Antiobesity effect of trans-10,cis-12-conjugated linoleic acid-producing Lactobacillus plantarum PL62 on diet-induced obese mice

AIMS: To observe the antiobesity activity of trans-10,cis-12-conjugated linoleic acid (CLA)-producing lactobacillus in mice. METHODS AND RESULTS: Lactobacillus plantarum PL62, which can grow in the presence of linoleic acid, was selected and studied. The culture supernatant of Lact. plantarum PL62 contained trans-10,cis-12-conjugated linoleic acid (6.4 microg ml(-1)), and the crude enzyme prepared from washed cells produced trans-10,cis-12 CLA (1395 microg mg(-1) protein). Lact. plantarum PL62 reduced the weights of epididymal, inguinal, mesenteric, and perirenal white adipose tissues and significantly reduced the blood levels of total glucose and body weights of mice (P<0.01). CONCLUSIONS: trans-10,cis-12-CLA-producing Lact. plantarum PL62 can exert the same antiobesity activity as trans-10,cis-12-CLA in mice. SIGNIFICANCE AND IMPACT OF THE STUDY: trans-10,cis-12-CLA-producing Lactobacillus can be a replacement for CLA for obesity treatment via the continuous production of trans-10,cis-12-CLA. The results provide a novel opportunity to develop foods with antiobesity activity.     

Dietary manipulations of body fat-reducing potential of conjugated linoleic acid in rats.

To study whether the body fat-reducing potential of conjugated linoleic acid (CLA) could be increased through dietary manipulations, the effects of the combination of CLA with different proteins, fats, and sesamin were examined in rats. Male rats were fed diets containing 1% CLA or linoleic acid (LA) in combination with different proteins (20% of casein or soybean protein), fats (7% perilla oil or soybean oil) and 0.2% sesamin (SES) for 3 or 4 weeks. When the dietary fat source was soybean oil, CLA, as compared with LA, significantly reduced weights of epididymal and perirenal adipose tissues, irrespective of the dietary protein sources. However, the highest reducing effect was shown when soybean protein was given as a protein source. SES stimulated the reduction of epididymal and perirenal adipose tissue weights in both protein diets. In contrast, CLA increased the weight of brown adipose tissue, and SES further increased it in combination with soybean oil but not with perilla oil. No effect of dietary manipulation was observed on serum leptin and TNF-alpha levels. Thus, the body fat-reducing potential of CLA can be increased by an appropriate combination with food factors that may stimulate fatty acid beta-oxidation.     

Acute reduction of serum leptin level by dietary conjugated linoleic acid in Sprague-Dawley rats

The purpose of this study was to clarify the effect of conjugated linoleic acid on lipid accumulation in adipose tissue. Sprague-Dawley rats were fed a diet containing 2% conjugated linoleic acid for 1, 3, 6, and 12 weeks. In rats fed 2% conjugated linoleic acid, the weight of perirenal white adipose tissue was comparable with that of rats fed a conjugated linoleic acid-free diet. For fatty acid composition of perirenal white adipose tissue, both 16:1/16:0 and 18:1/18:0 ratios were significantly lower in the conjugated linoleic acid-fed group than the control group. Although there was no remarkable difference in serum triglyceride, total cholesterol, and phospholipid levels between dietary groups, serum leptin level was significantly lower than the control group, and lipid content in the perirenal white adipose tissue exerted a tendency toward low compared to the control value at 1-week feeding. On the other hand, leptin level in perirenal white adipose tissue was significantly lower in the conjugated linoleic acid-fed group than the control group at 12-week feeding. In conclusion, these observations suggest dietary conjugated linoleic acid is an acute reducer of serum leptin level. This may afford an explanation of the mechanism of anti-obesity effect in conjugated linoleic acid.     

Adiposity and serum parameters in hamsters fed energy restricted diets supplemented or not with trans-10,cis-12 conjugated linoleic acid

Numerous studies have demonstrated that conjugated linoleic acid (CLA) modulates body composition, reducing body fat accumulation in various mammalian species. However, very few studies have been carried out to assess the effect of CLA on previously stored body fat. The aim of the present work was to analyse the effectiveness of trans-10,cis-12 CLA in improving alterations produced by high-fat feeding in body fat and serum parameters when it was included in an energy-restricted diet. For this purpose male Syrian Golden hamsters were fed on high-fat diet for 7 weeks in order to increase their body fat content, and a further 25% energy-restricted diet supplemented or not with 0.5% trans-10,cis-12 CLA for 3 weeks. Adipose tissues, liver and gastrocnemious muscles were dissected and weighed. Adipocyte diameter and number were assessed in epididymal adipose tissue. Total cholesterol, triacylglycerols, non-esterified fatty acids and glucose were measured in serum. Three weeks of energy restriction resulted in a reduction in body weight and white adipose tissue size in all anatomical locations, without changes in liver and gastrocnemious muscle weights. Epididymal adipocyte size was reduced, but total adipocyte number remained unchanged. Serum cholesterol, triacylglycerols and glucose were significantly reduced. No differences were observed between the restricted groups (control and CLA supplemented). In conclusion, under our experimental conditions, the addition of trans-10,cis-12 CLA to the diet does not increase the benefits produced by energy restriction.     

Conjugated linoleic acid reduces body fats and cytokine levels of mice

In order to discover the effect of CLA on the body fat size and serum cytokine levels, four groups of male mice were fed diets containing either 1% linoleic acid (LA) or conjugated linoleic acid (CLA) with or without 0.2% sesamin for 8 weeks. The weight gain and feed efficiency were significantly lower in the CLA groups. CLA significantly reduced relative weights (g/100 g body weight) of epididymal and perirenal adipose tissues, in particular the former. Concentrations of serum TNF-alpha and leptin were significantly reduced by dietary CLA. Sesamin did not show additional effects in all of these parameters. There was a positive correlation between cytokine production and body-fat reducing potential of CLA. These results indicated that mice appeared to be a hyperresponder to dietary CLA insofar as the reduction of body fat size is concerned.     

Effects of different doses of resveratrol on body fat and serum parameters in rats fed a hypercaloric diet

Recently resveratrol, a compound naturally occurring in various plants, has been proposed as a potential anti-obesity compound. The aim of the present work was to analyse the effects of different doses of resveratrol on body fat and serum parameters in rats. Thirty-two male Sprague-Dawley rats were randomly divided into four groups and fed on a hypercaloric diet for 6 weeks. The doses oftrans-resveratrol used were 6, 30 and 60 mg/kg body weight/d in RSV1, RSV2 and RSV3 groups respectively. The stability of resveratrol when added to the diet was evaluated. Blood samples were collected, and white adipose tissue from different anatomical locations, interscapular brown adipose tissue, gastrocnemious muscles and liver were weighed. Commercial kits were used to measure serum cholesterol, glucose, triacylglycerols and non-esterified fatty acids. While the lowest dose did not have a body fat reducing effect, the intermediate dose reduced all the white adipose depots. The highest dose significantly reduced mesenteric and subcutaneous depots but not epididymal and perirenal tissues. Although the reduction in all the anatomical locations analysed was 19% in the RSV3 group, in the RSV2 group it was 24%. No significant differences among the experimental groups were found in brown adipose tissue, gastrocnemious muscle or liver weights. Serum parameters were not affected by resveratrol intake because no differences among the experimental groups were observed. These results suggest that resveratrol is a molecule with potential anti-obesity effect. The most effective of the three experimental doses was 30 mg/kg body weight/d.     

Anti-obesity properties of a Sasa quelpaertensis extract in high-fat diet-induced obese mice

This study explores the anti-obesity properties of a Sasa quelpaertensis leaf extract (SQE) in high-fat diet (HFD)-induced obese C57BL/6 mice and mature 3T3-L1 adipocytes. SQE administration with HFD for 70 d significantly decreased the body weight gain, adipose tissue weight, and serum total cholesterol and triglyceride levels in comparison with the HFD group. SQE administration also reduced the serum levels of glutamic oxaloacetic transaminase, glutamic pyruvic transaminase and lactate dehydrogenase, and the accumulation of lipid droplets in the liver, suggesting a protective effect against HFD-induced hepatic steatosis. SQE administration restored the HFD-induced decreases with phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in epididymal adipose tissue. SQE also induced AMPK phosphorylation in mature 3T3-L1 adipocytes. These results suggest that SQE exerted an anti-obesity effect on HFD-induced obese mice by activating AMPK in adipose tissue and reducing lipid droplet accumulation in the liver.     

A comparison between CLNA and CLA effects on body fat, serum parameters and liver composition

The potential of conjugated linoleic acid (CLA) as an anti-obesity molecule for humans is still a matter for debate. Thus, a great deal of scientific work is focussed on the research of new effective molecules without deleterious effects on health. The aim of the present work was to analyse the effects of jacaranda seed oil, rich in a conjugated linolenic acid (CLNA), jacaric acid (cis-8,trans-10,cis-12), on body fat, serum parameters and liver composition in rats, and to compare these effects with those oftrans-10,cis-12 CLA. Twenty-six male Wistar rats were divided into three groups fed with high-fat diets, supplemented or not (control group) with 0.5%trans-10,cis-12 CLA (CLA group) or 0.5% jacaric acid (CLNA group) for 7 weeks. No statistical differences in food intake or in final body weight were found. Whereas CLA reduced adipose tissue size, CLNA did not. Both CLA and CLNA significantly reduced non-HDL-cholesterol. In spite of a lack of significant changes in glucose and insulin levels, HOMA-IR index was significantly increased, as well as did non-esterified fatty acid levels in CLNA-fed rats. No changes in liver composition were observed. In conclusion, under our experimental conditions, jacaric acid, unlike CLA, does not show a body-fat lowering effect. Even though it leads to a healthy lipoprotein profile, it impairs insulin function. Consequently, it cannot be proposed as an anti-obesity molecule.     

Conjugated linoleic acid conversion by dairy bacteria cultured in MRS broth and buffalo milk

AIMS: To evaluate strains of Lactobacilli, Bifidobacteria and Streptococci for their ability to produce conjugated linoleic acid (CLA) from free linoleic acid (LA). METHODS AND RESULTS: Eight dairy bacteria tolerant to LA were grown in MRS broth containing LA (200 microg ml(-1)) and CLA was assessed. Seven bacteria were able to form CLA after 24 h of incubation, varying percentage conversion between 17% and 36%. Lactobacillus casei, Lactobacillus rhamnosus, Bifidobacterium bifidum and Streptococcus thermophilus showed the highest LA conversion and were inoculated into buffalo milk supplemented with different concentration of LA. The production of CLA at 200 microg ml(-1) of LA was two- or threefold in milk than MRS broth. All evaluated strains were able to produce CLA from high LA levels (1000 microg ml(-1)). CONCLUSIONS: The most tolerant strain to LA was Lact. casei. Lacttobacillus rhamnosus produced the maximum level of CLA at high LA concentrations (800 microg ml(-1)). The selected bacteria may be considered as adjunct cultures to be included on dairy fermented products manufacture. Low concentration of LA must be added to the medium to enhance CLA formation. SIGNIFICANCE AND IMPACT OF THE STUDY: The production of CLA by strains using milks from regional farms as medium offer a possible mechanism to enhance this beneficial compound in dairy products and those the possibility to develop functional foods.     

Conjugated linoleic acid reduces adiposity and increases markers of browning and inflammation in white adipose tissue of mice

The objective of this study was to examine the mechanism by which conjugated linoleic acid (CLA) reduces body fat. Young male mice were fed three combinations of fatty acids at three doses (0.06%, 0.2%, and 0.6%, w/w) incorporated into AIN76 diets for 7 weeks. The types of fatty acids were linoleic acid (control), an equal mixture of trans-10, cis-12 (10,12) CLA plus linoleic acid, and an equal isomer mixture of 10,12 plus cis-9, trans-11 (9,11) CLA. Mice receiving the 0.2% and 0.6% dose of 10,12 CLA plus linoleic acid or the CLA isomer mixture had decreased white adipose tissue (WAT) and brown adipose tissue (BAT) mass and increased incorporation of CLA isomers in epididymal WAT and liver. Notably, in mice receiving 0.2% of both CLA treatments, the mRNA levels of genes associated with browning, including uncoupling protein 1 (UCP1), UCP1 protein levels, and cytochrome c oxidase activity, were increased in epididymal WAT. CLA-induced browning in WAT was accompanied by increases in mRNA levels of markers of inflammation. Muscle cytochrome c oxidase activity and BAT UCP1 protein levels were not affected by CLA treatment. These data suggest a linkage between decreased adiposity, browning in WAT, and low-grade inflammation due to consumption of 10,12 CLA.     

Antifungal activity of two Lactobacillus strains with potential probiotic properties

Aflatoxin (highly toxic and carcinogenic secondary metabolites produced by fungi) contamination is a serious problem worldwide. Modern agriculture and animal production systems need to use high-quality and mycotoxin-free feedstuffs. The use of microorganisms to preserve food has gained importance in recent years due to the demand for reduced use of chemical preservatives by consumers. Lactic acid bacteria are known to produce various antimicrobial compounds that are considered to be important in the biopreservation of food and feed. Lactobacillus rhamnosus L60 and Lactobacillus fermentum L23 are producers of secondary metabolites, such as organic acids, bacteriocins and, in the case of L60, hydrogen peroxide. The antifungal activity of lactobacilli strains was determined by coculture with Aspergillus section Flavi strains by two qualitative and one quantitative methods. Both L23 and L60 completely inhibited the fungal growth of all aflatoxicogenic strains assayed. Aflatoxin B (1) production was reduced 95.7-99.8% with L60 and 27.5-100% with L23. Statistical analysis of the data revealed the influence of L60 and L23 on growth parameters and aflatoxin B (1) production. These results are important given that these aflatoxicogenic fungi are natural contaminants of feed used for animal production, and could be effectively controlled by Lactobacillus L60 and L23 strains with probiotic properties.     

Effect of conjugated linoleic acid on body fat,tumor necrosis factor alpha and resistin secretion in spontaneously hypertensive rats

Conjugated linoleic acid (CLA) is a naturally occurring group of dienoic derivaties of linoleic acid found mainly in beef and dairy products. CLA has been reported to reduce body fat, as well as to possess anticarcinogenic, antiatherogenic and procatabolic activities in animals. The objective of this study was to evaluate the effect of CLA supplementation to spontaneously hypertensive rats (SHR) on body fat, biochemical parameters of serum related tumor necrosis factor alpha (TNF-α) and resistin secretion. Thirty rats were divided in three groups, the first group of spontaneously hypertensive rats received a standard diet (V-SHR group, n=10), a second group of SHR was fed 1.5% of conjugated linoleic acid (CLA-SHR group, n=10) and the third was the control, non-hypertensive group (KW, n=10) also on a standard diet including 7.5% of sunflower oil during eight weeks.After CLA diet administration, spontaneously hypertensive rats showed a significant reduction in blood pressure, serum glucose, cholesterol and triacylglycerols, together with reduction of index of body fat, pericardic, abdominal and epididymal adipose tissue. These effects were accompanied by a decrease in the secretion of TNF-α and resistin.     

Structural analysis of conjugated linoleic acid produced by Lactobacillus plantarum,and factors affecting isomer production

An isomer of the conjugated linoleic acid (CLA) produced from linoleic acid by Lactobacillus plantarum was identified as cis-9,trans-11-octadecadienoic acid by proton nuclear magnetic resonance spectroscopy. Together with earlier results, we concluded that the bacterium produces two CLA isomers, cis-9,trans-11- and trans-9,trans-11-octadecadienoic acid from linoleic acid. The addition of L-serine, glucose, AgNO3, or NaCl to the reaction mixture reduced production of the latter.     

Leptin-induced matrix metalloproteinase-2 secretion is suppressed by trans-10,cis-12 conjugated linoleic acid

It has long been recognized that leptin, a hormone made by adipocytes, is an important circulating signal for the regulation of body weight. In addition, matrix metalloproteinase (MMP), especially MMP-2, an adipocyte-secreted protein which promotes multi-cellular adipose clusters, is up-regulated in obesity. The present study is designed to evaluate whether trans-10,cis-12 conjugated linoleic acid (t-CLA) can suppress leptin-induced MMP-2 secretion in 3T3-L1 cells. The result showed that expressions of adipocyte marker proteins were significantly reduced by t-CLA-treated cultures, but not by linoleic acid (LA)-treated ones. Interestingly, MMP-2 secretion was significantly increased by leptin-treated cultures, thereby leading to accelerate adipocyte differentiation, indicating that MMP-2 was a necessary mediator of adipogenesis. However, increasing concentration of t-CLA significantly reduced leptin-induced MMP-2 secretion and triglyceride (TG) content. These findings provide support for a role for t-CLA in the regulation of metabolism in leptin-induced adipose tissue development.     

Influence of Dietary Conjugated Linoleic Acid and Fat Source on Body Fat and Apoptosis in Mice*

Objective: To determine whether altered dietary essential fatty acid (linoleic and arachidonic acid) concentrations alter sensitivity to conjugated linoleic acid (CLA)‐induced body fat loss or DNA fragmentation. Research Methods and Procedures: Mice were fed diets containing soy oil (control), coconut oil [essential fatty acid deficient (EFAD)], or fish oil (FO) for 42 days, and then diets were supplemented with a mixture of CLA isomers (0.5% of the diet) for 14 days. Body fat index, fat pad and liver weights, DNA fragmentation in adipose tissue, and fatty acid profiles of adipose tissue were determined. Results: The EFAD diet decreased (p < 0.05) linoleic and arachidonic acid in mouse adipose tissue but did not affect body fat. Dietary CLA caused a reduction (p < 0.05) in body fat. Mice fed the EFAD diet and then supplemented with CLA exhibited a greater reduction (p < 0.001) in body fat (20.21% vs. 6.94% in EFAD and EFAD + CLA‐fed mice, respectively) compared with mice fed soy oil. Dietary FO decreased linoleic acid and increased arachidonic acid in mouse adipose tissue. Mice fed FO or CLA were leaner (p < 0.05) than control mice. FO + CLA‐fed mice did not differ in body fat compared with FO‐fed mice. Adipose tissue apoptosis was increased (p < 0.001) in CLA‐supplemented mice and was not affected by fat source. Discussion: Reductions in linoleic acid concentration made mice more sensitive to CLA‐induced body fat loss only when arachidonic acid concentrations were also reduced. Dietary essential fatty acids did not affect CLA‐induced DNA fragmentation.     

Combined Effects of Dietary Protein Type and Fat Level on the Body Fat-Reducing Activity of Conjugated Linoleic Acid (CLA) in Rats

The interaction of dietary protein type and fat level on the body fat-reducing activity of conjugated linoleic acid (CLA) was studied in male rats fed diets containing casein (CAS) or soy protein (SOY) as a protein source with low fat (LF, 6.0% soybean oil) or high fat (HF, 13.0% soybean oil) combinations for 4 weeks. CLA was added at the 1.0% level to all diets. The weight of perirenal adipose tissue tended to be lower in the SOY groups than in the corresponding CAS groups, and the difference between the LF diets was significant. The weight of epididymal adipose tissue showed a similar but insignificant trend. The weight of brown adipose tissue was heaviest on the SOY-HF diet and lowest on two CAS diets, the SOY-LF diet being intermediate. The concentration of serum leptin was lowest on the SOY-LF diet and was significantly lower than that of the corresponding CAS group, but this difference disappeared when the dietary fat level increased. The serum cholesterol-lowering activity of SOY in relation to CAS was reproduced even when CLA was given. Thus the body fat-reducing activity of CLA was most marked when rats were fed the SOY-LF diet. Although the CAS-HF diet increased body fat deposition, the magnitude of the reduction by lowering dietary fat level was more marked than in the case of SOY. These results indicate a complicated interaction of dietary manipulations with the body fat-reducing effect of CLA, but the combination of CLA with the SOY-LF diet appears to be an appropriate approach.     

Combined effects of dietary protein type and fat level on the body fat-reducing activity of conjugated linoleic acid (CLA) in rats

The interaction of dietary protein type and fat level on the body fat-reducing activity of conjugated linoleic acid (CLA) was studied in male rats fed diets containing casein (CAS) or soy protein (SOY) as a protein source with low fat (LF, 6.0% soybean oil) or high fat (HF, 13.0% soybean oil) combinations for 4 weeks. CLA was added at the 1.0% level to all diets. The weight of perirenal adipose tissue tended to be lower in the SOY groups than in the corresponding CAS groups, and the difference between the LF diets was significant. The weight of epididymal adipose tissue showed a similar but insignificant trend. The weight of brown adipose tissue was heaviest on the SOY-HF diet and lowest on two CAS diets, the SOY-LF diet being intermediate. The concentration of serum leptin was lowest on the SOY-LF diet and was significantly lower than that of the corresponding CAS group, but this difference disappeared when the dietary fat level increased. The serum cholesterol-lowering activity of SOY in relation to CAS was reproduced even when CLA was given. Thus the body fat-reducing activity of CLA was most marked when rats were fed the SOY-LF diet. Although the CAS-HF diet increased body fat deposition, the magnitude of the reduction by lowering dietary fat level was more marked than in the case of SOY. These results indicate a complicated interaction of dietary manipulations with the body fat-reducing effect of CLA, but the combination of CLA with the SOY-LF diet appears to be an appropriate approach.     

Conjugated linoleic acid biosynthesis by human-derived Bifidobacterium species

AIMS: To assess strains of Lactobacillus, Lactococcus, Pediococcus and Bifidobacterium for their ability to produce the health-promoting fatty acid conjugated linoleic acid (CLA) from free linoleic acid. METHODS AND RESULTS: In this study, strains of Lactobacillus, Lactococcus, Pediococcus and Bifidobacterium were grown in medium containing free linoleic acid. Growth of the bacteria in linoleic acid and conversion of the linoleic acid to CLA was assessed. Of the bacteria assessed, nine strains of Bifidobacterium produced the c9, t11 CLA isomer from free linoleic acid. The t9, t11 CLA isomer was also produced by some strains, but at much lower concentrations. CONCLUSIONS: The production of CLA by bifidobacteria exhibited considerable interspecies variation. Bifidobacterium breve and B. dentium were the most efficient CLA producers among the range of strains tested, with B. breve converting up to 65% linoleic acid to c9, t11 CLA when grown in 0.55 mg ml(-1) linoleic acid. Strains also varied considerably with respect to their sensitivity to linoleic acid. SIGNIFICANCE AND IMPACT OF THE STUDY: The production of CLA by probiotic bifidobacteria offers a possible mechanism for some health-enhancing properties of bifidobacteria and provides novel opportunities for the development of functional foods.     

Combined effects of rosiglitazone and conjugated linoleic acid on adiposity, insulin sensitivity, and hepatic steatosis in high-fat-fed mice

Dysfunctional cross talk between adipose tissue and liver tissue results in metabolic and inflammatory disorders. As an insulin sensitizer, rosiglitazone (Rosi) improves insulin resistance yet causes increased adipose mass and weight gain in mice and humans. Conjugated linoleic acid (CLA) reduces adipose mass and body weight gain but induces hepatic steatosis in mice. We examined the combined effects of Rosi and CLA on adiposity, insulin sensitivity, and hepatic steatosis in high-fat-fed male C57Bl/6 mice. CLA alone suppressed weight gain and adipose mass but caused hepatic steatosis. Addition of Rosi attenuated CLA-induced insulin resistance and dysregulation of adipocytokines. In adipose, CLA significantly suppressed lipoprotein lipase and fatty acid translocase (FAT/CD36) mRNA, suggesting inhibition of fatty acid uptake into adipose; addition of Rosi completely rescued this effect. In addition, CLA alone increased markers of macrophage infiltration, F4/80, and CD68 mRNA levels, without inducing TNF-alpha in epididymal adipose tissue. The ratio of Bax to Bcl2, a marker of apoptosis, was significantly increased in adipose of the CLA-alone group and was partially prevented by treatment of Rosi. Immunohistochemistry of F4/80 demonstrates a proinflammatory response induced by CLA in epididymal adipose. In the liver, CLA alone induced microsteatotic liver but surprisingly increased the rate of very-low-density lipoprotein-triglyceride production without inducing inflammatory mediator-TNF-alpha and markers of macrophage infiltration. These changes were accompanied by significantly increased mRNA levels of stearoyl-CoA desaturase, FAT/CD36, and fatty acid synthase. The combined administration of CLA and Rosi reduced hepatic liver triglyceride content as well as lipogenic gene expression compared with CLA alone. In summary, dietary CLA prevented weight gain in Rosi-treated mice without attenuating the beneficial effects of Rosi on insulin sensitivity. Rosi ameliorated CLA-induced lipodystrophic disorders that occurred in parallel with rescued expression of adipocytokine and adipocytes-abundant genes.