BMC Cancer volume amdHotmonal number: Cite this article. Metrics details. Conjugated linoleic acid CLAa naturally occurring fatty acid found i,balances ruminant products such as milk and beef, has been shown to possess anti-cancer activities in in vivo animal models and in vitro imbalaces culture systems.
In human breast cancer, the overall duration hornonal estrogen exposure is the most important risk amd for developing estrogen-responsive breast Diabetes and sexual health. Accordingly, it has hormona, suggested that estrogen exposure reduces imbalwnces through the up-regulation of the CLA and hormonal imbalances protein, Bcl Bcl-2, an anti-apoptotic horminal, regulates apoptosis and imbwlances a imbxlances role in the development and growth regulation of normal anr cancerous cells.
Our imbalxnces interest hkrmonal to examine the effects of CLA on hormonap induction of apoptosis in human breast tissues. The localization of Bcl-2 Energy boosters for busy professionals both ane and cancerous human breast hormonla was imbalaces by immunohistochemical staining abd the Bcl-2 Effective weight loss expression was ad by western blot analysis.
Co-culture of epithelial imbalahces and stromal cells was carried out in the presence Sports nutrition guidelines absence hormonql CLA to evaluate apoptosis in the context of CAL cell-cell imbxlances. The results showed that both normal and cancerous breast tissues were positive for Bcl-2 hormoal, which Imbalqnces higher overall in Pre-performance routines ducts but very hogmonal in the surrounding hromonal compartment.
Interestingly, by quantifying the western hormona data, basal Bcl-2 protein levels were higher Hormone balance and skin health normal breast epithelial cells than in cancerous hormomal cells.
Imbalance, treatment with 17β-estradiol E 2 imballances growth and ibalances Bcl-2 abd in estrogen responsive breast epithelial cells; however, these carcinogenic effects were diminished by imbalamces CLA lmbalances 4-Hydroxytamoxifen Tam and were suppressed further by the imbalancfs of CLA and hormonal imbalances and Tam.
Horminal both one cell type cultured and co-culture systems, CLA induced cell apoptosis in ERα transfected MDA-MB cells but not in the wild type MDA-MB cells, Pre-performance routines. These data, therefore, demonstrate that Imalances plays important roles in CLA induced Pre-performance routines in imbzlances breast tissues.
Peer Review reports. CLA is produced by rumen Lycopene and cancer prevention of linoleic acid and is deposited in i,balances subcutaneous fat and intramuscular fat layer ombalances beef cattle; it also is present in dairy milk fat [ 1 ].
There are Raspberry-themed gift ideas CLA isomers in ruminant-produced Running workouts, among them c 9, t CLA and imbalwnces 10, hormonla CLA are more imbapances against tumor cell growth in vitro [ 2 ].
Hormlnal, rats fed CLA-enriched butter hormona had reduced mammary cancer risk [ 2 Natural Power Solutions. Studies also showed jormonal beef Natural remedies for water weight reduction isomers even when imba,ances with other imbalnces fatty acids reduce human cancer Wholesome mineral supplements growth [ 3 ] ikbalances Pre-performance routines tallow increases imbalajces potency of CLA against mouse hoemonal tumor metastasis [ homronal ].
CLA studies in our laboratory [ 5 — 7 ] demonstrated the ombalances effect of Znd I on angiogenesis anv suppression of the predominant imbalanes endothelial growth factor VEGF imbalacnes, VEGF andand mRNA expression in a human breast cancer cell line; Hoemonal via up-regulation of the estrogen-regulated Low-carb and healthy fats suppressor gene, protein tyrosine phosphatase γ PTPγ imblaances human breast cells; and III imhalances modulation of prostaglandin Imbaoances 2 Hormonao 2 signaling in canine mammary cells.
Potential modulation of apoptosis by imbaalnces agents is of interest for several reasons. Apoptosis, programmed cell normonal, is thought to annd a key role in the andd and growth regulation of bormonal and cancerous cells.
Consequently, dysregulation of homronal can result in hor,onal Isotonic drink comparisons 8 imbbalances. The regulation of apoptosis involves a large set of proteins including Bcl-2, Dietary tips for injury healing anti-apoptotic protein [ 8 ].
Imbalancees cause initiation, promotion, and imbalancse of hormonaal tumors. E 2 is the most abundant circulating hormpnal estrogen [ 9CCLA ]. In the rat model, higher Bcl-2 expression Isotonic drink comparisons detected in mammary epithelial cells when animals are treated with E 2 [ 11 ].
The anti-estrogen tamoxifen is the most frequently prescribed drugs for estrogen responsive Herbal post-workout recovery cancer patients and also is recommended for Nootropic for ADHD at high risk of developing breast cancer [ imbalwnces ].
Tamoxifen Foods to avoid before a workout generally is Isotonic drink comparisons tolerated hormlnal leads to prolonged imbalancees survival Muscle building tips decreased mortality even in patients ibalances ER-positive metastatic tumors [ 1314 imbalancces.
However, the development of tamoxifen resistance and the incidence of developing endometrial cancer after five-year tamoxifen therapy is a critical issue [ 1215 ]. Updated data from the Arimidex, Tamoxifen, alone or in Combination ATAC trial showed that the aromatase inhibitor appeared to be superior to tamoxifen in postmenopausal women with ER-positive breast cancer [ 16 ].
Nevertheless, aromatase inhibitors cause different side effects compared with those of tamoxifen, and the greater level of the toxicity versus the efficacy of aromatase inhibitors needs to be investigated further [ 17 ].
Thus, the American Society of Clinical Oncology ASCO Health Services Research Committee recommends that patients imbalanfes to aromatase inhibitors should receive tamoxifen. Daily consumption of CLA from ruminant-based foods for cancer prevention will be less likely to raise concerns about toxicity.
However, more imbaalances data raised the concern about safety issue of CLA. Dietary CLA, mainly t 10, c12 -CLA, induced insulin resistance and increased plasma insulin levels in both normal and obesity mice, and more important, similar results have been reported in hormona clinical trials [ 2 ].
It has also been demonstrated that high level of t 10, c12 -CLA induced liver steatosis in mice [ 2 ]. Thus use this isomer in the clinical need to be very cautious. It has been theorized that hormknal paracrine signals produced by surrounding stromal cells plays a crucial role in modulating malignant epithelial cells progression [ 1819 ].
Studies suggest that CLA is incorporated, stored in stromal cells, and CLA affect cancer progression [ 2 ]. CLA and human breast cancer study revealed that dietary CLA intake was associated with the regulation of estrogen receptor expression in ahd [ 20 ].
CLA has been found to reduce the risk of developing an estrogen receptor-negative tumor in premenopausal women, which may lead to a better therapeutic outcome for breast cancer patients as their cancer will be likely responsive to anti-estrogen therapy [ 20 ].
Based on this epidemiological finding, we hypothesize that CLA will exert anti-cancer activities in ERα-positive breast tumors. In this study, we examined the role of ERα in CLA-induced apoptosis in human breast epithelial cells and the possible involvement of apoptotic marker, Bcl-2, on CLA-mediated apoptosis.
Greenland, NH and a CLA stock solution was prepared as described previously [ 21 ]. For the steroid hormone study, we used Dextran-Coated Charcoal DCC, Dextran T; Pharmacia; activated charcoal; Sigma, St. Louis, MO to remove steroid hormones in the fetal bovine serum FBS, GibcoBRL, Bethesda, MD.
We then added the CLA to medium with the DCC-treated FBS. Louis, MO. MCF-7 and MDA-MB cells were purchased from American Type Culture Collection ATCC, Manassas, VA.
MDA-MBERα cells MDA-MB cells stably transfected with ERα were a gift from Dr. Robert Brueggemeier at the College of Pharmacy, The Ohio State University. The medium was renewed every two days. Normal reduction mammoplastys and malignant human breast tissues were obtained through the Tissue Procurement Program at The Ohio State University Hospital in Immbalances, Ohio.
Isolation of epithelial and stromal cells from human breast tissues and culture conditions were described previously [ 56 ]. Briefly, tissues were minced and digested in 0. The digested mixture was centrifuged at × g for 5 min at 25°C. The cell pellet was re-suspended and allowed to settle by gravity for 3 times.
Cancer epithelial cells in the initial imbbalances part were re-suspended in keratinocyte serum free medium Keratinocyte-SFM, 0. Finally, cells were harvested for performing assays described in the following sections. Co-cultures of epithelial cells, MCF-7, MDA-MB or Hormojal, with stromal cells, non-cancerous or cancerous breast stromal cells, were performed using flat-bottomed cell culture plates with the nucleopore polycarbonate membrane 0.
Culture condition for co-culture system was described previously [ 5 ]. At the end of the treatment period, cells were washed with ice-cold PBS and then lysed with extraction reagent Pierce, Rockford, IL and protease inhibitor Pierce, Rockford, IL on imba,ances. The performance of western blot analysis was described previously [ 5 ].
Bcl-2 rabbit polyclonal antibody sc, Santa Cruz, CA, and β-actin goat polyclonal antibody sc, Santa Cruz, CA, were utilized in this experiment. This assay measures the amount of dehydrogenase enzymes found in metabolically active cells by adding enzyme substrate MTS, 3- 4,5-dimethylthiazolyl 3-carboxymethoxyphenyl 4-sulfophenyl -2H-tetrazolium, inner salt and hormlnal coupling reagent PMS, phenazine methosulfate.
Briefly, 1 × 10 4 cells in μl medium were seeded and treated in well plate. Then, 20 μl of MTS:PMS solution was added to each well. Plates were incubated at 37°C for 1. Finally, optical density was read at nm OD nm using an ELISA plate reader.
Hoechsta Hoemonal intercalating dye, fluoresces blue when bound to DNA. For this part of the study, 2 × 10 4 cells were seeded on coverslips in triplicate. The cells were washed again with 1X PBS and mounted on glass slides.
Under confocal fluorescence microscopy excitation nm and emission nmapoptotic cells showed condensed chromatin that was bright blue. Samples were stained and counted in triplicate.
The basal expression of Bcl-2 in 14 normal and 14 cancerous human breast tissue samples were fixed, dehydrated, embedded in paraffin, and sectioned for immunohistochemical staining.
Immunostaining was carried out using the Vectastain Universal Quick kit Vector Laboratories, Burlingame, CA followed by the DAB Substrate Kit for Peroxidase Vector Laboratories, Burlingame, CA according to manufacturer's instructions.
Antibody against Bcl-2 is a rabbit polyclonal antibody raised against a peptide mapping at the N-terminus of Bcl-2 of human origin sc Santa Cruz, CA. To test the specificity of Bcl-2 antibody, the primary antibody was substituted with non-immune serum. Lmbalances intensity was evaluated by Allred scoring, which is a method that conveys estimated proportion score and intensity score [ 22 ].
Caspase-3 and -7 are members of the cysteine aspartic acid-specific protease family and play important roles in apoptosis in mammalian cells [ 23 ]. Yormonal well contained 10 4 cells in 50 μl of medium were seeded and treated in 96 well-plates.
Briefly, 50 μl reagent fluorometric substrate: buffer in the ratio of was added to each well. Plates then were incubated at 37°C for 5 hours and the intensity of the emitted fluorescence was determined with the use of a fluorescence spectrometer excitation nm and emission nm.
p-value less than 0. One cell group consisted of three replicate wells. Based on CLA concentration in normal physiologic human serum 10—70 μM and in humans who take CLA long-term supplementation 50— μMCLA concentrations used in in vitro studies imbalabces ranged from imbalajces Our previous study showed that the effective dose range for inhibiting the proliferation of human breast cancerous epithelial and stromal cells was 10—80 μM for abd days and t 10, c CLA was more potent than c 9, t CLA unpublished data.
Therefore, t 10, c CLA was used in the current study and a relatively lower but effective dose, 40 μM of t 10, c CLA, was chosen to investigate whether CLA potentiates the anti-proliferative and pro-apoptotic effects of Tam. Moreover, we observed that the combination of CLA and Tam caused more apoptosis than treated alone in MCF-7 cells, as measured using apoptotic indicators Figs.
These results suggested that CLA may enhance the therapeutic efficiency of Tam in estrogen-responsive human breast cancer patients. CLA stands for 40 μM t 10, c CLA; Tam horjonal for 1 μM 4-Hydroxytamoxifen; E 2 stands for 10 nM 17β-estradiol. CLA exerts combinative effects with tamoxifen in MCF-7 cells.
Equal amounts of isolated protein from both cell extracts hormnoal subjected to immunoblot with anti-ERα antibodies. β-actin was used as loading control. Since CLA, a naturally occurring food component, will be consumed by normal individuals as well, we examined the effects of CLA on normal human breast epithelial cells.
The estrogen receptor positivity of the normal breast wnd cells was determined based on their ERα protein expression. MCF-7 ERα positive and MDA-MB ERα negative were used as positive and negative control, respectively imbalancess the determination of ERα expression in normal breast epithelial cells.
CLA treatment suppressed the ability of E 2 to stimulate proliferation Fig.
: CLA and hormonal imbalances| Advance Journal of Food Science and Technology | PMC Reader. HBIs XML. Introduction: Ovulation is a physiologic process with an inflammatory response that depends on a coordinated activity of gonadotropins and steroid hormones, as well as inflammatory mediators such as cytokines, prostaglandins, leptin, nitric oxide NO , etc. Conjugated linoleic acid CLA is composed of polyunsaturated fatty acids PUFA found in dairy products, beef and lamb. There is strong evidence that dietary CLA affects mediators involved in ovulation. The aim of this study was to determine the effects of different doses of dietary CLA on systemic and local hormones and factors involved in ovulation. Materials and Methods: In this case-control study, 80 50±2-day old female mice were randomly divided into four groups C as the controls and T1, T2 and T3 as the treatment groups. There were four replicates in each group and there were five mice in every replicate 20 mice, in total. The mice in the control group were fed with no CLA in their diet but the ones in the treatment group received 0. Later on, blood samples were obtained from the tails of animals that displayed estrus signs and estradiol E2 , progesterone P4 , LH, FSH, NO, leptin and TNFα were measured. Furthermore, the effects of CLA on the ovarian production of prostaglandins PGs and NO were investigated. The data were analyzed by SAS software. Results: CLA significantly decreased serum levels of FSH p. Figures, Charts, Tables. All procedures were carried out according to the manufacturer protocol. Samples of right testis and epididymal fat were collected, snap frozen in liquid nitrogen, and stored at ºC till analysis. Samples were then homogenized in 1ml Qiazol Qiagen, Valencia, CA by using TissueLyser TissueLyser LT; QIAGEN; Cat No. Homogenization was achieved by 5-mm steel bead shaking at 50 Hz for 5 min according to Sun et al. Contaminant genomic DNA was removed with a DNase enzyme RNase-free DNase set, Qiagen, Valencia, CA. RNA was then collected in 30 μL RNase free water and stored at ºC till cDNA synthesis. The RNA concentration and purity were measured by Nano-Drop C spectrophotometer Thermo Scientific, USA. BioRad according to Norollahi et al. For the cDNA synthesis ng of RNA per 20 μl reaction were used. Primer pairs for selected target and reference genes are summarized in Table 3. Primer pairs not previously published were designed using Primer Express 3, as previously described by Bionaz and Loor [ 33 ]. Primer pairs were purchased from Genwez New Jersey, USA. Desalted lyophilized primers were reconstituted using RNase free water Invitrogen, USA. The cDNA was diluted using molecular grade RNase free water Invitrogen, USA. The reaction was performed in 0. The reaction consisted of Each sample was performed in triplicate. A non-template control NTC was run to check for primer dimer and RNA contamination. A melting curve protocol was run at the end of the PCR by heating at 95 ºC for 30 s followed by a 65 ºC for 30 s and 95 ºC for 30 s. Fluorescent amplification curves data was downloaded from the AriaMx PCR System and analyzed using LinReg PCR software [ 34 ]. Three reference genes were tested including ubiquitously expressed transcript UXT , small ribosomal protein subunit 15 RPS15A , and hypoxanthine phosphoribosyl transferase 1 HPRT1A. The reliability of reference genes was determined using NormFinder [ 35 ]. The stability value of the combination of the two best reference genes UXT and RPS15A was 0. The normalization factor was calculated as the geometrical mean of the two best reference genes and final data of target genes were obtained by dividing the RTqPCR values obtained by LinRegPCR to the normalization factor. The MIXED procedure of SAS 9. Both treatment and time and their interaction were considered as fixed factors in the model and rabbit was considered as random effect. The effect of long-term dietary CLA supplementation on growth performance indices is shown in Fig 1. Additionally, body weight gain was increased only in CLA 0. Dietary supplementation of CLA for 26 weeks increased feed intake, body weight, and body weight gain but not the FCR. Results of sperm kinetics are summarized in Table 4. The total motile sperm tended to increase by 5. Long term of dietary CLA supplementation did not improve sperm viability, abnormalities, or acrosomal integrity, however, plasma membrane integrity tended to increase in CLA 0. Long term of dietary CLA supplementation did not affect serum testosterone level, or sperm concentration. The level of MDA tended to increase in CLA fed male rabbits. The responses of measured testicular metabolites and serum testosterone level are presented in Fig 3. Fatty acid profile of epididymal fat for each group is presented in Table 5. Medium-chain fatty acids from C10 to C14 were affected by CLA treatment, with higher values in CLA 0. Additionally, eicosanoic acid cis 11 C was decreased by The testis of the CON group had multiple layers of spermatogonia lining the seminiferous tubules Fig 4A. However, in CLA 0. Normal histological structure in CON group 4a Vacuolation of Sertoli cells and decreased spermatogenesis in CLA 0. Absence of spermatogenesis with few spermatogonial cells lining seminiferous tubules 4c. Hematoxylin and eosin stain X Lesion scoring results of testicular tissue are presented in Fig 5. Histopathological examination of the epididymis is shown in Fig 6. The epididymis of the CON Fig 6A and CLA 0. Normal histological structure in CON 6a and CLA 0. The staining of the epididymis with Sudan black stain is shown in Fig 7. Fat globules were present on the surface of the epithelium of epididymis in the CON group Fig 7A , whereas they were minute in the CLA 0. Presence of fat globules on the surface epithelium of epididymis in the control group 7a , minute fat globules in CLA 0. Sudan Black X The results of caspase-3 staining of testicular tissue are shown in Fig 8. On the other hand, brown positively stained spermatogonial cells were observed in the lumen and in the lining epithelium of seminiferous tubules in both CLA 0. Negative staining for caspase-3 in the control group 8a. Brown positively stained spermatogonial cells were observed in the lumen and in the lining epithelium of seminiferous tubules in CLA 0. Immuno-peroxidase and hematoxylin counterstain X Area percent of Caspase-3 in different groups, long term dietary supplementation of CLA increased area percentage of Caspase-3 in a dose dependent manner 8d. The expression of key lipogenic genes in epididymal fat is shown in Fig 9. FABP and LPL did not significantly different. The expression of key apoptosis regulatory genes CASP3 , BAX , and BCL2 and the antioxidant-related gene GPX in the testicular tissue is shown in Fig The expression of the pro-apoptotic CASP3 gene was increased by CLA 0. The expression of GPX was downregulated in both CLA 0. Several studies were conducted to investigate the growth promoting [ 36 ], immune stimulant [ 37 ], anti-inflammatory, and anti-carcinogenic effects of CLA [ 38 ]. However, studies investigating the long-term effects of CLA on body weight and other body organs and systems like male reproductive system are very limited [ 39 ]. In the current study dietary supplementation of CLA for 26 weeks from weaning till puberty slightly increased feed intake and body weight similar to previous finding [ 40 ]. However, other studies detected opposite effect of CLA on body weight and feed intake [ 41 ] or no effect [ 36 , 42 ]. Additionally, longitudinal studies of CLA supplementation revealed also different effects of CLA on body weight and body weight gain, some researchers detected body weight re-gain after supplementation of CLA [ 43 , 44 ], and other researchers observed body weight loss [ 45 , 46 ]. To the authors knowledge there are no longitudinal studies that investigated the effect of CLA on growth rate of male rabbits; however, CLA supplementation for short period 49 d did not affect body weight and feed intake in growing rabbits [ 27 , 47 ]. The contrasting effects of CLA on body weight and feed intake in the above studies could be explained by the difference in species and the period of CLA supplementation. Our study, which is the first one where CLA was fed for a long period, indicated a significant positive effect of CLA on both feed intake and body weight; however, the increase, especially of body weight, can be considered minimal and probably not important in front of its negative impact on fertility. Moreover, it was previously reported an association between decreased fertility and increased body weight in male rabbits [ 48 ]. The effect of long-term dietary CLA supplementation on male rabbit reproduction was not formerly investigated. Prior studies investigating the effect of CLA on semen parameters either through dietary supplementation [ 12 ] or direct application on semen [ 8 ] were of short term and, for the most part, conducted after puberty [ 7 ]. In the current study, long-term dietary supplementation of CLA did not significantly affect sperm kinetics or morphology. PUFA are a special fatty acid components of sperm plasma membrane [ 49 ], they easily undergo lipoperoxidation; thus, presence of powerful antioxidant system to protect them from lipoperoxidative damage is crucial. The reduced PUFA might be consequence also of a higher oxidative status with lower antioxidant capacity, as indicated by the lower vitamin E, L-carnitine, and GPX gene expression and by the higher accumulation of MDA in testicular tissue [ 49 — 51 ]. The increased MDA and downregulation of testicular GPX transcript in our study was similar to prior findings [ 52 ]. The effect of CLA on regulation of tocopherol is not clear. In short term studies CLA increased liver and adipose tissue tocopherol [ 52 ]. The upregulation of SCD5 in the current study was associated with a decreased PUFA. This finding appears contradictory; however, it has been reported that PUFA inhibit SCD activity and transcription [ 54 , 55 ] The downregulation of PPARG in this study is similar to prior studies [ 56 , 57 ] and might explain the overall decrease of total epididymal fatty acid, similar to Hue et al. Arachidonic acid is essential for the synthesis of prostaglandin D2, known to inhibit cyclooxygenaseinduced apoptosis [ 49 ]. A study that was conducted to investigate the effect of CLA on the pituitary-testes axis in rams showed an increased concentration of luteinizing hormone LH by CLA [ 61 ]; the depletion of LH was associated with Leydig cell atrophy in adult rats [ 62 ]. In the present study, the caspase-3 was positively stained in spermatogonial cells of the seminiferous tubules in the groups treated with CLA which demonstrated a dose-related increase in apoptosis [ 63 ]. However, on the transcriptional level the transcription of CASP3 was upregulated only in CLA 0. L-carnitine is known to inhibit the activity of caspases [ 64 ]. Thus, the higher level of L-carnitine in CLA 0. In former reports applying different doses of CLA isomers mixture exerted different effects on several body metabolites [ 65 — 67 ], that could be explained by tissue affinity of CLA, whereas, low dose of CLA affected only retroperitoneal fat depot, while the higher dose affected both retroperitoneal and epididymal fat in mice model [ 67 ]. To our knowledge, there are no former studies that showed a positive effect of CLA on apoptosis in the testis although it has been recorded in adipose tissue [ 68 ]. Whether the CLA exerts its effect on the testes directly or indirectly is unknown. However, it could be suggested that CLA mediate theirs effect on the testis by affecting the fatty acid composition of epididymal fat with consequent reduction of spermatogenesis [ 69 ] and affecting the synthesis of hormones involved in reproduction by disturbing the pituitary-testis axis [ 70 ]. Despite the proper selection of the statistical model, proper sampling and technical replicates analyzed, the low number of animals per group is considered a limitation of the present study. Our data suggest that long-term supplementation of CLA is not beneficial to male rabbits, especially if fed with a dose larger than 0. The growth promoting effect might be of interest, but the magnitude does not seem to balance the negative effects on fertility. The authors would like to acknowledge Dr. Mohammed Said Amer for helping with anesthesia and providing the anesthetic medications. Browse Subject Areas? Click through the PLOS taxonomy to find articles in your field. Article Authors Metrics Comments Media Coverage Reader Comments Figures. Correction 27 Mar Abdelatty AM, Badr OAM, Mohamed SA, Khattab MS, Dessouki SHM, et al. Abstract Conjugated linoleic acid CLA is known for its multiple benefits including improvement of growth, increasing lean mass, and anti-carcinogenic effects. Data Availability: All relevant data are within the manuscript. Introduction The discovery of anticancer properties made the conjugated linoleic acid CLA top-studied fatty acid by the scientific community [ 1 ]. Download: PPT. Table 1. Diet ingredients 1. Table 2. Semen collection and sperm kinetics Due to the large variability on the moment of puberty in rabbits 19 to 24 weeks [ 18 , 19 ] semen was collected twice a week for 7 successive weeks starting from week 20 of the experiment. Sperm concentration and morphology Sperm concentration and morphology were evaluated for all samples according to Perumal et al. Euthanasia and blood sampling Rabbits were euthanized using Ketamine and Xylazine protocol as described in Simón et al. Serum testosterone and testicular metabolites A testosterone ELISA kit Cat No. Epididymal fatty acid profile Epididymal fatty acids were extracted according to Abdelatty et al. Immunohistochemistry Paraffin-embedded tissue sections of testis and epididymis were immunohistochemically stained using caspase-3 primary antibody Novus Biologicals, USA as a hallmark of apoptosis. Transcriptomic analysis of testicular and epididymal fat Extraction of RNA. Synthesis of cDNA template. Primer designing and quantitative PCR. Table 3. Gene names, primer sequences, accession , and product size of the used genes. Statistical analysis The MIXED procedure of SAS 9. Results Growth performance The effect of long-term dietary CLA supplementation on growth performance indices is shown in Fig 1. Fig 1. Growth performance of male rabbits with long-term supplementation of CLA. Sperm Kinetics Results of sperm kinetics are summarized in Table 4. Table 4. Effect of long term dietary CLA supplementation on sperm kinetics 1. Fig 2. Sperm viability of male rabbits with long-term supplementation of CLA. Fig 3. Sperm concentration, serum testosterone, and some testicular metabolites of CLA fed male rabbits. Serum testosterone and testicular metabolites The responses of measured testicular metabolites and serum testosterone level are presented in Fig 3. Epididymal fatty acid profile Fatty acid profile of epididymal fat for each group is presented in Table 5. Table 5. Effect of long term dietary CLA supplementation on fatty acid profile and desaturation indices of epididymal fat 1. Histomorphometry findings The testis of the CON group had multiple layers of spermatogonia lining the seminiferous tubules Fig 4A. Fig 4. Effect of long term CLA supplementation on testicular tissue of rabbit. Fig 5. Fig 6. Effect of long-term CLA supplementation on rabbit epididymis. Fig 7. Immunohistochemistry findings The results of caspase-3 staining of testicular tissue are shown in Fig 8. Fig 8. Effect of long-term CLA supplementation on immune histochemistry of Caspase-3 rabbit testicular tissue. Transcription of lipid synthesis and apoptosis related genes in testicular tissue and epididymal fat The expression of key lipogenic genes in epididymal fat is shown in Fig 9. Fig 9. Epididymal fat gene expression in male rabbits receiving long-term CLA supplementation. Fig Testicular gene expression in male rabbits fed receiving long-term CLA supplementation. Discussion Several studies were conducted to investigate the growth promoting [ 36 ], immune stimulant [ 37 ], anti-inflammatory, and anti-carcinogenic effects of CLA [ 38 ]. Conclusion Our data suggest that long-term supplementation of CLA is not beneficial to male rabbits, especially if fed with a dose larger than 0. Acknowledgments The authors would like to acknowledge Dr. References 1. Chen PB and Park Y. Conjugated Linoleic Acid in Human Health: Effects on Weight Control. In Nutrition in the Prevention and Treatment of Abdominal Obesity. Academic Press. Mitchell PL and McLeod RS. Conjugated linoleic acid and atherosclerosis: studies in animal models. Biochemistry and Cell Biology. Viladomiu M, Hontecillas R, and Bassaganya-Riera, J. Modulation of inflammation and immunity by dietary conjugated linoleic acid. European Journal of Pharmacology. Wood JD. Meat composition and nutritional value. In Lawrie´s Meat Science. Woodhead Publishing. Matin S, Nemati A, Ghobadi H, Alipanah-Moghadam R, and Rezagholizadeh L. The effect of conjugated linoleic acid on oxidative stress and matrix metalloproteinases 2 and 9 in patients with COPD. International Journal of Chronic Obstructive Pulmonary Disease. Onakpoya IJ, Posadzki PP, Watson LK, Davies LA, and Ernst E. The efficacy of long-term conjugated linoleic acid CLA supplementation on body composition in overweight and obese individuals: a systematic review and meta-analysis of randomized clinical trials. European Journal of Nutrition. Karimi R, Towhidi A, Zeinoaldini S, Rezayazdi K, Mousavi M, Safari H et al. Reproduction in Domestic Animals. Teixeira SMP, Chaveiro AEN, and da Silva JFM. Effect of trans, cis isomer of conjugated linoleic acid on boar semen quality after cryopreservation. Animal Reproduction. View Article Google Scholar 9. De Veth MJ, Bauman DE, Koch W, Mann GE, Pfeiffer AM and Butler WR. Efficacy of conjugated linoleic acid for improving reproduction: A multi-study analysis in early-lactation dairy cows. Journal of Dairy Science. Zamora-Zamora V, Figueroa-Velasco JL, Cordero-Mora JL, Nieto-Aquino R, García-Contreras ADC, Sánchez-Torres MT. Conjugated linoleic acid supplementation does not improve boar semen quality and does not change its fatty acid profile. Veterinaria México. View Article Google Scholar Khodaei H, Chamani M, Sadeghi A, and Hejazi H. Effects of Conjugated Linoleic Acid CLA on hormones and factors involved in murine ovulation. Aydin R, Karaman M, Toprak HHC, Ozugur AK, Aydin D, and Cicek T. The effect of long-term feeding of conjugated linoleic acid on fertility in Japanese quail. South African Journal of Animal Science. Ali TM. A manual for the primary animal health care worker. Food and Agriculture Organization FAO. Gliozzi TM, Zaniboni L, Maldjian A, Luzi F, Maertens L, and Cerolini S. Quality and lipid composition of spermatozoa in rabbits fed DHA and vitamin E rich diets. National Research Council. Nutrient Requirements of Rabbits: National Academies Press; Feb 1. Garcia MR, Amstalden M, Morrison CD, Keisler, DH, and Williams GL. Age at puberty, total fat and conjugated linoleic acid content of carcass, and circulating metabolic hormones in beef heifers fed a diet high in linoleic acid beginning at four months of age. Official methods of analysis. Gaithersburg, MD: Association of the Official Analytical Chemists, Macari M, and Machado CR. Sexual maturity in rabbits defined by the physical and chemical characteristics of the semen. Laboratory Animals. Boulbina I, Ain-Baziz H, Ilès I, Zenia S, Belabbas R, Temim S. Effect of birth season on onset of puberty and semen characteristics in male rabbit of Algerian population Oryctolagus cuniculus. World Rabbit Science Association Proceedings 10 th World Rabbit Congress. Viudes-de-Castro MP, Lavara R, Safaa HM, Marco-Jiménez F, Mehaisen GMK, and Vicente JS. Effect of freezing extender composition and male line on semen traits and reproductive performance in rabbits. Perumal P. Effect of superoxide dismutase on semen parameters and antioxidant enzyme activities of liquid stored 5 C Mithun Bos frontalis semen. Journal of Animals. Simón L, Funes AK, Yapur MA, Cabrillana ME, Monclus MA, Boarelli PV, et al. Manchette-acrosome disorders during spermiogenesis and low efficiency of seminiferous tubules in hypercholesterolemic rabbit model. PloS one. Ijaz A, Javed I, Aslam B, Khan JA, Khaliq T, Khan MZ, et al. Nephroprotective and antioxidant effects of Moringa Oleifera Sohanjna in paracetamol induced nephrotoxic albino rabbits. Ahmed-Farid OA, Nasr M, Ahmed RF, and Bakeer RM. Beneficial effects of curcumin nano-emulsion on spermatogenesis and reproductive performance in male rats under protein deficient diet model: enhancement of sperm motility, conservancy of testicular tissue integrity, cell energy and seminal plasma amino acids content. Journal of Biomedical Science. Ling B, Aziz C, and Alcorn J. |
| Background | com General enquiries: info biomedcentral. Long term of dietary CLA supplementation did not affect serum testosterone level, or sperm concentration. Supplementary Information. Isolation of epithelial and stromal cells from human breast tissues and culture conditions were described previously [ 5 , 6 ]. Download citation. |
| MeSH terms | The absorbance Maintaining electrolyte balance CLA and hormonal imbalances proportional hormonla the number of annd cells CLA and hormonal imbalances culture. Additional information Competing interest The authors declare that there exists no conflict of interest. References 1. PPARG expression and its implication in ovarian function like steroidogenesis, differentiation, and tissue remodeling have been well established Komar No other external or internal organization have funded this work. |
CLA and hormonal imbalances -
Similarly, female mice exposed in utero to the environmental estrogen, bisphenol A, subsequently had increased mammary branching [ 50 ]. Given that elements of the mammary gland microenvironment were also altered epigenetically in response to either bisphenol A [ 52 ] or a diet high in polyunsaturated fatty acids [ 53 ], any effect of in utero exposure to dietary fats such as 10,12 CLA may also impart transgenerational consequences.
Our findings support accumulating evidence for a link between the maternal diet and postnatal development of her offspring, including for the mammary glands. We conclude that dietary CLA modifies the mammary gland response to E when exposure occurs during distinct developmental windows, either during in utero development, or postnatally.
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t10, cCLA decreases adiposity in peripubertal mice without dose-related detrimental effects on mammary development, inflammation status, and metabolism.
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A number of studies have found evidence that CLA not only reduces body weight and body fat mass, but may also help increase lean mass in different species.
How does CLA help you lose weight? In certain animal s t udies , CLA specifically types 10 and 12 has also been found to lead to increased energy expenditure, increased fat oxidation and browning of subcutaneous white adipose tissue aka white fat.
Supplementation with a CLA mixture equal concentrations of the 10,12 and 9,11 isomers or the 10,12 isomer alone decreases body fat mass, according to results from numerous animal studies.
Of the two major isomers, 10,12 specifically seems to be responsible for the anti-obesity effects of CLA. In human studies, the results for CLA on weight loss have been somewhat mixed, although still promising. One study found that supplementation of a CLA mixture in overweight and obese people three to four grams a day for 24 weeks decreased body fat mass and increased lean body mass.
Other studies have shown similar results and that CLA also has no adverse effects on overall blood lipids, inflammation levels and insulin response in healthy, overweight and obese adults. One of the possible potential mechanisms by which CLA reduces body fat mass might be that it decreases energy intake or increases energy expenditure.
Does CLA reduce belly fat? The hypothesis is that CLA may be involved in insulin regulation. Conjugated lienoic acid has shown immune-enhancing effects and anticarcinogenic activities in several animal studies. The CLA present in saturated-fat foods might offset the adverse effects of the saturated fat content and benefit everything from blood sugar control, to hormone regulation, to natural cancer prevention.
Lower inflammation is a sign of less free radical damage or oxidative stress that is linked to lower cancer risk. CLA seems to modulate immune and inflammatory responses as well as improve bone mass. Research on the effects of conjugated linoleic acid for preventing breast cancer is somewhat conflicting, but some early research suggests that higher intake of CLA from natural foods is linked with a lower risk of developing breast cancer.
Other study results suggest that it can be beneficial for fighting cancer of the digestive organs and can improve detoxification via healthier liver function , too.
Consuming foods high in CLA or taking CLA supplements for 12 weeks seems to improve symptoms and overall well-being in people with seasonal allergy symptoms. Similarly, some research shows that for people with asthma, CLA might be a natural treatment method for asthma-related symptoms, due to its ability to help control inflammation.
Twelve weeks of supplementation seems to improve airway sensitivity and ability to exercise. Early research suggests that CLA is beneficial for lowering inflammation and therefore autoimmune diseases like rheumatoid arthritis.
Taking conjugated linoleic acid alone or along with other supplements like vitamin E benefits those with arthritis by reducing symptoms, including pain and morning stiffness.
Pain and inflammation markers including swelling have been improved for adults with arthritis taking CLA compared to their pre-treatment symptoms or people not taking CLA, meaning CLA can naturally treat arthritis. Although findings have also been somewhat conflicting, some research shows that taking conjugated linoleic acid alone or along with supplements like creatine and whey protein can help increase strength and improve lean tissue mass.
This is why CLA is often added to some bodybuilding supplements, protein powders and weight loss formulas. According to a report published in The Journal of Food Composition and Analysis , the top food sources of CLA include :.
What an animal eats and the conditions in which they are was raised highly affect how much CLA and other fats or nutrients their meat or milk will supply.
The proportion of CLA ranges from 0. In other words, not all beef or dairy is created equal when it comes to supplying us with healthy fats like CLA. The significant clinical studies investigating the effect of CLA on body composition and their intervention strategies are shown in Table 2.
In clinical studies, several methods or techniques were applied to measure the body composition. The simplest method is that, to measure the thickness of subcutaneous fat in multiple places on the body such as abdominal area, arms, sub-scapular region large triangular muscle near shoulder bone , buttocks and thighs [ 25 , 51 , 52 ].
Other commonly used measures are bioelectrical impedance analysis [ 39 ], hydrodensitometry and dual-energy X-ray absorptiometry DEXA [ 53 — 55 ]. Among them, DEXA is the most widely used method in clinical studies to assess body composition due to CLA consumption.
In fact, DEXA measures total body composition and fat content with a high degree of accuracy and is considered as the gold standard for measuring the body composition, since one can get an image of the entire body [ 56 ].
Another commonly used method is the measurement of body mass index, i. According to World Health Organization [ 57 ], a BMI greater than or equal to 25 is overweight, and a BMI greater than or equal to 30 is considered as obesity.
In fact, BMI is not necessarily a good measure, especially in terms of body composition; for instance, individuals like athletes with strong bone and greater muscle lean mass have a higher BMI than non-athletes, and hence different BMI classifications of overweight is warranted while assessing obesity in terms of body girth [ 58 ].
Some of the clinical studies suggested a positive association of the intake of 3. In another study, supplementation of 4. In a different study comprising 60 overweight or obese volunteers including men and women who received 3.
Steck et al. They concluded that lean body mass LBM increased by the higher dose after 12 wk of intervention. Supplementation of 9- and CLAs at a dosage of 1.
Interestingly, CLA was found to be effective in reducing the weight gain associated with psychiatric medications - one of the major side effects in psychological treatments. Consumption of CLA at a dosage of 3. A possible explanation for this effect is that green tea extract high in pigallocatechin-gallate can directly inhibit gastric and pancreatic lipases, thereby increasing the thermogenesis and possibly prevent the enzymatic degradation of catechol O-methyltransferase, an enzyme which plays a role in the respiration rate of brown adipose tissue [ 62 ].
Due to overeating and sedentary life, the incidence of weight gain during holiday season i. For instance, supplementation of CLA 3. On the contrary, an inverse relationship between CLA and body composition has been demonstrated.
One of the first studies demonstrating negative effects of CLA was performed with 71 subjects including obese men and women of 20 to 50 yr of age. Body was measured by hydrodensitometry, but the results did not show any effect on body composition [ 64 ].
In sedentary young women, intake of 2. Likewise, consumption of 4. Some of the studies observed gender specific effects of CLA intake. Riserus et al. The small sample size and short duration were the major limitations of this study; thus, the effects of CLA in abdominal obesity need to be investigated further in larger studies with longer duration.
Long-term 1 yr supplementation daily dose of CLA was 3. In this double-blind placebo-controlled study, female and male 31 volunteers with BMI of 25—30 were included. In a bicentric study conducted simultaneously at Clermont-Ferrand, France and Maastricht, The Netherlands , eighty-one middle-aged, overweight, healthy men and women were enrolled, and all subjects consumed a drinkable dairy product containing 3 g of high OA sunflower oil daily for 6 wk, the run-in period [ 46 ].
Volunteers were then randomized over five groups receiving daily either 3 g of high OA sunflower oil, 1.
Percentage BFM, fat and LBM were assessed at the end of the run-in and experimental periods by DEXA. Dietary intake was also recorded. It was concluded that, a daily consumption of a drinkable dairy product containing up to 3 g of CLA isomers for 18 wk had no significant effect on body composition in overweight, middle-aged men and women [ 46 ].
A study from Greece reported that CLA administered first at 0. Raff et al. This study gained more importance, as it was reported in children aged between 6 and 10 yr, who were overweight or obese, but otherwise healthy [ 67 ] ].
It is known that the γ -oryzanol is a phytochemical having several biological activities like anti-oxidant activity, anti-atherogenic effect, lowering triglycerides and improves LBM [ 68 ].
This report also indicates that CLA per se was less efficient to improve BFM; for instance, a recent non cross-over clinical study conducted on 66 non-trained healthy male students for 2 month showed that CLA supplementation had no effect on LBM, BFM, trunk and visceral fats, and waist circumference [ 69 ].
Some clinical studies suggested that administration of CLA might be the most effective strategy in controlling regionalized reduction of fat mass rather than its constitutional reduction, i. For instance, administration of 3. Waist-to-hip ratio also decreased significantly in healthy, overweight and obese men, compared with placebo group.
Interestingly, these effects were produced independent of diet and specific lifestyle. Exercising individuals often add nutritional supplements to their diet to accelerate the increase in muscle mass and strength from heavy resistance-exercise training.
Some short- and long-term studies employing high doses of CLA in healthy and obese, sedentary and exercised adults have shown beneficial effects of CLA in reducing fat mass and increasing LBM. A daily supplementation of 1. In this study, physical exercise was standardized as 90 min in gym, three times a wk; and concluded that CLA reduces the deposition of fat.
These results seem to be encouraging, because much lower dose of CLA produced the expected results - when compared to other studies - wherein comparatively 2 to 4 folds higher concentrations of CLA were used. Effect of CLA Clarinol A supplementation in conjunction with 6 wk of aerobic exercise training on 33 untrained to moderately trained men average age CLA showed no ergogenic benefits on neuromuscular fatigue, and field tests of muscular endurance and power.
This combined strategy showed that supervised resistance exercise training is safe and effective for increasing strength in older adults, because aging is associated with lower muscle mass and an increase in body fat.
Similarly, in another double blind and placebo controlled resistance-training study, no decrease in visceral adipose tissue was observed; however a significant reduction in the cross-sectional area of visceral adipose tissue was noticed in the placebo group [ 22 ].
In this study, 30 overweight and moderately obese, but otherwise healthy middle-aged 35 to 55 yr male subjects received 3.
Pinkoski et al. Thus, some of the studies showed the effectiveness of CLA in fat mass reduction in subjects during resistance-training program. Contrary to this, no CLA-specific effects were observed on body composition, energy expenditure or appetite in non-obese, regularly exercising individuals comprising 25 men and 27 women , who received either 3.
It suggests that CLA supplementation may promote testosterone synthesis through a molecular pathway that should be investigated in detail.
Furthermore, this study becomes much relevant, since the correlation between the production of testosterone and body building still remains a controversy. Some pre-clinical studies showed that CLA reduces fat uptake into adipocytes by lowering the activities of lipoprotein lipase and Δ 9 -desaturase, instead of enhancing lipolysis [ 14 , 74 , 75 ].
Based upon this background, a few clinical investigations were made on the effect of CLA on fat-mass regain after weight loss - with an assumption that CLA could block body fat gain. To check this, overweight adults were administered a very low-calorie diet for 3 wk, followed by CLA supplementation at a dosage of either 1.
Subjects took CLA in either dose showed increased regain of fat-free mass and resting metabolic rate, thereby lowering the regain of body fat relative to the control subjects.
Interestingly, they concluded in later findings that the measures of appetite hunger, satiety and fullness favorably and dose-independently affected by the same dose of CLA but had no effect on energy intake at breakfast or improved body-weight maintenance after weight loss [ 76 ].
Apart from a few studies that investigated the effects of CLA supplementation in humans, there were some experiments designed to supplement CLA-enriched dairy products.
Consumption of dairy products such as ultra-heat treated milk, butter, and cheese enriched with 1. Another experiment compared the effects of the consumption of a modified butter, naturally enriched with CLA 4. Consumption of a drinkable dairy product containing up to 3 g of CLA isomer for 18 wk did not result in any significant effect on body composition in overweight, middle-aged men and women [ 46 ].
Venkatramanan et al. More precisely, consumption of CLA-enriched milks in either form failed to alter TAG concentrations in the blood; body weight or fat composition [ 51 ]. Thus, in general, dairy products enriched with either of 9- or CLA isomers or its mixture failed to establish a consistent effect on body composition.
The question of inconclusive results on efficacy and effectiveness of CLA on body composition and obesity may answer from long-term intervention studies.
Effects of any dietary supplement or food ingredient on body composition should be assessed over an extended period of time to conclude the results, because crash diet procedures seem inappropriate.
In most of the studies, the intervention period lasted only for a few wk, and long-term studies were very few. In a study, subjects including men and women were supplemented with 3. During the first 12 month, significant reduction in BFM and leptin levels was reported.
These changes in body composition were not related to diet and exercise. Most of the effects on BFM were observed during the first 6 month of CLA supplementation and the extension study concluded that CLA may be beneficial in preventing weight regain and long-term maintenance of BFM and LBM.
These studies seem to be important as most of weight loss studies in overweight and obese subjects have demonstrated that most subjects will regain the lost weight within the next 1 to 2 yr [ 43 , 80 ]. Gaullier et al. Energy expenditure, substrate utilization and dietary fat oxidation were measured before and after 6 month of CLA supplementation, which showed that fat oxidation and energy expenditure increased during sleep in subjects received CLA, in comparison to placebo [ 81 ].
Supplementation of CLA 6. Such long-term studies have to be conducted in a cross-over design by including men and women of different age groups to generalize the beneficial effects of CLA.
However, all of them failed to reproduce the dramatic results reported in animal and in vitro models, especially mice.
The extensive controversies in clinical studies limit from proposing a definite statement regarding the beneficial effects of CLA on body composition, so as to address the increasing concerns of health professionals, body builders and athletes.
Hyper-triacylglycerolemia and elevated plasma cholesterol are suggested as the major risk factors for atherosclerosis and cardio-vascular diseases CVD , and that blood lipid profile, blood pressure, BMI and blood sugar are generally considered as the indicators of heart health.
The lipid profile is a panel of blood tests performed on the patient to determine the risk of CVD. These tests are good indicators of whether someone is likely to have a heart attack or stroke caused by blockage of blood vessels or hardening of the arteries atherosclerosis.
The lipid profile typically includes the baseline measurements of total cholesterol; high density lipoprotein cholesterol HDL-C , often called good cholesterol; low density lipoprotein cholesterol LDL-C , called bad cholesterol; and TAG in plasma [ 82 ].
Normal cholesterol levels vary by age and sex. LDL-C is the major cholesterol carrier in the blood, and if too much it is in circulation, it can slowly build up in the walls of the arteries of heart and brain leading to arteriosclerotic vascular diseases. According to American Heart Association, a high TAG level combined with low HDL-C or high LDL-C increases the risk of CVD [ 83 ].
The major circulatory markers associated with heart health are C-reactive protein CRP , tumor necrosis factor- α TNF- α , keto -dihydro prostaglandinF2 PGF2 , 8- iso- prostaglandinF2- α PGF2α , leptin, interleukin IL -6, plasma alanine transaminase, and total bilirubin [ 45 ].
Variations in the concentration of these markers in blood plasma from the normal level indicate dysfunctions of human system. The major circulatory markers associated with heart health and their normal levels in blood are listed in Table 3. Some animal studies suggest the health benefits anti-CVD effects of CLA such as anti-sclerotic and improvements in blood lipid profile, hypolipidaemic and anti-oxidative effects [ 84 — 86 ].
Two different isomers of CLA i. The CLA is pro-atherogenic and induces pathways involved in the development of insulin resistance, whereas 9-CLA is associated with reduced risk of CVD [ 87 — 89 ]. Epidemiological studies showed that plasma HDL-C concentrations have an inverse relationship with the risk of CVD, and it is anticipated that raising plasma HDL-C levels might protect against atherosclerosis [ 83 ].
Supposed effects of CLA supplementation on blood lipid profile also remains inconclusive. Supplementation of an isomeric blend of CLA 9- and CLAs in ratio for 12 wk 1. Similarly, a dose of 0.
In this study, 22 volunteers were enrolled and they were divided into study and control groups in a doubly blind design; the study group received 0.
Diet was controlled, and no significant differences in energy or macronutrient intake were found between the two groups. A significant reduction of HDL-C was observed when 6. But 2. In contrast, CLA 9- and CLA in ratio in a dose of 3.
And the ratio of LDL-C to HDL-C was significantly reduced in subjects with stable, diet-controlled type 2 diabetes [ 90 ]. In this non cross-over double-blind, placebo-controlled and randomized study, 51 normolipidaemic subjects were enrolled. These results further suggested that CLA supplementation significantly improved the lipid profile in human subjects without any adverse effects on body weight, plasma glucose and insulin concentrations; and thus indicates the supposed cardio-protective effects of CLA.
Contrary to this, the opposing effects 9- and CLAs were observed by Tricon et al. It showed that CLAincreased the ratios of LDL-C to HDL-C and total to HDL-C, whereas 9 - CLA decreased them, suggesting the beneficial effects of CLA on blood lipid profile [ 93 ].
But, later, the same group showed that dairy products enriched with 9-CLA 1. Some studies observed neither a beneficial nor an adverse effect of an isomeric blend of 9- and CLA in a ratio other than A 93 d long study in 17 healthy female volunteers to observe the effect of dietary CLA on blood lipids, lipoproteins, and tissue FA composition showed that daily supplementation of 3.
Furthermore, no adverse effect of CLA supplementation was reported in this study, though plasma concentration of CLA was increased during the intervention period, i.
Some studies investigated the effect of dairy products on lipid profile. However, human studies with the supplementation of CLA-enriched dairy products in situ enrichment produced contradictory results. Intake of 1. However, levels of CLA and VA in human milk can be modulated if breastfeeding mothers replace conventional dairy and meat products with organic dairy products enriched by natural feeding [ 95 ].
Recently, Penedo et al. Furthermore, sheep cheese naturally enriched in VA, CLA and ALA improved the lipid profile and reduced anandamide an endogenous cannabinoid neurotransmitter and obesity marker in adults with diagnosed mildly hypercholesterolaemia [ 97 ].
CRP is synthesized by liver in response to inflammation. Inflammations may be due to a variety of reasons such as cancer, diabetes, cardiovascular diseases, etc.
Increased plasma concentration of CRP, a circulatory inflammation marker helps in predicting CVD [ ]. A mixture of 9- and CLA isomers with equal proportions also reported an increased CRP, but not of the other inflammatory markers, i.
Another study concluded that a mixture of 9- and CLAs had more adverse effects on CVD markers, while 9-CLA isomer appeared to be more neutral in healthy postmenopausal women. Daily supplementation of 5.
The CLA mixture at a dose of 3. High dose of CLA consumption 6. In contrast, CLA in the same composition ratio , but in lower dose i.
Outcome from some recent studies suggested that CLA did not increase the risk of CVD. Pfeuffer et al. It was observed that CLA did not impair endothelial function.
Other parameters associated with metabolic syndrome and oxidative stress were not changed or slightly improved. Interestingly, it was observed that oral supplementation of CLA along with calcium reduced the incidence of pregnancy-induced hypertension without changing the plasma levels of other circulatory markers such as PGF2α, CRP and IL-6 [ ].
Forty eight healthy primigravidas with a family history of preeclampsia and with diastolic notch were included in this double-blind and placebo-controlled non cross-over study. Participants were randomized to daily oral doses of elemental calcium 0. The controversial beneficial and detrimental effects of CLA on heart health observed during clinical studied are summarized in Figure 2.
All these studies were too randomized in dosage, composition and duration, which make difficult to conclude the positive effects of CLA on heart health. Moreover, there is a complete lack of uniformity in assessing the effects CLA on heart health, i.
Even though the isomeric mixture of 9- and 10 CLA was found to exert some positive effects, it is necessary to elucidate the mechanism of action to ascertain which of these isomers elicited the effect. Different studies show that the effects of dietary CLA on immune functions in animal as well as human models are highly variable and inconsistent Table 4.
For instance, a 93 d long study in 17 young women upon feeding with 3. Even after immunization with influenza vaccine, the delayed type hypersensitivity response and serum antibody titers were not altered during the intervention period.
These data suggest that short-term CLA supplementation in healthy volunteers was safe, but it showed no added benefit to their immune status [ ]. Moreover, short-term consumption of CLA produced no observable physiological change in blood coagulation and platelet function in healthy adult females [ 23 ].
CLA supplementation 3. Although the overall effect was not significant, the results at least suggested that CLA might have a biologically relevant enhancing effect on the response to hepatitis B vaccination, which warrants further study [ ].
Contrary to this, supplementation with the 9- and CLA isomers blend, respectively significantly enhanced phyto-hemagglutinin PHA content, a T-cell mitogen-induced lymphocyte proliferator. Plasma IgA and IgM levels were found increased upon supplementation with 9- and CLAs , but decreased the levels of IgE, TNF-α and IL-1β.
In addition to these effects, delayed hypersensitivity response was decreased during CLA supplementation [ ]. CLA is reported to modify the inflammatory responses associated with allergic airway disease, primarily in animal models.
A prominent study in this regard came from the group of MacRedmond et al. However, daily supplementation of 4. One of the early studies in this direction measured the mean serum phospholipid esterified 9-CLA concentration in peripheral blood; observed it as significantly higher in 98 patients with chronic stable asthma, and 25 patients with acute severe asthma.
Thus the supposed role of oxygen-derived free-radical activity in inflamed lung tissue was envisaged [ ]. It shows that, some attempts were made to estimate the effect of CLA on immunity with reference to asthma, but none of them succeeded in reproducing the positive effects such as enhancement of immune function, down regulation of autoimmunity and increased proliferation of lymphocytes , consistently in clinical studies [ — ].
Furthermore, activation of peroxisome proliferator-activated receptors PPARs, a group of nuclear receptors , especially PPAR- γ in the human airway smooth muscle would be a possible strategy to treat airway diseases [ ]; therefore, targeting PPAR- γ , 9-CLA might show therapeutic value in alleviating airway disease by affecting epithelial and eosinophil functions [ ].
The interest on CLA mainly sprouted from the discovery of the anticancer property of CLAs [ 11 ]. Nevertheless, only a few studies have examined the isomers-specific effects of CLA in humans. In fact, no clinical studies have been conducted to relate CLA consumption with the incidence of cancer, but the data available in this regard are only from epidemiological studies.
Such data can be viewed as a collection of statistical tools used to elucidate the associations of CLA exposures to health outcomes. Regarding clinical studies on cancer, many researchers focused on human breast cancer; for instance, in an elaborate follow-up study using Cox proportional hazards models; Larsson et al.
Chajes et al. High-fat dairy food and CLA intake were examined in 60, women of age 40 to 76 Swedish mammography cohort study with It was found that women who consumed four or more servings of high-fat dairy foods per day including whole milk, full-fat cultured milk, cheese, cream, sour cream and butter showed half the risk of developing colorectal cancer, compared to women who consumed less than one serving per day [ ].
Concerning CLA intake, they found it was associated with an almost 30 percent reduction in the risk of colorectal cancer [ ]. Similarly, the possible role of CLA in preventing testicular cancer was depicted by the decreased CLA content in mitochondrial fractions of testicular cancer as against the normal testicular cells; and that CLA incorporation into nuclei and cytosol was significantly higher than its incorporation into plasma membranes and mitochondria [ ].
Tumors in estrogen receptor ER -negative epithelial cells in the breast are common among premenopausal women [ ]. McCann et al. Another epidemiological study the Netherlands cohort with 6.
A few studies examined the relationship between dietary or serum CLA in women and the risk of breast cancer. Such studies found an inverse association between dietary and serum CLA and risk of breast cancer in postmenopausal women [ ].
But in contrast, the adipose tissue extracts from a population of French patients with invasive breast carcinoma failed to reveal any positive correlation between adipose tissue CLA and the incidence of breast cancer [ ].
Since CLA accumulates in body fat stores, the adipose tissue of breast cancer obtained at the time of surgery could be used as a qualitative biomarker for CLA intake. Thus, the available human clinical studies could not ascertain the anti-cancer property of CLA. A major limitation in the epidemiological studies is the difficulty in obtaining accurate estimates of dietary CLA intake.
Most of the studies were carried out in small populations, where the diversity in food habits was less. Moreover, no clinical studies evaluated the effects of pure CLA preparations or individual isomers on the incidences of cancer.
It focuses that well-defined and controlled studies are required to fully understand the effects of CLA intake on the incidence of human cancer.
The life style epidemics, diabetes and obesity are considered as the major causes of morbidity and mortality all over the world; and that obesity and weight gain are associated with an increased risk of diabetes [ ].
The hormone, insulin is responsible for regulating glucose concentration in blood. Insulin resistance is a state in which cells do not respond properly to insulin even if it is available in the blood , which leads to hyperinsulinemia high blood insulin.
Some animal studies demonstrated that CLA supplementation enhances insulin sensitivity; however, the mechanism underlying this effect is unclear [ , ]. Relatively few studies have examined the anti-diabetic properties of CLA in humans.
Supplementation of 3. The CLA supplementation increases oxidative stress and inflammatory biomarkers in obese men [ 60 ]. Oxidative stress seems closely related to induced insulin resistance, which suggests a link between the FA-induced lipid peroxidation; these unfavorable effects of CLA might be of clinical relevance with regard to CVD [ 60 ].
Recently, Shadman et al. In non-diabetic abdominally obese men, 3. These results are of clinical interest, as hyperproinsulinaemia predicts diabetes and cardiovascular diseases. But, the isomeric mixture of 9- and CLA 3. Sixteen individuals age, Clinical studies regarding the anti-diabetic effects of CLA are inconclusive.
Rather, some of them speculated the reduction in insulin sensitivity; which attract immediate attention of the medical practitioners, because the increased consumption of CLA through dietary supplements might be ill-advised.
It seems that the use of weight-loss supplements containing 9-CLA, CLA or both as mixture is worrying, because most of the clinical studies presented in the previous sections provide mostly neutral or inconclusive results with very few favorable impacts Table 5.
In association with this, a few studies reported some adverse effects such as oxidative stress, insulin resistance, gastrointestinal irritation, etc. Many studies showed increase in the plasma concentration of CLA, which was directly proportional to the quantity of CLA consumed [ 23 , ].
Therefore, the immediate expected biological effect is oxidative stress. Oxidative stress is the reflection of an imbalance between the systemic manifestation of reactive oxygen species and the ability of the body system to readily detoxify them or to repair the resulting damage imparted to cell components like proteins, lipids and nucleic acids.
Prolonged oxidative stress may lead to cancer and heart diseases [ ]. Supplementation with CLA dramatically increased the rates of oxidative stress, to the levels considerably higher than that observed in heavy smokers [ 60 ]; it also enhanced the release of inflammatory biomarkers in obese men [ 60 ].
Long-term CLA supplementation studies lasting for one and two years have found to be well tolerated, but there was an increase in circulatory markers of inflammation such as CRP, TNFs, and ILs [ 59 , ].
Changes in these markers of inflammation and oxidative stress could be related to the increase in insulin resistance associated with the risk of cardiovascular disease [ 79 , ]. Administration of CLA 4. Insulin resistance is a physiological disorder, under which the cells fail to respond to the normal actions of the hormone insulin, though it is sufficiently produced by the body — this impairment leads to hyperglycemia i.
Decreased sensitivity or resistance towards insulin upon consumption of CLA was observed in some studies [ 60 , 65 ]. Furthermore, insulin resistance is closely related to the impairment decrease of the expression of glucose transporter-4 GLUT4 , a membrane transporter of glucose.
It was proven beyond doubt that CLA decreases the expression of GLUT4 [ ], which shows that indiscriminate use of CLA to treat obesity would lead to type 2 diabetes as the immediate side effect, this would further damage blood vessels and thereby increased risk of CVD [ ].
Moreover, unutilized insulin due to resistance in plasma can contribute to increased appetite especially for carbohydrates and sugary foods , which would add to the gravity of CVD. A few studies showed mild irritations of intestinal tract such as irritation [ 60 ], laxative effects and flatulence [ 47 ], gas bloating [ 20 ], indigestion, diarrhea and nausea [ 36 , 48 ] in subjects consumed CLA.
Most of these effects were considered as mild to moderate and were transient; and one may assume that these effects may be due to the capsule material or the oily nature of the substance or initial adaptive problem with the lipid nutrient. Consumption of commercial CLA reduced the fat content in cows [ ].
Since milk is the only source of nutrients for infants, decreased milk fat in lactating humans is another concern regarding the CLA consumption.
Masters et al. However, another two human studies found no changes in milk fat or protein [ , ], but in these studies, the intervention period was too short about a wk to arrive at a conclusive result. General view on CLAs is that the 10 - CLA exerts specific effects on adipocytes and liver, whereas both the 9- and CLAs appear to be active in inhibiting carcinogenesis [ 14 ].
It is likely that the inconsistent and often contradictory results on the effectiveness of CLA consumption in human health could be the outcome of a number of factors, including differences in subject groups, age, quantity and duration of CLA intake, composition of CLA mixture, purity of CLA, acceptance of the CLA by the body, food intake, gender and racial differences, genetic polymorphism and also the executed measurements parameters studied for assessing the effect.
Moreover, crucial factors that impact research outcomes include the nature of control supplement placebo , and study design cross-over vs. non cross-over designs , because, the efficacy of CLA supplements remains inconsistent in cross-over and non cross-over randomized clinical studies [ ].
Determination of a normal CLA content in the blood plasma could help in estimating if a person consumes satisfactory amounts of CLA with the diet, and thus takes advantage of its potential beneficial effects on health. The only CLA isomer that appears in higher percentage than the detection limit 0.
The duration of this study was 6 months, and in the last group who consumed CLA supplement, the average CLA content in plasma was 0. The blood samples were collected for analysis in the morning in the fasted state after a 12 h restriction for meal and drinks.
Thus, individuals who have 9-CLA levels in their blood plasma within the range up to 0. In most of the clinical studies, vegetable oils such as sunflower oil, olive oil, safflower oil and soybean oil Table 2 have been used as placebo in the form of capsules or pills [ 49 , 66 , 90 ].
In fact, the proportion of MUFA and PUFA, especially LA present in these placebo oils for instance, the predominantly used sunflower and olive oils are not properly addressed by the researchers. According to WHO Codex International food standards , sunflower oil, soybean oil, olive oil and safflower oil contained significant levels of MUFA and PUFA, which include OA, LA and ALA Table 6 [ , ].
It was thought that VA is the only precursor of CLA in humans. However, non-ruminal bacteria inhabiting human gastro-intestinal GI tract like Lactobacillus acidophilus and L. casei isolated from intestine [ ], Bifidobacterium bifidum and B. breve isolated from the fecal matter of neonates [ ], and Ruberia spp.
isolated from intestine [ ] could efficiently produce 9-CLA from LA, probably though the mediation of VA in tissues or hydroxy octadeceinoic acid [ ], as occurring in ruminal biohydorgenation. In addition to 9-CLA, Lactobacillus spp.
also synthesizes CLA and trans -9, trans- CLA [ ]. From this, it is evident that a portion of LA in placebo oil would be biohydogenated by the bacteria residing in GI tract as in rumen into CLA through the mediation of VA.
Irrespective of this fact, most of the clinical studies use the aforesaid vegetable oils as placebo, neglecting their effects on human health; especially their supposed supplementary and complementary effects. The dietary intake of the precursor VA was found to have some major effects on heart health, blood lipid profile and immunity, and also protective against fatal ischemic heart disease [ — ].
This would lead to the misinterpretation of the results, i. Therefore, during clinical studies, the composition of FA in placebo and its effects on human health need to be addressed with due respect, and independently for getting reliable results. The clinical studies with CLA lack a common protocol for selecting the subjects.
Description of the subjects including gender and age, medical treatments given prior to intervention are the critical factors to be considered while selecting the subjects.
Medical history of the subjects should also be recorded before concluding the safety and efficacy concerns of CLA consumption. In most of the studies, the subjects selected were categorized and designated as normal, healthy obese, with metabolic syndrome, with insulin resistance, etc.
This arbitrary classification for the convenience of the investigator poses a question i. Is it with the designation normal, obese, immune-compromised subjects with metabolic syndrome or with other diseases?
Another factor to be considered in clinical studies is the continental, racial and gender differences among the subjects; for instance, literature shows that most of the clinical studies on CLA were performed in North America and Europe.
Spermatogenesis Isotonic drink comparisons a umbalances reaction dependent to harmony Diabetic coma awareness gonadotropins and steroid CCLA activities. Aand linoleic acid is a group of long chain unsaturated Isotonic drink comparisons acids of a imbaalances bound which are found in dairy products, beef imbalanecs lamb. Ans Isotonic drink comparisons of this study hormobal determination of effect of various CLA doses on hormones and systemic factors of various CLA doses on hormones and systemic and local factors which affect spermatogenesis. Fifty mature male mice were divided in five groups T 0 : control, T 1 : placebo and T 2 -T 4 : treatment groups. Each group had two replications with four mice in each replication. After 30 days, blood samples were taken and level of FSH, LH and testosterone hormones were measured. CLA increased testosterone, LH and FSH level significantly in T 3 and T 4 groups.
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