Dietary protein modulates the effect of CLA on lipid metabolism in rats

Utilizing the underutilized plant resources for development of life style foods: Putting nutrigenomics to use

Sufficient amount of minerals, vitamins, and proteins in human diet play indispensable role in maintaining the active metabolism for better human health. All the essential nutrients that are requisite for an individual's survival are acquired from plants as well as animals. Micronutrients and macronutrients directly influence the metabolic pathways and their deficiencies play a substantial role in development of manifold disorders. In addition to environmental factors, quality and quantity of foods are key factors in maintaining the human health. Transition from healthy to diseased state is concurrent with the pattern of gene expression that is largely influenced by nutrition and environment. A combined approach to study the influence of nutrition on expression of numerous genes can be well explored through nutrigenomic studies. Nutrigenomics includes studies wherein applied genomics is used to investigate nutritional science to understand the compartmentalization of genes that influence the cause of diet-related complications. This review describes the role of underutilized crops as frontline foods to circumvent the health complications through the nutrigenomic studies. Further dynamics of nutrigenomic tools to study the impact of nutrition on the changing pattern of genome stability and gene expression for developing precise safety measures against wide range of health ailments linked to metabolic networks. Additionally, this review provides detailed information on nutrigenomic studies undertaken to unravel the potential of underutilized crops to augment the human health and to carry the agronomic/genomic approaches to enhance nutritional profile of underutilized crops to overcome diet-related disorders.

Linoleic Acids Overproducing Lactobacillus casei Limits Growth, Survival, and Virulence of Salmonella Typhimurium and Enterohaemorrhagic Escherichia coli

Probiotics, particularly lactic acid bacteria, are biologic agents which limit the growth, virulence, and survival/colonization of various enteric bacterial pathogens and serve as potential alternatives to antibiotics. Mechanisms that contribute to this antimicrobial effect include producing bioactive metabolites/acids, increasing nutrient and receptor-mediated competition, and modulating gut microbiome ecology. However, these functions of common probiotic strains are limited due to the finite quantity of metabolites they produce and their total number in the gut ecosystem. Conjugated linoleic acids (CLAs), critical metabolites of Lactobacillus, have multiple beneficial effects on human health including anti-carcinogenesis, anti-inflammation, anti-oxidation, and anti-pathogenicity. In this study, we aim to overexpress the myosin cross-reactive antigen gene (mcra) in Lactobacillus casei (LC) to enhance the production of CLA and investigate its effectiveness against enteric bacterial pathogens, specifically Salmonella enterica serovar Typhimurium (ST) and enterohaemorrhagic Escherichia coli (EHEC). By inserting mcra in L. casei, we generated LC-CLA and found the total linoleic acid production by an individual bacterial cell was raised by 21-fold. The adherence ability of LC-CLA on human epithelial cells increased significantly and LC-CLA competitively excluded both ST and EHEC in a mixed-culture condition. Furthermore, LC-CLA significantly altered the physicochemical properties, biofilm formation abilities, interactions with host cells of both ST and EHEC, and triggered anti-inflammatory activities of host cells. These findings offer insights on applying a genetically engineered probiotic to control gut intestinal infections caused by ST and EHEC and prevent foodborne enteric illness in human.

The Effect of Vegan Protein-Based Diets on Metabolic Parameters, Expressions of Adiponectin and Its Receptors in Wistar Rats

Vegan protein-based diet has attracted increasing interest in the prevention of metabolic syndrome (MetS). Meanwhile, adiponectin has become a highly potential molecular target in the prevention of MetS. Our study will identify a potential vegan protein diet for the prevention of MetS using rat models. Thirty-six Wistar rats were randomly assigned into three groups and given diets containing one of the following proteins for 12 weeks: casein (CAS, control diet), soy protein (SOY), and gluten-soy mixed protein (GSM). Changes in metabolic parameters as well as the expressions of adiponectin and its receptors were identified. Compared to CAS diet, both SOY and GSM diets led to decreases in blood total cholesterol and triglycerides, but only GSM diet led to an increase in HDL-cholesterol; no marked difference was observed in blood glucose in all three groups; HOMA-IR was found lower only in SOY group. Among groups, the order of serum adiponectin level was found as GSM > SOY > CAS. Similar order pattern was also observed in expression of adiponectin in adipose tissue and AdipoR1 mRNA in skeletal muscle. Our results suggested for the first time that, besides SOY diet, GSM diet could also be a possible substitute of animal protein to prevent MetS.

Nutrigenomics and its Impact on Life Style Associated Metabolic Diseases

Post-human genome revelation observes the emergence of 'Nutigenomics' as one of the exciting scientific advancement influencing mankind around the world. Food or more precisely 'nutrition' has the major impact in defining the cause-response interaction between nutrient (diet) and human health. In addition to substantial understanding of nutrition-human-health interaction, bases of 'nutrigenomic' development foster on advent in transcriptomics, genomics, proteomics and metabolomics as well as insight into food as health supplement. Interaction of selected nutrient with associated genes in specific organ or tissue necessary to comprehend that how individual's genetic makeup (DNA transcribed into mRNA and then to proteins) respond to particular nutrient. It provided new opportunities to incorporate natural bioactive compounds into food for specific group of people with similar genotype. As inception of diabetes associated with change in gene expression of, not limited to, protein kinase B, insulin receptor, duodenal homeobox and glucokinase, thus, targeting such proteins by modifying or improving the nutritional availability or uptake may help to devise novel food, supplements, or nutraceuticals. In this article, various aspects of R&D in nutrigenomics are reviewed to ascertain its impact on human health, especially with life-style associated diseases.

Modulation of adipose tissue inflammation by bioactive food compounds

Adipose tissue has an important endocrine function in the regulation of whole-body metabolism. Obesity leads to a chronic low-grade inflammation of the adipose tissue, which disrupts this endocrine function and results in metabolic derangements, such as type-2 diabetes. Dietary bioactive compounds, such as polyphenols and certain fatty acids, are known to suppress both systemic and adipose tissue inflammation and have the potential to improve these obesity-associated metabolic disorders. Mechanistically, polyphenolic compounds including non-flavonoids, such as curcumin and resveratrol, and flavonoids, such as catechins (tea-polyphenols), quercetin and isoflavones, suppress nuclear factor-κB (NF-κB) and mitogen-activated protein (MAP) kinases (MAPK) pathways while activating the 5' adenosine monophosphate-activated protein kinase (AMPK) pathway in adipose tissue. Dietary polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), conjugated linoleic acid (CLA) and monounsaturated fatty acids (MUFA), such as oleic acid, also impart anti-inflammatory effects through several mechanisms. These include activation of AMPK and peroxisome proliferator-activated receptor gamma (PPAR-γ), as well as suppression of toll-like receptors (TLRs) and NF-κB pathway. This review discusses the major molecular mechanisms of dietary polyphenols and fatty acids, alone or in combination, which are responsible for adipose tissue-associated anti-inflammatory effects.

The effect of equol injection in ovo on lipid metabolism and hepatic lipogenic gene expression in broilers

This study investigated the effects of in ovo administration of equol (Eq) on post-hatch growth and hepatic lipid metabolism in broiler chickens. Fertilized eggs (146 eggs/group) were injected with 0 μg (control, Con), 20 μg (low dose, L) and 100 μg (high dose, H) Eq in the albumen on the 7th day of incubation. Except a trend increase in the weight of total fat (P = 0.09), Eq had no effect on growth or liver weight in broilers at 49 days of age. Males presented higher liver and BWs and lower total fat and relative liver weights than females (P < 0.01). However, there were no significant effects of Eq or Eq-gender interactions on growth performance or tissues weight (P > 0.05). With respect to lipid parameters in the serum, the results showed that female broilers presented higher triacyglycerol (TG) and low-density lipoprotein cholesterol concentrations than males, whereas there was no gender difference in serum total cholesterol (TC) or high-density lipoprotein cholesterol (HDLC) concentration (P > 0.05). Eq administration significantly decreased serum TG and TC but increased HDLC concentrations in serum of broilers at 49 days of age (P < 0.05), whereas there were no interactions between gender and Eq (P > 0.05). To elucidate the mechanism behind the significant changes of serum TG and TC levels, the expression of genes involved in lipid metabolism in the liver was investigated in female chickens using reverse transcription-PCR. Carnitine palmitoyl transferase I (CPTI) messenger RNA (mRNA) was significantly upregulated by 20 and 100 μg Eq (P < 0.05). High-dose Eq significantly decreased fatty acid synthase (FAS) and enhanced cholesterol-7alpha-hydroxylase (CYP7A1) mRNA levels in the liver (P < 0.05). Eq had no significant effects on acetyl-CoA carboxylase, sterol regulatory element binding protein-1c, malic enzyme, low-density lipoprotein receptor or 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA in the liver (P > 0.05). These results in female broilers suggest that Eq decreased blood TG by upregulating CPTI and downregulating FAS mRNA expression in the liver, and that high serum cholesterol levels stimulated CYP7A1 gene transcription in the liver.

In vitro study of the effect of diesterified alkoxyglycerols with conjugated linoleic acid on adipocyte inflammatory mediators

Background

Adipocytes contribute to inflammation and the innate immune response through expression of inflammatory mediators. High levels of these mediators have been related to chronic inflammation state and insulin resistance, cardiovascular diseases and diabetes type 2, among other disorders. 3-octadecylglycerol (batyl alcohol) has been described as an inflammatory agent, whereas Conjugated Linoleic Acid (CLA) is considered effective against obesity. In this study we examined the anti-inflammatory activity and mechanisms of modified alkoxyglycerols. Tumor necrosis factor (TNF-α) activated mature adipocytes were used as cellular model of inflammation. Secreted levels and gene expressions of some inflammatory mediators, such as the adipokines, interleukin (IL)-1β, IL-6 and IL-10; and the levels of leptin and adiponectin hormones were quantified in presence and absence of alkoxyglycerols and when human adipocyte cells were or not activated by TNF-α. The aim of this study is to describe the effects of nonesterified alkoxyglycerols, CLA and diesterified alkoxyglycerols with CLA (DEA-CLA) and check if they present beneficial properties using an in vitro model of some chronic diseases related to the inflammatory process, such as obesity, using human mature adipocytes activated with TNF-α.

Results

Our data suggest that DEA-CLA, product of the esterification between the CLA and batyl alcohol, present beneficial effects on adipocytes close to observed and described for CLA (i.e. decrease of IL-1β) and no adverse effects as observed for batyl alcohol (i.e. decrease of IL-10). In addition, DEA-CLA presented similar activity to CLA showing a trend to increase the secreted levels of adiponectin and decreasing the secreted levels of leptin.

Conclusions

CLA and DEA-CLA modify adipocyte inflammatory mediators and also could play a role on energy homeostasis through depletion of leptin levels.

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.

Effects of soy protein and isoflavone on hepatic fatty acid synthesis and oxidation and mRNA expression of uncoupling proteins and peroxisome proliferator-activated receptor gamma in adipose tissues of rats

Soy protein rich in isoflavones profoundly affects lipid metabolism in experimental animals. To distinguish the roles of the protein and isoflavone components of a soy protein preparation in regulating lipid metabolism, we compared the effects of diets containing methanol-washed soy protein low in isoflavone supplemented with a 0-, 0.5- and 4-g/kg isoflavone preparation on hepatic fatty acid metabolism and adipose tissue gene expression in rats. Diets containing soy protein irrespective of the isoflavone levels decreased the activities and mRNA expression of enzymes involved in hepatic fatty acid synthesis to similar levels. Methanol-washed soy protein compared to casein increased the mRNA expression of peroxisome proliferator-activated receptor (PPAR) alpha, and supplementing the soy protein diet with isoflavone further increased this parameter dose-dependently. However, methanol-washed soy protein compared to casein was totally ineffective in altering the activities and mRNA levels of enzymes involved in fatty acid oxidation. Supplementation of soy protein diets with isoflavone slightly increased these parameters. The mRNA level of uncoupling protein (UCP) 1 in brown adipose tissue was significantly increased and mRNA levels of UCP2 and 3, and PPARgamma2 tended to be higher in rats fed methanol-washed soy protein not supplemented with isoflavone than in the animals fed casein. Adding isoflavone to the soy protein diets dose-dependently increased these parameters. These results suggested that the protein rather than isoflavone component is primarily responsible for the physiological activity of soy protein rich in isoflavones in reducing hepatic lipogenesis. However, isoflavones may have a role in regulating heptic fatty acid oxidation and adipose tissue gene expression.

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.

Bovine milk in human nutrition--a review

Milk and milk products are nutritious food items containing numerous essential nutrients, but in the western societies the consumption of milk has decreased partly due to claimed negative health effects. The content of oleic acid, conjugated linoleic acid, omega-3 fatty acids, short- and medium chain fatty acids, vitamins, minerals and bioactive compounds may promote positive health effects. Full-fat milk has been shown to increase the mean gastric emptying time compared to half-skimmed milk, thereby increasing the gastrointestinal transit time. Also the low pH in fermented milk may delay the gastric emptying. Hence, it may be suggested that ingesting full-fat milk or fermented milk might be favourable for glycaemic (and appetite?) regulation. For some persons milk proteins, fat and milk sugar may be of health concern. The interaction between carbohydrates (both natural milk sugar and added sugar) and protein in milk exposed to heat may give products, whose effects on health should be further studied, and the increasing use of sweetened milk products should be questioned. The concentration in milk of several nutrients can be manipulated through feeding regimes. There is no evidence that moderate intake of milk fat gives increased risk of diseases.

Dietary soy and tea combinations for prevention of breast and prostate cancers by targeting metabolic syndrome elements in mice

BACKGROUND

The prevalence of metabolic syndrome is high and is increasing in parallel with increasing incidences of breast and prostate cancers. The combination of soy with tea was shown to have synergistic effects on preventing breast and prostate tumors, but the effects of soy and tea combinations on metabolic syndrome-related elements have not been investigated.

OBJECTIVE

We aimed to determine the effects of soy and tea components, alone and in combination, on abdominal adipose mass and serum concentrations of adipokines, growth factors, and sex hormones in male and female mice.

DESIGN

Male and female FVB/N mice were treated with soy, tea components, or both. Food intake and body weight were monitored weekly. At the end of the experiment, abdominal white adipose tissue was weighed, and serum concentrations of biomarkers were measured.

RESULTS

Whole teas, but not the tea polyphenol extracts, significantly reduced abdominal white adipose tissue by 43-60% in female mice and by 65-70% in male mice. The combination of soy phytochemical concentrate and green tea reduced serum insulin-like growth factor-I concentrations in both male and female mice in a synergistic manner. The soy phytochemical concentrate and tea combinations reduced serum estrogen concentrations in female mice in a synergistic manner. Soy phytochemical concentrate and teas also significantly reduced serum leptin concentrations in both male and female mice and testosterone concentrations in male mice.

CONCLUSION

Further research is warranted to investigate whether soy and tea combinations may prevent breast or prostate cancer in a synergistic manner in part by alleviating metabolic disorders.

Modulation of carbohydrate metabolism and peptide hormones by soybean isoflavones and probiotics in obesity and diabetes

Soybean and its isoflavones have been shown to have beneficial effects on carbohydrate and lipid metabolism and on renal function. Probiotics may potentiate the beneficial effects of isoflavones by converting the inactive isoflavone glycoside to aglycones, which are biologically active, thereby producing a synergistic effect. We therefore studied the effects of soybean isoflavones in the presence and absence of probiotics on glucose and triglyceride metabolism and the peptide hormones involved in their metabolism. Lean and obese SHR/N-cp rats were fed AIN-93 diets containing 0.1% soybean isoflavone mixture, 0.1% probiotics mixture or both. Plasma was analyzed for glucose, triglycerides, parameters of renal function and peptide hormones -- insulin, leptin, glucagon and ACTH -- that are involved in glucose and lipid metabolism. Isoflavones given alone lowered plasma glucose in both phenotypes while triglyceride was decreased only in lean animals. Isoflavones also lowered aspartate amino transferase and alanine amino transferase in both phenotypes. Isoflavones had significant effect on plasma insulin, leptin and glucagon in lean rats but not in obese rats. Thus, our data show that in lean animals, isoflavones have hypoglycemic and hypolipidemic effect, and the effect is mediated by changes in peptide hormones. When lipid levels are very high as in obese rats, isoflavones fail to lower plasma triglyceride levels. Probiotics do not appear to enhance the effect of isoflavones.

Conjugated linoleic acid evokes de-lipidation through the regulation of genes controlling lipid metabolism in adipose and liver tissue

Conjugated linoleic acid (CLA) is a unique lipid that elicits dramatic reductions in adiposity in several animal models when included at < or = 1% of the diet. Despite a flurry of investigations, the precise mechanisms by which conjugated linoleic acid elicits its dramatic effects in adipose tissue and liver are still largely unknown. In vivo and in vitro analyses of physiological modifications imparted by conjugated linoleic acid on protein and gene expression suggest that conjugated linoleic acid exerts its de-lipidating effects by modulating energy expenditure, apoptosis, fatty acid oxidation, lipolysis, stromal vascular cell differentiation and lipogenesis. The purpose of this review shall be to examine the recent advances and insights into conjugated linoleic acid's effects on obesity and lipid metabolism, specifically focused on changes in gene expression and physiology of liver and adipose tissue.

Conjugated linoleic acids: are they beneficial or detrimental to health?

Conjugated linoleic acids (CLAs) comprise a family of positional and geometric isomers of linoleic acid (18:2n-6; LA) that are formed by biohydrogenation and oxidation processes in nature. The major dietary sources of these unusual fatty acids are foods derived from ruminant animals, in particular dairy products. The main form of CLA, cis-9, trans-11-18:2, can be produced directly by bacterial hydrogenation in the rumen or by delta-9 desaturation of the co-product vaccenic acid (trans-11-18:1) in most mammalian tissues including man. The second most abundant isomer of CLA is the trans-10, cis-12-18:2 form. Initially identified in grilled beef as a potential anti-carcinogen a surprising number of health benefits have subsequently been attributed to CLA mixtures and more recently to the main individual isoforms. It is also clear from recent studies that the two main isoforms can have different effects on metabolism and cell functions and can act through different cell signalling pathways. The majority of studies on body compositional effects (i.e. fat loss, lean gain), on cancer and cardiovascular disease attenuation, on insulin sensitivity and diabetes and on immune function have been conducted with a variety of animal models. Observations clearly emphasise that differences exist between mammalian species in their response to CLAs with mice being the most sensitive. Recent studies indicate that some but not all of the effects observed in animals also pertain to human volunteers. Reports of detrimental effects of CLA intake appear to be largely in mice and due mainly to the trans-10, cis-12 isomer. Suggestions of possible deleterious effects in man due to an increase in oxidative lipid products (isoprostanes) with trans-10, cis-12 CLA ingestion require substantiation. Unresponsiveness to antioxidants of these non-enzymatic oxidation products casts some doubt on their physiological relevance. Recent reports, albeit in the minority, that CLAs, particularly the trans-10, cis-12 isomer, can elicit pro-carcinogenic effects in animal models of colon and prostate cancer and can increase prostaglandin production in cells also warrant further investigation and critical evaluation in relation to the many published anti-cancer and anti-prostaglandin effects of CLAs.

Cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid isomers do not modify body composition in adult sedentary or exercised rats

Dietary CLA isomers were shown to reduce adipose tissues in growing animals, mainly in mice, but their effects in adult animals remain unclear. This study was conducted to determine whether these effects depend on the isomer fed, on physical activity, or on the initial level of body fat. Male Wistar rats (4 mo old) were fed for 6 wk diets containing either no CLA, the cis-9, trans-11 CLA isomer (10 g/kg), the trans-10, cis-12 CLA isomer (10 g/kg), or both isomers (10 g/kg each). Half of the rats were assigned to exercise by treadmill running (1 h/d, 22 m/min). The initial body fat level was normal (12.7%) in a first trial, and high (18.9%) in a second trial. Chemical and anatomical body compositions were determined by chemical analysis and organ dissection. In both trials, the CLA diets, whatever the isomer, had no effect on food intake and body weight changes, on body chemical composition (fat, protein and water contents or gains), or on the body anatomical composition (weights or gains in epididymal and perirenal adipose tissues, in liver and in 4 muscles). There was no interaction between CLA treatment and physical activity. In conclusion, adult male rats do not appear to be responsive to the fat-to-lean partitioning effect of CLA described in growing rats. This was not affected by exercise or initial body fat level.