depletion and inhibition of nitric oxide synthesis brought about by Sct. In conclusion, N-3 demonstrated antagonistic and non-additive actions with Sct. Moreover, the effects of the combined administration of Sct and N-3 were comparable to that of metformin; therefore, they might be considered as therapeutic alternatives in diabetes.

Analyzing the association between fish consumption and osteoporosis in a sample of Chinese men

BACKGROUND

The main purpose of this study was to estimate the associations between frequency of fish food consumption and osteoporosis (OP) in general Chinese men.

METHODS

We conducted a large-scale, community-based, cross-sectional study to investigate the associations by using self-report questionnaire to access frequency of fish food intake. A total of 1092 men were available for data analysis in this study. Multiple regression models controlling for confounding factors to include frequency of fish food consumption variable were performed to investigate the relationships for OP.

RESULTS

Positive correlations between frequency of fish food consumption and T score were reported (β = 0.084, P value = 0.025). Multiple regression analysis indicated that the frequency of fish food consumption was significantly associated with OP (P < 0.05 for model 1 and model 2). The men with high frequency of fish food consumption had a lower prevalence of OP.

CONCLUSIONS

The findings indicated that frequency of fish food consumption was independently and significantly associated with OP. The prevalence of OP was less frequent in Chinese men preferring fish food habits.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02451397 retrospectively registered 28 May 2015.

High fat diet enriched with saturated, but not monounsaturated fatty acids adversely affects femur, and both diets increase calcium absorption in older female mice

Diet induced obesity has been shown to reduce bone mineral density (BMD) and Ca absorption. However, previous experiments have not examined the effect of high fat diet (HFD) in the absence of obesity or addressed the type of dietary fatty acids. The primary objective of this study was to determine the effects of different types of high fat feeding, without obesity, on fractional calcium absorption (FCA) and bone health. It was hypothesized that dietary fat would increase FCA and reduce BMD. Mature 8-month-old female C57BL/6J mice were fed one of three diets: a HFD (45% fat) enriched either with monounsaturated fatty acids (MUFAs) or with saturated fatty acids (SFAs), and a normal fat diet (NFD; 10% fat). Food consumption was controlled to achieve a similar body weight gain in all groups. After 8wk, total body bone mineral content and BMD as well as femur total and cortical volumetric BMD were lower in SFA compared with NFD groups (P<.05). In contrast, femoral trabecular bone was not affected by the SFAs, whereas MUFAs increased trabecular volume fraction and thickness. The rise over time in FCA was greater in mice fed HFD than NFD and final FCA was higher with HFD (P<.05). Intestinal calbindin-D9k gene and hepatic cytochrome P450 2r1 protein levels were higher with the MUFA than the NFD diet (P<.05). In conclusion, HFDs elevated FCA overtime; however, an adverse effect of HFD on bone was only observed in the SFA group, while MUFAs show neutral or beneficial effects.

Phospholipase A₂-Generated Lipid Mediators in the Brain: The Good, the Bad, and the Ugly

Phospholipase A2 (PLA2) generates arachidonic acid, docosahexaenoic acid, and lysophospholipids from neural membrane phospholipids. These metabolites have a variety of physiological effects by themselves and also are substrates for the synthesis of more potent lipid mediators such as eicosanoids, platelet activating factor, and 4-hydroxynonenal (4-HNE). At low concentrations, these mediators act as second messengers. They affect and modulate several cell functions, including signal transduction, gene expression, and cell proliferation, but at high concentrations, these lipid mediators cause neurotoxicity. Among the metabolites generated by PLA2, 4-HNE is the most cytotoxic metabolite and is associated with the apoptotic type of neural cell death. Levels of 4-HNE are markedly increased in neurological disorders such as Alzheimer disease, Parkinson disease, ischemia, spinal cord trauma, and head injury. The purpose of this review is to summarize and integrate the vast literature on metabolites generated by PLA2 for a wider audience. The authors hope that this discussion will jump-start more studies not only on the involvement of PLA2 in neurological disorders but also on the importance of PLA2-generated lipid mediators in physiological and pathological processes.

Plasma n-3 Polyunsaturated Fatty Acids and Bone Mineral Density in Renal Transplant Recipients

OBJECTIVE

Renal transplant recipients (RTR) suffer high rates of bone loss and increased risk of fracture. Marine n-3 polyunsaturated fatty acids (n-3 PUFA), found mainly in fish and seafood, may have beneficial effects on bone and are positively associated with bone mineral density (BMD) in healthy elderly. The aim of this study was to investigate if this association prevails despite the more complex causes of bone loss in RTR.

DESIGN, SUBJECTS, AND METHODS

A total of 701 RTR were included in a cross-sectional analysis. BMD of lumbar spine, proximal femur, and distal forearm were measured by dual energy x-ray absorptiometry scan, and blood samples were drawn in the fasting state for measurement of plasma fatty acid composition 10 weeks posttransplant. Multiple linear regression analysis was used to assess the association between plasma marine n-3 PUFA levels and BMD.

RESULTS

Mean age was 52.2 years, and two-thirds were men. Based on femoral neck T-scores, 26% of patients were osteoporotic and 52% osteopenic. Z-scores increased significantly across quartiles of marine n-3 PUFA levels, and marine n-3 PUFA was a positive predictor of BMD at total hip and lumbar spine after multivariate adjustment. No association was found between n-6 PUFA content and BMD.

CONCLUSIONS

Plasma marine n-3 PUFA levels were positively associated with BMD at the hip and lumbar spine 10 weeks posttransplant.

TNF Receptors Predict Hip Fracture Risk in the WHI Study and Fatty Acid Intake Does Not Modify This Association

CONTEXT

Chronic inflammation may increase the risk of fracture, and omega-3 polyunsaturated fatty acids (PUFAs) may reduce fracture risk via down-regulation of inflammatory cytokine gene expression and other mechanisms.

OBJECTIVE

We investigated associations between baseline samples of inflammatory markers, TNFα soluble receptors 1 and 2 (TNFα-sR1 and -sR2), and incident hip fracture. These associations were then tested for effect modification by dietary PUFA intake estimated by a baseline food frequency questionnaire.

DESIGN AND SETTING

A nested case-control study was conducted among participants of the Women's Health Initiative Observational Study (ages, 50-79 y). Multivariable conditional logistic regression models were constructed to account for the paired design.

PARTICIPANTS

This study sampled 400 pairs of hip fracture cases and controls without incident hip fracture, matched on age, year of enrollment, and menopausal hormone use.

MAIN OUTCOME MEASURES

Odds ratio of hip fracture by quartile of TNF soluble receptors.

RESULTS

The odds ratio of hip fracture comparing the highest to lowest quartiles was 2.24 (95% confidence interval, 1.05-4.79; P for linear trend, .048) for TNFα-sR1 and 2.83 (95% confidence interval, 1.34-5.99; P for linear trend, .011) for TNFα-sR2, adjusted for FRAX hip fracture score, nutritional variables, and selected factors impacting inflammation; there was a gradient of risk by increasing quartile in TNFα-sR1. PUFA intake did not modify these associations.

CONCLUSIONS

Women with the highest levels of TNFα-sR1 and TNFα-sR2 had a greater than 2-fold increased hip fracture risk, independent of other fracture risk factors. These associations did not differ by high vs low PUFA intake.

Pros and cons of fatty acids in bone biology

Despite the growing interest in deciphering the causes and consequences of obesity-related disorders, the mechanisms linking fat intake to bone behaviour remain unclear. Since bone fractures are widely associated with increased morbidity and mortality, most notably in elderly and obese people, bone health has become a major social and economic issue. Consistently, public health system guidelines have encouraged low-fat diets in order to reduce associated complications. However, from a bone point of view, mechanisms linking fat intake to bone alteration remain quite controversial. Thus, after more than a decade of dedicated studies, this timely review offers a comprehensive overview of the relationships between bone and fatty acids. Using clinical evidences as a starting-point to more complex molecular elucidation, this work highlights the complexity of the system and reveals that bone alteration that cannot be solved simply by taking ω-3 pills. Fatty acid effects on bone metabolism can be both direct and indirect and require integrated investigations. Furthermore, even at the level of a single cell, one fatty acid is able to trigger several different independent pathways (receptors, metabolites…) which may all have a say in the final cellular metabolic response.

Dietary protein derived from dried bonito fish improves type-2 diabetes mellitus-induced bone frailty in Goto-Kakizaki rats

Type-2 diabetes mellitus (T2DM) induces bone frailty. Protein and polyunsaturated fatty acids (PUFA) contained in fish can be effective in enhancing bone quality, but the bone developing effect of fish protein containing less PUFA has not been evaluated in young animals with T2DM. We prepared a bonito fish (BF) and defatted BF (DBF) and hypothesized that protein contained in BF and DBF would be effective for mitigating the effects of T2DM-induced bone frailty. We mainly evaluated the effect of dietary BF and DBF on bone and apparent calcium absorption in young Goto-Kakizaki (GK) rats with T2DM. GK rats were divided into 3 groups based on diets (casein, BF, and DBF) and fed with each diet for 6 wk. Wistar rats were fed with the casein diet as a non-T2DM control. Bone mass, bone strength, apparent calcium absorption, and serum biochemical parameters were determined. The dry weight and strength of the femurs were lower in the GK rats than in the Wistar rats fed with the casein diet. Dietary intake of the BF and DBF diets enhanced the maximum load and dry weight of the femurs and suppressed the serum alkaline phosphatase activity although the apparent calcium absorption was lower in the GK rats fed with the BF and DBF diets than in those fed with the casein diet. These parameters were not different between the rats fed with the BF and DBF diets. Our data suggest that protein contained in the BF and DBF diets improved T2DM-induced bone frailty.

Omega-3 fatty acids prevent the ketamine-induced increase in acetylcholinesterase activity in an animal model of schizophrenia

AIMS

Schizophrenia is a debilitating neurodevelopmental disorder that is associated with dysfunction in the cholinergic system. Early prevention is a target of treatment to improve long-term outcomes. Therefore, we evaluated the preventive effects of omega-3 fatty acids on AChE activity in the prefrontal cortex, hippocampus and striatum in an animal model of schizophrenia.

MAIN METHODS

Young Wistar rats (30 days old) were initially treated with omega-3 fatty acids or vehicle alone. Animals received ketamine to induce an animal model of schizophrenia or saline plus omega-3 fatty acids or vehicle alone for 7 consecutive days beginning on day 15. A total of 22 days elapsed between the treatment and intervention. Animals were sacrificed, and brain structures were dissected to evaluate AChE activity and gene expression.

KEY FINDINGS

Our results demonstrate that ketamine increased AChE activity in these three structures, and omega-3 fatty acids plus ketamine showed lower values for the studied parameters, which indicate a partial preventive mechanism of omega-3 fatty acid supplementation. We observed no effect on AChE expression. Together, these results indicate that omega-3 fatty acid supplementation effectively reduced AChE activity in an animal model of schizophrenia in all studied structures. In conclusion, the present study provides evidence that ketamine and omega-3 fatty acids affect the cholinergic system, and this effect may be associated with the physiopathology of schizophrenia. Further studies are required to investigate the mechanisms that are associated with this effect.

Association of dietary fat intake with the risk of hip fractures in an elderly Chinese population: A matched case-control study

AIM

The aim of the present study was to examine the association between dietary fat intake and the risk of hip fractures in an elderly Chinese population.

METHODS

A case-control study of 646 patients with newly diagnosed hip fractures and 646 controls, matched by age (±3 years) and sex, was carried out among elderly Chinese (55-80 years) in Guangdong, China. Their dietary fat intake was measured and calculated using a 79-item food-frequency questionnaire.

RESULTS

After adjusting for potential confounders, a dose-dependent increased risk of hip fractures was found to be associated with higher intakes of total fat, animal fat, saturated fatty acids and mono-unsaturated fatty acids (P for trend < 0.005). The adjusted odds ratios (95% confidence intervals) for hip fractures from a comparison of extreme quartiles were 1.92 (1.26-2.92) for total fat, 2.60 (1.70-3.99) for animal fat, 1.95 (1.30-2.93) for saturated fatty acids and 2.22 (1.46-3.39) for animal mono-unsaturated fatty acids, respectively. No significant association was observed for plant fat or polyunsaturated fatty acids (P for trend = 0.063 for plant fat and 0.174 for polyunsaturated fatty acids).

CONCLUSIONS

Our findings suggest that higher consumption of total fat and animal fat rich in saturated fatty acids might increase the risk of hip fractures in elderly Chinese.

Major nutrient patterns and bone mineral density among postmenopausal Iranian women

Our understanding of the influence of overall nutrient intake on bone mineral density (BMD) is limited because most studies to date have focused on the intakes of calcium, vitamin D, or a few isolated nutrients. Therefore, we examined the association of major nutrient patterns with BMD in a sample of postmenopausal Iranian women. In this cross-sectional study, 160 women aged 50-85 years were studied and their lumbar spine and femoral neck BMDs were measured using dual-energy X-ray absorptiometry. Dietary intakes were assessed using a validated 168-item food frequency questionnaire, and daily intakes of 30 nutrients were calculated. All nutrient intakes were energy adjusted by the residual method and were submitted to principal component factor analysis to identify major nutrient patterns. Overall, three major nutrient patterns were identified, among which only the first pattern, which was high in folate, total fiber, vitamin B6, potassium, vitamin A (as retinol activity equivalent), vitamin C, β-carotene, vitamin K, magnesium, copper, and manganese, had a significant association with BMD. After controlling for potential confounders, multivariate adjusted mean of the lumbar spine BMD of women in the highest tertile of the first pattern scores was significantly higher than those in the lowest tertile (mean difference 0.08; 95% confidence interval 0.02-0.15; P = 0.01). A nutrient pattern similar to pattern 1, which is associated with high intakes of fruits and vegetables, may be beneficial for bone health in postmenopausal Iranian women.

The effect of long-term supplementation with different dietary ω-6/ω-3 ratios on mineral content and ex vivo prostaglandin E2 release in bone of growing rabbits

BACKGROUND/OBJECTIVES

The aim of this research was to study the different long term effects of consumption of dietary oil sources with varying omega-6/omega-3 (ω-6/ω-3) polyunsaturated fatty acids (PUFAs) ratios on bone marrow fatty acid level, ex vivo prostaglandin E₂ (PGE₂) release, and mineral content of bone in rabbits.

MATERIALS/METHODS

For this purpose, weaning and female New Zealand white rabbits were purchased and randomly divided into five groups and offered ad libitum diets containing 70 g/kg of added oil for 100 days. The dietary lipid treatments were formulated to provide the following ratios of ω-6/ω-3 fatty acids: 8.68 soy bean oil (SBO control), 21.75 sesame oil (SO), 0.39 fish oil (FO), 0.63 algae oil (DHA), and 0.68 algae oils (DHA/ARA). DHA and ARA are two types of marine microalgae of the genus Crypthecodinium cohnii.

RESULTS

The dietary treatments had significant effects on the bone marrow fatty acids of rabbits. Rabbits fed the FO diet, containing the highest ω-3 PUFA concentration, and those fed the SBO diet showed the highest ω-6 PUFA. On the other hand, a positive correlation was observed between Ex vivo PGE₂ level and the ω-6/ω-3 dietary ratio. Significant effects of dietary treatment on femur Ca, P, Mg, and Zn contents were observed in both genders.

CONCLUSIONS

Findings of the current study clearly demonstrated that dietary PUFA, particularly ω-6/ω-3 and ARA/EPA ratios are important factors in determining bone marrow fatty acid profile, and this in turn determines the capacity of bone for synthesis of PGE₂, thereby reducing bone resorption and improving bone mass during growth.

High-dose eicosapentaenoic acid and docosahexaenoic acid supplementation reduces bone resorption in postmenopausal breast cancer survivors on aromatase inhibitors: a pilot study

Postmenopausal breast cancer survivors are living longer; however, a common class of drugs, aromatase inhibitors (AI), depletes estrogen levels, promotes bone loss, and heightens fracture risk. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may offset AI effects to bone because of the known effects on cellular processes of bone turnover. Therefore, we hypothesized that 4 g of EPA and DHA daily for 3 mo would decrease bone turnover in postmenopausal breast cancer survivors on AI therapy in a randomized, double-blind, placebo controlled pilot study that included 38 women. At baseline and 3 mo, serum fatty acids, bone turnover, and inflammatory markers were analyzed. Serum EPA and DHA, total and long-chain (LC) omega (n)-3 polyunsaturated fatty acids (PUFA) increased, whereas arachidonic acid, total and LC n-6 PUFA, and the LC n-6:n-3 PUFA ratio decreased compared to placebo (all P < .05). Bone resorption was inhibited in the fish oil responders compared to placebo (P < .05). Inflammatory markers were not altered. This short-term, high-dose fish oil supplementation study's findings demonstrate that fish oil can reduce bone resorption; however, longer-term studies are needed to assess bone density preservation and to explore mechanistic pathways in this population at high risk for bone loss.

Investigating the role of polyunsaturated fatty acids in bone development using animal models

Incorporating n-3 polyunsaturated fatty acids (PUFA) in the diet may promote the development of a healthy skeleton and thereby reduce the risk of developing osteoporosis in later life. Studies using developing animal models suggest lowering dietary n-6 PUFA and increasing n-3 PUFA intakes, especially long chain n-3 PUFA, may be beneficial for achieving higher bone mineral content, density and stronger bones. To date, the evidence regarding the effects of α-linolenic acid (ALA) remain equivocal, in contrast to evidence from the longer chain products, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). This review reports the results of investigations into n-3 PUFA supplementation on bone fatty acid composition, strength and mineral content in developing animal models as well as the mechanistic relationships of PUFA and bone, and identifies critical areas for future research. Overall, this review supports a probable role for essential (ALA) and long chain (EPA and DHA) n-3 PUFA for bone health. Understanding the role of PUFA in optimizing bone health may lead to dietary strategies that promote bone development and maintenance of a healthy skeleton.

The association of red blood cell n-3 and n-6 fatty acids with bone mineral density and hip fracture risk in the women's health initiative

Omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFA) in red blood cells (RBCs) are an objective indicator of PUFA status and may be related to hip fracture risk. The primary objective of this study was to examine RBC PUFAs as predictors of hip fracture risk in postmenopausal women. A nested case-control study (n = 400 pairs) was completed within the Women's Health Initiative (WHI) using 201 incident hip fracture cases from the Bone Mineral Density (BMD) cohort, along with 199 additional incident hip fracture cases randomly selected from the WHI Observational Study. Cases were 1:1 matched on age, race, and hormone use with non-hip fracture controls. Stored baseline RBCs were analyzed for fatty acids using gas chromatography. After removing degraded samples, 324 matched pairs were included in statistical analyses. Stratified Cox proportional hazard models were constructed according to case-control pair status; risk of fracture was estimated for tertiles of RBC PUFA. In adjusted hazard models, lower hip fracture risk was associated with higher RBC α-linolenic acid (tertile 3 [T3] hazard ratio [HR]: 0.44; 95% confidence interval [CI], 0.23-0.85; p for linear trend 0.0154), eicosapentaenoic acid (T3 HR: 0.46; 95% CI, 0.24-0.87; p for linear trend 0.0181), and total n-3 PUFAs (T3 HR: 0.55; 95% CI, 0.30-1.01; p for linear trend 0.0492). Conversely, hip fracture nearly doubled with the highest RBC n-6/n-3 ratio (T3 HR: 1.96; 95% CI, 1.03-3.70; p for linear trend 0.0399). RBC PUFAs were not associated with BMD. RBC PUFAs were indicative of dietary intake of marine n-3 PUFAs (Spearman's rho = 0.45, p < 0.0001), total n-6 PUFAs (rho = 0.17, p < 0.0001) and linoleic acid (rho = 0.09, p < 0.05). These results suggest that higher RBC α-linolenic acid, as well as eicosapentaenoic acid and total n-3 PUFAs, may predict lower hip fracture risk. Contrastingly, a higher RBC n-6/n-3 ratio may predict higher hip fracture risk in postmenopausal women.

Higher fish intake is associated with a lower risk of hip fractures in Chinese men and women: a matched case-control study

OBJECTIVES

Fish is rich in nutrients that are favorable to bone health, but limited data are available regarding the relationship between fish intake and hip fractures. Our study examined the association between habitual fish intake and risk of hip fractures.

METHODS

A case-control study was performed between June 2009 and June 2012 in Guangdong Province, China. Five hundred and eighty-one hip fracture incident cases, aged 55 to 80 years (mean: 71 years), were enrolled from four hospitals. 1∶1 matched controls by gender and age (±3 years) were also recruited from communities and hospitals. Face-to-face interviews were used to obtain habitual dietary intake and information on various covariates.

RESULTS

Univariate conditional logistic regression analyses showed significantly dose-dependent inverse correlations between the risk of hip fractures and the intake of fresh-water fish, sea fish, mollusca, shellfish, and total fish in all of the subjects (p-trend: <0.001-0.016). After adjusting for covariates, the associations were slightly attenuated but remained significant for all (p-trend: <0.001-0.017) except for fresh-water fish (p = 0.553). The ORs (95%CI) of hip fractures for the highest (vs. lowest) quartile were 0.80 (0.48-1.31) for fresh-water fish, 0.31 (0.18-0.52) for sea fish, 0.55 (0.34-0.88) for mollusca and shellfish, and 0.47 (0.28-0.79) for total fish, respectively. Stratified and interaction analyses showed that the association was more significant in males than in females (p-interaction = 0.052).

CONCLUSION

Higher intake of seafood is independently associated with lower risk of hip fractures in elderly Chinese. Increasing consumption of sea fish may benefit the prevention of hip fractures in this population.

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

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

A systematic review of omega-3 fatty acids and osteoporosis

Some epidemiological evidence suggests that diets high in omega 3 fatty acids (n-3 FAs) may be beneficial for skeletal health. The aim of this systematic review was to determine if randomized controlled trials (RCTs) support a positive effect of n-3 FAs on osteoporosis. A systematic search was performed in PubMed and EMBASE databases. We included RCTs with skeletal outcomes conducted in adults or children (> = 1 year old) using n-3 FA fortified foods, diets or supplements alone or in combination with other vitamins/minerals, versus placebo. Primary outcomes were incident fracture at any site and bone mineral density (BMD) in g/cm2. Secondary outcomes included bone formation or resorption markers and bone turnover regulators. A total of 10 RCTs met inclusion criteria. Effect sizes with 95 % confidence intervals were estimated to compare studies across various treatments and outcome measures. No pooled analysis was completed due to heterogeneity of studies and small sample sizes. No RCTs included fracture as an outcome. Four studies reported significant favorable effects of n-3 FA on BMD or bone turnover markers. Of these, three delivered n-3 FA in combination with high calcium foods or supplements. Five studies reported no differences in outcomes between n-3 FA intervention and control groups; one study included insufficient data for effect size estimation. Strong conclusions regarding n-3 FAs and bone disease are limited due to the small number and modest sample sizes of RCTs, however, it appears that any potential benefit of n-3 FA on skeletal health may be enhanced by concurrent administration of calcium.

Evaluation of effects of eicosapentaenoic acid on Na⁺-K⁺-ATPase in sheep pulmonary artery

In the present study, we have evaluated the effects of eicosapentaenoic acid (EPA) on Na(+)-K(+)-ATPase in sheep pulmonary artery. Acute (30 min) and prolonged (24 h) exposure of arterial rings to EPA (30 μM) significantly decreased potassium chloride (KCl)-induced relaxation, an index of functional Na(+)-K(+)-ATPase activity. In acute exposure, the pD(2) and E (max) (the maximal response) values for KCl-induced relaxation were 3.21 ± 0.33 and 61.58 ± 11.30% (n = 5) versus control 3.58 ± 0.07 and 82.44 ± 2.36% (n = 24), respectively. The pD(2) and E (max) values for KCl-induced relaxation in arterial rings exposed to EPA for 24 h in organ culture were 2.52 ± 0.11 and 55.00 ± 5.72% versus control 3.04 ± 0.19 and 80.74 ± 11.96%, respectively; n = 4. Exposure of the arterial rings to EPA (30 μM) for 24 h in organ culture, significantly decreased (17.58 ± 2.15%) the protein expression of α(1) isoform of Na(+)-K(+)-ATPase. Acute exposure to EPA for 30 min significantly decreased (21.06 ± 5.89%) the Na(+)-K(+)-ATPase activity as measured by inorganic phosphate (Pi) release. EPA, up to 100 μM concentration, marginally (<10% of 80 mM KCl contraction) increased the basal tone of the pulmonary artery. Additionally, EPA (10-30 μM) had no effect on Mg(2+)-ATPase activity as well as on cyclic guanosine monophosphate (cGMP) production. All these results show that EPA has inhibitory effect on Na(+)-K(+)-ATPase in sheep pulmonary artery but prolonged exposure had no additional effect on sodium pump, and EPA-induced inhibition of Na(+)-K(+)-ATPase may be due to attenuation in protein expression of α(1) isoform of Na(+)-K(+)-ATPase independent of cGMP production.

Combined effects of soy isoflavone and fish oil on ovariectomy-induced bone loss in mice

Both soy isoflavone and n-3 polyunsaturated fatty acids are known to reduce the levels of bone-resorbing cytokines; however, the synergistic effects of these food ingredients have not been examined yet. This study was performed to elucidate the effect of concomitant intake of soy isoflavone and fish oil on bone mass in ovariectomized mice. Eight-week-old ddY female mice were subjected to ovariectomy (OVX) or sham surgery, and then fed an AIN-93G with safflower oil (So) as a control lipid source, isoflavone-supplemented safflower oil (So + I), fish oil instead of safflower oil (Fo) or isoflavone-supplemented fish oil (Fo + I) for 4 weeks. Femoral bone mineral density was significantly decreased by OVX; however, this decrease was inhibited by the intake of isoflavone and/or fish oil. Histomorphometric analyses showed that bone volume and trabecular thickness in the distal femoral trabecular bone were significantly lower in the So group than in the sham group, but those were restored in the Fo + I groups. The number of osteoclasts was significantly decreased by isoflavone intake. The increased rate of bone resorption after OVX was inhibited by isoflavone and/or fish oil. The serum concentration of tumor necrosis factor alpha was increased after OVX, but was significantly lower with the combination of isoflavone with fish oil than isoflavone or fish oil alone. The results of this study indicated that the intakes of soy isoflavone and/or fish oil might have ameliorating effects on bone loss due to OVX. Further, the concomitant intake of soy isoflavone and fish oil at a low dose showed better effects on cytokines related with bone resorption.

The effect of polyunsaturated fatty acids on bone health

The essential polyunsaturated fatty acids (PUFAs) are divided into two classes, n-3 (ω-3) and n-6 (ω-6) and their dietary precursors are α-linolenic (ALA) and linoleic acid (LA), respectively. PUFAs are precursors of a wide range of metabolites, for example eicosanoids like prostaglandins and leukotrienes, which play critical roles in the regulation of a variety of biological processes, including bone metabolism.

A large body of evidence supports an effect of PUFA on bone metabolism which may be mediated by regulation of osteoblastogenesis and osteoclast activity, change of membrane function, decrease in inflammatory cytokines, such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumour necrosis factor alpha (TNF-α), modulation of peroxisome proliferators-activated receptor γ (PPARγ) and influence in NO secretion and NO synthase.

Animal studies have shown that a higher dietary omega-3/omega-6 fatty acids ratio is associated with beneficial effects on bone health. Human studies conducted in elderly subjects suggest that omega-3 instead of omega-6 has a positive effect on bone metabolism. In spite of increasing evidence, studies conducted in humans do not allow us to draw a definitive conclusion on the usefulness of PUFAs in clinical practice.

Fatty acid profile in patients with phenylketonuria and its relationship with bone mineral density

BACKGROUND

Patients with phenylketonuria (PKU) undergo a restrictive vegan-like diet, with almost total absence of n-3 fatty acids, which have been proposed as potential contributors to bone formation in the healthy population. The PKU diet might lead these patients to bone mass loss and, consequently, to the development of osteopenia/osteoporosis. Therefore, we proposed to analyze their plasma fatty acid profile status and its relationship with bone health.

METHODS

We recruited 47 PKU patients for this cross-sectional study and divided the cohort into three age groups (6-10 years, 11-18 years, 19-42 years). We measured their plasma fatty acid profile and bone mineral density (BMD) (both at the femoral neck and the lumbar spine). Seventy-seven healthy controls also participated as reference values of plasma fatty acids.

RESULTS

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and total n-3 fatty acids were significantly diminished in PKU patients compared with healthy controls. DHA, EPA, and total n-3 fatty acids were also positively associated with bone mineral density (r = 0.83, p = 0.010; r = 0.57, p = 0.006; r = 0.73, p = 0.040, respectively). There was no association between phenylalanine (Phe), Index of Dietary Control (IDC), calcium, 25-hydroxivitamin D concentrations, daily calcium intake, and BMD.

CONCLUSION

Our results suggest a possible influence of essential fatty acids over BMD in PKU patients. The lack of essential n-3 fatty acids intake in the PKU diet might affect bone mineralization. Further clinical trials are needed to confirm the effect of the n-3 essential fatty acids on bone accrual in a cohort of PKU patients.

Omega-3 fatty acid application reduces yolk and plasma cholesterol levels in Japanese quails

The aim of this study was to determine the effects of fish oil, rich in omega-3 fatty acids, on the cholesterol levels in egg yolk and plasma in Japanese quail. Additionally, the effects of these fatty acids on selected biochemical parameters, and yolk and quail weights were investigated. Thirty healthy laying Japanese quails were divided into two groups including control and omega-3 fatty acid treated group. Fish oil capsules were administrated orally to the quails in the omega-3 treated group every other day for 3 weeks. Yolk cholesterol level was found to be significantly lower in the omega-3 treated group compared to the control. Plasma cholesterol levels were lower; plasma calcium levels were higher at 3rd week in omega-3 fatty acid treated group than those in control. On the other hand, plasma phosphorus and glucose levels in omega-3 fatty acid group were significantly lower at 3rd week than those at the beginning of experiment. In conclusion, it was found that orally supplemented omega-3 fatty acid reduced the levels of cholesterol in egg yolk and plasma in quails.

A Mediterranean dietary style improves calcium utilization in healthy male adolescents

OBJECTIVE

To examine the effects of consuming a diet based on the Mediterranean patterns on calcium availability and metabolism in male adolescents.

DESIGN

A longitudinal study divided into two periods: a 3-day basal period, during which the subjects (n = 20; 12.9 +/- 1.14 years) consumed their usual diet (basal diet, BD), and a 28-day nutritional intervention period, in which an intervention Mediterranean-type diet - was consumed (ID).

METHODS

Dietary calcium utilization was assessed by means of calcium intake in food and calcium output in feces and urine as measured by flame absorption spectrophotometry. In addition, markers of calcium metabolism (serum Ca, parathyroid hormone and total alkaline phosphatase) and bone resorption (urine deoxypiridinoline) were measured.

RESULTS

No differences in total calcium intake were found between the two diets, but food sources of dietary calcium varied significantly. Compared with the BD, the consumption of the ID resulted in significant increases in calcium absorption (approximately 40%, p = 0.04) and retention (approximately 80%, p = 0.008), and a considerable decrease in urinary calcium excretion (approximately 40%, p = 0.01).The variations observed in bone markers reflected a higher bone turnover rate after the ID consumption.

CONCLUSIONS

A varied diet based on Mediterranean diet patterns during adolescence greatly improves dietary calcium utilization, which may help to maximize the peak bone mass and prevent related diseases, such as osteoporosis.

Long-chain polyunsaturated fatty acids and the regulation of bone metabolism

The role of prostaglandin E2 (PGE2) in the regulation of bone remodeling is well established. There is increasing evidence that various long-chain polyunsaturated fatty acids (LCPUFAs), as well as nonprostanoid LCPUFA metabolites, also have critical roles in regulating bone metabolism and may have therapeutic potential in the management of postmenopausal osteoporosis. Although only the 18-carbon precursors for the n-3 and n-6 LCPUFAs are deemed "dietary essential," the ability of the body to convert these precursor fatty acids into the more highly unsaturated 20- and 22-carbon LCPUFAs decreases with aging, menopause, and various lifestyle factors (e.g., smoking). Increasing dietary LCPUFA intake increases tissue and blood LCPUFA concentrations, as well as the concentrations of their metabolites. Modification of dietary LCPUFA content, particularly increasing the intake of n-3 LCPUFAs, has been shown to minimize the decline in bone mass caused by menopause in women and ovariectomy in animal models. This review summarizes findings from both in vivo and in vitro studies and outlines the effects of LCPUFAs and their metabolites on calcium balance, osteoblastogenesis, osteoclastogenesis, and osteoblast and osteoclast function.

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.

Soy isoflavones and fatty acids: effects on bone tissue postovariectomy in mice

Osteoporosis is a silent disease that leads to fragility fractures that can diminish quality of life and contribute to death. With no ideal drug treatment available to manage osteoporosis, soy isoflavones (ISO), and omega-3 long chain PUFAs in fish oil (FO) may be integral in a dietary strategy that prevents bone loss. The overall objective of this study was to determine if combining ISO with omega-3 long chain PUFAs resulted in greater protection against the loss of bone mineral and skeletal weakening in ovariectomized mice. Ovariectomized CD-1 mice were randomized to control diet or a diet containing ISO alone (250 mg of genistein + 250 mg of daidzein/kg diet), FO alone (7% menhaden oil), or ISO + FO. Each dietary intervention prevented the loss of bone mineral density (BMD) in the femur and preserved femur strength, but only FO, either alone or combined with ISO, resulted in a higher BMD of lumbar vertebra (LV). Most notably, FO + ISO resulted in a higher peak load of LV4, indicating that vertebra were more resistant to fracture. Whether a dietary strategy providing FO in combination with ISO attenuates bone loss in postmenopausal women awaits investigation.

n-3 Fatty acids are positively associated with peak bone mineral density and bone accrual in healthy men: the NO2 Study

BACKGROUND

Knowledge of the influence of nutritional intake on bone health is limited. Polyunsaturated fatty acids have been suggested to influence bone growth and modeling in humans, although data are sparse.

OBJECTIVE

The objective was to investigate the role of fatty acids in bone accumulation and the attainment of peak bone mass in young men.

DESIGN

The cohort studied consisted of 78 healthy young men with a mean age of 16.7 y at baseline. Bone mineral density (BMD; in g/cm(2)) of total body, hip, and spine was measured at baseline and at 22 and 24 y of age. Fatty acid concentrations were measured in the phospholipid fraction in serum at 22 y of age.

RESULTS

Concentrations of n-3 fatty acids were positively associated with total BMD (r = 0.27, P = 0.02) and spine BMD (r = 0.25, P = 0.02) at 22 y of age. A positive correlation between n-3 fatty acid concentrations and the changes in BMD at the spine (r = 0.26, P = 0.02) was found between 16 and 22 y of age. Concentrations of docosahexaenoic acid (DHA, 22:6n-3) were positively associated with total BMD (r = 0.32, P = 0.004) and BMD at the spine (r = 0.30, P = 0.008) at 22 y of age. A positive correlation was also found between DHA concentrations and the changes in BMD at the spine (r = 0.26, P = 0.02) between 16 and 22 y of age.

CONCLUSION

The results showed that n-3 fatty acids, especially DHA, are positively associated with bone mineral accrual and, thus, with peak BMD in young men.

The effect of marine oil-derived n-3 fatty acids on transepithelial calcium transport in Caco-2 cell models of healthy and inflamed intestines

Marine oil-derived n-3 fatty acids have been shown to stimulate intestinal Ca absorption in animal studies, but the effects of such fatty acids on Ca absorption in human subjects are relatively unknown. In particular, n-3 fatty acids may be of therapeutic value for some Crohn's disease patients who experience Ca malabsorption. Therefore, the aim of the present study was to investigate the effect of 20 : 5n-3 and 22 : 6n-3 on transepithelial Ca transport across monolayers of healthy Caco-2 cells as well as of TNF-α-treated Caco-2 cells (an in vitro model of Crohn's disease). Caco-2 cells were seeded onto permeable filter supports and allowed to differentiate into monolayers, which were treated with 80 μm-20 : 5n-3, 80 μm-22 : 6n-3, or 40 μm-20 : 5n-3+40 μm-22 : 6n-3 for 6 or 8 d, with or without co-treatment with TNF-α (10 ng/ml) (n 11–15 monolayers per treatment). On day 16, transepithelial and transcellular transport of 45Ca and fluorescein transport (a marker of paracellular diffusion) were measured. Treatment of healthy and inflamed Caco-2 cells with 20 : 5n-3, 22 : 6n-3 and both fatty acids combined for 8 d significantly (P < 0·005–0·01) increased total transepithelial Ca transport compared with that in control, effects which were mediated by an enhanced rate of transcellular Ca transport. The effects of n-3 fatty acids on Ca absorption after 6 d were less clear-cut. In conclusion, the present in vitro findings highlight the need to investigate the effect of marine oil-based n-3 fatty acids on Ca absorption in vivo in studies of healthy human subjects as well as of Crohn's disease patients.

An increase in dietary n-3 fatty acids decreases a marker of bone resorption in humans

Human, animal, and in vitro research indicates a beneficial effect of appropriate amounts of omega-3 (n-3) polyunsaturated fatty acids (PUFA) on bone health. This is the first controlled feeding study in humans to evaluate the effect of dietary plant-derived n-3 PUFA on bone turnover, assessed by serum concentrations of N-telopeptides (NTx) and bone-specific alkaline phosphatase (BSAP). Subjects (n = 23) consumed each diet for 6 weeks in a randomized, 3-period crossover design: 1) Average American Diet (AAD; [34% total fat, 13% saturated fatty acids (SFA), 13% monounsaturated fatty acids (MUFA), 9% PUFA (7.7% LA, 0.8% ALA)]), 2) Linoleic Acid Diet (LA; [37% total fat, 9% SFA, 12% MUFA, 16% PUFA (12.6% LA, 3.6% ALA)]), and 3) alpha-Linolenic Acid Diet (ALA; [38% total fat, 8% SFA, 12% MUFA, 17% PUFA (10.5% LA, 6.5% ALA)]). Walnuts and flaxseed oil were the predominant sources of ALA. NTx levels were significantly lower following the ALA diet (13.20 +/- 1.21 nM BCE), relative to the AAD (15.59 +/- 1.21 nM BCE) (p < 0.05). Mean NTx level following the LA diet was 13.80 +/- 1.21 nM BCE. There was no change in levels of BSAP across the three diets. Concentrations of NTx were positively correlated with the pro-inflammatory cytokine TNFalpha for all three diets. The results indicate that plant sources of dietary n-3 PUFA may have a protective effect on bone metabolism via a decrease in bone resorption in the presence of consistent levels of bone formation.

Conjugated linoleic acid enhances transepithelial calcium transport in human intestinal-like Caco-2 cells: an insight into molecular changes

Conjugated linoleic acid (CLA) has been shown to enhance paracellular and transcellular Ca transport across human intestinal-like Caco-2 cell monolayers. The mechanisms of action, however, are still unclear. Therefore, this study investigated the molecular mechanisms underlying CLA-induced stimulation of Ca transport by use of preliminary microarray data together with more detailed and comprehensive quantitative reverse transcriptase-PCR analysis. While molecular expression of junctional adhesion molecule (JAM), ZO-2, ZO-3, claudin 2 and claudin 3 were unaltered, ZO-1, occludin, and claudin 4 were all up-regulated (1.6, 1.6, 2.4-fold, respectively; P<0.001-0.01) and claudin 1 down-regulated (2.5-fold; P<0.05) by trans-10, cis-12 CLA, which may underpin its effects on tight-junction function and paracellular Ca transport. On the other hand, expression of key genes involved in transcellular Ca transport (CaT1, ECaC1, calbindin D(9k), vitamin D receptor and PMCA) were unaffected by trans-10, cis-12 CLA. The mechanism by which CLA enhances transcellular Ca transport remains unclear.