Conjugated linoleic acid: health implications and effects on body composition

Synergistic effects of punicic acid and alpha lipoic acid ameliorate inflammatory and metabolic genes expression in C2C12 myoblast cells under oxidative stress condition

Inflammation is a reaction of the immune system to infection and injury; in fact, it positioned at the center of metabolic disorders, particularly obesity, type 2 diabetes, and cardiovascular diseases. Thus play a major role not only in their development, but also exerts as a crucial linking factor among those diseases. In this regard, one of the strategies for tackling this problem is application of antioxidants to treat such diseases. The present study was performed to evaluate the synergistic effects of punicic acid (PUA) and alpha-lipoic acid (ALA) as antioxidants and radical scavenging reagents on the expression of some inflammatory and metabolism-related genes under oxidative stress in the muscle cells. The experimental treatments consisted of a range of 20, 40, 80, 160, and 320 µM of PUA, and 5, 25, 50, 100, and 200 µM of ALA with a 200 µM concentration of H2 O2 as an oxidative stress inducer. Accordingly, fatty acid treatments were applied for 24 h, and H2 O2 was treated for 1 h. Our results indicated that the simultaneous treatment of PUA and ALA at optimal concentrations (80 and 50 µM, respectively) decreased the expression of inflammation genes and increased the expression of regulatory genes (Pparγ, Pgc-1α) related to metabolism (p < .05). Unexpectedly, H2 O2 treatment increased the Fndc5 expression (p < .05). Maximal upregulation of Pparγ, Pgc-1α were obtained when fatty acids combination (PUA and ALA) were used in the culture of H2 O2 treated cells (p < .05). Therefore, our findings suggest that the simultaneous use of PUA and ALA fatty acids could reduce oxidative stress, and the expression of inflammatory genes, thereby improving the cell metabolism.

Dietary Supplementation with Oregano and Linseed in Autochthonous "Facciuta Lucana" Goats: Effects on Meat Quality Traits in Suckling Kids

Extruded linseed (Linum usitatissimum) in ruminant diets has been investigated as a strategy to improve the nutritional value and healthiness of meat fat; however, increased polyunsaturated fatty acids may limit the shelf-life of meat. Oregano (Origanum vulgare) has a documented antioxidant activity. The aim of the study was to investigate the effects of dietary supplementation with extruded linseed and oregano on goat milk quality and whether the characteristics of goat milk affect the physical and chemical features, fatty acid profile, meat lipid oxidation, and sensory properties of meat from suckling kids. Thirty-six male kids were weaned and divided into three homogeneous groups (n = 12); each group was either fed a control diet (C), or a diet containing 3% extruded linseed with or without the addition of 0.6% oregano ("L + O" and "L", respectively). The diets containing linseed lowered (p < 0.05) the saturated fatty acid content in meat, and increased (p < 0.05) monounsaturated and polyunsaturated fatty acids and conjugated linoleic acid. Oregano addition to the linseed diet proved to be effective in preserving meat shelf-life, as shown by a significant (p < 0.01) reduction in the malondialdehyde concentration after 10 days of storage, and improved meat succulence, tenderness, juiciness, and overall acceptance.

Effect of inclusion of bakery by-products in the dairy cow's diet on milk fatty acid composition

Bakery by-products (BP), rich in fats and sugars, are unconventional feed sources for cows whose effects on milk fat composition have not yet been evaluated. This research paper aimed to assess the effects of dietary BP inclusion rate and feeding period on the milk fatty acid composition. Twenty-four Simmental cows were fed a diet without BP (CON) for 1 week. Then they either continued with the CON diet or switched to one of the BP diets (with 15% or 30% BP in diet dry matter) for 3 weeks. Milk samples were taken before diet change and three times during BP feeding and analysed for fatty acid composition. Data showed that increasing BP content in the diet increased total fatty acid intake, especially of 18 : 1 n9. In the milk fat, the percentages of total monounsaturated fatty acids especially of the 18 : 1 origin linearly increased with increasing dietary BP level. The percentage of fatty acids de novo synthesized in the mammary gland (the sum of 4 : 0-14 : 0) remained similar among diets (32-34% of total fatty acids). The 16 : 0 percentage dropped from 32.5 to 29.6% and from 33.6 to 28.3% for 15% and 30% BP, respectively. Only 30% BP elevated the percentage of conjugated linoleic acids (CLA: by 59%) compared with CON throughout the 3 weeks. Proportions of 18 : 2 n6 and 18 : 3 n3 and the n6:n3 ratio were unaffected by BP and feeding time. BP feeding improved all those estimated health indices of the milk fat that are suggested to be related to coronary health. In summary, the inclusion of BP in dairy rations beneficially shifted the milk fatty acid profile to more 18 : 1 fatty acids at the expense of 16 : 0. At a 30% inclusion rate, BP feeding showed an additional benefit of increased CLA content in milk fat.

Measuring Conjugated Linoleic Acid (CLA) Production by Bifidobacteria

The biological significance of conjugated fatty acids (CFAs) has been linked to positive health effects based on biomedical, in vitro, and clinical studies. Of note, conjugated linoleic acids (CLAs) are the most widely characterized fatty acids as geometric isomers cis-9,trans-11 and trans-10,cis-12 CLA occur naturally in ruminant fats, dairy products, and hydrogenated oils. Concerning CLAs, it is known that bacterial biohydrogenation, a process whereby ruminal bacteria or starter cultures of lactic acid bacteria have the ability to synthesize CLA by altering the chemical structure of essential fatty acids via enzymatic mechanisms, produces a multitude of isomers with desirable properties. Bifidobacterium species are classed as food grade microorganisms and some of these strains harness molecular determinants that are responsible for the bioconversion of free fatty acids to CLAs. However, molecular mechanisms have yet to be fully elucidated. Reports pertaining to CLAs have been attributed to suppressing tumor growth, delaying the onset of diabetes mellitus and reducing body fat in obese individuals. Given the increased attention for their bioactive properties, we describe in this chapter the qualitative and quantitative methods used to identify and quantify CLA isomers produced by bifidobacterial strains in supplemented broth media. These approaches enable rapid detection of potential CLA producing strains and accurate measurement of fatty acids in biological matrices.

Traditional plain yogurt: a therapeutic food for metabolic syndrome?

Dairy products have an important role in a healthy diet due to their high-quality protein and rich micronutrients. Yogurt, a fermented milk product, has a similar composition to milk but is a more concentrated product in terms of group B vitamins, minerals, and proteins. It is known that bioactive metabolites and live enzymes that occur by fermentation and digestion, affect the health positively by improving gut microbiota. In recent years, the prevalence of metabolic syndrome, which threatens public health, is increasing rapidly. As with other noninfectious diseases, the diet has an important effect on the prevention and treatment of metabolic syndrome. It has been demonstrated that yogurt has a high-quality amino acid pattern, reduces energy intake by stimulating satiety, and regulates blood glucose level. In addition to the rich protein variety, yogurt also contains peptides that positively affect blood pressure. Unlike milk, increased acidity during the fermentation of yogurt positively affects calcium absorption. Calcium plays an important role in the control of blood glucose and energy metabolism through insulin-dependent and non-insulin-dependent routes. In addition to reducing inflammation, calcium has a positive effect on the regulation of the blood lipid profile by increasing fecal fat excretion. There are many lipid and lipoid nutrients such as saturated fatty acids, phospholipids, sphingolipids, and conjugated linoleic acid that may affect the blood lipid profile in yogurt positively or negatively. There are seen very few randomized controlled studies that are focused on the relationship between yogurt and metabolic syndrome, and these are based on contradictory results. In this review, based on the clinical studies conducted to date, and the nutrient content of yogurt, possible mechanisms of these contradictory results are investigated.

PhoQ is an unsaturated fatty acid receptor that fine-tunes Salmonella pathogenic traits

The Salmonella enterica PhoP/PhoQ two-component signaling system coordinates the spatiotemporal expression of key virulence factors that confer pathogenic traits. Through biochemical and structural analyses, we found that the sensor histidine kinase PhoQ acted as a receptor for long-chain unsaturated fatty acids (LCUFAs), which induced a conformational change in the periplasmic domain of the PhoQ protein. This resulted in the repression of PhoQ autokinase activity, leading to inhibition of the expression of PhoP/PhoQ-dependent genes. Recognition of the LCUFA linoleic acid (LA) by PhoQ was not stereospecific because positional and geometrical isomers of LA equally inhibited PhoQ autophosphorylation, which was conserved in multiple S. enterica serovars. Because orally acquired Salmonella encounters conjugated LA (CLA), a product of the metabolic conversion of LA by microbiota, in the human intestine, we tested how short-term oral administration of CLA affected gut colonization and systemic dissemination in a mouse model of Salmonella-induced colitis. Compared to untreated mice, CLA-treated mice showed increased gut colonization by wild-type Salmonella, as well as increased dissemination to the spleen. In contrast, the inability of the phoP strain to disseminate systemically remained unchanged by CLA treatment. Together, our results reveal that, by inhibiting PhoQ, environmental LCUFAs fine-tune the fate of Salmonella during infection. These findings may aid in the design of new anti-Salmonella therapies.

Highly selective isomerization of cottonseed oil into conjugated linoleic acid catalyzed by multiwalled carbon nanotube supported ruthenium

Supported ruthenium (Ru) has the capacity to catalyze the conjugation of double bonds in linoleic acid (LA) into conjugated linoleic acids (CLAs). It has been reported that CLAs have shown a lot of benefits to human health. To enhance the selectivity of cottonseed oil (CSO) to CLAs, various Ru catalysts supported by multiwalled carbon nanotubes (Ru/MWCNTs) were prepared using a microwave-heated ethylene glycol method. All catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectrometry (ICP-OES). The catalytic efficiency/selectivity of Ru/MWCNTs and two commercially available Ru catalysts (Ru/C and Ru/Al₂O₃) were investigated in a solvent-free system by catalyzing the isomerization of CSO. TEM analysis showed that Ru nanoparticles with average sizes of 1.0 nm to 1.8 nm were uniformly dispersed on the surface of the supports. Among the as-synthesized Ru/MWCNTs, catalyst S1 (diameter < 8 nm, length 0.5–2 μm) and catalyst S4 (diameter < 8 nm, length 10–30 μm) exhibit excellent catalytic performance for isomerization of CSO with high yield of total CLA (15.91% and 11.56%, respectively) and high turnover frequency (TOF) of 10.39 and 11.38 h⁻¹, which is much better than two typical commercial Ru catalysts (Ru/Al₂O₃ and Ru/C). It has been revealed that the average particle size and chemical state of Ru on the surface of MWCNTs have influence on the activity and selectivity of the isomerization reaction.

Ruthenium supported on multiwalled carbon nanotubes is a highly efficient catalyst for the linoleic acid conjugation of cottonseed oil.

Changes in lipids composition and metabolism in colorectal cancer: a review

Altered metabolism of lipids is currently considered a hallmark characteristic of many malignancies, including colorectal cancer (CRC). Lipids are a large group of metabolites that differ in terms of their fatty acid composition. This review summarizes recent evidence, documenting many alterations in the content and composition of fatty acids, polar lipids, oxylipins and triacylglycerols in CRC patients' sera, tumor tissues and adipose tissue. Some of altered lipid molecules may be potential biomarkers of CRC risk, development and progression. Owing to a significant role of many lipids in cancer cell metabolism, some of lipid metabolism pathways may also constitute specific targets for anti-CRC therapy.

A comprehensive analysis of the composition, health benefits, and safety of apple pomace

Apple processing results in peel, stem, seeds, and pulp being left as a waste product known as apple pomace. This review comprehensively assessed apple pomace composition for nutritional value and bioactive substances and evaluated potential health benefits and safety. Apple pomace is a rich source of health-benefitting nutrients, including minerals, dietary fiber, antioxidants, and ursolic acid, which suggests it has potential use as a dietary supplement, functional food, and/or food additive. Preclinical studies have found apple pomace and its isolated extracts improved lipid metabolism, antioxidant status, and gastrointestinal function and had a positive effect on metabolic disorders (eg, hyperglycemia, insulin resistance, etc.). Safety studies have shown apple pomace to be a safe livestock feed additive and to have pesticide concentrations within safety thresholds established for human consumption. Commercial development of apple pomace for human consumption requires more research focusing on standardized methods of nutrient reporting, mechanistic studies, and human clinical trials.

The use of energy-protein supplement increases performance of high-yielding dairy cows and improves health-promoting properties of milk

Lipid additives are of particular importance in the diet of high-yielding dairy cows. The aim of this study was to determine the effects of a specially designed energy-protein supplement on dairy cows’ performance and milk composition. The experiment was conducted on 24 Polish Holstein-Friesian cows fed total mixed ration. Two kilograms of energy-protein supplement/cow.day were added to the ration for one group of cows whereas the other was fed solely the total mixed ration. The supplement consisted of whole flax seeds, wheat bran, flaxseed and fish oils, and rapeseed cake and its composition is protected by a patent. Feed intake and daily milk yield were recorded automatically for each cow. Gross milk composition and fatty acid profile of milk were determined. An ANOVA was performed to determine the influence of the supplement on performance traits and milk composition. Energy-protein supplement had a positive impact on dry matter intake and milk yield of cows. It had a little effect on the gross milk composition and somatic cell count. The effect of the additive on fatty acids in milk was beneficial, therefore its use in high-yielding dairy cows nutrition is recommended to improve health-promoting properties of milk.

Supplementation of cow milk naturally enriched in polyunsaturated fatty acids and polyphenols to growing rats

This study investigated whether intake of cow milk, naturally enriched with polyunsaturated fatty acids (PUFA, omega-3) and polyphenols (from propolis extract and vitamin E), from manipulation of cow's diet, would result in positive metabolic effects in rats from weaning until adulthood. Male Wistar rats were fed a standard chow diet or a hypercaloric diet (metabolically disturbed rats, obese) which was supplemented with either whole common milk, milk enriched with PUFA (PUFA-M) or milk enriched with PUFA and polyphenols (PUFA/P-M), at 5mL/kg body weight,having water as control. Whole milk supplementation increased initial weight gain and reduced gain in the adulthood of rats. Intake of common milk reduced cholesterol levels in non-obese rats and reduced insulin resistance in obese rats. PUFA-milk showed a decreasing effect on plasma triacylglycerol and VLDL concentrations, increasing plasma HDL concentration and reducing adipocyte size of non-obese rats, but no effect was observed in obese rats. PUFA/P-milk in obese rats resulted in greater deposition of muscle mass and mesenteric fat, with a tendency to lower LDL levels, and resulted a visceral fat accumulation in non-obese rats. Thus, whole common milk and PUFA-rich milk have shown to be beneficial in a normal metabolic condition, whereas common milk and milk enriched with PUFA and polyphenols improve metabolic effects of obesity.

Physiological Properties of Conjugated Linoleic Acid and Implications for Human Health

Conjugated linoleic acid (CLA) refers to a mixture of positional and geometric dienoic isomers of linoleic acid found naturally in animal products of ruminant sources. Recent interest in CLA research stems from the well-documented anticarcinogenic, antiatherogenic, antidiabetic, and antiobesity properties of CLA in rodents. However, there has been very little published human research on CLA. This review discusses the physiologic properties of CLA and their potential implications for human health.

Genetic and environmental relationships of detailed milk fatty acids profile determined by gas chromatography in Brown Swiss cows

The aim of this study was to characterize the profile of 47 fatty acids, including conjugated linoleic acid (CLA), 13 fatty acid groups, and 5 Δ(9)-desaturation indices in milk samples from Brown Swiss cows. The genetic variation was assessed and the statistical relevance of the genetic background for each trait was evaluated using the Bayes factor test. The additive genetic, herd-date, and residual relationships were also estimated among all single fatty acids and groups of fatty acids. Individual milk samples were collected from 1,158 Italian Brown Swiss cows and a detailed analysis of fat percentages and milk fatty acid compositions was performed by gas chromatography. Bayesian animal models were used for (co)variance components estimation. Exploitable genetic variation was observed for most of the de novo synthesized fatty acids and saturated fatty acids, except for C4:0 and C6:0, whereas long-chain fatty acids and unsaturated fatty acids (including CLA) were mainly influenced by herd-date effects. Herd-date effect explained large portions of the total phenotypic variance for C18:2 cis-9,cis-12 (0.668), C18:3 cis-9,cis-12,cis-15 (0.631), and the biohydrogenation and elongation products of these fatty acids. The desaturation ratios showed higher heritability estimates than the individual fatty acids, except for CLA desaturation index (0.098). Among the medium-chain fatty acids, C12:0 had greater heritability than C14:0 (0.243 vs. 0.097, respectively). Both C14:0 and C16:0 showed negative additive genetic correlations with the main monounsaturated and polyunsaturated fatty acids of milk fat, suggesting that their synthesis in the mammary gland may be influenced by the presence of unsaturated fatty acids. No correlation was observed between C4:0 and the other short-chain fatty acids (except for C6:0), confirming the independence of C4:0 from de novo mammary fatty acid synthesis. Among the genetic correlations dealing with potentially beneficial fatty acids, C18:0 was positively correlated with vaccenic and rumenic acids and negatively with linoleic acid. Finally, fatty acids C6:0 through C14:0 showed relevant correlations due to unknown environmental effects, suggesting the potential existence of genetic variances in micro-environmental sensitivity. This study allowed us to acquire new knowledge about the genetic and the environmental relationships among fatty acids. Likewise, the existence of genetic variation for most of de novo synthetized fatty acids and saturated fatty acids was also observed. Overall, these results provide useful information to combine feeding with genetic selection strategies for obtaining a desirable milk fatty acids profile, depending on the origin of fatty acids in milk.

Complementary and alternative medicine for the treatment of obesity: a critical review

CONTEXT

Obesity and its associated morbidities pose a major health hazard to the public. Despite a multiplex of available diet and exercise programs for losing and maintaining weight, over the past years, interest in the use of complementary and alternative medicine (CAM) for obesity treatment has greatly increased.

EVIDENCE ACQUISITION

We searched PubMed, Google scholar and the Cochrane databases for systemic reviews, review articles, meta-analysis and randomized clinical trials up to December 2013.

RESULTS

In this review, the efficacy and safety of the more commonly used CAM methods for the treatment of obesity, namely herbal supplements, acupuncture, and non-invasive body-contouring, are briefly discussed. The evidence supporting the effectiveness and safety of these methods is either lacking or point to a negligible clinical benefit, barely surpassing that of the placebo. Furthermore, several limitations are observed in the available scientific literature. These shortcomings include, without being limited to, uncontrolled trial designs, non-random allocation of subjects to treatment arms, small number of patients enrolled, short durations of follow-up, and ambiguous clinical and laboratory endpoints.

CONCLUSIONS

Further investigations are necessary to accurately determine the efficacy, safety, standard dosage/procedure, and potential side effects of the various CAM methods currently in use.

Conjugated linolenic acids and their bioactivities: a review

Conjugated linolenic acid (CLNA) is a mixture of positional and geometric isomers of octadecatrienoic acid (α-linolenic acid, cis9,cis12,cis15-18:3 n-3) found in plant seeds. Three 8,10,12-18:3 isomers and four 9,11,13-18:3 isomers have been reported to occur naturally. CLNA isomers such as punicic acid, α-eleostearic acid and jacaric acid have been attributed to exhibit several health benefits that are largely based on animal and in vitro studies. This review has summarized and updated the evidence regarding the metabolism and bioactivities of CLNA isomers, and comprehensively discussed the recent studies on the effects of anti-carcinogenic, lipid metabolism regulation, anti-inflammatory, anti-obese and antioxidant activities of CLNA isomers. The available results may provide a potential application for CLNA isomers from natural sources, especially edible plant seeds, as effective functional food ingredients and dietary supplements for the above mentioned disease management. Further research, especially human randomized clinical trials, is warranted to investigate the detailed physiological effects, bioactivity and molecular mechanism of CLNA.

The effect of conjugated linoleic acids and omega-3 fatty acids supplementation on lipid profile in atherosclerosis

Background:

Cardiovascular diseases (CVD) are the most serious cause of mortality in developed and developing countries. Epidemiological studies indicated that dyslipidemia is the major risk factor of CVD. Dyslipidemia can be modified either by proper lifestyle or medical intervention or by the combination of both. Conjugated linoleic acids (CLA) and ω3 fatty acids have beneficial effects on plasma lipids and lipoproteins. The aim of this study was to evaluate the effect of CLA and omega-3 fatty acids (ω-3 fatty acids) supplementation on lipid profile in atherosclerosis patient.

Materials and Methods:

This study was a 2-month clinical randomized trial. Ninety atherosclerotic patients with angiographically diagnosed coronary atherosclerosis who were referred to Emam Reza Heart Clinic of Shiraz University of Medical Sciences from February to march 2011 were selected if they fulfilled the inclusion criteria. The participants were randomly classified into 3 groups receiving 3 g/d CLA or 1 920 mg/d ω3 or placebo for 2 months. High-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), triglycerides (TG), and total cholesterol were measured before and after the intervention. This study was a two-month clinical randomized trial.

Results:

Data were analyzed using SPSS software (SPSS Inc, Chicago, version19). Although CLA did not appear to have a significant effect on TG, ω3 supplementation significantly reduced TG level. Consumption of CLA and ω3 supplementation did not significantly affect HDL cholesterol, LDL cholesterol, and total cholesterol.

Conclusions:

ω3 supplementation significantly reduced TG level but CLA and ω3 did not show significant changes in other indices of lipid profile in atherosclerotic patients.

Conjugated linoleic acid is related to bone mineral density but does not affect parathyroid hormone in men

The relationships between conjugated linoleic acid (CLA) status, bone, body composition, and the effect of CLA on calciotropic hormones are unclear. A cross-sectional study was designed to examine the association between c9, t11 CLA status in erythrocyte membranes (RBC) and body composition. This preceded a dose-response trial investigating if c9, t11 CLA affected parathyroid hormone (PTH). It was hypothesized that (1) higher c9, t11 CLA status in RBC will be associated with a lower fat and higher bone mass and that (2) PTH will be reduced by 30% after supplementation of c9, t11 CLA. Fifty-four men (age, 19-53 years) were included in the cross-sectional analysis, of which 31 were studied in the dose-response trial and randomized to 1 of 3 groups: placebo (n = 10), 1.5 g/d (n = 11), or 3.0 g/d (n = 10) of c9, t11 CLA for 16 weeks. Men with RBC c9, t11 CLA status above the median had higher whole body bone mineral density (BMD) (1.359 ± 0.024 vs 1.287 ± 0.023 g/cm(2); P = .04) and whole body lean mass (WBL) percentage (78.8% ± 0.9% vs 75.3% ± 1.0%; P = .01), whereas body mass index (24.8 ± 0.5 kg/m(2) vs 27.3 ± 0.9 kg/m(2); P = .01) and whole body fat mass percentage (17.3% ± 0.9% vs 21.3% ± 1.1%; P = .007) were lower. In regression analysis, RBC c9, t11 CLA status accounted for a significant proportion (r(2) = 0.10) of the variation in whole body BMD (P = .03). There were no time or treatment differences among any bone or biomarkers of bone metabolism including PTH. These findings indicate that RBC c9, t11 CLA status, a reflection of long-term (~4 months) dietary CLA intake, positively relates to BMD. However, c9, t11 CLA supplementation does not appear to affect PTH in healthy men.

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.

Dietary strategies to improve nutritional value, oxidative stability, and sensory properties of poultry products

Consumers demand both safer and more nutritious food products exempt of non-natural origin preservatives or other food additives. In this frame, products with lower fat content and/or a higher ratio in unsaturated fatty acids, especially n-3 fatty acids, are desired because these lipids can help prevent the development of cardiovascular and inflammatory pathologies. The intake of meat products is of interest because they are an excellent source of vitamins and minerals. In addition, the shelf-life of meat products can be extended by the presence of natural antioxidants coming from different sources such as plant extracts. Therefore, different strategies have been studied to improve the nutritional value, oxidative stability, and sensory characteristics of meat products and eggs through different mineral and natural dietary supplements. In comparison to other strategies, dietary supplements present the advantage that first the living animals may efficiently distribute the compounds throughout the tissues and second, the dietary supplementation is safer because the resulting enriched meat products and eggs ensure tolerable amounts in humans. Poultry meats and eggs are widely consumed and their fatty acid profile and tocopherol content can be easily modified through different dietary strategies thus being excellent models to improve their nutritional value and oxidative stability.

Trans-8,cis-10+cis-9,trans-11-conjugated linoleic acid mixture alters body composition in Syrian golden hamsters fed a hypercholesterolaemic diet

The effectiveness of conjugated linoleic acid (CLA) as a weight-loss nutraceutical continues to be debatable, suggesting that there may be value in exploring the physiological effects of the lesser-known isomers. The effects of the minor isomer,trans-8,cis-10 (t8,c10)-CLA, in the form of an equimolar mixture with thecis-9,trans-11 (c9,t11) isomer, on body weight and body composition, circulating glucose and lipid concentrations, and liver weights were studied in sixty male Syrian golden hamsters. Animals were randomised to receive for 28 d a semi-purified, hypercholesterolaemic diet (5 % dietary fat and 0·25 % cholesterol) supplemented at the 2 % level with either thet8,c10+c9,t11-CLA mixture,c9,t11-CLA ortrans-10,cis-12 (t10,c12)-CLA replacing lard and safflower-seed oil (control). Results show that compared with control, thet8,c10+c9,t11-CLA mixture andt10,c12-CLA-fed animals had lower (P < 0·0001) fat mass following supplementation. Animals consumingt10,c12-CLA also possessed higher lean mass compared with control andc9,t11-CLA groups (P < 0·001). However, the livers of these animals were larger (P < 0·0001) compared with those in the control and other CLA groups. Body weights of the hamsters did not differ across the experimental groups. CLA treatments had no effect on serum glucose or lipid profile, except for inducing higher (P < 0·05) non-HDL-cholesterol concentration witht10,c12-CLA compared with thec9,t11 isomer. Overall, these results indicate that in male hamsters fed a hypercholesterolaemic diet, thet8,c10+c9,t11-CLA mixture does not have an impact on blood lipid profile, but is able to effectively reduce fat mass, without incurring an accompanying liver enlargement.

Dairy food consumption and obesity-related chronic disease

Dairy food comprises a range of different products with varying nutritional components. In the context of a healthy diet, dairy food may provide protection against and amelioration of chronic diseases related to obesity. These include overweight, insulin resistance/metabolic syndrome/type 2 diabetes, hypertension/stroke, and cardiovascular disease. Eliciting how dairy food may have this impact represents a challenge for modern nutritional science and requires an integration of knowledge from observational studies of population dietary patterns and disease prevalence, and experimental studies testing the effect of dairy food consumption. It also benefits from the recent identification of biomarkers of dairy fat intake and from mechanistic studies that support the plausibility of the observed effects. Future research might discriminate between types of dairy foods and focus on the synergy provided by the food matrix, rather than simply the component parts of the food.

Conjugated linoleic acid suppresses colon carcinogenesis in azoxymethane-pretreated rats with long-term feeding of diet containing beef tallow

BACKGROUND

We have indicated previously that long-term feeding of beef tallow increases colorectal cancer in rats. In this study, we investigated the effects of conjugated linoleic acid (CLA) on colon carcinogenesis in rats under long-term feeding of beef tallow diets, pretreated with azoxymethane (AOM).

METHODS

Six-week-old male Sprague-Dawley rats were fed with 10% beef tallow diet only, 10% beef tallow with 1% CLA in triglyceride form (CLA-TG), or 10% beef tallow with 1% CLA in free fatty acid form (CLA-FFA). Colon carcinogenesis was induced by two intraperitoneal injections of AOM. Aberrant crypt foci (ACFs) were examined at 12 weeks. Cancer, cell proliferation, apoptosis, Wnt signaling, and the arachidonic acid cascade were examined at 44 weeks.

RESULTS

At 12 weeks, CLA-TG and CLA-FFA attenuated the increase in ACFs induced by 10% beef tallow and AOM pretreatment. At 44 weeks, both forms of CLA attenuated multiple colon cancers, and CLA-FFA reduced the incidence of colon cancer to 50% of that seen with CLA-TG. CLA-TG and CLA-FFA decreased the number of 5-bromo-2'-deoxyuridine-positive cells in AOM-pretreated rats fed with 10% beef tallow. CLA-FFA increased the number of apoptotic cells and the activity of caspase-3 in the colon mucosa, and CLA-TG enhanced the activity of caspase-3. Both forms of CLA suppressed Wnt signaling and the arachidonic acid cascade in rats treated with beef tallow and AOM.

CONCLUSION

These results suggested that CLA-TG and CLA-FFA suppressed colon carcinogenesis in rats with long-term feeding of a 10% beef tallow diet, through several mechanisms. The results of the present study with rats might be applicable to humans.

Lipase-catalyzed synthesis of conjugated linoleyl beta-sitosterol and its cholesterol-lowering properties in mice

Conjugated linoleyl beta-sitosterol (CLS) was prepared from beta-sitosterol and conjugated linoleic acid (CLA) via lipase-catalyzed synthesis in n-hexane in the presence of molecular sieves. Its plasma cholesterol-lowering properties were also studied. The optimal biosynthesis conditions were as follows: beta-sitosterol concentration of 50 micromol/mL, the molar ratio of CLA to beta-sitosterol of 1:1, the lipase concentration of 20 mg/mL, and 4 A molecular sieve concentration of 60 mg/mL in n-hexane at 50 degrees C with vigorous shaking of 150 rpm for 72 h, and the highest yield of CLS reached 72.6%. The isolated CLS mixed with mice feed had good cholesterol-lowering properties. It decreased serum total cholesterol (TC), serum triacylglycerols (TAGs), serum low-density lipoprotein cholesterol (LDL-C), atherogenic index (AI), liver weight (LW), liver index (LI), liver TC, and TAGs of mice, which was shown that CLS could prevent the formation of atherosclerosis and moderate the fat pathologic changes of liver. However, the HDL-C was not decreased, which proved the advantage of CLS over the other cholesterol-lowering products.

Conjugated linoleic acids as functional food: an insight into their health benefits

This review evaluates the health benefits of the functional food, conjugated linoleic acids (CLA) - a heterogeneous group of positional and geometric isomers of linoleic acid predominantly found in milk, milk products, meat and meat products of ruminants. During the past couple of decades, hundreds of reports - principally based on in vitro, microbial, animal, and of late clinical trials on humans - have been accumulating with varying biological activities of CLA isomers. These studies highlight that CLA, apart form the classical nuclear transcription factors-mediated mechanism of action, appear to exhibit a number of inter-dependent molecular signalling pathways accounting for their reported health benefits. Such benefits relate to anti-obesitic, anti-carcinogenic, anti-atherogenic, anti-diabetagenic, immunomodulatory, apoptotic and osteosynthetic effects. On the other hand, negative effects of CLA have been reported such as fatty liver and spleen, induction of colon carcinogenesis and hyperproinsulinaemia. As far as human consumption is concerned, a definite conclusion for CLA safety has not been reached yet. Parameters such as administration of the type of CLA isomer and/or their combination with other polyunsaturated fatty acids, mode of administration (eg., as free fatty acid or its triglyceride form, liquid or solid), daily dose and duration of consumption, gender, age, or ethnic and geographical backgrounds remain to be determined. Yet, it appears from trials so far conducted that CLA are functional food having prevailing beneficial health effects for humans.

Isomer specificity of conjugated linoleic acid (CLA): 9E,11E-CLA

Conjugated linoleic acids (CLA) were identified in 1980's, since then it has been intensively studied due to its various beneficial health effects such as anti-inflammatory, anti-atherogenic, anti-carcinogenic and anti-diabetic/obesity effects. Isomer specificity of a number of CLA isomers, especially predominant isomer 9Z,11E- and 10E,12Z-CLA, is now recognized. However, the less prevalent CLA isomers have not been well characterized. Recently, studies have reported the distinctively different effects of 9E,11E-CLA in colon cancer cells, endothelial cells, and macrophage cells compared to the rest of CLA isomers. In this review, various effects of CLAs, especially anti-inflammatory and anti-atherogenic effects, will be discussed with focusing on the isomer-specific effects and potential mechanism of action of CLA. At last, recent studies about 9E,11E-CLA in in vitro and animal models will be discussed.

Beneficial health effects of milk and fermented dairy products--review

Milk is a complex physiological liquid that simultaneously provides nutrients and bioactive components that facilitate the successful postnatal adaptation of the newborn infant by stimulating cellular growth and digestive maturation, the establishment of symbiotic microflora, and the development of gut-associated lymphoid tissues. The number, the potency, and the importance of bioactive compounds in milk and especially in fermented milk products are probably greater than previously thought. They include certain vitamins, specific proteins, bioactive peptides, oligosaccharides, organic (including fatty) acids. Some of them are normal milk components, others emerge during digestive or fermentation processes. Fermented dairy products and probiotic bacteria decrease the absorption of cholesterol. Whey proteins, medium-chain fatty acids and in particular calcium and other minerals may contribute to the beneficial effect of dairy food on body fat and body mass. There has been growing evidence of the role that dairy proteins play in the regulation of satiety, food intake and obesity-related metabolic disorders. Milk proteins, peptides, probiotic lactic acid bacteria, calcium and other minerals can significantly reduce blood pressure. Milk fat contains a number of components having functional properties. Sphingolipids and their active metabolites may exert antimicrobial effects either directly or upon digestion.

Changes in some components of the muscle lipids of three freshwater fish species under natural extreme cold and temperate conditions

Fatty acid composition, conjugated linoleic acid and cholesterol contents in the muscles of three freshwater fish species (Barbus plebejus escherichi, Capoeta capoeta capoeta and Rutilus rutilus) were determined under natural extreme temperate (July) and cold (January) conditions. The aim of the study was to determine whether there were differences in these components of the muscle lipids among these three fish species under extreme natural conditions. Samples were analyzed using gas chromatography. Palmitic, oleic, docosahexaenoic and eicosapentaenoic acids were the predominant fatty acids in all fish in both months. The percentages of polyunsaturated fatty acids, n - 3 polyunsaturated fatty acids, n - 6 polyunsaturated fatty acids and eicosapentaenoic + docosahexaenoic acids in the muscle of B. plebejus escherichi and C. capoeta capoeta were significantly higher in January (P < 0.05) than in July. The ratio of n - 6 to n - 3 polyunsaturated fatty acids was lower than 0.60 in all fish species, with C. capoeta capoeta showing the lowest ratio in January (0.36). The levels of cholesterol and conjugated linoleic acid ranged from 103.46 to 150.10 mg/100 g oil and from 16.27 to 35.45 mg/100 g oil, respectively, for all samples in both months. There were no statistical differences in cholesterol levels among the three fish species in July and January. Conjugated linoleic acid contents were significantly higher in January in B. plebejus escherichi and C. capoeta capoeta. Of the three species tested, the extreme temperate and cold conditions affected B. plebejus escherichi the most.

Conjugated linoleic acid content of human plasma

Conjugated linoleic acid (CLA), a naturally occurring anticarcinogen found in dairy products, is an intermediary product of ruminal biohydrogenation of polyunsaturated fatty acids. Few data exist on the CLA content of the human blood plasma. The determination of a "normal" content could help in estimating if a person consumes satisfactory amounts of CLA with the diet and thus takes advantage of its potential beneficial effects on health. The purpose of this study was to compare the plasma CLA content of individuals not consuming dairy products (group 1, n = 12), individuals consuming normal amounts of dairy products (group 2, n = 77) and individuals consuming CLA supplement (group 3, n = 12). The only CLA isomer that presented higher percentage than the detection limit (0.03% of total fatty acids) was rumenic acid (cis9, trans11-octadecadienoic acid). An interesting finding is that compared to the other two groups, group 3 members show the highest average plasma content in rumenic acid, i.e. 0.20% of total fatty acids. The present study could be characterized as the first step in the direction of establishing a normal CLA content of human plasma. Based on these results, it could be suggested that the lower limit of the plasma CLA content is approximately 0.1% of total fatty acids.

The animal fat paradox and meat quality

The purpose of this paper is to address some of the paradoxical issues and perceptions regarding animal fats and the related effects on meat quality and consumer perceptions. Meat scientists have been studying carcass characteristics for many years and although the factors that influence the accumulation, distribution and composition of carcass fat in livestock have been extensively researched, the role, value and perceptions of animal fats in meat quality differ significantly in importance between producers, abattoirs, butchers, retailers and consumers. Fat and long-chain fatty acids, whether in adipose tissue or muscle, contribute to important aspects of meat quality and are central to the nutritional and sensory values of meat. In this review the nutritional value of fat, as well as the importance of fat in terms of carcass and meat quality will be highlighted. The 'quality' of meat depends greatly on the socio-demographic backgrounds of the consumer. The aim is to focus on the global importance of fat in the carcass to the producer, processor and consumer. There is currently no clear cut definition for fat quality because the acceptability and perceived quality of fat varies significantly in terms of quantity, colour, consistency and chemical composition in different species of livestock around the world. The association between animal fats and human health is critical and recommendations by health professionals range from excluding fats altogether to a moderate consumption of fats due to their essential role in the body. Recently the emphasis has shifted away from fat quantity to fat quality. Despite these recommendations and years of bad publicity in terms of the adverse affects of animal fats in human health, the livestock industry seems reluctant to shift its focus to fat quality rather than quantity. This approach may adversely affect future meat consumption by consumers who are becoming increasingly critical about the food they eat.

Conjugated linoleic acid (CLA) and obesity

Background

The term conjugated linoleic acid (CLA) refers to several positional and geometric conjugated dienoic isomers of linoleic acid (LA), of which the trans-10,cis-12 isomer has been reported to reduce adiposity and increase lean mass in mice and other animals when included at ≤1% of the diet. However, most dietary CLA in humans is obtained from dairy products, accounting for the cis-9,trans-11 CLA isomer, also known as rumenic acid, for more than 90% of the total CLA intake. Commercial CLA preparations industrially produced, containing trans-10,cis-12 and cis-9,trans-11 CLA isomers in diverse proportions, are attracting consumers’ interest because of the purported body fat-lowering effects of CLA, coupled to the perception of a ‘natural’ compound devoid of harmful effects. Nevertheless, despite numerous studies on CLA effects on body composition for nearly a decade, the mechanisms by which CLA isomers elicit their effects remain largely unknown. The purpose of this paper is to provide an updated review of the studies performed on animals and humans, as well as to describe the potential mechanisms involved in CLA effects on body weight and composition and metabolism.

Method

Literature review.

Results

Experiments in humans have not been able to show a significant effect on body weight, body composition or weight regain related to either of the CLA isomers. In fact, some studies suggest a tendency towards a decrease in body fat mass and an increase in body lean mass, while some others raise concern about the possibility of deleterious effects of trans-10,cis-12 CLA on lipid profile, glucose metabolism and insulin sensitivity.

Conclusions

Evidence regarding effectiveness of CLA in humans is not concluding.