Conjugated Linoleic Acid Consumption Research Articles

Conjugated Linoleic Acid in Cancer Therapy.

Conjugated Linoleic Acid (CLA) is a polyunsaturated dietary fatty acid. Probiotics can biohydrogenate CLA with multiple health benefits, especially in cancer treatment. In vitro, in vivo, and clinical studies have confirmed CLA isomers to possess anti-cancer activity. CLA has demonstrated its potential as an alternative treatment for cancer and also used as an adjuvant to reduce the side effects of existing treatment methods. The mechanism of the anticancer activity of CLA is still not clear; however, it may involve intervention with the cell cycle and modulation of gene expression. A greater potential of CLA for cancer treatment has been supported by more and more clinical trials to evaluate its potential. Some advanced technologies are in progress to overcome the flaws of current methods and enhance the microbial production of CLA. In conclusion, nutritional enrichment as a functional food and direct consumption of CLA may contribute to cancer management.

Jacaranda oil administration improves serum biomarkers and bioavailability of bioactive conjugated fatty acids, and alters fatty acid profile of mice tissues.

Jacaric acid, a conjugated linolenic acid (CLNA) present in jacaranda oil (JO), is considered a potent anticarcinogenic agent. Several studies have focused on its biological effects, but the metabolism once consumed is not clear yet. The aim of this work was to evaluate the effects of two different daily doses of JO on serum parameters and fatty acid (FA) profile of mice tissues after 4 weeks of feeding. No significant changes on body weight gain, food intake, or tissue weight were determined after 0.7 or 2ml/kg of JO supplementation compared to control animals. Significantly lower blood low-density lipoproteins-cholesterol (20mg/dl) and glucose (~147-148mg/dl) levels were detected in both oil-treated groups compared to control (31.2 and 165mg/dl, respectively). Moreover, jacaric acid was partially converted into cis9, trans11 conjugated linoleic acid (CLA) and thus further incorporated into tissues. Liver evidenced the highest total conjugated fatty acid content (1.1%-2.2%), followed by epididymal (0.7%-1.9%) and mesenteric (1.4%-1.8%) fat. Lower saturated and higher unsaturated fatty acid content was detected in both oil-treated groups compared to control. Our results support the safety of JO and its potential application with a functional or nutraceutical propose, by increasing human CLNA consumption and further availability of CLA.

Maternal conjugated linoleic acid consumption prevented TAG alterations induced by a high-fat diet in male adult rat offspring.

Maternal nutritional programming by a high-fat (HF) diet is related to hepatic lipid accumulation and steatosis in offspring. Conjugated linoleic acid (CLA) might ameliorate impaired hepatic lipid homoeostasis; therefore, the aim was to investigate the potential preventive effect of maternal CLA consumption on TAG metabolism alterations induced by HF diets in adult male rat offspring receiving or not receiving CLA. Female Wistar rats were fed a control (C) diet, HF diet or HF diet supplemented with CLA (HF+CLA) for 4 weeks before mating and throughout pregnancy and lactation. After weaning, for 9 weeks, male offspring of C or HF rats continued with the same diets as their mothers (C/C or HF/HF groups, respectively) and male offspring of HF+CLA rats were fed HF or HF+CLA diets (HF+CLA/HF or HF+CLA/HF+CLA groups, respectively). Nutritional parameters, serum and liver TAG levels, the TAG secretion rate (TAG-SR) and the activities as well as gene expression of key hepatic enzymes involved in TAG regulation were assessed. The most interesting results were that maternal CLA decreased epididymal white adipose tissue weight and prevented serum and liver TAG accumulation induced by a HF diet in adult male offspring receiving or not receiving CLA. The prevention of liver steatosis in HF+CLA/HF+CLA and HF+CLA/HF offspring was associated with an increased hepatic TAG-SR. Overall, this study provides evidence that maternal CLA consumption programmes TAG regulation and in this way contributes to lowering lipid levels in tissues and preventing liver steatosis in particular.

Developing cookies formulated with goat cream enriched with conjugated linoleic acid.

Goat fat is one of the best sources of conjugated linoleic acid (CLA), a fatty acid which has health benefits. However, though CLA is generated in ruminants, CLA consumption is limited to meats and milk products. This study aimed to replace vegetable fat with goat milk fat enriched with CLA. From differing fat sources, four cookie recipes were developed: CVF–vegetable fat cookies; CB–butter cookies; CG–goat milk fat cookies without CLA; CGCLA–goat milk fat cookies with CLA. The cookies were evaluated using physical (color and texture), physical-chemical parameters (lipids, proteins, total sugars, fiber, ash, moisture and Aw), consumer testing (n = 123), and lipid profiles. The CGCLA presented higher values in the color parameters. The highest and the lowest scores obtained for hardness were respectively 5.54 (CB) and 2.21 (CVF). Lipids and total sugars varied inversely; the highest percentages of lipids were in the CVF and CG samples which obtained lower total sugar content. There were no differences in acceptance or preference for the four formulations. The goat cream formulations (CG and CGCLA) were as well accepted as the CFV formulation. For lipid profiles, CFV presented the highest percentage of trans-fatty acids (TFA) at 16.76%. CGCLA presented 70% more CLA than either CB or CG, certifying that CGCLA presents CLA in relevant quantities, even after cooking. The CGCLA presented higher levels of CLA, and in this study it was verified that goat milk cream enriched with CLA can be used in producing cookies, adding functional and nutritional properties, and offering another alternative(s) to produce food from goat milk fat.

Effects of Conjugated Linoleic Acid Intake in the Form of Dietary Supplement or Enriched Food on C-Reactive Protein and Lipoprotein (a) Levels in Humans: A Literature Review and Meta-Analysis.

Background:C-reactive protein (CRP) and lipoprotein (a) (Lp[a]) play essential roles in cardiovascular disease incidence. This study aimed to review the association between the intake of conjugated linoleic acid (CLA) in the form of dietary supplement or enriched food with different treatment durations and the levels of Lp(a) and CRP in human studies. Methods:All the articles published in Cochrane Library, ProQuest, Scopus, and Google Scholar from November 2014 to October 2015 were searched and the clinical trials on the effects of CLA on Lp(a) and CRP levels were assessed. Of the 2249 articles initially retrieved, 21 eligible randomized clinical trials were enrolled in this systematic review. The publication dates of the eligible articles ranged from 2005 to 2013. The mean difference and the standard deviation of changes in CRP and Lp(a) levels in intervention and control groups were used as effect-size measures for meta-analysis. The obtained data from the eligible randomized controlled trials were meta-analyzed using Stata, version 13.Results:The intake of CLA as a dietary supplement led to a significant increase in CRP levels (standardized mean difference [SMD]=0.41, 95% CI: 0.28 to 0.54; P=0.001). Subgroup analysis based on the duration of CLA consumption showed that CLA consumption more than 24 weeks resulted in a significant increase in the levels of CRP (SMD=0.52, 95% CI: 0.36 to 0.68; P=0.001) and Lp(a) (SMD=0.24, 95% CI: 0.01 to 0.47; P=0.04). Conclusion:The current systematic review and meta-analysis showed that the long-term consumption of CLA increases the levels of CRP and Lp(a).

Maternal suppplementation with conjugated linoleic acid reduce anxiety and lipid peroxidation in the offspring brain

BackgroundMaternal consumption of fatty acids can alter neuronal membrane function, synaptic connections, and protect the brain from alterations caused by disturbances such as lipid peroxidation and anxiety in the offspring. We aimed to investigate how the maternal consumption of conjugated linoleic acid (CLA) interferes in anxiety behavior of the offspring and cerebral lipid peroxidation. MethodsThree groups were formed: control (CG) - diet without CLA; CLA1 - diet containing 1% of CLA; and CLA3 - diet containing 3% of CLA. These diets were offered to the mothers from the 7th day of gestation until the end of lactation. The following behavioral tests were used: Elevated plus maze (EPM), Open Field (OF) and Light-dark Box (LDB). Levels of malondialdehyde (MDA) and glutathione were measured in the offspring's brains. Data were analyzed by ANOVA followed by the Holm–Sidak post-test or the Kruskal–Wallis test (p < 0.05). ResultsCLA1 and CLA3 showed higher number of entries in the open arms and time spent in the central area in EPM, they translocated and ambulated more in the clear area of the LDB and presented more rearing in the OF compared to CG (p < 0.05); moreover, they presented higher concentration of glutathione and lower MDA in brain tissue (p < 0.05). LimitationsWe evaluated the effect of maternal consumption of CLA on anxiety and lipid peroxidation in rats’ offspring, but a similar study should be performed in humans. ConclusionsMaternal intake of CLA induced a decrease in the parameters of anxiety and cerebral lipid peroxidation in the offspring.

Egg Yolk as Means for Providing Essential and Beneficial Fatty Acids

AbstractThe new American Dietary Guidelines now recommend optimizing the types of fat consumed instead of reducing or eliminating fat from the diet. Chicken eggs are a means to deliver essential and beneficial human dietary fatty acids (FA), and can be staple component of healthy eating behavior. Additionally, polyunsaturated fatty acids can be increased in the avian egg yolk by simply incorporating selected lipid sources into the avian diet. Poultry feed rich in omega‐3 FA (omega‐3) has allowed commercialization of enriched eggs containing up to 600 mg of omega‐3. Conjugated linoleic acid (CLA) has also been used in the research setting to enrich eggs to provide a portion of the 3–4 g CLA day−1 needed to promote weight loss to combat obesity. However, Americans consume only 50% of the omega‐3 recommended adequate intake, and average CLA consumption is under 600 mg day−1. While a variety of foods are naturally rich in omega‐3, conventional sources of CLA are limited to bovine milk and meat, which do not provide enough CLA to produce clinical effects in a balanced diet. Since eggs and egg‐based products are common in the Western diet, eggs enriched with both omega‐3 and CLA using dietary additions to poultry feed may promote consumption of the recommended levels of these FA. This article reviews the design of poultry eggs with enhanced lipid profiles through dietary intervention, and discusses the future direction of enriched egg research.

Seasonal Variation in Fat Quality and Conjugated Linoleic Acid Content of Dairy Products from the Tropics: Evidence of Potential Impact on Human Health.

Seasonal variation in conjugated linoleic acid (CLA) content and atherogenicity index (AI) of retail dairy products (whole milk, butter, and prato, a soft yellow cheese) from Brazil was investigated. CLA content of dairy products ranged from 0.55 to 1.53 g CLA/100 g fatty acids and was on average 25% higher during the rainy season compared to the dry season. Dairy products from the rainy season also had lower AI levels, indicating a lower risk of causing cardiovascular disease in consumers. This seasonality led to estimated seasonal variations of milk fat quality consumed by the population of southeastern Brazil, meaning 15% and 19% variation in daily intake of CLA and AI values, respectively. Dietary consumption of CLA (g/day) was greater in the rainy season, despite higher intake of dairy products during the dry season. We show that dairy products produced during the rainy season in Brazil are expected to be more beneficial to human health than are those produced during the dry season.

Biohydrogenation of Linoleic Acid by Lactic Acid Bacteria for the Production of Functional Cultured Dairy Products: A Review.

Conjugated linoleic acid (CLA) isomers have attracted significant attention due to their important physiological properties, which have been observed in humans. Many lactic acid bacteria (LAB) demonstrate the ability to produce CLA isomers (C18:2 cis-9, trans-11 and C18:2 trans-10, cis-12) from the linoleic acid (LA) present in milk or in synthetic media. CLA isomers can be synthesized in vitro by LAB using vegetable oils rich in LA. The aim of this review is to present an update on the studies that have been conducted on the production of CLA isomers from LA mainly by LAB and of the factors that influence this conversion (source and concentration of LA and fermentation conditions). In addition, this review presents the relationship between the consumption of CLA isomers and their health benefits in humans such as anti-atherosclerosis and anti-carcinogenic effects. There is considerable variation between the studies concerning the beneficial effects of CLA in animal models, which have not been reflected in human studies. This can be attributed to the differences in the doses of CLA isomers used and to the different sources of CLA. Furthermore, the regulatory and scientific information classifying the physiological properties of CLA, which serve as support for the claims of its potential as a functional ingredient, are presented. More research is needed to determine whether CLA production by LAB can be enhanced and to determine the optimal requirements for these microbial cultures. Furthermore, safety and efficacy of CLA consumption have to be investigated in the future.

Conjugated Linoleic Acid: Potential Health Benefits as a Functional Food Ingredient.

Conjugated linoleic acid (CLA) has drawn significant attention since the 1980s for its various biological activities. CLA consists mainly of two isomers, cis-9,trans-11 and trans-10,cis-12, and the mixture of these two (CLA mix or 50:50) has been approved for food as GRAS (generally recognized as safe) in the United States since 2008. Along with its original discovery as an anticancer component, CLA has been shown to prevent the development of atherosclerosis, reduce body fat while improving lean body mass, and modulate immune and/or inflammatory responses. This review summarizes the clinical trials involving CLA since 2012; additional uses of CLA for age-associated health issues are discussed; and CLA's potential health concerns, including glucose homeostasis, oxidative stress, hepatic steatosis, and milk-fat depression, are examined. With ongoing applications to food products, CLA consumption is expected to rise and close monitoring of not only its efficacy but also its known and unknown consequences are required to ensure proper applications of CLA.

Scientific Opinion on the substantiation of a health claim related to an equimolar mixture of the CLA isomers c9,t11 and t10,c12 (marketed as Clarinol® and Tonalin®) and “contributes to a reduction in body fat mass” pursuant to Article 13(5) of Regulation

Following an application from BASF SE and Stepan Lipid Nutrition, submitted for the authorisation of a health claim pursuant to Article 13(5) of Regulation (EC) No 1924/2006 via the Competent Authority of the Netherlands, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on the scientific substantiation of a health claim related to an equimolar mixture (marketed under the trade names Clarinol® and Tonalin®) of the two conjugated linoleic acid (CLA) isomers c9,t11 and t10,c12. The Panel considers that the food is sufficiently characterised. The claimed effect is “contributes to a reduction in body fat mass”. In previous assessments on the safety of these equimolar isomeric mixtures of CLA, the NDA Panel considered that the observed increase in plasma and urinary concentrations of isoprostanes, which may indicate an increase in lipid peroxidation, and the increase in some markers of subclinical inflammation associated with CLA consumption, together with the limited data available on the effects of CLA on vascular function, may indicate a potential for vascular damage in the longer term. The Panel considers that the information provided does not establish that a reduction in body fat mass, when accompanied by an increase in markers of lipid peroxidation and inflammation, is a beneficial physiological effect for the target population. The Panel concludes that a cause and effect relationship has not been established between the consumption of an equimolar mixture of the CLA isomers c9,t11 and t10,c12, marketed under the trade names of Clarinol® and Tonalin®, and a beneficial physiological effect.

A proof of principle clinical trial to determine whether conjugated linoleic acid modulates the lipogenic pathway in human breast cancer tissue

Conjugated linoleic acid (CLA) is widely used as a "nutraceutical" for weight loss. CLA has anticancer effects in preclinical models, and we demonstrated in vitro that this can be attributed to the suppression of fatty acid (FA) synthesis. We tested the hypothesis that administration of CLA to breast cancer patients would inhibit expression of markers related to FA synthesis in tumor tissue, and that this would suppress tumor proliferation. Women with Stage I-III breast cancer were enrolled into an open label study and treated with CLA (1:1 mix of 9c,11t- and 10t,12c-CLA isomers, 7.5 g/d) for ≥ 10 days before surgery. Fasting plasma CLA concentrations measured pre- and post-CLA administration, and pre/post CLA tumor samples were examined by immunohistochemistry for Spot 14 (S14), a regulator of FA synthesis, FA synthase (FASN), an enzyme of FA synthesis, and lipoprotein lipase (LPL), the enzyme that allows FA uptake. Tumors were also analyzed for expression of Ki-67 and cleaved caspase 3. 24 women completed study treatment, and 23 tumors were evaluable for the primary endpoint. The median duration of CLA therapy was 12 days, and no significant toxicity was observed. S14 expression scores decreased (p = 0.003) after CLA administration. No significant change in FASN or LPL expression was observed. Ki-67 scores declined (p = 0.029), while cleaved caspase 3 staining was unaffected. Decrements in S14 or Ki-67 did not correlate with fasting plasma CLA concentrations at surgery. Breast tumor tissue expression of S14, but not FASN or LPL, was decreased after a short course of treatment with 7.5 g/day CLA. This was accompanied by reductions in the proliferation index. CLA consumption was well-tolerated and safe at this dose for up to 20 days. Overall, CLA may be a prototype compound to target fatty acid synthesis in breast cancers with a "lipogenic phenotype".

Oleic acid attenuates trans‐10, cis‐12 (10,12) conjugated linoleic acid (CLA)‐mediated inflammatory signaling in primary human adipocytes

CLA is a popular weight loss supplement consisting of 10,12 and cis‐9, trans‐11 (9,11) isomers that reduces adiposity. However, the consumption of CLA, particularly the 10,12 isomer, is associated with adverse side effects including chronic inflammation and insulin resistance. We hypothesized that these side effects of 10,12 CLA were linked to reduced activity of lipogenic enzymes including stearoyl‐CoA desaturase (SCD)‐1, a delta‐9 desaturase essential for the production of monounsaturated fatty acid (MUFA)s that are required for phospholipid and neutral lipid synthesis. Furthermore, blocking SCD‐1 increases saturated fatty acids like palmitate and stearate, which increase inflammation and insulin resistance. Thus, cultures of human adipocytes were treated with 50 uM 10,12 CLA and 30–300 uM oleic acid for 18–48 h. Consistent with our hypothesis, oleic acid reduced CLA‐mediated inflammatory gene expression in a dose‐dependent manner. However, oleic acid treatment did not attenuate CLA‐mediated insulin resistance. Notably, supplementation with stearic acid, a substrate for SCD‐1, or 9,11 CLA did not prevent inflammatory gene expression in 10,12 CLA‐treated cultures. Collectively, these data show that oleic acid attenuates CLA‐mediated inflammatory signaling, possibly by alleviating stress caused by SCD‐1 inhibition. Supported by NIH NIDDK‐ODS 5R01 DK063070‐09 and the UNCG URA program.

Conjugated Linoleic Acid Supplementation for 8 Weeks Does Not Affect Body Composition, Lipid Profile, or Safety Biomarkers in Overweight, Hyperlipidemic Men

The usefulness of conjugated linoleic acid (CLA) as a nutraceutical remains ambiguous. Our objective was, therefore, to investigate the effect of CLA on body composition, blood lipids, and safety biomarkers in overweight, hyperlipidemic men. A double-blinded, 3-phase crossover trial was conducted in overweight (BMI ≥ 25 kg/m2), borderline hypercholesterolemic [LDL-cholesterol (C) ≥ 2.5 mmol/L] men aged 18–60 y. During three 8-wk phases, each separated by a 4-wk washout period, 27 participants consumed under supervision in random order 3.5 g/d of safflower oil (control), a 50:50 mixture of trans 10, cis 12 and cis 9, trans 11 (c9, t11) CLA:Clarinol G-80, and c9, t11 isomer:c9, t11 CLA. At baseline and endpoint of each phase, body weight, body fat mass, and lean body mass were measured by DXA. Blood lipid profiles and safety biomarkers, including insulin sensitivity, blood concentrations of adiponectin, and inflammatory (high sensitive-C-reactive protein, TNFα, and IL-6) and oxidative (oxidized-LDL) molecules, were measured. The effect of CLA consumption on fatty acid oxidation was also assessed. Compared with the control treatment, the CLA treatments did not affect changes in body weight, body composition, or blood lipids. In addition, CLA did not affect the β-oxidation rate of fatty acids or induce significant alterations in the safety markers tested. In conclusion, although no detrimental effects were caused by supplementation, these results do not confirm a role for CLA in either body weight or blood lipid regulation in humans.

Dietary conjugated linoleic acid (CLA) for finishing Nile tilapia

A 8-week feeding trial was conducted to evaluate the nutritional value of dietary conjugated linoleic acid (CLA) for finishing Nile tilapia evaluating its effects on growth performance, whole body and filet compositions, fatty acid composition, plasma lipid parameters, filet texture, liquid loss and holding capacity. Triplicate groups of Nile tilapia were hand-fed until apparent satiation on diets in which CLA oil was supplemented at 0 (control), 5 or 10 g kg−1. No differences were observed on weight gain, feed intake, feed/gain ratio, protein efficiency ratio, hepatosomatic index, visceral fat, filet yield and survival between treatments. Fish-fed CLA diets had increased whole body crude protein and reduced filet lipid content. The total plasma cholesterol and triacylglycerol decreased with CLA supplementation. Neither 5 nor 10 g kg−1 dietary CLA improved liquid-holding capacity and filet texture when compared with fish fed the control diet. Fish-fed dietary CLA showed lower whole body and filet C18:3(n-6), C18:3(n-3) and C20:2(n-6) levels and higher levels of C18:0. CLA deposition in filet and whole body (16 mg–235 mg g−1 of tissue) are higher than presented in natural sources of CLA, proving to be a great product to increase CLA consumption by humans.

Protection of cortical neurons from excitotoxicity by conjugated linoleic acid

Conjugated linoleic acid (CLA) is an isomeric mixture of 18-carbon polyunsaturated fatty acids with conjugated double bonds derived from linoleic acid. CLA is sourced nutritionally from dairy products and ruminant animal meat and is associated with beneficial heath effects in several disorders, including cancer, atherosclerosis, diabetes, obesity, and inflammation. We investigated the potential for CLA to protect neurons from death in stroke simulated by exposing cultured mouse embryonic cortical neurons to glutamate. CLA (10 30 μM) significantly protected neuronal survival in response to glutamate (3 μM) excitotoxicity when given concurrently with glutamate. CLA (30 μM) also reduced neuron death when given up to 5 h after glutamate exposure (73.1 ± 13.3% protection, p < 0.01), suggesting potential utility as a post-injury therapeutic tool. The cis-9, trans-11 CLA isomer, which comprises about 40% of the commercial CLA mixture used, was identified as the active neuroprotective species. The other major species, trans-10, cis-12 CLA (40%) was without significant neuroprotective effect. CLA significantly increased neuronal Bcl-2 levels when given with glutamate and attenuated glutamate-induced dissipation of mitochondrial membrane potential, suggesting a stabilizing influence on mitochondrial function. These results show that CLA is capable of strong neuroprotective effects in glutamate excitotoxicity at concentrations likely achieved by consumption of CLA as a dietary supplement.

Milk Enriched with Conjugated Linoleic Acid Fails to Alter Blood Lipids or Body Composition in Moderately Overweight, Borderline Hyperlipidemic Individuals

Background: Dietary conjugated linoleic acid (CLA) represents a group of positional and geometric isomers of conjugated dienoic derivatives of linoleic acid. The effects of dietary CLA on blood lipids and body composition in humans remain controversial.Objective: To examine whether consumption of milk enriched naturally or synthetically with cis 9, trans 11 (c-9, t-11) and trans 10, cis 12 (t-10, c-12) CLA isomers alters blood lipid indices, including concentrations of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triacyglycerol; indices of liver function including plasma alanine transaminase and total bilirubin; C-reactive protein; tumor necrosis factor-alpha; and body weight and composition in moderately overweight, borderline hyperlipidemic humans.Design: A randomized, 3-phase, crossover, single-blind clinical trial was carried out in moderately overweight, borderline hyperlipidemic individuals who consumed (1) milk naturally enriched in CLA (4.2%) containing c-9, t-11 only providing 1.3 g/d of CLA; (2) milk enriched with a 4.2% synthetic mixture of t-10, c-12 and c-9, t-11 CLA isomers providing 1.3 g/d of CLA; or (3) untreated milk as a control providing 0.2 g/d CLA. Dietary phases were each 8 weeks in duration and were separated by 4-week washout periods. Plasma lipid levels were measured in blood samples collected at the beginning and end of each dietary phase. Magnetic resonance imaging was carried out at the beginning and end of each dietary phase to assess any changes in regional body fat composition.Results: Compared with the control intervention, consumption of the two CLA-enriched milks failed to alter plasma total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or triacyglycerol concentrations; body weight; or fat composition. CLA consumption did not significantly affect plasma alanine transaminase, total bilirubin, C-reactive protein, or tumor necrosis factor-alpha concentrations.Conclusion: Results from this study fail to support the role of milk enriched naturally with CLA containing c-9, t-11 or synthetically with c-9, t-11 and t-10, c-12 CLA isomers in modulation of lipid profiles or body composition in moderately overweight, borderline hyperlipidemic individuals.

Incorporation of conjugated linoleic acid into mouse tissues and the regulation of feed intake and body fat in the short term

Conjugated linoleic acid (CLA) is known to decrease feed intake and body fat in mice. Our objectives were to determine the incorporation of CLA into tissues and the effect on serum hormones during the first 7 d of CLA consumption. Mice (n=150; 9‐wk‐old) were fed 0 (ad libitum or pair‐fed to CLA‐fed mice) or 2% CLA (ad libitum) for 1, 2, 3, 5, or 7 d. A body fat index was calculated; liver, adipose tissue, and brain were analyzed for fatty acid profiles; and serum insulin, leptin, and PYY were measured. CLA and pair‐fed mice ate less (P &lt; 0.05) than control mice on d 1, 2, 3, and 7, but CLA‐fed mice were leaner than control and pair‐fed mice only on d 7 (P &lt; 0.01). CLA was detected in adipose tissue starting on d 2 and in liver on d 1, but CLA was not detectable in the brain. Serum insulin tended (P = 0.11 and 0.13, respectively) to be increased in CLA‐fed mice on d 5 and 7, and serum leptin was non‐significantly reduced in CLA‐fed mice compared to control mice on d 7. The CLA‐induced reduction in feed intake was not sufficient to cause the loss of body fat as pair‐fed mice were not leaner than controls. The lack of CLA in the brain indicates that the effect on feed intake may be indirect.

Meta-análise do uso de ácido linoleico conjugado na alimentação de suínos

O objetivo deste trabalho foi realizar uma meta-análise da associação do ácido linoleico conjugado (CLA) com o desempenho e a qualidade de carcaça e de carne em suínos (Sus scrofa domesticus). A base de dados utilizada contemplou 15 artigos publicados entre 1999 e 2006, e totalizou 216 dietas e 5.223 animais. A meta-análise foi realizada por meio de análises gráficas (para observar coerência biológica dos dados), de correlação (para identificar variáveis correlacionadas) e de variância-covariância. O modelo da análise de variância incluiu apenas as variáveis de carne e carcaça mais correlacionadas com o consumo de CLA pelos animais, além das codificações para os efeitos inter e intra-experimentos. A inclusão do ácido linoleico apresentou correlação negativa com a eficiência alimentar e positiva com o consumo de ração e o ganho de peso dos animais. Não houve alteração do consumo de ração, do ganho de peso e da eficiência alimentar dos suínos. O ácido linoleico conjugado aumentou em 9% o conteúdo de carne magra na carcaça, e seu consumo variou a espessura média de toucinho. O ácido linoleico conjugado aumenta o conteúdo de carne magra e reduz a espessura de toucinho na carcaça, sem influenciar o desempenho e a qualidade da carne em suínos.

Dietary conjugated linoleic acid improves antioxidant capacity in broiler chicks

1. The influence of dietary conjugated linoleic acid (CLA) on the antioxidant status in the absence or presence of endotoxin exposure was studied with male broiler chicks. 2. In experiment 1, a total of 240 1-d-old broilers were allotted into 4 dietary groups (0, 2·5, 5·0 or 10·0 g pure CLA/kg) to study the influence of CLA on growth performance and antioxidant defence systems. The results showed that growth performance was not altered by 42 d of CLA consumption. Increased total superoxide dismutase (TSOD) activities in liver, serum and muscle were observed in chicks given 10·0 g CLA/kg diet. Dietary CLA at 10·0 g/kg also markedly elevated liver catalase (CAT) activity. Malondialdehyde (MDA), a marker of lipid peroxidation, decreased in liver, serum and muscle in chicks given 5·0 and 10·0 g CLA/kg diet. 3. In experiment 2, a total of 120 1-d-old broilers were fed on a control diet (without CLA) or 10·0 g CLA/kg diet. Half of the birds fed on each diet were injected intraperitoneally with 0·25 mg/kg body weight of Salmonella enteritidis lipopolysaccharide (LPS) at 16, 18 and 20 d of age. Decreased glutathione peroxidase (GSH-Px), TSOD activity and increased ceruloplasmin and MDA concentrations were seen in the challenged chicks. Dietary CLA prevented the loss of body weight gain and feed conversion ratio of chicks followed repeated endotoxin exposure. CLA partially inhibited the increase of serum ceruloplasmin and MDA at 17 and 21 d of age and notably suppressed the decrease of serum TSOD activity at 21 d of age. 4. These results suggested that dietary CLA enhances the activity of antioxidant enzymes including TSOD and CAT. Supplementation of CLA has been shown to ameliorate the antioxidant balance and performance of chicks during oxidative stress.