Tag Archives: animal

EPA and DHA Improve Bone Properties in Mice

Abstract

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.

Bonnet N, Ferrari SL
J. Nutr. Biochem. Jul 2011
PMID: 21036590

DHA, Not EPA or DPA, Vital For Healthy Bones in Rats

Abstract

Bone mineral content is positively correlated to n-3 fatty acids in the femur of growing rats.

The present study was conducted to determine whether provision of preformed dietary docosapentaenoic acid (DPAn-6) can replace DHA for normal long bone growth as assessed by dual-energy X-ray absorptiometry for mineral content (BMC). A newly modified artificial rearing method was employed to generate n-3 fatty acid-deficient rats. Except the dam-reared (DR; 3.1 % alpha-linolenic acid) group, newborn pups were separated from their mothers at age 2 d and given artificial rat milk containing linoleic acid (LA), or LA supplemented with 1 % DHA (22 : 6n-3; DHA), 1 % DPAn-6 (DPA), or 1 % DHA plus 0.4 % DPAn-6 (DHA/DPA). The rats were later weaned onto similar pelleted diets. At adulthood, the rats were euthanised and bones (femur, tibia, and lumbar vertebrae) collected for tissue fatty acid analysis and bone mineral density (BMD) determination. The analyses showed that long bones such as femur and tibia in DPAn-6-treated rats contained higher DPAn-6 content and generally had the lowest BMC and BMD values. Hence, DPAn-6 did not replace DHA for normal bone growth and maximal BMC in femur, indicating an indispensible role of DHA in bone health. In conclusion, DHA accumulates in the osteoblast-rich and nerve-abundant periosteum of femur; DHA but not EPA appears to be a vital constituent of marrow and periosteum of healthy modelling bone; and both DHA and total n-3 PUFA strongly correlate to BMC.

Li Y, Seifert MF, Lim SY, Salem N…
Br. J. Nutr. Sep 2010
PMID: 20420751

EPA + DHA Have Favorable Effect on Bone Density and Strength in Mice

Abstract

Femur EPA and DHA are correlated with femur biomechanical strength in young fat-1 mice.

Evidence suggests that n-3 polyunsaturated fatty acids (PUFA) are beneficial for maintenance of bone health and possibly bone development. This study used the fat-1 mouse, a transgenic model that synthesizes n-3 PUFA from n-6 PUFA, to determine if outcomes of bone health were correlated with n-3 PUFA in femurs. Control and fat-1 mice were fed an AIN-93G diet containing 10% safflower oil from weaning through 12 weeks of age. Femur bone mineral content (BMC) and density were determined by dual-energy X-ray absorptiometry, and biomechanical strength properties, surrogate measures of fracture risk, were measured by a materials testing system. Femur fatty acid composition was determined by gas chromatography. At 12 weeks of age, femur n-3 PUFA were higher among fat-1 mice compared to control mice. The n-6/n-3 PUFA ratio in the femur was negatively correlated with BMC (r=-.57, P=.01) and peak load at femur midpoint (r=-.53, P=.02) and femur neck (r=-.52, P=.02). Moreover, long-chain n-3 PUFA, eicosapentaenoic acid, and docosahexaenoic acid were significantly and positively correlated or displayed a trend suggesting positive correlations, with BMC and peak load. In conclusion, the results of the present study suggest that n-3 PUFA have a favorable effect on mineral accumulation and functional measures of bone in fat-1 mice at young adulthood.

Lau BY, Ward WE, Kang JX, Ma DW
J. Nutr. Biochem. Jun 2009
PMID: 18708283

Fish Oil Decreases Bone Loss in Ovariectomized Mice

Abstract

Dietary n-3 fatty acids decrease osteoclastogenesis and loss of bone mass in ovariectomized mice.

The mechanisms of action of dietary fish oil (FO) on osteoporosis are not fully understood. This study showed FO decreased bone loss in ovariectomized mice because of inhibition of osteoclastogenesis. This finding supports a beneficial effect of FO on the attenuation of osteoporosis.
Consumption of fish or n-3 fatty acids protects against cardiovascular and autoimmune disorders. Beneficial effects on bone mineral density have also been reported in rats and humans, but the precise mechanisms involved have not been described.
Sham and ovariectomized (OVX) mice were fed diets containing either 5% corn oil (CO) or 5% fish oil (FO). Bone mineral density was analyzed by DXA. The serum lipid profile was analyzed by gas chromatography. Receptor activator of NF-kappaB ligand (RANKL) expression and cytokine production in activated T-cells were analyzed by flow cytometry and ELISA, respectively. Osteoclasts were generated by culturing bone marrow (BM) cells with 1,25(OH)2D3. NF-kappaB activation in BM macrophages was measured by an electrophoretic mobility shift assay.
Plasma lipid C16:1n6, C20:5n3, and C22:6n3 were significantly increased and C20:4n6 and C18:2n6 decreased in FO-fed mice. Significantly increased bone mineral density loss (20% in distal left femur and 22.6% in lumbar vertebrae) was observed in OVX mice fed CO, whereas FO-fed mice showed only 10% and no change, respectively. Bone mineral density loss was correlated with increased RANKL expression in activated CD4+ T-cells from CO-fed OVX mice, but there was no change in FO-fed mice. Selected n-3 fatty acids (docosahexaenoic acid [DHA] and eicosapentaenoic acid [EPA]) added in vitro caused a significant decrease in TRACP activity and TRACP+ multinuclear cell formation from BM cells compared with selected n-6 fatty acids (linoleic acid [LA] and arachidonic acid [AA]). DHA and EPA also inhibited BM macrophage NF-kappaB activation induced by RANKL in vitro. TNF-alpha, interleukin (IL)-2, and interferon (IFN)-gamma concentrations from both sham and OVX FO-fed mice were decreased in the culture medium of splenocytes, and interleukin-6 was decreased in sham-operated FO-fed mice. In conclusion, inhibition of osteoclast generation and activation may be one of the mechanisms by which dietary n-3 fatty acids reduce bone loss in OVX mice.

Sun D, Krishnan A, Zaman K, Lawrence R…
J. Bone Miner. Res. Jul 2003
PMID: 12854830

EPA + DHA, but Especially EPA, Effective in Diabetic Rats with Osteopenia

Abstract

Effect of eicosapentaenoic acid and docosahexaenoic acid on diabetic osteopenia.

To evaluate the effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are polyunsaturated fatty acids, on diabetic osteopenia, we measured the bone fragility in streptozotocin-induced diabetic rats. The fragility of femur was increased in diabetic rats, which was prevented in part by EPA or DHA. Moreover, EPA prevented osteopenia even in diabetic rats fed a low zinc feed, which was a potent accelerator of diabetic osteopenia. Plasma alkaline phosphatase activity and parathyroid hormone level showed no difference between the two groups of diabetic rats with or without EPA. Urinary excretion of calcium and phosphate was increased and plasma inorganic phosphate level was high in diabetic rats, suggesting severe mineral loss. In diabetic rats fed EPA, although urinary and plasma calcium levels did not change significantly, urinary phosphate excretion and plasma inorganic phosphate concentration were slightly lowered, which suggested that EPA may have an effect in suppressing phosphate release from bones in diabetic rats. These data suggest that EPA and DHA could be effective on diabetic osteopenia, but to elucidate the precise mechanisms, further examinations will be needed.

Yamada Y, Fushimi H, Inoue T, Matsuyama Y…
Diabetes Res. Clin. Pract. Oct 1995
PMID: 8745204

Higher Omega-3, but Especially DHA, Preserve Bone in Ovariectomized Rats

Abstract

Dietary ratio of n-6/n-3 PUFAs and docosahexaenoic acid: actions on bone mineral and serum biomarkers in ovariectomized rats.

Hypoestrogenic states escalate bone loss in animals and humans. This study evaluated the effects of the amount and ratio of dietary n-6 and n-3 polyunsaturated fatty acids (PUFAs) on bone mineral in 3-month-old sexually mature ovariectomized (OVX) Sprague-Dawley rats. For 12 weeks, the rats were fed either a high-PUFA (HP) or a low-PUFA (LP) diet with a ratio of n-6/n-3 PUFAs of 5:1 (HP5 and LP5) or 10:1 (HP10 and LP10). All diets (modified AIN-93G) provided 110.4 g/kg of fat from safflower oil and/or high-oleate safflower oil blended with n-3 PUFAs (DHASCO oil) as a source of docosahexaenoic acid (DHA). Fatty acid analyses confirmed that the dietary ratio of 5:1 significantly elevated the amount of DHA in the periosteum, marrow and cortical and trabecular bones of the femur. Dual-energy X-ray absorptiometry measurements for femur and tibia bone mineral content (BMC) and bone mineral density showed that the DHA-rich diets (HP5 and LP5) resulted in a significantly lower bone loss among the OVX rats at 12 weeks. Rats fed the LP diets displayed the lowest overall serum concentrations of the bone resorption biomarkers pyridinoline (Pyd) and deoxypyridinoline, whereas the bone formation marker osteocalcin was lowest in the HP groups. Regardless of the dietary PUFA content, DHA in the 5:1 diets (HP5 and LP5) preserved rat femur BMC in the absence of estrogen. This study indicates that the dietary ratio of n-6/n-3 PUFAs (LP5 and HP5) and bone tissue concentration of total long-chain n-3 PUFAs (DHA) minimize femur bone loss as evidenced by a higher BMC in OVX rats. These findings show that dietary DHA lowers the ratio of 18:2n-6 (linoleic acid)/n-3 in bone compartments and that this ratio in tissue correlates with reduced Pyd but higher bone alkaline phosphatase activity and BMC values that favor bone conservation in OVX rats.

Watkins BA, Li Y, Seifert MF
J. Nutr. Biochem. Apr 2006
PMID: 16102959

Fish Oil, Especially DHA, Increases Bone Density in Rats

Abstract

Is docosahexaenoic acid more effective than eicosapentaenoic acid for increasing calcium bioavailability?

Experimental animal and human studies have indicated that long chain polyunsaturated fatty acids (LCPUFA) may enhance calcium absorption, reduce urinary calcium excretion, and increase bone calcium content. In the present study, the effect of LCPUFA, as provided in evening primrose oil, fish and tuna oils, on calcium bioavailability was investigated. Growing male rats were fed a semi-synthetic diet for 6 weeks, after which calcium absorption, bone mineral density (ex vivo), bone calcium content, and bone biomechanics were measured. Calcium absorption, ex vivo bone mineral density, and bone calcium content were significantly higher in the animals fed tuna oil compared with those of a control group fed corn oil. Significant correlations were found between the docosahexaenoic acid (DHA) (22:6n-3) content of the red cell membranes and bone density and bone calcium content. DHA increased accretion of calcium in bone significantly more so than eicosapentaenoic acid (EPA) (20:5n-3).

Kruger MC, Schollum LM
Prostaglandins Leukot. Essent. Fatty Acids Nov 2005
PMID: 16154334

Fish Oil Reduces Resorption in Rats with Periodontal Disease

Abstract

Omega-3 fatty acid effect on alveolar bone loss in rats.

Gingival inflammation and alveolar bone resorption are hallmarks of adult periodontitis, elicited in response to oral micro-organisms such as Porphyromonas gingivalis. We hypothesized that omega (omega)-3 fatty acids (FA) dietary supplementation would modulate inflammatory reactions leading to periodontal disease in infected rats. Rats were fed fish oil (omega-3 FA) or corn oil (n-6 FA) diets for 22 weeks and were infected with P. gingivalis. Rats on the omega-3 FA diet exhibited elevated serum levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), documenting diet-induced changes. PCR analyses demonstrated that rats were orally colonized by P. gingivalis; increased IgG antibody levels substantiated this infection. P. gingivalis-infected rats treated with omega-3 FA had significantly less alveolar bone resorption. These results demonstrated the effectiveness of an omega-3 FA-supplemented diet in modulating alveolar bone resorption following P. gingivalis infection, and supported that omega-3 FA may be a useful adjunct in the treatment of periodontal disease.

Kesavalu L, Vasudevan B, Raghu B, Browning E…
J. Dent. Res. Jul 2006
PMID: 16798867

DHA More Potent Inhibitor of Osteoclasts than EPA

Abstract

Docosahexaenoic acid is more potent inhibitor of osteoclast differentiation in RAW 264.7 cells than eicosapentaenoic acid.

Fish oil rich in n-3 polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) protects inflammation induced bone loss in chronic inflammatory diseases like rheumatoid arthritis, periodontitis, and osteoporosis. EPA and DHA differentially regulate functional parameters and gene expression in different cell types. One of the risk factors for bone loss in inflammatory bone diseases is the elevation of bone-resorbing osteoclasts and a very few studies so far have indicated that attenuation of osteoclastogenesis might be one of the mechanisms by which n-3 PUFA exert its effect on bone loss protection. However, the precise mechanism underlying this process remains unclear. Receptor activator of NF-kappaB ligand (RANKL) is known to be the most critical mediator of osteoclastogenesis. Therefore, in this study, we examined the differential effect of EPA and DHA on RANKL-stimulated osteoclastogenesis and RANKL signaling using a murine monocytic cell line RAW 264.7. DHA was found to inhibit osteoclast differentiation, activation and function more potently than EPA. The differential potential also closely correlated with the inhibition of osteoclast-specific genes like tartrate resistant acid phosphatase, cathepsin K, calcitonin receptor, matrix metalloproteinase-9 expression and osteoclast-specific transcription factor, c-Fos, as well as osteotropic proinflammatory cytokine, TNF-alpha to a greater extent with DHA than EPA. Further, pretreatment of RAW 264.7 cells with DHA also showed significantly reduced activation of NF-kappaB and p38MAPK than EPA. Our findings suggest that DHA may be much more effective than EPA in alleviating RANKL induced proinflammatory cytokine production, intracellular signaling activation, thereby decreasing osteoclast activation and bone resorption.

Rahman MM, Bhattacharya A, Fernandes G
J. Cell. Physiol. Jan 2008
PMID: 17929247

DHA prevents, and GLA Exacerbates, Bone Loss in Ovariectomized Rats

Abstract

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.

Poulsen RC, Firth EC, Rogers CW, Moughan PJ…
Calcif. Tissue Int. Dec 2007
PMID: 18008020