The Combination of Dietary Conjugated Linoleic Acid and Treadmill Exercise Lowers Gain in Body Fat Mass and Enhances Lean Body Mass in High Fat–Fed Male Balb/C Mice

A standardized herbal combination of Astragalus membranaceus and Paeonia japonica promotes skeletal muscle hypertrophy in a treadmill exercise mouse model

Background

Maintaining a normal range of muscle mass and function is crucial not only for sustaining a healthy life but also for preventing various disorders. Numerous nutritional or natural resources are being explored for their potential muscle hypertrophic properties.

Aim

We aimed to evaluate the muscle hypertrophic effects of APX, a 1:1 mixture of Astragalus membranaceus and Paeonia japonica. In addition to the myotube differentiation cell assay, we utilized a weighted exercise-based animal model and evaluated changes in muscle hypertrophy using dual-energy X-ray absorptiometry (DXA) and histological analysis.

Results

The 8-week treadmill exercise led to notable decreases in body weight and fat mass but an increase in muscle mass compared to the control group. Administration of APX significantly accelerated muscle mass gain (p < 0.05) without altering body weight or fat mass compared to the exercise-only group. This muscle hypertrophic effect of APX was consistent with the histologic size of muscle fibers in the gastrocnemius (p > 0.05) and rectus femoris (p < 0.05), as well as the regulation of myogenic transcription factors (MyoD and myogenin), respectively. Furthermore, APX demonstrated a similar action to insulin-like growth factor 1, influencing the proliferation of C2C12 myoblast cells (p < 0.01) and their differentiation into myotubes (p < 0.05) compared to the control group.

Conclusion

The present study provides experimental evidence that APX has muscle hypertrophic effects, and its underlying mechanisms would involve the modulation of MyoD and myogenin.

Mixed conjugated linoleic acid sex-dependently reverses high-fat diet-induced insulin resistance via the gut-adipose axis

Conjugated linoleic acid (CLA) may prevent the development of obesity and metabolic disorders. However, the effects of CLA on inflammation and glucose metabolism are controversial. The underlying mechanisms governing the gut microbiota and sexual dimorphisms have also not been elucidated. The present study assessed the effect of CLA on glucose and lipid metabolism in established obesity and examined the mechanism of action based on gut microbiota. Four-week-old C57BL/6J mice were fed a high-fat diet (HFD) for 10 weeks to induce obesity. The diet-induced obese (DIO) mice were fed an HFD supplemented with mixed CLA (50% cis-9, trans-11 isomer and 50% trans-10, cis-12 isomers, 0.2% wt/wt) for 15 weeks. CLA supplementation remarkably reversed body weight in both sexes. CLA favored anti-inflammatory microbiota in male mice, mediating increased short-chain fatty acids and decreased lipopolysaccharide (LPS) production, which alleviated global inflammation and improved insulin sensitivity via inhibition of the TLR4-NF-κB pathway in adipose tissue. CLA promoted the growth of hydrogen sulfide-producing Desulfovibrio and the release of LPS in female mice, which aggravated adipose inflammation and insulin resistance. Although CLA impaired glucose metabolism in females, brown adipose tissue was significantly activated with browning of white adipose tissue in both sexes, which led to enhanced energy expenditure. Fecal transplantation from CLA-treated mice to DIO mice mimicked the sex-dependent phenotype. In conclusion, CLA decreased body weight and increased energy expenditure but sex-dependently modulated insulin resistance via the gut-adipose axis.

The Effect of Treadmill Treatment on Oxidative Stress Markers and Endogenous Antioxidant Status in Obesity Mice

AIM:

This study aimed to determine the effect of treadmill treatment on oxidative stress markers and endogenous antioxidant status seen from MDA, GSH, MnSOD enzyme specific activity and blood catalase of obese mice.

MATERIALS AND METHODS:

This research is experimental laboratory research using post-test control design group only. The study lasted for 28 days and was divided into 4 groups of study, i.e., group K (normal control), KP (obesity control), P1 (obesity mice with 1 x 10-minute treadmill treatment a day), and P2 (obesity mice with 2 x 10-minute treadmill treatment a day).

RESULTS:

The treadmill treatment had an effect on the improvement of the oxidative status of mice with a decrease of MDA level of obesity mice blood (p ≤ 0.05) compared to KP control. An elevated endogenous antioxidant status of obesity mice was seen from elevated GSH levels, MnSOD specific activity and blood catalase of obesity mice (p ≤ 0.05) compared with KP controls. Treatment of 1 x 10-minute treadmill per day decreased blood MDA level, increased GSH enzyme and increased specific activity of MnSOD enzyme and blood catalase of obese mice.

CONCLUSIONS:

The 2 x 10-minute daily treadmill did not differ significantly in improving the oxidative status and endogenous antioxidant status compared with the treadmill 1 x 10 minutes a day (p ≥ 0.05).

Adaptations of Skeletal Muscle Mitochondria to Obesity, Exercise, and Polyunsaturated Fatty Acids

Mitochondria intricately modulate their energy production through the control of mitochondrial adaptation (mitochondrial biogenesis, fusion, and/or fission) to meet energy demands. Nutrient overload may result in dysregulated mitochondrial biogenesis, morphology toward mitochondrial fragmentation, and oxidative stress in the skeletal muscle. In addition, physical activity and diet components influence mitochondrial function. Exercise may stimulate mitochondrial biogenesis and promote mitochondrial fusion/fission in the skeletal muscle. Moreover, some dietary fatty acids, such as n-3 polyunsaturated fatty acids and conjugated linoleic acid, have been identified to positively regulate mitochondrial adaptation in the skeletal muscle. This review discusses the association of mitochondrial impairments and obesity, and presents an overview of various mechanisms of which exercise training and mitochondrial nutrients promote mitochondrial function in the skeletal muscle.

Paternal exercise protects mouse offspring from high-fat-diet-induced type 2 diabetes risk by increasing skeletal muscle insulin signaling

Paternal obesity increases, while paternal exercise decreases, offspring obesity and type 2 diabetes (T2D) risk; however, no studies have determined whether a paternal high-fat (HF) diet and exercise interact to alter offspring body weight (BW), adiposity and T2D risk. Three-week-old male C57BL/6 mice were fed a normal-fat (NF) diet (16% fat) or an HF diet (45% fat) and assigned to either voluntary wheel running exercise or cage activity for 3 months prior to mating with NF-diet-fed dams. After weaning, male offspring were fed an NF or HF diet for an additional 3 months. F1 male mice whose fathers ate an HF diet had decreased % body fat accompanied by decreased gene expression of beige adipocyte marker FGF21. However, paternal HF-diet-induced reductions in F1 offspring % body fat normalized but did not reduce T2D risk. Exercise was protective against paternal HF-diet-induced insulin resistance by increasing the expression of insulin signaling (GLUT4, IRS1 and PI3K) markers in skeletal muscle resulting in normal T2D risk. When fathers were fed an HF diet and exercised, a postnatal HF diet increased beiging (PPARγ). Thus, these findings show that increases in T2D risk in male offspring when the father consumes an HF diet can be normalized when the father also exercises preconception and that this protection may occur by increases in insulin signaling potential within offspring skeletal muscle. Future studies should further determine the physiological mechanism(s) underlying the beneficial effects of exercise through the paternal lineage.

Exercise-induced adaptations to white and brown adipose tissue

The beneficial effects of exercise on skeletal muscle and the cardiovascular system have long been known. Recent studies have focused on investigating the effects of exercise on adipose tissue and the effects that these exercise-induced adaptations have on overall metabolic health. Examination of exercise-induced adaptations in both white adipose tissue (WAT) and brown adipose tissue (BAT) has revealed marked differences in each tissue with exercise. In WAT, there are changes to both subcutaneous WAT (scWAT) and visceral WAT (vWAT), including decreased adipocyte size and lipid content, increased expression of metabolic genes, altered secretion of adipokines and increased mitochondrial activity. Adaptations specific to scWAT include lipidomic remodeling of phospholipids and, in rodents, the beiging of scWAT. The changes to BAT are less clear: studies evaluating the effect of exercise on the BAT of humans and rodents have revealed contradictory data, making this an important area of current investigation. In this Review, we discuss the exercise-induced changes to WAT and BAT that have been reported by different studies and highlight the current questions in this field.

Influence of trans fatty acids on glucose metabolism in soleus muscle of rats fed diets enriched in or deprived of linoleic acid

PURPOSE

Industrial trans fatty acid (TFA) intake leads to impaired glucose metabolism. However, the overall effects reported are inconsistent and vary with the dietary FA composition and TFA isomer type and levels. We investigated TFA effects on glucose uptake, incorporation and oxidation, and glycogen synthesis in incubated soleus muscle under basal conditions or after treatment with insulin and/or palmitate.

METHODS

Male Wistar rats were fed either linoleic acid (LA)-enriched (⁺LA) or LA-deprived (^-LA) diet, supplemented (⁺LA + TFA or ^-LA + TFA) or not with TFA, for 60 days. Soleus muscle glucose metabolism was assessed in the absence or presence of insulin and/or palmitic acid.

RESULTS

Under basal conditions, TFA enhanced glucose uptake and oxidation regardless of the LA status. Both TFA-supplemented groups had lower insulin response to glucose metabolism. Under insulin-stimulated conditions, TFA prevented the palmitate inhibition of muscle glucose uptake and metabolism in the ⁺LA + TFA group.

CONCLUSION

Dietary TFA enhanced glucose utilization in incubated soleus muscle under basal conditions and prevented the palmitate-induced inhibition in insulin-stimulated conditions. However, TFA reduced the insulin response to glucose uptake and metabolism. The effects mentioned above were influenced by the FA profile modifications induced by the dietary LA levels, suggesting that lipid metabolization and incorporation into plasma membrane are important determining factors of glucose metabolism and insulin sensitivity.

Conjugated linoleic acid supplementation does not maximize motor performance and abdominal and trunk fat loss induced by aerobic training in overweight women

ABSTRACT Objective: To analyze the effect of eight weeks of conjugated linoleic acid supplementation on physical performance, and trunk and abdominal fat in overweight women submitted to an aerobic training program. Methods: Twenty-eight overweight women (body mass index ³25 kg/m2) were divided randomly and double-blindly to receive conjugated linoleic acid or placebo, both associated with an aerobic exercise program (frequency = three times a week, duration=30 min/session, intensity=80% of maximum heart rate). Conjugated linoleic acid (3.2 g) and placebo (4.0 g) supplements were consumed daily (four capsules) for eight weeks. Maximum speed and time to exhaustion were determined in incremental treadmill test. Trunk fat was estimated by dual-energy X-Ray absorptiometry. Waist circumference was used as indicator of abdominal fat. Results: Main effect of time (p<0.05) showed increased maximum speed (conjugated linoleic acid=+6.3% vs. placebo=+7.5%) and time to exhaustion (conjugated linoleic acid=+7.1% vs. placebo=+8.6%) in the incremental treadmill test, with no differences between the groups (p>0.05). Similarly, significant reductions (p<0.05) in trunk fat (conjugated linoleic acid=-1.7% vs. placebo=-1.5%) and abdominal fat (conjugated linoleic acid=-4.7% vs. placebo=-4.0%) were found after eight weeks of intervention, with no differences between the groups (p>0.05). Conclusion: The results of this study suggest that conjugated linoleic acid supplementation does not maximize motor performance, and loss of body and abdominal fat induced by aerobic training in overweight women.

Impact of Conjugated Linoleic Acid (CLA) on Skeletal Muscle Metabolism

Conjugated linoleic acid (CLA) has garnered special attention as a food bioactive compound that prevents and attenuates obesity. Although most studies on the effects of CLA on obesity have focused on the reduction of body fat, a number of studies have demonstrated that CLA also increases lean body mass and enhances physical performances. It has been suggested that these effects may be due in part to physiological changes in the skeletal muscle, such as changes in the muscle fiber type transformation, alteration of the intracellular signaling pathways in muscle metabolism, or energy metabolism. However, the mode of action for CLA in muscle metabolism is not completely understood. The purpose of this review is to summarize the current knowledge of the effects of CLA on skeletal muscle metabolism. Given that CLA not only reduces body fat, but also improves lean mass, there is great potential for the use of CLA to improve muscle metabolism, which would have a significant health impact.

Orchidectomy-induced alterations in volumetric bone density, cortical porosity and strength of femur are attenuated by dietary conjugated linoleic acid in aged guinea pigs

Age-related osteoporosis and sarcopenia are ascribed in part to reductions in anabolic hormones. Dietary conjugated linoleic acid (CLA) improves lean and bone mass, but its impact during androgen deficiency is not known. This study tested if CLA would attenuate the effects of orchidectomy (ORX)-induced losses of bone and lean tissue. Male guinea pigs (n=40; 70-72 weeks), were randomized into four groups: (1) SHAM+Control diet, (2) SHAM+CLA diet, (3) ORX+Control diet, (4) ORX+CLA diet. Baseline blood sampling and dual-energy X-ray absorptiometry (DXA) scans were conducted, followed by surgery 4 days later with the test diets started 7 days after baseline sampling. Serial blood sampling and DXA scans were repeated 2, 4, 8 and 16 weeks on the test diets. Body composition and areal BMD (aBMD) of whole body, lumbar spine, femur and tibia were measured using DXA. At week 16, muscle protein fractional synthesis rate (FSR), volumetric BMD (vBMD), microarchitecture and bone strength were assessed. Body weight declined after SHAM and ORX surgery, with slower recovery in the ORX group. Dietary CLA did not affect weight or lean mass, but attenuated gains in fat mass. Lean mass was stable in SHAM and reduced in ORX by 2 weeks with whole body and femur bone mineral content (BMC) reduced by 4 weeks; CLA did not alter BMC. By week 16 ORX groups had lower free testosterone and myofibrillar FSR, yet higher cortisol, osteocalcin and ionized calcium with no alterations due to CLA. ORX+Control had higher prostaglandin E2 (PGE2) and total alkaline phosphatase compared to SHAM+Control whereas ORX+CLA were not different from SHAM groups. Femur metaphyseal vBMD was reduced in ORX+CTRL with the reduction attenuated by CLA. Femur cortical thickness (Ct.Th.) and biomechanical strength were reduced and cortical porosity (Ct.Po.) elevated by ORX and attenuated by CLA. This androgen deficient model with a sarcopenic-osteoporotic phenotype similar to aging men responded to dietary CLA with significant benefits to femur density and strength.

Conjugated linoleic Acid prevents ovariectomy-induced bone loss in mice by modulating both osteoclastogenesis and osteoblastogenesis

Postmenopausal osteoporosis due to estrogen deficiency is associated with severe morbidity and mortality. Beneficial effects of conjugated linoleic acid (CLA) on bone mineral density (BMD) have been reported in mice, rats and humans, but the effect of long term CLA supplementation against ovariectomy-induced bone loss in mice and the mechanisms underlying this effect have not been studied yet. Eight-week old ovariectomized (Ovx) and sham operated C57BL/6 mice were fed either a diet containing 0.5 % safflower oil (SFO) or 0.5 % CLA for 24 weeks to examine BMD, bone turn over markers and osteotropic factors. Bone marrow (BM) cells were cultured to determine the effect on inflammation, osteoclastogenesis, and osteoblastogenesis. SFO/Ovx mice had significantly lower femoral, tibial and lumbar BMD compared to SFO/Sham mice; whereas, no difference was found between CLA/Ovx and CLA/Sham mice. CLA inhibited bone resorption markers whereas enhanced bone formation markers in Ovx mice as compared to SFO-fed mice. Reverse transcriptase polymerase chain reaction and fluorescence activated cell sorting analyses of splenocytes revealed that CLA inhibited pro-osteoclastogenic receptor activator of NF-κB (RANKL) and stimulated decoy receptor of RANKL, osteoprotegerin expression. CLA also inhibited pro-inflammatory cytokine and enhanced anti-inflammatory cytokine production of lipopolysaccharide-stimulated splenocytes and BM cells. Furthermore, CLA inhibited osteoclast differentiation in BM and stimulated osteoblast differentiation in BM stromal cells as confirmed by tartrate resistant acid phosphatase and Alizarin Red staining, respectively. In conclusion, CLA may prevent postmenopausal bone loss not only by inhibiting excessive bone resorption due to estrogen deficiency but also by stimulating new bone formation. CLA might be a potential alternative therapy against osteoporotic bone loss.

Exercise protects against diet-induced insulin resistance through downregulation of protein kinase Cβ in mice

Physical exercise is an important and effective therapy for diabetes. However, its underlying mechanism is not fully understood. Protein kinase Cβ (PKCβ) has been suggested to be involved in the pathogenesis of obesity and insulin resistance, but the role of PKCβ in exercise-induced improvements in insulin resistance is completely unknown. In this study, we evaluated the involvement of PKCβ in exercise-attenuated insulin resistance in high-fat diet (HFD)-fed mice. PKCβ(-/-) and wild-type mice were fed a HFD with or without exercise training. PKC protein expression, body and tissue weight change, glucose and insulin tolerance, metabolic rate, mitochondria size and number, adipose inflammation, and AKT activation were determined to evaluate insulin sensitivity and metabolic changes after intervention. PKCβ expression decreased in both skeletal muscle and liver tissue after exercise. Exercise and PKCβ deficiency can alleviate HFD-induced insulin resistance, as evidenced by improved insulin tolerance. In addition, fat accumulation and mitochondrial dysfunction induced by HFD were also ameliorated by both exercise and PKCβ deficiency. On the other hand, exercise had little effect on PKCβ(-/-) mice. Further, our data indicated improved activation of AKT, the downstream signal molecule of insulin, in skeletal muscle and liver of exercised mice, whereas PKCβ deficiency blunted the difference between sedentary and exercised mice. These results suggest that downregulation of PKCβ contributes to exercise-induced improvement of insulin resistance in HFD-fed mice.

Endurance exercise and conjugated linoleic acid (CLA) supplementation up-regulate CYP17A1 and stimulate testosterone biosynthesis

A new role for fat supplements, in particular conjugated linoleic acid (CLA), has been delineated in steroidogenesis, although the underlying molecular mechanisms have not yet been elucidated. The aims of the present study were to identify the pathway stimulated by CLA supplementation using a cell culture model and to determine whether this same pathway is also stimulated in vivo by CLA supplementation associated with exercise. In vitro, Leydig tumour rat cells (R2C) supplemented with different concentrations of CLA exhibited increasing testosterone biosynthesis accompanied by increasing levels of CYP17A1 mRNA and protein. In vivo, trained mice showed an increase in free plasma testosterone and an up-regulation of CYP17A1 mRNA and protein. The effect of training on CYP17A1 expression and testosterone biosynthesis was significantly higher in the trained mice supplemented with CLA compared to the placebo. The results of the present study demonstrated that CLA stimulates testosterone biosynthesis via CYP17A1, and endurance training led to the synthesis of testosterone in vivo by inducing the overexpression of CYP17A1 mRNA and protein in the Leydig cells of the testis. This effect was enhanced by CLA supplementation. Therefore, CLA-associated physical activity may be used for its steroidogenic property in different fields, such as alimentary industry, human reproductive medicine, sport science, and anti-muscle wasting.

Fish oil has beneficial effects on allergen-induced airway inflammation and hyperreactivity in mice

Background

Fish oil (FO) is rich in n-3 polyunsaturated fatty acids (PUFA), which have been suggested to be anti-inflammatory and are associated with improvement of several inflammatory diseases. In this study, we investigated the influence of FO on allergen-induced lung inflammation and airway hyperreactivity in mice.

Methods

Male A/J mice were fed either a standard-chow (SC) or a FO diet (FO) for 8 weeks. After 4 weeks, each group was further randomized for ovalbumin (SC-OVA and FO-OVA) or saline (SC-SAL and FO-SAL) challenge. Resistance and elastance were measured at baseline and after aerosolized methacholine, 24h after the last challenge. Bronchoalveolar lavage (BAL) was performed for leukocyte counts. Lung tissue mucus deposition, peribronchiolar matrix deposition and eosinophil infiltration were quantified. Serum immunoglobulin E (IgE) and IgG1 (ref 2.2), lung IL-4, IL-5, IL-10, IL-13, IL-17, INFγ and eotaxin-1 and 2 were detected by ELISA and nuclear factor kappa B (NFκB), GATA-3 and peroxisome proliferator-activated receptor gamma (PPARγ) expression was measured by Western blot.

Results

Levels of serum IgE and IgG1 were significantly higher in OVA sensitized mice. OVA challenge resulted in increased eosinophil infiltration, increased inflammatory cytokine production, peribronchiolar matrix and mucus deposition and airway hyperreactivity to aerosolized methacholine. Elevated lung NFκB and GATA-3 expression was noted in OVA-challenged mice. These changes were attenuated in mice fed with FO diet. Higher PPARγ expression was also detected in the lungs from the FO-fed groups.

Conclusion

Our results demonstrate that FO intake attenuated classical asthma features by suppressing the systemic sensitization, thus providing evidence that FO might be a prophylactic alternative for asthma prevention.

Effects of dietary conjugated linoleic acid and biopolymer encapsulation on lipid metabolism in mice

Forty mice were randomly divided into four groups on the basis of the diet to be fed as follows: 5% (low) fat diet (T1: LF); 20% (high) fat diet (T2: HF); 20% fat containing 1% conjugated linoleic acid (CLA) (T3: HFC); and 20% fat containing 1% CLA with 0.5% biopolymers (T4: HFCB). The high-fat with CLA diet groups (HFC and HFCB) and the low-fat diet group (LF) tended to have lower body weights and total adipose tissue weights than those of the high-fat diet group (HF). Serum leptin and triglyceride were significantly lower in the high fat with CLA-fed groups (HFC and HFCB) and the low-fat diet group (LF) than those in the high-fat diet group (HF). It is noteworthy that the high-fat with CLA and biopolymers group (HFCB) showed the lowest serum triglyceride and cholesterol concentrations. In the high-fat-fed group (HF), voluntary travel distance as a measure of physical activity decreased after three weeks of feeding. However, the CLA-fed groups showed increased physical activity. The groups fed high-fat diets supplemented with CLA alone and with CLA and biopolymers had higher viscosity of small intestinal contents than that in the low- and high-fat dietary groups.

Effect of conjugated linoleic acid on testosterone levels in vitro and in vivo after an acute bout of resistance exercise

The purposes of the present study were to investigate the effect of conjugated linoleic acid (CLA) supplementation on testosterone levels in vitro on a cell line derived from Leydig cells (R2C) and in vivo in the blood of physically active subjects before and after a resistance exercise bout. In vitro R2C cells were treated with different CLA concentrations (0-30 μM) for 24 and 48 hours. After treatment, supernatant media were tested to determine testosterone secretion. The CLA increased the testosterone secretion only after 48 hours. In vivo, 10 resistance-trained male subjects, in a double-blind placebo-controlled and crossover study design were randomized for 3 weeks of either 6 g·d⁻¹ CLA or placebo. Blood was drawn pre and post each resistance exercise bout to determine the total testosterone and sex hormone-binding globulin (SHBG) levels. No significant differences were observed for total testosterone or SHBG pre and post each resistance exercise bout; although after the resistance exercise bouts, total testosterone increased moderately (effect size = moderate), whereas after CLA supplementation, there was a large increase in total testosterone (effect size = large). CLA supplementation induced an increase in testosterone levels in Leydig cells in vitro after 48 hours but not in vivo before and after a resistance exercise bout. These findings suggest that CLA supplementation may promote testosterone synthesis through a molecular pathway that should be investigated in the future, although this effect did not have an anabolic relevance in our in vivo model.

Dietary coral calcium and zeolite protects bone in a mouse model for postmenopausal bone loss

In patients diagnosed with osteoporosis, calcium is lost from bones making them weaker and easily susceptible to fractures. Supplementation of calcium is highly recommended for such conditions. However, the source of calcium plays an important role in the amount of calcium that is assimilated into bone. We hypothesize that naturally occurring coral calcium and zeolite may prevent ovariectomy-induced bone loss. We have measured bone loss in ovariectomized mice supplemented with coral calcium and Zeolite. Female C57BL/6 mice were either sham-operated or ovariectomized and fed diets containing coral calcium or zeolite for 6 months. Serum was analyzed for bone biochemical markers and cytokines. Bones were analyzed using dual x-ray absorbtiometry, peripheral quantitative computed tomography, and micro-computed tomography densitometry. In the distal femoral metaphysis, total bone and cortical bone mass was restored and the endocortical surface was significantly decreased in coral calcium and zeolite fed ovariectomized (OVX) mice. Trabecular number and the ratio of bone volume to total volume was higher in OVX mice after coral calcium and zeolite feeding, while trabecular separation decreased in the different treatment OVX groups. Coral calcium protected bone to a lesser extent in the proximal tibia and lumbar vertebrae. Overall, coral calcium and zeolite may protect postmenopausal bone loss.

Implication of conjugated linoleic acid (CLA) in human health

Conjugated linoleic acid (CLA) has drawn significant attention in the last two decades for its variety of biologically beneficial effects. CLA reduces body fat, cardiovascular diseases and cancer, and modulates immune and inflammatory responses as well as improves bone mass. It has been suggested that the overall effects of CLA are the results of interactions between two major isomers, cis-9,trans-11 and trans-10,cis-12. This review will primarily focus on current CLA publications involving humans, which are also summarized in the tables. Along with a number of beneficial effects of CLA, there are safety considerations for CLA supplementation in humans, which include effects on liver functions, milk fat depression, glucose metabolism, and oxidative stresses.

Effect of conjugated linoleic acid supplementation on weight loss and body fat composition in a Chinese population

OBJECTIVE

Conjugated linoleic acid (CLA) has several benefits, including body fat reduction, as proved in animals. However, the results of CLA-induced body composition alterations in humans are inconsistent, and no related data are available for Chinese populations. This study aimed to determine whether CLA affects body weight (BW) loss and body composition of overweight and obese Chinese subjects.

METHODS

In this randomized, double-blind, placebo-controlled trial, subjects with a body mass index (BMI) of 24 to 35 kg/m(2) randomly received 1.7 g of cis-9,trans-11 and trans-10,cis-12 CLA (n = 30) or placebo (salad oil; n = 33) in 200 mL of sterilized milk twice daily for 12 wk. Changes in body composition were determined by bioimpedance measurements.

RESULTS

Sixty-three subjects completed the study (CLA, n = 30). After 12 wk, compared with the baseline, the BW, BMI, total fat mass, fat percentage, subcutaneous fat mass, and waist-to-hip ratio decreased in the CLA group (P < 0.05). The CLA group was stratified by BMI and gender. The BW, BMI, subcutaneous fat mass, and waist-to-hip ratio decreased in 27 subjects with a BMI ≥ 27, and these indices, except subcutaneous fat mass, were lower in female subjects. The levels of total cholesterol, triacylglycerol, low-density lipoprotein, and plasma fasting glucose increased, whereas those of high-density lipoprotein decreased after 3 mo of CLA treatment. The changes were not significantly different from the baseline values.

CONCLUSION

The supplementation of CLA for 12 wk in overweight and grade I obese Chinese subjects yielded lower obesity indices, with no obvious adverse effects.

Conjugated linoleic acid combined with physical activity reduces body fat accumulation but does not modify lean body mass in male and female Wistar rats

Several biological and clinical studies have suggested that conjugated linoleic acid (CLA) prevents body fat accumulation and increases lean body mass. CLA is available as a concentrated dietary supplement and is purported to provide the aforementioned benefits for people who perform physical activity. This study was conducted to evaluate the effect of a CLA-supplemented diet combined with physical activity on the body composition of Wistar rats. Two groups of Wistar rats of both sexes, between 45 and 60 days old, were fed a diet containing 5.5% soybean oil (control group) or a CLA-supplemented diet (0.5% CLA and 5.0% soybean oil) (test group). Half the rats in both groups were assigned to exercise by running on a treadmill. The biochemical and anatomical body compositions were analyzed. In both groups, CLA had no effect on the dietary consumption or the weight of the liver, heart, and lungs. However, it did influence the overall weight gain of exercised male rats and the chemical and anatomical body composition in exercised and sedentary rats of both sexes. The results confirm that a CLA-supplemented diet with and without physical activity reduced body fat accumulation in rats of both sexes. However, there is no evidence of an increase in the lean body mass of the exercised rats.

Ácido linoléico conjugado: efeitos no perfil lipídico e na composição corporal de camundongos exercitados

Objetivo: Avaliar os efeitos do CLA associado à dieta hiperlipídica sobre o perfil lipídico e composição corporal de camundongos knockout para o gene da ApoE exercitados. Métodos: 32 camundongos foram divididos e submetidos à dieta normo e hiperlipídica suplementadas ou não com 1% de CLA. Todos realizaram exercício físico em esteira, durante 12 semanas. Utilizou-se o teste de Kruskal-Wallis ao nível de significância de 5%. Resultados: Os animais que ingeriram dieta hiperlipídica com CLA aumentaram o colesterol total e o LDL, comparado com os alimentados com dieta normolipídica associada ou não ao CLA. Observou-se aumento no ganho de peso dos camundongos que ingeriram dieta hiperlipídica com CLA, comparado com os normolipídicos suplementados com CLA. Conclusões: O CLA na concentração de 1% não alterou nenhum dos parâmetros analisados, independente da dieta, e não foi protetor contra os efeitos da dieta hiperlipídica.

t10c12-CLA maintains higher bone mineral density during aging by modulating osteoclastogenesis and bone marrow adiposity

Conjugated linoleic acid (CLA) has been shown to positively influence calcium and bone metabolism. Earlier, we showed that CLA (equal mixture of c9t11-CLA and t10c12-CLA) could protect age-associated bone loss by modulating inflammatory markers and osteoclastogenesis. Since, c9t11-CLA and t10c12-CLA isomers differentially regulate functional parameters and gene expression in different cell types, we examined the efficacy of individual CLA isomers against age-associated bone loss using 12 months old C57BL/6 female mice fed for 6 months with 10% corn oil (CO), 9.5% CO + 0.5% c9t11-CLA, 9.5% CO + 0.5% t10c12-CLA or 9.5% CO + 0.25% c9t11-CLA + 0.25% t10c12-CLA. Mice fed a t10c12-CLA diet maintained a significantly higher bone mineral density (BMD) in femoral, tibial and lumbar regions than those fed CO and c9t11-CLA diets as measured by dual-energy-X-ray absorptiometry (DXA). The increased BMD was accompanied by a decreased production of osteoclastogenic factors, that is, RANKL, TRAP5b, TNF-alpha and IL-6 in serum. Moreover, a significant reduction of high fat diet-induced bone marrow adiposity was observed in t10c12-CLA fed mice as compared to that of CO and c9t11-CLA fed mice, as measured by Oil-Red-O staining of bone marrow sections. In addition, a significant reduction of osteoclast differentiation and bone resorbing pit formation was observed in t10c12-CLA treated RAW 264.7 cell culture stimulated with RANKL as compared to that of c9t11-CLA and linoleic acid treated cultures. In conclusion, these findings suggest that t10c12-CLA is the most potent CLA isomer and it exerts its anti-osteoporotic effect by modulating osteoclastogenesis and bone marrow adiposity.

Defining a longitudinal survival model to examine forced treadmill running as a countermeasure for diet-induced weight gain

Diet-induced weight gain increases disease risk via disruption of the innate immune system. Flow cytometry is commonly used to assess the immune system; however, in mice such measurements traditionally require terminal procedures and tissue collection to generate sufficient sample. The present study refined an existing flow cytometry method to reduce the number of mice needed to longitudinally measure monocytes. CD-1 male mice were randomly assigned to one of the three groups: DS (diet-induced weight gain + sedentary), DE (diet-induced weight gain + forced treadmill running [total distance 35,755 ± 1832 m]) or NS (normal weight gain + sedentary). DS and DE consumed a 60% fat diet and NS consumed a 10% fat diet ad libitum. Saphenous vein blood samples were collected weekly for a period of six weeks and three-colour flow cytometry was used to measure changes in monocyte (CD11b(+)/14(+)) concentration and cell-surface toll-like receptor 4 (TLR4) expression. DS (18%) and DE (17%) gained more weight than NS (P < 0.001). On a group basis, DS expressed 17% more TLR4 than DE and NS (P = 0.005). The present study demonstrates that a longitudinal survival model can be used to reduce the number of animals needed to complete flow cytometry experiments. Exercise during diet-induced weight prevented some (decreased monocyte TLR4 expression) but not all aspects of innate immune system function.

trans-10,cis-12-Conjugated linoleic acid instigates inflammation in human adipocytes compared with preadipocytes

We showed previously in cultures of primary human adipocytes and preadipocytes that lipopolysaccharide and trans-10,cis-12-conjugated linoleic acid (10,12-CLA) activate the inflammatory signaling that promotes insulin resistance. Because our published data demonstrated that preadipocytes are the primary instigators of inflammatory signaling in lipopolysaccharide-treated cultures, we hypothesized that they played the same role in 10,12-CLA-mediated inflammation. To test this hypothesis, we employed four distinct models. In model 1, a differentiation model, CLA activation of MAPK and induction of interleukin-8 (IL-8), IL-6, IL-1beta, and cyclo-oxygenase-2 (COX-2) were greatest in differentiated compared with undifferentiated cultures. In model 2, a cell separation model, the mRNA levels of these inflammatory proteins were increased by 10,12-CLA compared with bovine serum albumin vehicle in the adipocyte fraction and the preadipocyte fraction. In model 3, a co-culture insert model, inserts containing approximately 50% adipocytes (AD50) or approximately 100% preadipocytes (AD0) were suspended over wells containing AD50 or AD0 cultures. 10,12-CLA-induced IL-8, IL-6, IL-1beta, and COX-2 mRNA levels were highest in AD50 cultures when co-cultured with AD0 inserts. In model 4, a conditioned medium (CM) model, CM collected from CLA-treated AD50 but not AD0 cultures induced IL-8 and IL-6 mRNA levels and activated phosphorylation of MAPK in naive AD0 and AD50 cultures. Consistent with these data, 10,12-CLA-mediated secretions of IL-8 and IL-6 from AD50 cultures were higher than from AD0 cultures. Notably, blocking adipocytokine secretion prevented the inflammatory capacity of CM from 10,12-CLA-treated cultures. These data suggest that CLA instigates the release of inflammatory signals from adipocytes that subsequently activate adjacent preadipocytes.

Antiobesity mechanisms of action of conjugated linoleic acid

Conjugated linoleic acid (CLA), a family of fatty acids found in beef, dairy foods and dietary supplements, reduces adiposity in several animal models of obesity and some human studies. However, the isomer-specific antiobesity mechanisms of action of CLA are unclear, and its use in humans is controversial. This review will summarize in vivo and in vitro findings from the literature regarding potential mechanisms by which CLA reduces adiposity, including its impact on (a) energy metabolism, (b) adipogenesis, (c) inflammation, (d) lipid metabolism and (e) apoptosis.

Preinfection aerobic treadmill training improves resistance against Trypanosoma cruzi infection in mice

Exercise performed before infections has been linked to improvement of the immune response against infections. The purpose of this study was to evaluate the influence of preinfection moderate-intensity treadmill training on acute Trypanosoma cruzi infection in mice. Ninety-nine female BALB/c mice were divided into 4 groups, as follows: training + infection (T+I) (n = 41); no training + infection (NT+I) (n = 38); training + no infection (T+NI) (n = 10); and no training + no infection (NT+NI) (n = 10). The exercise program for trained groups was carried out on a motorized treadmill for 8 weeks. Infected groups were inoculated with the Y strain of T. cruzi. Infectivity, prepatent period, patent period, parasitemia peak, mortality, survival time, weight, food intake, tumor necrosis factor-alpha serum levels, and peritoneal macrophage hydrogen peroxide production were evaluated. We found that preinfection training induced statistically significant reductions in parasitemia peak (p < 0.03) and weight loss (p < 0.04). However, no statistically significant differences were found for the other parameters evaluated when trained and nontrained infected groups were compared. We conclude that preinfection aerobic training induces some improvement in the immune response to T. cruzi infection in female BALB/c mice.

Efeito da suplementação com ácido linoléico conjugado e do treinamento em natação sobre a composição corporal e os parâmetros bioquímicos de ratos Wistar em crescimento

OBJETIVO: Avaliar os efeitos da suplementação com ácido linoléico conjugado, associada ao treinamento moderado em natação, sobre a composição corporal, o consumo e a eficiência alimentar, a glicemia, o perfil lipídico e o glicogênio muscular e hepático de ratos Wistar. MÉTODOS: Ratos Wistar (30 dias) foram divididos em: sedentário, sedentário suplementado, treinado e treinado suplementado. Permaneceram em gaiolas individuais com comida e água ad libitum, temperatura de 23ºC (com variação de1ºC) e ciclo claro-escuro de 12 horas, durante 8 semanas. A sessão de natação durou 1 hora e foi realizada três vezes/semana, bem como a suplementação com ácido linoléico conjugado a 2%. Após sacrifício, o plasma, os tecidos adiposos brancos e o marrom, o músculo gastrocnêmio e o fígado foram coletados e pesados. RESULTADOS: A suplementação per se não promoveu modificação na ingestão alimentar e na massa corporal dos animais. Houve aumento na glicemia de jejum (p<0,05), nas lipoproteínas de alta densidade (p<0,05), no colesterol total (p<0,05) e redução dos triacilgliceróis. A suplementação associada ao treinamento reduziu a massa corporal (p<0,05) e aumentou o peso relativo do tecido adiposo, do fígado e a glicemia de jejum. CONCLUSÃO: A suplementação com ácido linoléico conjugado associada à prática de exercício físico parece ter influência no balanço energético, mas, por outro lado, o aumento no peso do fígado indica que a ingestão deste ácido graxo pode ter efeitos indesejáveis, aumentando as chances de desenvolvimento do fígado gorduroso. Estes achados apontam perspectivas para novos estudos envolvendo análises histológicas do fígado, expressão gênica de enzimas chaves do metabolismo lipídico e de carboidratos, associados ou não a diferentes protocolos de treinamento físico.

Effects of mild calorie restriction and high-intensity interval walking in middle-aged and older overweight Japanese

We investigated whether a combination of mild calorie restriction (MCR) and high-intensity interval walking (HIW) improved physical fitness more than HIW alone in middle-aged and older overweight Japanese (40-69years old, BMI23.6kg/m(2)). Forty-seven women and 16 men were divided into MCR+HIW and HIW groups. All subjects performed HIW: 5 sets of 3-min low-intensity walking (40% peak aerobic capacity for walking, VO(2peak)) and 3-min high-intensity walking (70% VO(2peak)) per day, 4days per week, for 16weeks while energy expenditure was monitored with a tri-axial accelerometer. The MCR+HIW group consumed meal replacement formula (240kcal): a mixture of low-carbohydrates and -fat and high-protein, for either lunch or dinner everyday and therefore, had approximately 87% of the energy intake of the HIW group during the intervention period. Although the HIW group showed improvements in BMI, blood pressure, and several blood chemicals, the MCR+HIW group had greater improvement. Moreover, the medical expenditure for the 6months including the intervention period was 59% lower in the MCR+HIW group than in the HIW group. Our strategy of a short-term combination of MCR and HIW may thus prevent lifestyle-associated diseases and improve health in middle-aged and older overweight Japanese.

Effect of CLA isomers and their mixture on aging C57Bl/6J mice

BACKGROUND

Dietary supplements containing conjugated linoleic acid (CLA) are widely promoted for weight loss management over the counter. Recently, FDA approved the CLA as Generally Recognized as Safe category so that it can be used in various food and beverages. The combined effect of CLA isomers have been studied extensively in animals and humans, however, the role of individual isomers remains unraveled.

AIM

The present investigation addresses the effects of CLA isomers on body composition and body weight as well as safety using female C57Bl/6J aging mice.

METHODS

Two main CLA isomers and their mixture were fed to 12-months-old female C57Bl/6J mice. Ten percent corn oil (CO) based fat diet supplemented with 0.5% purified cis 9 trans 11 (c9,t11) CLA or trans 10 cis 12 (t10,c12) CLA or their mixture (CLA mix, 50:50) for 6 months. The lean mass, fat mass, glucose, non-esterified fatty acids, and insulin were examined at the end of study.

RESULTS

As a result of 6 months dietary intervention, both t10,c12 CLA and CLA mix groups showed increased lean mass and reduced fat mass compared to that of c9,t11 CLA and CO group. However, insulin resistance and liver hypertrophy were observed in t10,c12 CLA and CLA mix groups based on the results of homeostasis model assessment, revised quantitative insulin-sensitivity check index (R-QUICKI), intravenous glucose tolerance test, and liver histology. Liver histology revealed that increased liver weight was due to hypertrophy.

CONCLUSION

In conclusion, the major CLA isomers have a distinct effect on fat mass, glucose, and insulin metabolism. The t10,c12 isomer was found to reduce the fat mass and to increase the lean mass but significantly contributed to increase insulin resistance and liver hypertrophy, whereas c9,t11 isomer prevented the insulin resistance. Between the two major CLA isomers, the t10,c12 was attributed to reduce fat mass whereas, c9,t11 improves the insulin sensitivity.

Conjugated linoleic acid (CLA) prevents age-associated skeletal muscle loss

In this study, we examined the effect of CLA isomers in preventing age-associated muscle loss and the mechanisms underlying this effect, using 12-months-old C57BL/6 mice fed 10% corn oil (CO) or a diet supplemented with 0.5% c9t11-CLA, t10c12-CLA, or c9t11-CLA+t10c12-CLA (CLA-mix) for 6months. Both t10c12-CLA and CLA-mix groups showed significantly higher muscle mass, as compared to CO and c9t11-CLA groups, measured by dual-energy X-ray absorptiometry and muscle wet weight. Enhanced mitochondrial ATP production, with higher membrane potential, and elevated muscle antioxidant enzymes (catalase and glutathione peroxidase) production, accompanied by slight increase in H(2)O(2) production was noted in t10c12-CLA and CLA-mix groups, as compared to that of CO and c9t11-CLA groups. Oxidative stress, as measured by serum malondialdehyde and inflammation, as measured by LPS-treated splenocyte IL-6 and TNF-alpha, were significantly less in CLA isomers groups. Thus, CLA may be a novel dietary supplement that will prevent sarcopenia by maintaining redox balance during aging.

Beneficial effects of conjugated linoleic acid and exercise on bone of middle-aged female mice

Conjugated linoleic acids (CLA) are a group of polyunsaturated fatty acids that has recently been shown to have several beneficial effects on different diseases, including prevention of bone loss. The important feature of CLA is to reduce fat mass, thereby reducing body weight significantly. Although loss of body weight is known to increase bone loss, there is increasing evidence that CLA maybe beneficial to bone. Another factor that can reduce body weight is exercise (EX). It is well established that moderate EX stimulates bone formation. In this study, we analyzed the changes in bone using pQCT densitometry in middle-aged C57Bl/6 mice fed CLA (0.5%) and/or exercised. Twelve-month-old mice were divided into the following groups: group 1, corn oil, sedentary (CO SED); group 2, corn oil, exercise (CO EX); group 3, CLA, sedentary (CLA SED); and group 4, CLA, exercise (CLA EX). Mice were maintained in the respective experimental regimens for 10 weeks, after which mice were scanned using DEXA and killed. The lumbar vertebrae, femur, and tibia were analyzed using pQCT densitometry. CLA, when given alone or in combination with EX, significantly reduced body weight and increased lean mass. CLA treatment also significantly increased bone mass. Further, additional increase in bone mass was observed in mice treated with a combination of CLA and EX in almost all the bone sites analyzed. We conclude that CLA, when consumed as a dietary supplement along with moderate treadmill EX, significantly increases bone mass in middle-aged female mice.

Different effect of high fat diet and physical exercise in the hippocampal signaling

Obesity is an epidemic disease that may affect brain function. The present study examined the effect of high fat diet (HF) and physical exercise on peripheral tissue and hippocampal signaling. CF-1 mice (n = 4, per cage) were divided into groups receiving high fat (HF) or control (CD) diets for 5 months, with or without voluntary exercise. Serum triacylglycerol, total cholesterol, HDLc, liver triacylglycerol and glycogen concentrations were evaluated (n = 6). Also, the phosphorylation state of the AKT --> ERK 1/2 --> CREB pathway (AKT, pAKTser473, ERK 1/2, pERK 1/2, CREB and pCREB, n = 4-6) was analyzed in the hippocampus. HF diet caused an increase in AKT phosphorylation at ser473 (P < 0.05), while exercise increased the phosphorylation of ERK 1/2 (P < 0.05) and CREB (P < 0.05). As expected, exercise reversed some of the harmful effects of HF, i.e., increased liver deposition of fat (P < 0.05) and fat gain in the abdominal region (P < 0.05). In conclusion, the effects of exercise and HF diet on brain signaling appear to affect the hippocampal AKT --> ERK 1/2 --> CREB pathway in independent ways: HF intake caused increased phosphorylation of AKTser473, while exercise increased ERK 1/2 --> CREB signaling. The physiological relevance of these findings in brain function remains to be elucidated.

Body composition and selected blood parameters in mice fed a combination of fibre and conjugated linoleic acid

Feeding mice conjugated linoleic acid (CLA) reduces body fat. Soluble fibre decreases apparent lipid digestibility. The objective of the present study was to examine whether a combination of dietary CLA and soluble fibre would further decrease the proportion of body fat than a diet with CLA alone. Therefore, we fed mice diets with CLA and different amounts of Nutrim, containing 10% soluble fibre. CLA was added to the control diet at the expense of high oleic acid sunflower oil (HOSF) component and Nutrim was added at the expense of an isoenergetic combination of starch, dextrose and cellulose. The diets were fed for 28 days. Weight gain after 28 days was less in CLA-fed animals than in HOSF-fed animals. Both CLA and Nutrim increased the body water content. CLA reduced total body fat and epidydymal fat but Nutrim did not. No interaction of CLA and fibre was detected. We, therefore, must conclude that under the present experimental conditions dietary CLA and fibre do not interact to reduce body fat deposition.

The Effects of Simultaneous Administration of Dietary Conjugated Linoleic Acid and Telmisartan on Cardiovascular Risks in Rats

Dietary conjugated linoleic acid (CLA) and the antihypertensive drug, telmisartan, have both been shown to modify cardiovascular risks. The effects of a combination of these two agents have, however, not been investigated. This 20 week study sought to assess the therapeutic potential of a CLA/telmisartan co-administration in rats fed a high-fructose high-fat diet. Thirty-three male Sprague-Dawley rats were randomly assigned to five experimental groups, including control, losartan, telmisartan, CLA, and CLA + telmisartan-treated animals. Body weight, blood pressure, and blood levels of lipids, glucose, insulin, and inflammatory markers were measured. Co-administration of CLA and telmisartan resulted in significant (P < 0.05) reductions in body weight, visceral fat, serum total cholesterol, triglycerides, glucose, plasma insulin concentrations, and systolic blood pressure compared with those in the control group. Moreover, plasma levels of IL1-alpha and IFN-gamma were reduced and levels of IL1-beta, IL-4, IL-6, and IL-10, plus TNF-alpha were increased in the co-therapy group, compared with controls. In conclusion, this study suggests that a combination of CLA with telmisartan may modify several risk factors of cardiovascular disease commonly seen in metabolic syndrome. This combination of nutraceuticals and pharmaceuticals may be a safe and cost-effective strategy in a number of high-risk subjects. Future studies will further document clinical benefits of such combination therapy.

Dietary chickpeas reverse visceral adiposity, dyslipidaemia and insulin resistance in rats induced by a chronic high-fat diet

The improved effects of dietary chickpeas on visceral adiposity, dyslipidaemia and insulin resistance were examined. Rats were fed a normal-fat diet (NFD), a high-fat diet (HFD) or a high-fat plus chickpea diet (HFD+CP) for 8 months. The epididymal fat pad weight v. total body weight of rats was higher in the HFD group (0.032 (sd 0.0042) g/g) than in the NFD group (0.015 (sd 0.0064) g/g) and smaller in the HFD+CP group (0.023 (sd 0.0072) g/g) compared with the HFD group (P < 0.05). Chickpea treatment also induced a favourable plasma lipid profile reflecting decreased TAG, LDL-cholesterol (LDL-C) and LDL-C:HDL-cholesterol levels (P < 0.05). HFD-fed rats had higher TAG concentration in muscle and liver, whereas the addition of chickpeas to the HFD drastically lowered TAG concentration (muscle, 39 %; liver, 23 %). The activities of lipoprotein lipase (LPL) in epididymal adipose tissue and hepatic TAG lipase in liver recorded a 40 and 23 % increase respectively in HFD rats compared with those in NFD rats; dietary chickpeas completely normalised the levels. Furthermore, chickpea-treated obese rats also showed a markedly lower leptin and LPL mRNA content in epididymal adipose tissue. An insulin tolerance test, oral glucose tolerance test and insulin-releasing test showed that chickpeas significantly improved insulin resistance, and prevented postprandial hyperglycaemia and hyperinsulinaemia induced by the chronic HFD. The present findings provide a rational basis for the consumption of chickpeas as a functional food ingredient, which may be beneficial for correcting dyslipidaemia and preventing diabetes.

Conjugated linoleic acid reduces adipose depots without reduction of stearoyl coenzyme A desaturase 1 gene expression

AIMS AND METHODS

This study investigated the effects of conjugated linoleic acid (CLA) on the body weight, fat deposition and the expression of stearoyl coenzyme A desaturase 1 (SCD1) in the livers of male ICR mice that were fed with either beef tallow (BT) or fish oil (FO) supplemented with CLA. Mice weighing 25-30 g were divided into four groups, BT and BT supplemented with 0.5% CLA (BTC), FO and FO supplemented with 0.5% CLA (FOC). Each group consisted of 8 mice, and they were fed the experimental diets for 4 weeks. The experimental diets were composed of 59.18% carbohydrates, 19.73% proteins and 21.09% fat in terms of their contributions to total calories, and other nutrients were identical. CLA was added to the diets of the CLA supplementation groups at 0.5% (w/w). The measurement of triglyceride (TG) was done by using a kit. Fatty acid compositions were analyzed in both the plasma and the liver using a gas chromatograph. The levels of SCD1 expression were analyzed by RT-PCR in the liver.

RESULTS

No significant difference was found in the levels of food intake, body weight and food efficiency among experimental groups. However, the levels of both epididymal and visceral fat weight were significantly lower in the CLA-supplemented groups, BTC and FOC (p < 0.05). The level of the triglyceride concentration was also significantly lower in the CLA-supplemented groups (p < 0.05). The levels of the liver SCD1 gene expression were also higher in the CLA-supplemented groups. However, significant inhibition of conversion from C16:0 to C16:1 was found in both fatty acid compositions of the liver (p < 0.05).

CONCLUSION

Addition of 0.5% CLA did not inhibit the liver SCD1 gene expression; however, it showed decreasing effects on the fat pad weight, the concentration of TG and on fatty acid composition, leading to a decrease in the fat depositions. Such effects were clearer when CLA was supplemented to BT rather than FO.

Six months supplementation with conjugated linoleic acid induces regional-specific fat mass decreases in overweight and obese

Long-term supplementation with conjugated linoleic acid (CLA) reduces body fat mass (BFM) and increases or maintains lean body mass (LBM). However, the regional effect of CLA was not studied. The study aimed to evaluate the effect of CLA per region and safety in healthy, overweight and obese adults. A total of 118 subjects (BMI: 28-32 kg/m2) were included in a double blind, placebo-controlled trial. Subjects were randomised into two groups supplemented with either 3 x 4 g/d CLA or placebo for 6 months. CLA significantly decreased BFM at month 3 (Delta=- 0 x 9 %, P=0 x 016) and at month 6 (Delta=- 3 x 4 %, P=0 x 043) compared with placebo. The reduction in fat mass was located mostly in the legs (Delta=- 0 x 8 kg, P<0 x 001), and in women (Delta=-1 x 3 kg, P=0 x 046) with BMI >30 kg/m2 (Delta=-1 x 9 kg, P=0 x 011), compared with placebo. The waist-hip ratio decreased significantly (P=0 x 043) compared with placebo. LBM increased (Delta=+0 x 5 kg, P=0 x 049) within the CLA group. Bone mineral content was not affected (P=0 x 70). All changes were independent of diet and physical exercise. Safety parameters including blood lipids, inflammatory and diabetogenic markers remained within the normal range. Adverse events did not differ between the groups. It is concluded that supplementation with CLA in healthy, overweight and obese adults decreases BFM in specific regions and is well tolerated.

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

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

Safety of Dietary Conjugated Linoleic Acid (CLA) in a 12-weeks Trial in Healthy Overweight Japanese Male Volunteers

A study was conducted to investigate the short-term safety of dietary conjugated linoleic acid (CLA) in overweight Japanese male volunteers. The study design was a randomized, double-blind placebo-controlled trial including 60 healthy overweight volunteers (body mass index (BMI), 25 approximately 35 kg/m(2)). The subjects were randomly assigned to three groups: 5.4 g CLA-triacylglycerol (3.4 g as CLA), 10.8 g CLA-triacylglycerol (6.8 g as CLA) and placebo (10.8 g safflower oil) daily for 12 weeks. The CLA-triaclyglycerol contained 9c,11t- and 10t,12c-isomers at an equal proportion. The safety was evaluated by analyses of blood parameters and by clinical examinations at the baseline, and at 6 and 12 weeks, including vital signs and adverse effects. All subjects completed the study. The occurrence of adverse events tended to be higher in the CLA groups than in the placebo group, but all of the adverse events were mild to moderate, within normal ranges, and temporary. Serum aspartate aminotransferase (AST) activity did not differ significantly between the groups at 12 weeks, but in the high CLA group it was slightly increased from the baseline. Serum alanine aminotransferase (ALT) activity was higher in the high CLA group than in the placebo group after 12 weeks and was higher than at the baseline in both CLA groups. However, statistical analysis of the population of apparently healthy volunteers who had normal blood parameters at the baseline revealed that AST and ALT levels did not differ significantly among the 3 groups at 12 weeks. Moreover, no clinically significant changes in vital signs were observed in any of the groups. These results indicate that CLA at a dose of 3.4 g/day is a safe dietary level in healthy Japanese populations in terms of the parameters examined.

Conjugated linoleic acid and chromium lower body weight and visceral fat mass in high-fat-diet-fed mice

More than half of the U.S. population has a body mass index of 25 kg/m2 or more, which classifies them as overweight or obese. Obesity is often associated with comorbidities such as diabetes, cardiovascular diseases, and cancer. CLA and chromium have emerged as major dietary supplements that reduce body weight and fat mass, and increase basal metabolic rate in animal models. However, studies show that CLA induces insulin resistance in mice and in humans, whereas Cr improves insulin sensitivity. Hence, we designed the present study to examine the combined effect of CLA and Cr on body composition and insulin sensitivity in a Balb/c mice (n = 10/group) model of high-fat-diet-induced obesity. CLA alone lowered body weight, total body fat mass, and visceral fat mass, the last of which decreased further with the combination of CLA and Cr. This effect was accompanied by decreased serum leptin levels in CLA-fed and CLA + Cr-fed mice, and by higher energy expenditure (EE) and oxygen consumption (OC) in CLA + Cr-fed mice. Serum levels of glucose, insulin, the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6), as well as insulin resistance index (IRI), decreased with CLA, whereas CLA and Cr in combination had significant effects on insulin and IL-6 concentrations and IRI. In summary, CLA + Cr decreased body weight and fat mass in high-fat-diet-fed mice, which may be associated with decreased leptin levels and higher EE and OC.