Conjugated linoleic acid and phytosterols counteract obesity induced by high-fat diet

Synergistic effect rescue animal model from NASH caused by diet-inflammation inducer

Excessive intake of pro-inflammatory fatty acids is related to the development of insulin resistance, impaired oxidative stress enzymes, and lipid disorders, leading to inflammation and development of non-alcoholic steatohepatitis (NASH). Diet and physical exercise are considered to prevent and treat metabolic disorders caused by chronic inflammatory states (responsible for insulin resistance and diabetes type 2) in individuals with obesity and nonalcoholic fatty liver diseases (NAFLD). Our investigation tested the hypothesis that Hass avocado oil, a monounsaturated fatty acid and a source of phytosterol, may improve liver and metabolic parameters without adverse effects when combined with physical exercise. Rats ingested a high-fat diet for seven weeks and were then subjected to more six weeks with a standard diet, Hass avocado-oil ingestion, and swimming. The intervention showed significantly improvements by synergistic effect between Hass avocado-oil and swimming exercise (P < 0.05), including improving adiponectin, leptin, and fasting blood glucose levels, alleviating insulin resistance, reducing serum TNF-α, improving glutathione enzyme levels, and decreasing lipotoxicity in the liver and blood and serum triacylglycerides in blood (P < 0.05). Liver tissue markers of apoptosis and necrosis such as CK-18 filaments and dimethylamine (DMA) were significantly higher in the intervention group (P < 0.05). We were unable to fully confirm our hypothesis. Although the synergistic effects between Hass avocado-oil and the swimming regimen offer a promising chance of recovering liver health by improving 10 health biological markers, we must not ignore the cellular damage due to apoptosis and necrosis in liver cells and DMA. The data on metabolomic profile and avocado-oil-treated livers highlight the need for further investigation.

Conjugated linoleic acid (CLA) as a functional food: Is it beneficial or not?

Conjugated linoleic acid (CLA) has attracted great attention in recent years as a popular class of functional food that is broadly used. It refers to a group of geometric and positional isomers of linoleic acid (LA) with a conjugated double bond. The main natural sources of CLA are dairy products, beef and lamb, whereas only trace amounts occur naturally in plant lipids. CLA has been shown to improve various health issues, having effects on obesity, inflammatory, anti-carcinogenicity, atherogenicity, immunomodulation, and osteosynthesis. Also, compared to studies on humans, many animal researches reveal more positive benefits on health. CLA represents a nutritional avenue to improve lifestyle diseases and metabolic syndrome. Most of these effects are attributed to the two major CLA isomers [conjugated linoleic acid cis-9,trans-11 isomer (c9,t11), and conjugated linoleic acid trans-10,cis-12 isomer (t10,c12)], and their mixture (CLA mix). In contrast, adverse effects of CLA have been also reported, such as glucose homeostasis, insulin resistance, hepatic steatosis and induction of colon carcinogenesis in humans, as well as milk fat inhibition in ruminants, lowering chicken productivity, influencing egg quality and altering growth performance in fish. This review article aims to discuss the health benefits of CLA as a nutraceutical supplement and highlight the possible mechanisms of action that may contribute to its outcome. It also outlines the feasible adverse effects of CLA besides summarizing the recent peer-reviewed publications on CLA to ensure its efficacy and safety for proper application in humans.

Evaluation of the functional quality of rapeseed oil obtained by different extraction processes in a Sprague-Dawley rat model

The nutritional function of vegetable oil is influenced by different oil extraction methods. In this study, the effects of different processing techniques on the quality of rapeseed oil and animal lipid metabolism were evaluated. Results showed that rapeseed oil obtained by the aqueous enzymatic extraction (AEE) method had the highest polyphenol (152.08 ± 11.44 mg GAE per kg), α-tocopherol (208.97 ± 15.84 mg kg-1), and β-carotene (5.40 mg kg-1) contents and a better oxidation resistance. It was noted in an experiment on rats fed with diets containing rapeseed oils that AEE rapeseed oil reduces total cholesterol (TC), triacylglycerol (TG), low-density lipoprotein cholesterol (LDL-C), aspartate transaminase (ALT) and alanine transaminase (AST) in high-fat diet rats by 27.09%, 11.81%, 35.52%, 31.02% and 27.61%, respectively, and the body and liver weights of rats were decreased. mRNA expression indicated that AEE could significantly down-regulate fatty acid synthase (FAS) and up-regulate acyl-CoA oxidase 1 (ACOX1) gene expression levels (P < 0.05). These results suggested that the AEE method can increase the content of trace active substances in rapeseed oil and ameliorate chronic diseases induced by a high-fat diet.

Passion fruit peel intake decreases inflammatory response and reverts lipid peroxidation and adiposity in diet-induced obese rats

This study investigated Passiflora edulis peel flour (PEPF) intake and its effect against high-fat diet-induced obesity. PEPF is a source of fiber and phenolic compounds, which can decrease oxidative stress and inflammatory cytokines, both linked to chronic inflammatory response and fat deposition in obesity. Therefore, we hypothesized that PEPF intake could decrease inflammatory cytokines and oxidative stress observed in obesity, leading to decrease of fatness and chronic inflammatory response. The aims of the study were to evaluate the lipid peroxidation, the expression of antioxidants enzymes, and inflammatory parameters in obese rats. Male Sprague-Dawley rats were divided into 3 groups (n = 8 per group) according to the diets: control (based on AIN-93G), high-fat (HF, 35% fat w/w), and HF with PEPF (HFPF), and the experiment lasted for 10 weeks. PEPF showed high dietary fiber content and bioactive compounds, such as ferulic acid, and β-carotene. PEPF intake was effective in reducing body weight gain (13.31%) and total body fat (22.58%). The lipid peroxidation in the liver and adipose tissue decreased in the HFPF group compared to HF-fed animals, whereas hepatic glutathione peroxidase and glutathione reductase activity and their expressions in the liver were higher in HFPF than HF. In addition, the PEPF intake decreased inflammatory cytokines in serum. These results suggest that PEPF intake decreases oxidative stress, possibly by the increase of antioxidant enzymes expression. Furthermore, PEPF decreases inflammatory response and protects from adiposity. Then, PEPF could act as an adjuvant to control of early parameters in obesity dysfunction.

Effect of β-sitosterol self-microemulsion and β-sitosterol ester with linoleic acid on lipid-lowering in hyperlipidemic mice

Background

The hypolipidemic effect of phytosterols has been wildely recognized, but its application is limited due to its insolubility in water and low solubility in oil. In this study, β-sitosterol ester with linoleic acids and β-sitosterol self-microemulsions were prepared and their hypolipidemic effects on hyperlipidemia mice were studied.

Methods

Firstly, the mice were randomly divided into normal group and model group,they were fed with basic diet and high-fat diet for 70 days respectively. After high-fat model mice was successfully established, the model group was further divided into eight groups: HFD (high-fat diet feeding), SELA-TSO(8 ml/kg, SELA:700 mg/kg), TSO (8 ml/kg), SSSM (8 ml/kg,SS:700 mg/kg), NLSM (8 ml/kg), SSHT-TSO (8 ml/kg, SS: 700 mg/kg) and SS-TSO (8 ml/kg, SS: 700 mg/kg) groups, and treated with β-sitosterol ester with linoleic acid, β-sitosterol self-microemulsion, commercial β-sitosterol health tablets and β-sitosterol powder for 35 days, respectively, and blank control groups were established. At the end of the treatment period, the blood lipid level, tissues, cholesterol and lipids in feces of mice in each group were investigated. Statistical and analytical data with SPSS 17.0 Software,statistical significance was set at p* < 0.05 and p** < 0.01 levels .

Results

The order of lowering blood lipid effect is listed as: SSSM> SELA-TSO > SSHT-TSO > SS-TSO, which shows that β-sitosterolself-microemulsion have the highest treatment effect among the experimental groups.

Conclusions

In this study, a new formulation of β-sitosterol was developed, and its hypolipidemic effect was investigated. The results showed that β-sitosterol self-microemulsion has a good blood lipid lowering effect.

Effect of Conjugated Linoleic Acid on Memory and Reflex Maturation in Rats Treated During Early Life

In the critical period of neurodevelopment (gestation and lactation), maternal consumption of essential fatty acids (FAs) can alter the offspring cognitive function permanently causing damage. Lipids can regulate neurotrophin and compose brain tissue. However, the effects of maternal consumption of a mixture of conjugated linoleic acid (CLA) on an offspring nervous system are not completely clear. We aimed to investigate the impacts of different CLA concentrations mixed into the maternal diet during early life on neonatal reflex maturation and cognitive functions of the offspring. Three groups were formed: control (CG): receiving a standard diet; CLA1: receiving a diet containing 1% of CLA, and CLA3: receiving a diet containing 3% of CLA, offered during gestation and lactation. After birth, the reflex responses of the offspring were observed from the 1st to the 21st day. After weaning, the animals’ anxiety and memory were assessed using open field (OF) and novel object recognition tests. Fatty acids in the breast milk and the offspring’s brain were also quantified. The data were analyzed using one-way ANOVA and the Kruskal–Wallis test. CLA1 presented accelerated palmar grasp disappearance versus CLA3 and negative-geotaxis versus CG; and the CLA3 presented increases for most reflexes (cliff-avoidance, vibrissa-placing, negative-geotaxis, and auditory-startle response), and decrease in reflexes palmar grasp and free-fall righting versus CG (p < 0.05). CLA3 group explored less of the OF in the second exposure. CLA1 and CLA3 presented an increased exploration ratio for new objects, which indicates memory improvement. The milk tested from CLA3 demonstrated an increase in polyunsaturated fatty acids (PUFAs), and a decrease in monounsaturated fatty acids. The amount of CLA in milk was greater in CLA1 and CLA3 and in the brain offspring both presented moderated amounts of CLA. Maternal treatment with the CLA mixture induced anticipated reflex maturation and improved memory in the offspring. Even though CLA was detected in the brains in only trace amounts, offspring’s brain PUFA and SFA levels were increased. Further studies aimed to delineate the effect of maternal CLA supplementation on offspring’s brain lipid metabolism and long-term neurologic outcome are needed to confirm these findings.

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

BACKGROUND

Maternal 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.

METHODS

Three 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).

RESULTS

CLA1 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).

LIMITATIONS

We 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.

CONCLUSIONS

Maternal intake of CLA induced a decrease in the parameters of anxiety and cerebral lipid peroxidation in the offspring.

Intake of stigmasterol and β-sitosterol alters lipid metabolism and alleviates NAFLD in mice fed a high-fat western-style diet

OBJECTIVE

To investigate and compare the effects of two common dietary phytosterols, stigmasterol and β-sitosterol, in altering lipid metabolism and attenuating nonalcoholic fatty liver disease (NAFLD).

METHODS

Stigmasterol and β-sitosterol were administered to mice at 0.4% in a high-fat western-style diet (HFWD) for 17 weeks.

RESULTS

Stigmasterol and β-sitosterol significantly ameliorated HFWD-induced fatty liver and metabolic abnormalities, including elevated levels of hepatic total lipids, triacylglycerols, cholesterol and liver histopathology. Both phytosterols decreased the levels of intestinal bile acids, accompanied by markedly increased fecal lipid levels. In addition, they altered the expression of genes involved in lipid metabolism. β-Sitosterol was less effective in affecting most of these parameters. Lipidomic analysis of liver and serum samples showed that stigmasterol prevented the HFWD-induced elevation of some di- and triacylglycerol species and lowering of some phospholipid species. Stigmasterol also decreased serum levels of ceramides.

CONCLUSION

Stigmasterol and β-sitosterol, at a dose corresponding to that suggested for humans by the FDA for lowering cholesterol levels, are shown to alleviate HFWD-induced NAFLD. Stigmasterol was more effective than β-sitosterol, possibly because of its suppression of hepatic lipogenic gene expression and modulation of circulating ceramide levels.

Effects of Phytosterol Supplementation on Serum Levels of Lipid Profiles, Liver Enzymes, Inflammatory Markers, Adiponectin, and Leptin in Patients Affected by Nonalcoholic Fatty Liver Disease: A Double-Blind, Placebo-Controlled, Randomized Clinical Trial

OBJECTIVE

Considering the high prevalence of nonalcoholic fatty liver disease and based on the evidence about the role of dietary cholesterol in liver inflammation, and also with regard to the effect of phytosterols on the metabolism of cholesterol, we aimed at exploring the therapeutic potential of phytosterol supplementation against nonalcoholic fatty liver disease.

METHOD

Thirty-eight patients with nonalcoholic fatty liver disease were randomly divided into two groups: The phytosterol group (n = 19) received a 1.6-g phytosterol supplement daily and the control group (n = 19) received 1.6 g starch daily as placebo for an 8-week period. Blood samples of all patients were taken at baseline (week 0) and at the end of the study (week 8) for measurement of lipid profiles, liver enzymes, inflammatory markers, adiponectin, and leptin.

RESULTS

Phytosterol supplementation significantly improved the levels of low-density lipoprotein cholesterol, aspartate aminotransferase, alanine aminotransferase, and tumor necrosis factor alpha compared to the placebo group. On the other hand, there were no significant differences between the two groups in total cholesterol, triglycerides, high-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, ratios of low-density lipoprotein cholesterol/high-density lipoprotein cholesterol and total cholesterol/high-density lipoprotein cholesterol, gamma-glutamyl transferase, interleukin 6, high-sensitivity C-reactive protein, adiponectin, and leptin.

CONCLUSIONS

The present study suggested that daily consumption of 1.6 g phytosterols efficiently lowers low-density lipoprotein cholesterol, aspartate aminotransferase, alanine aminotransferase, and tumor necrosis factor alpha in patients with nonalcoholic fatty liver disease.

Fucosterol inhibits adipogenesis through the activation of AMPK and Wnt/β-catenin signaling pathways

Fucosterol is a sterol constituent primarily derived from brown algae. Recently, the antiadipogenic effect of fucosterol has been reported; however, its molecular mechanism remains to be studied. Fucosterol effectively upregulated the phosphorylations of both adenosine monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), and downregulated the expression levels of lipogenesis-related factors. Moreover, fucosterol activated the major components of the Wnt/β-catenin signaling pathway, including β-catenin, disheveled 2 (DVL2), and cyclin D1 (CCND1), whereas it inactivated glycogen synthase kinase 3β (p-GSK3β) by stimulating its phosphorylation. In the presence or absence of fucosterol, the adipogenic transcriptional factors [peroxisome proliferator activated-receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), and sterol regulatory element binding protein-1c (SREBP-1c)] were upregulated by the inhibition of AMPK by compound C or the knockdown of β-catenin by siRNA. Overall, these data demonstrate that fucosterol prevents adipogenesis by mediating both AMPK- and Wnt/β-catenin-signaling pathways.