Conjugated Linoleic Acid Impairs Endothelial Function

Exploiting conjugated linoleic acid for health: a recent update

Conjugated linoleic acid (CLA) is widely used as a dietary supplement due to its reported benefits in enhancing immunity, regulating inflammation, treating obesity, and preventing cancer. However, there is a lack of comprehensive studies on its mechanisms and dose-effect relationships. Moreover, there are insufficient in-depth studies on CLA's new functions, safety, side effects, and clinical utility. This review systematically examines the structure and sources of CLA, summarizes its role in improving human health, and critically reviews the potential mechanisms behind these benefits. It also analyzes the side effects of CLA and addresses issues related to dosing and oxidative decomposition in CLA research. Additionally, the potential of using CLA-producing probiotics to manage diseases is explored. This review can guide and promote further research on CLA's functions and support the development of CLA dietary supplements. It will accelerate the development of CLA nutritional and medical foods, contribute to the improvement of human health, and have important social meaning and economic value.

The effect of conjugated linoleic acid supplementation in comparison with omega-6 and omega-9 on lipid profile: a graded, dose-response systematic review and meta-analysis of randomized controlled trials

Conjugated linoleic acid (CLA) is a geometrical isomer of linoleic acid, which has anti-inflammatory, anti-diabetic, anti-cancer, and anti-obesity properties. However, the studies reported inconstant results about the CLA-related effects on lipid profiles. As a result, meta-analysis and systematic review were performed to survey the CLA supplementation-related effect on lipid profile including high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (TC), and triglycerides (TG). To identify the relevant research, a systematic comprehensive search was initiated on the medical databases such as Scopus and PubMed/Medline until December 2022. The overall effect size was estimated by weighted mean difference (WMD) and 95% confidence interval (CI) in a random effect meta-analysis. In the final quantitative analysis, the meta-analysis considered 35 randomized controlled trials (RCTs) with 1,476 participants (707 controls and 769 cases). The pooled results demonstrated that CLA supplementation, compared with olive oil, significantly increased serum TG levels (WMD: 0.05 mmol/L; 95% CI: 0.01 to 0.1; p = 0.04; I2 = 0.0%, p = 0.91). With regard to TC level, CLA supplementation compared with placebo significantly reduced TC concentrations (WMD: -0.08 mmol/L; 95% CI: -0.14 to -0.02; p < 0.001; I2 = 82.4%). Moreover, the non-linear dose-response analysis indicated a decreasing trend of TC serum level from the 15th week of CLA supplementation compared with olive oil (Pnon-linearity = 0.01). The present meta-analysis and systematic review of 35 RCTs showed that the CLA intervention was able to raise the level of TG in comparison to olive oil; however, it can decrease TC level compared with placebo and olive oil.

The effects of conjugated linoleic acid supplementation on anthropometrics and body composition indices in adults: a systematic review and dose-response meta-analysis

Prior meta-analytic investigations over a decade ago rather inconclusively indicated that conjugated linoleic acid (CLA) supplementation could improve anthropometric and body composition indices in the general adult population. More recent investigations have emerged, and an up-to-date systematic review and meta-analysis on this topic must be improved. Therefore, this investigation provides a comprehensive systematic review and meta-analysis of randomised controlled trials (RCT) on the impact of CLA supplementation on anthropometric and body composition (body mass (BM), BMI, waist circumference (WC), fat mass (FM), body fat percentage (BFP) and fat-free mass (FFM)) markers in adults. Online databases search, including PubMed, Scopus, the Cochrane Library and Web of Science up to March 2022, were utilised to retrieve RCT examining the effect of CLA supplementation on anthropometric and body composition markers in adults. Meta-analysis was carried out using a random-effects model. The I2 index was used as an index of statistical heterogeneity of RCT. Among the initial 8351 studies identified from electronic databases search, seventy RCT with ninety-six effect sizes involving 4159 participants were included for data analyses. The results of random-effects modelling demonstrated that CLA supplementation significantly reduced BM (weighted mean difference (WMD): -0·35, 95 % CI (-0·54, -0·15), P < 0·001), BMI (WMD: -0·15, 95 % CI (-0·24, -0·06), P = 0·001), WC (WMD: -0·62, 95% CI (-1·04, -0·20), P = 0·004), FM (WMD: -0·44, 95 % CI (-0·66, -0·23), P < 0·001), BFP (WMD: -0·77 %, 95 % CI (-1·09, -0·45), P < 0·001) and increased FFM (WMD: 0·27, 95 % CI (0·09, 0·45), P = 0·003). The high-quality subgroup showed that CLA supplementation fails to change FM and BFP. However, according to high-quality studies, CLA intake resulted in small but significant increases in FFM and decreases in BM and BMI. This meta-analysis study suggests that CLA supplementation may result in a small but significant improvement in anthropometric and body composition markers in an adult population. However, data from high-quality studies failed to show CLA's body fat-lowering properties. Moreover, it should be noted that the weight-loss properties of CLA were small and may not reach clinical importance.

Conjugated Linoleic Acids Have Anti-Inflammatory Effects in Cultured Endothelial Cells

Conjugated linoleic acid (CLA) isomers may have a role in preventing atherosclerosis through the modulation of inflammation, particularly of the endothelium. However, whether low concentrations of CLAs are able to affect basal unstimulated endothelial cell (EC) responses is not clear. The aim of this study was to evaluate the effects of two CLAs (cis-9, trans-11 (CLA9,11) and trans-10, cis-12 (CLA10,12)) on the basal inflammatory responses by ECs. EA.hy926 cells (HUVEC lineage) were cultured under standard conditions and exposed to individual CLAs for 48 h. Both CLAs were incorporated into ECs in a dose-dependent manner. CLA9,11 (1 μM) significantly decreased concentrations of MCP-1 (p < 0.05), IL-6 (p < 0.05), IL-8 (p < 0.01) and RANTES (p < 0.05) in the culture medium. CLA10,12 (10 μM) decreased the concentrations of MCP-1 (p < 0.05) and RANTES (p < 0.05) but increased the concentration of IL-6 (p < 0.001). At 10 μM both CLAs increased the relative expression of the NFκβ subunit 1 gene (p < 0.01 and p < 0.05, respectively), while decreasing the relative expression of PPARα (p < 0.0001), COX-2 (p < 0.0001) and IL-6 (p < 0.0001) genes. CLA10,12 increased the relative expression of the gene encoding IκK-β at 10 μM compared with CLA9,11 (p < 0.05) and increased the relative expression of the gene encoding IκBα at 1 and 10 μM compared with linoleic acid (both p < 0.05). Neither CLA affected the adhesion of monocytes to ECs. These results suggest that low concentrations of both CLA9,11 and CLA10,12 have modest anti-inflammatory effects in ECs. Thus, CLAs may influence endothelial function and the risk of vascular disease. Nevertheless, at these low CLA concentrations some pro-inflammatory genes are upregulated while others are downregulated, suggesting complex effects of CLAs on inflammatory pathways.

The effects of conjugated linoleic acid supplementation on inflammatory cytokines and adipokines in adults: A GRADE-assessed systematic review and dose-response meta-analysis

Background and aims

Many studies have investigated the effect of conjugated linoleic acid (CLA) supplementation on inflammatory cytokines and adipokines. However, the results of these studies are not consistent. Therefore, this systematic review and meta-analysis were designed to comprehensively evaluate the effect of CLA supplementation on inflammatory cytokines and adipokines.

Methods

Randomized controlled trials (RCTs) examining the effects of CLA supplementation on C-reactive protein (CRP), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), adiponectin, and leptin, published up to March 2022, were identified through PubMed, SCOPUS, and ISI Web of Science databases. A random-effects model was used to calculate weighted mean differences (WMDs) with 95% confidence intervals (CI) for 42 studies that included 1,109 participants.

Results

Findings from 42 studies with 58 arms indicated that CLA supplementation significantly decreased IL-6 and TNF-α levels and also slightly increased CRP levels. However, adiponectin and leptin levels did not change after CLA supplementation. A subgroup analysis found that CLA supplementation reduced adiponectin and leptin in women.

Conclusion

Our results demonstrated that CLA supplementation increased CRP levels and decreased TNF-α and IL-6 levels. Therefore, it seems that CLA can have both proinflammatory and anti-inflammatory roles.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier (CRD42022331110).

The effects of conjugated linoleic acid supplementation on lipid profile in adults: A systematic review and dose-response meta-analysis

Background

The findings of trials investigating the effect of conjugated linoleic acid (CLA) administration on lipid profile are controversial. This meta-analysis of randomized controlled trials (RCTs) was performed to explore the effects of CLA supplementation on lipid profile.

Methods

Two authors independently searched electronic databases including PubMed, Web of Science, and Scopus until March 2022, in order to find relevant RCTs. The random effects model was used to evaluate the mean and standard deviation.

Results

In total, 56 RCTs with 73 effect sizes met the inclusion criteria and were eligible for the meta-analysis. CLA supplementation significantly alter triglycerides (TG) (WMD: 1.76; 95% CI: -1.65, 5.19), total cholesterols (TC) (WMD: 0.86; 95% CI: -0.42, 2.26), low-density lipoprotein cholesterols (LDL-C) (WMD: 0.49; 95% CI: -0.75, 2.74), apolipoprotein A (WMD: -3.15; 95% CI: -16.12, 9.81), and apolipoprotein B (WMD: -0.73; 95% CI: -9.87, 8.41) concentrations. However, CLA supplementation significantly increased the density lipoprotein cholesterol (HDL-C) (WMD: -0.40; 95% CI: -0.72, -0.07) concentrations.

Conclusion

CLA supplementation significantly improved HDL-C concentrations, however, increased concentrations of TG, TC, LDL-C, apolipoprotein A, and apolipoprotein B.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#recordDetails, identifier: CRD42022331100.

Effects of cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid supplementation on maternal reproductive parameters

Conjugated linoleic acid (CLA) is a mixture of positional isomers of linoleic acid found in ruminant products and meat. The diet supplementing with CLA is an emerging area, requiring studies to elucidate its effects on animals and human reproduction, as well as its side effects. Therefore, the aim of this study was to evaluate the effects of CLA gastric administration, during the pregestational and gestational period in biometric and reproductive parameters, as well as in ovarian morphophysiology. Animals were distributed in three groups: (1) control (n = 10); (2) fish oil (n = 10); and (3) CLA (n = 10), that daily received, by gavage, phosphate-buffered saline, fish oil and CLA, respectively, carried out over 50 days (before mating, mating and pregnancy). There was an increment in the nasoanal distance and Lee index of the CLA and fish oil-treated groups during the first weeks (P > 0.05). CLA administration did not affect the ovarian follicle mobilization (P > 0.05), the number of follicles (P > 0.05) and the integrated density of lipid content of oocytes included in antral follicles (P > 0.05). There was no effect of CLA administration on the litter weight (P > 0.05; F2 and F3), however, an increment (P < 0.05) in the number of pups per litter (F2) was observed. Overall, this study demonstrated the absence of side effects of the CLA gastric administration on mice reproductive performance and suggests that this treatment would transgenerationally enhance fertility in this species.

Beneficial effects of dietary supplementation with olive oil, oleic acid, or hydroxytyrosol in metabolic syndrome: Systematic review and meta-analysis

BACKGROUND AND AIMS

Olive oil and components might have a beneficial effect on Metabolic Syndrome (MetS). The aim of this review and meta-analysis was to assess whether those effects are related to hydroxytyrosol or oleic acid contents, or the combination of them as olive oil, and how powerful is this effect.

METHODS

A systematic literature search was performed in MEDLINE via Pubmed, Web of Science (WOS) core collection, and Virtual Health Library (VHL) via LILACS and IBECS (Spain). MeSH terms used were "obesity", "body weight", "body mass index", "adipose tissue", "lipid metabolism", "LDL", "HDL", "VLDL", "insulin resistance", "glucose", "insulin", "hypertension", "arterial pressure", "olive oil", "oleic acid", and other (non-MeSH) terms: "total antioxidant capacity", "total antioxidant status", "hydroxytyrosol" (PROSPERO ID: CRD42021247614). Results of the included studies were meta-analyzed with the RevMan 5.3 program, assuming a random effects model.

RESULTS

76 articles (67 different trials) were identified. Hydroxytyrosol had no effect on MetS [combined standardized mean differences (SMD) = 0.01 (CI 95%: [-0.23, 0.25], I² = 83%; p = 0.920)]. Oleic acid had no significant beneficial effect on MetS [SMD = 0.03 (CI 95%: [-0.01, 0.07], I² = 0%); p = 0.150], but it improved lipid profile [SMD = 0.06 (CI 95%: [-0.00, 0.12], I² = 0%); p = 0. 050]. Olive oil had no effect on MetS [SMD = -0.01 (CI 95%: [-0.05, 0.03]), I² = 55%; p = 0.550)]. The supplementation with hydroxytyrosol, oleic acid or olive oil showed a beneficial effect on antioxidant capacity related to components of MetS [SMD = 0.31 (CI 95%: [-0.34, 0.95], I² = 81%)]; p = 0.35).

CONCLUSION

Most articles compared olive oil and oleic acid with other strategies specially designed for MetS management. Our findings suggest that olive oil or oleic acid consumption are as good as the other strategies to manage MetS.

Effects of Olive Oil on Blood Pressure: Epidemiological, Clinical, and Mechanistic Evidence

The increasing access to antihypertensive medications has improved longevity and quality of life in hypertensive patients. Nevertheless, hypertension still remains a major risk factor for stroke and myocardial infarction, suggesting the need to implement management of pre- and hypertensive patients. In addition to antihypertensive medications, lifestyle changes, including healthier dietary patterns, such as the Dietary Approaches to Stop Hypertension (DASH) and the Mediterranean diet, have been shown to favorably affect blood pressure and are now recommended as integrative tools in hypertension management. An analysis of the effects of nutritional components of the Mediterranean diet(s) on blood pressure has therefore become mandatory. After a literature review of the impact of Mediterranean diet(s) on cardiovascular risk factors, we here analyze the effects of olive oil and its major components on blood pressure in healthy and cardiovascular disease individuals and examine underlying mechanisms of action. Both experimental and human studies agree in showing anti-hypertensive effects of olive oil. We conclude that due to its high oleic acid and antioxidant polyphenol content, the consumption of olive oil may be advised as the optimal fat choice in the management protocols for hypertension in both healthy and cardiovascular disease patients.

Fruit seeds and their oils as promising sources of value-added lipids from agro-industrial byproducts: oil content, lipid composition, lipid analysis, biological activity and potential biotechnological applications

Thousands of tons of fruit seeds are discarded every year worldwide as agro-industrial byproducts. Fruit seeds have a high oil content, are rich in monounsaturated fatty acids (FA) and in n-6 and n-3 polyunsaturated essential FA. Sterols, phospholipids, glycolipids, carotenoids, tocopherols and polyphenols are other seed phytochemicals that make them interesting from a commercial viewpoint. Fruit seeds have high potential as raw material for several industries, but their lipid profile remains poorly studied. Current analytical approaches for the analysis of lipids that are based on high-performance liquid chromatography and high-resolution mass spectrometry allow the separation and analysis of compounds with the accurate identification and structural characterization of molecular species in very small quantities. Even though lipidomic analysis of fruit seeds' lipids is still in its infancy, it will bring a new look over these value-added byproducts. This review covers the following topics: (a) the lipid content of various fruit seed oils; (b) their lipid composition (FA, triacylglycerol, sterol, phospholipid and glycolipid profiles), (c) current and future analytical methodologies for the analysis of lipids in fruit seeds; (d) biological activities of fruit seeds' extracts; and (e) potential biotechnological applications of fruit seed oils for their commercial valorization based on lipids.

The safety and effectiveness of commonly-marketed natural supplements for weight loss in populations with obesity: A critical review of the literature from 2006 to 2016

Objective: To evaluate the evidence published from 2006 to 2016 on the effectiveness and safety of commonly used natural supplements for weight loss in individuals with obesity.Methods: Amazon and Google were searched for names of mono-agent natural supplements marketed for weight loss and a list of the 10 supplements was created. Google Scholar, Pubmed, Science Direct, and the Cochrane Library were searched for articles that met inclusion.Results: At least one article was published on the effectiveness or safety of bitter orange, capsinoid, carnitine, chromium picolinate, Coleus forskohlii, conjugated linoleic acid, glucomannan, green tea and psyllium for weight loss in populations with obesity from 2006 to 2016. There was insufficient evidence to suggest that the natural supplements examined contribute to significant weight loss, with the exception of perhaps glucomannan in the form of PGX. In general, the majority of side-effects reported were minor to moderate, and gastrointestinal-related. However, in some cases extreme side-effects such as liver and kidney failure were observed.Conclusion: Contrary to popular belief, results of this review suggest that the use of natural supplements for weight loss are unlikely to contribute to meaningful weight loss and in some cases may contribute to harm.

Conjugated Linoleic Acid Effects on Cancer, Obesity, and Atherosclerosis: A Review of Pre-Clinical and Human Trials with Current Perspectives

Obesity and its comorbidities, including type 2 diabetes and cardiovascular disease, are straining our healthcare system, necessitating the development of novel strategies for weight loss. Lifestyle modifications, such as exercise and caloric restriction, have proven effective against obesity in the short term, yet obesity persists because of the high predilection for weight regain. Therefore, alternative approaches to achieve long term sustainable weight loss are urgently needed. Conjugated linoleic acid (CLA), a fatty acid found naturally in ruminant animal food products, has been identified as a potential anti-obesogenic agent, with substantial efficacy in mice, and modest efficacy in obese human populations. Originally described as an anti-carcinogenic fatty acid, in addition to its anti-obesogenic effects, CLA has now been shown to possess anti-atherosclerotic properties. This review summarizes the pre-clinical and human studies conducted using CLA to date, which collectively suggest that CLA has efficacy against cancer, obesity, and atherosclerosis. In addition, the potential mechanisms for the many integrative physiological effects of CLA supplementation will be discussed in detail, including an introduction to the gut microbiota as a potential mediator of CLA effects on obesity and atherosclerosis.

Cholesterol-Lowering Nutraceuticals Affecting Vascular Function and Cardiovascular Disease Risk

PURPOSE OF REVIEW

The aim of this review is to provide an update on the effects of the dietary supplementation with cholesterol-lowering nutraceuticals and nutraceutical combinations affecting vascular function and CV risk in clinical interventional studies.

RECENT FINDINGS

Current evidence supports the mild-to-moderate cholesterol-lowering efficacy of red yeast rice, berberine, plant sterols, fibers, and some nutraceutical combinations whereas data on the individual cholesterol-lowering action of other nutraceuticals are either less striking or even inconclusive. There is also promising evidence on the vascular protective effects of some of the aforementioned nutraceuticals. However, except for red yeast rice, clinical interventional studies have not investigated their impact on CV outcomes. Evidence of both cholesterol-lowering and vascular protection is a prerogative of few single nutraceuticals and nutraceutical combinations, which may support their clinical use; however, caution on their uncontrolled adoption is necessary as they are freely available on the market and, therefore, subject to potential misuse.

Dietary fats and F2-isoprostanes: A review of the clinical evidence

Evidence supports that a high dietary fat intake increases oxidative stress and the risk of diet-induced metabolic disorders such as obesity, diabetes and cardiovascular diseases. F₂-isoprostanes (F₂-isoP) are formed by the non-enzymatic oxidation of arachidonic acid and are widely used as reliable biomarkers of oxidative stress in clinical studies. Dietary fats may influence F₂-isoP levels, as they (1) are metabolic substrates for their formation, (2) modify the lipid composition of tissues, and (3) affect the plasma lipoprotein concentrations which are involved in F₂-isoP transport. This review examined the latest clinical evidence on how dietary fats can affect blood circulation and excretion of F₂-isoP in individuals with healthy or deteriorated metabolic profiles. Clinical studies reported that saturated or monounsaturated fat-rich diets did not affect F₂-isoP levels in adults with healthy or deteriorated metabolic profiles. Though, ω-3 polyunsaturated fatty acids decreased F₂-isoP levels in numerous studies, whereas trans-fatty acids raised F₂-isoP excretion. Yet, the reported heterogeneous results reveal important considerations, such as the health status of the participants, the biological fluids used to determine F₂-isoP, the analytical methods employed and the specific F₂-isoP isomers detected. Therefore, future clinical studies should be designed in order to consider these issues in the studies of the effects of fat intake on oxidative stress.

Lipid-lowering nutraceuticals in clinical practice: position paper from an International Lipid Expert Panel

In recent years, there has been growing interest in the possible use of nutraceuticals to improve and optimize dyslipidemia control and therapy. Based on the data from available studies, nutraceuticals might help patients obtain theraputic lipid goals and reduce cardiovascular residual risk. Some nutraceuticals have essential lipid-lowering properties confirmed in studies; some might also have possible positive effects on nonlipid cardiovascular risk factors and have been shown to improve early markers of vascular health such as endothelial function and pulse wave velocity. However, the clinical evidence supporting the use of a single lipid-lowering nutraceutical or a combination of them is largely variable and, for many of the nutraceuticals, the evidence is very limited and, therefore, often debatable. The purpose of this position paper is to provide consensus-based recommendations for the optimal use of lipid-lowering nutraceuticals to manage dyslipidemia in patients who are still not on statin therapy, patients who are on statin or combination therapy but have not achieved lipid goals, and patients with statin intolerance. This statement is intended for physicians and other healthcare professionals engaged in the diagnosis and management of patients with lipid disorders, especially in the primary care setting.

Conjugated linoleic acid improves glycemic response, lipid profile, and oxidative stress in obese patients with non-alcoholic fatty liver disease: a randomized controlled clinical trial

Aim

To investigate if conjugated linoleic acid supplementation (CLA) affects metabolic factors and oxidative stress in non-alcoholic fatty liver disease (NAFLD).

Methods

The study was a randomized, controlled clinical trial conducted in specialized and subspecialized clinics of Tabriz University of Medical Sciences from January 2014 to March 2015. 38 obese NAFLD patients were randomly allocated into either the intervention group, receiving three 1000 mg softgel of CLA with a weight loss diet and 400 IU vitamin E, or into the control group, receiving only weight loss diet and 400 IU vitamin E for eight weeks. Dietary data and physical activity, as well as anthropometric, body composition, metabolic factors, and oxidative stress were assessed at baseline and at the end of the study.

Results

Weight, body composition, and serum oxidative stress, insulin, and lipid profile significantly improved in both groups, while hemoglobin A1c (HbA1c) levels (P = 0.004), total cholesterol to high density lipoprotein ratio (P = 0.008), low density lipoprotein to high density lipoprotein ratio (LDL/HDL) (P = 0.002), and alanine aminotransferase to aspartate aminotransferase (ALT/AST) ratio (P = 0.025) significantly decreased in the intervention group. At the end of the study, fat mass (P = 0.001), muscle mass (P = 0.023), total body water (P = 0.004), HbA1c (P < 0.001), triglycerides (P = 0.006), LDL/HDL ratio (P = 0.027), and ALT/AST ratio (P = 0.046) were significantly better in the CLA group than in the control group.

Conclusion

CLA improved insulin resistance, lipid disturbances, oxidative stress, and liver function in NAFLD. Therefore, it could be considered as an effective complementary treatment in NAFLD.

Registration number: IRCT2014020516491N1.

Omega 6 fatty acids for the primary prevention of cardiovascular disease

BACKGROUND

Omega 6 plays a vital role in many physiological functions but there is controversy concerning its effect on cardiovascular disease (CVD) risk. There is conflicting evidence whether increasing or decreasing omega 6 intake results in beneficial effects.

OBJECTIVES

The two primary objectives of this Cochrane review were to determine the effectiveness of:1. Increasing omega 6 (Linoleic acid (LA), Gamma-linolenic acid (GLA), Dihomo-gamma-linolenic acid (DGLA), Arachidonic acid (AA), or any combination) intake in place of saturated or monounsaturated fats or carbohydrates for the primary prevention of CVD.2. Decreasing omega 6 (LA, GLA, DGLA, AA, or any combination) intake in place of carbohydrates or protein (or both) for the primary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases up to 23 September 2014: the Cochrane Central Register of Controlled Trials (CENTRAL) on the Cochrane Library (Issue 8 of 12, 2014); MEDLINE (Ovid) (1946 to September week 2, 2014); EMBASE Classic and EMBASE (Ovid) (1947 to September 2014); Web of Science Core Collection (Thomson Reuters) (1990 to September 2014); Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment Database, and Health Economics Evaluations Database on the Cochrane Library (Issue 3 of 4, 2014). We searched trial registers and reference lists of reviews for further studies. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions stating an intention to increase or decrease omega 6 fatty acids, lasting at least six months, and including healthy adults or adults at high risk of CVD. The comparison group was given no advice, no supplementation, a placebo, a control diet, or continued with their usual diet. The outcomes of interest were CVD clinical events (all-cause mortality, cardiovascular mortality, non-fatal end points) and CVD risk factors (changes in blood pressure, changes in blood lipids, occurrence of type 2 diabetes). We excluded trials involving exercise or multifactorial interventions to avoid confounding.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, extracted the data, and assessed the risk of bias in the included trials.

MAIN RESULTS

We included four RCTs (five papers) that randomised 660 participants. No ongoing trials were identified. All included trials had at least one domain with an unclear risk of bias. There were no RCTs of omega 6 intake reporting CVD clinical events. Three trials investigated the effect of increased omega 6 intake on lipid levels (total cholesterol, low density lipoprotein (LDL-cholesterol), and high density lipoprotein (HDL-cholesterol)), two trials reported triglycerides, and two trials reported blood pressure (diastolic and systolic blood pressure). Two trials, one with two relevant intervention arms, investigated the effect of decreased omega 6 intake on blood pressure parameters and lipid levels (total cholesterol, LDL-cholesterol, and HDL-cholesterol) and one trial reported triglycerides. Our analyses found no statistically significant effects of either increased or decreased omega 6 intake on CVD risk factors.Two studies were supported by funding from the UK Food Standards Agency and Medical Research Council. One study was supported by Lipid Nutrition, a commercial company in the Netherlands and the Dutch Ministry of Economic Affairs. The final study was supported by grants from the Finnish Food Research Foundation, Finnish Heart Research Foundation, Aarne and Aili Turnen Foundation, and the Research Council for Health, Academy of Finland.

AUTHORS' CONCLUSIONS

We found no studies examining the effects of either increased or decreased omega 6 on our primary outcome CVD clinical endpoints and insufficient evidence to show an effect of increased or decreased omega 6 intake on CVD risk factors such as blood lipids and blood pressure. Very few trials were identified with a relatively small number of participants randomised. There is a need for larger well conducted RCTs assessing cardiovascular events as well as cardiovascular risk factors.

Effects of Olive Oil on Markers of Inflammation and Endothelial Function-A Systematic Review and Meta-Analysis

The aim of the present systematic review was to synthesize data from randomized controlled trials investigating the effects of olive oil on markers of inflammation or endothelial function. Literature search in electronic databases Cochrane Trial Register, EMBASE, and MEDLINE was performed. Thirty studies enrolling 3106 participants fulfilled the selection criteria. Pooled effects of different interventions were assessed as mean difference using a random effects model. Olive oil interventions (with daily consumption ranging approximately between 1 mg and 50 mg) resulted in a significantly more pronounced decrease in C-reactive protein (mean difference: −0.64 mg/L, (95% confidence interval (CI) −0.96 to −0.31), p < 0.0001, n = 15 trials) and interleukin-6 (mean difference: −0.29 (95% CI −0.7 to −0.02), p < 0.04, n = 7 trials) as compared to controls, respectively. Values of flow-mediated dilatation (given as absolute percentage) were significantly more increased in individuals subjected to olive oil interventions (mean difference: 0.76% (95% CI 0.27 to 1.24), p < 0.002, n = 8 trials). These results provide evidence that olive oil might exert beneficial effects on endothelial function as well as markers of inflammation and endothelial function, thus representing a key ingredient contributing to the cardiovascular-protective effects of a Mediterranean diet. However, due to the heterogeneous study designs (e.g., olive oil given as a supplement or as part of dietary pattern, variations in control diets), a conservative interpretation of the results is necessary.

A Systematic Review of the Efficacy of Bioactive Compounds in Cardiovascular Disease: Carbohydrates, Active Lipids and Nitrogen Compounds

Background/Aims: The prevalence of cardiovascular diseases (CVD) is rising and it is the prime cause of death in all developed countries. Bioactive compounds (BACs) can play a role in CVD prevention and treatment. To examine the scientific evidence supporting BACs groups' efficacy in CVD prevention and treatment, we conducted a systematized review. Methods: All available information on Medline, LILACS and EMBASE; all randomized controlled trials (RCTs) with prospective, parallel or crossover designs in humans in which the BACs effect was compared with that of placebo/control. Vascular homeostasis, blood pressure, endothelial function, oxidative stress and inflammatory biomarkers were considered primary outcomes. Results: We selected 26 articles, verifying their quality based on the Scottish Intercollegiate Guidelines Network, establishing diverse quality levels of scientific evidence according to the design and bias risk of a study. Grades of recommendation were included, depending on the evidence strength of antecedents. Conclusions: Evidence shows that certain BACs' derivative from active lipids and nitrogen compounds, mainly from horse chestnut seed extract, sterol plants, allium derivatives, and certain doses of beta-glucans, can be helpful in decreasing the prevalence of CVD risk factors. However, further rigorous evidence is necessary to support and prove BACs' effect on CVD prevention and treatment.

A maternal high fat diet programmes endothelial function and cardiovascular status in adult male offspring independent of body weight, which is reversed by maternal conjugated linoleic acid (CLA) supplementation

Maternal high fat intake during pregnancy and lactation can result in obesity and adverse cardio-metabolic status in offspring independent of postnatal diet. While it is clear that maternal high fat intake can cause hypertension in adult offspring, there is little evidence regarding the role of dietary interventions in terms of reversing these adverse effects. Conjugated linoleic acid (CLA) is an omega 6 fatty acid with beneficial effects in obesity and metabolic status. However, the impact of CLA supplementation in the context of pregnancy disorders and high fat diet-induced developmental programming of offspring cardio-metabolic dysfunction has not been investigated. We have utilised a model of maternal overnutrition to examine the effects of CLA supplementation on programmed endothelial dysfunction during adulthood. Female Sprague-Dawley rats were fed either a purified control diet (CON) or purified control diet supplemented with 1% CLA (of total fat), a purified high fat (HF) diet (45%kcal from fat) and a purified HF diet supplemented with 1% CLA (of total fat) (HFCLA). All dams were fed ad libitum throughout pregnancy and lactation. Offspring were fed a standard chow diet from weaning (day 21) until the end of the study (day 150). Systolic blood pressure (SBP) was measured at day 85 and 130 by tail cuff plethysmography. At day 150, offspring mesenteric vessels were mounted on a pressure myograph and vascular responses to agonist-induced constriction and endothelium-dependent vasodilators were investigated. SBP was increased at day 85 and 130 in HF and HFCLA adult male offspring compared to CON and CLA groups with no effect of CLA supplementation. An overall effect of a maternal HF diet was observed in adult male vessels with a reduced vasoconstrictor response to phenylephrine and blunted vasodilatory response to acetylcholine (ACh). Furthermore, HF and HFCLA offspring displayed a reduction in nitric oxide pathway function and an increased compensatory EDHF function when compared to CON and CLA groups. These data suggest that a maternal HF diet causes a developmental programming of endothelial dysfunction and hypertension in male offspring which can be partially improved by maternal CLA supplementation, independent of offspring body weight.

Effect of conjugated linoleic acid on blood pressure: a meta-analysis of randomized, double-blind placebo-controlled trials

Background

Numerous studies on animals evidenced that conjugated linoleic acid (CLA) could decrease blood pressure (BP) in several rat models. However, such beneficial effect is not completely supported by studies on humans.

Methods

We searched the Pubmed, Cochrane Library, and the ClinicalTrials.gov databases for relevant randomized, double-blind placebo-controlled trials up to August 2014 to perform a meta-analysis. A random-effects model was used to calculate the combined treatment effects.

Results

Eight studies with nine trials, which involved 638 participants with CLA supplementation ranging from 2.0 g/day to 6.8 g/day, were included in this meta-analysis. Compared with placebo, the pooled estimate of change was −0.03 mm Hg (95% CI: −2.29, 2.24, P = 0.98) and 0.69 mm Hg (95% CI: −1.41, 2.80, P = 0.52) in systolic and diastolic BPs, respectively. No significant heterogeneity across studies for systolic BP; however, substantial heterogeneity for diastolic BP was identified. Publication bias was not found for both systolic and diastolic BPs.

Conclusion

The findings of this meta-analysis did not support the overall favorable effect of CLA supplementation on BP regulation.

Association of foods enriched in conjugated linoleic acid (CLA) and CLA supplements with lipid profile in human studies: a systematic review and meta-analysis

Objective

The present study aimed to review the association of conjugated linoleic acid (CLA) consumption in two forms, foods enriched in CLA and CLA supplements, with serum lipid profile in human studies.

Design

Systematic review and meta-analysis.

Setting

Search process was conducted in PubMed, Cochrane Library, Google Scholar, Scopus and Science Direct. Clinical trials that investigated the association of CLA intakes either in the form of supplements or enriched foods with lipid profile in healthy adults were included. All outcomes were recorded as continuous variables, and the effect size was measured by analysis of the mean and standard deviation before and after the intervention for case and control groups.

Subjects

Healthy adult population.

Results

CLA supplementation was associated with a significant decrease in LDL cholesterol (mean difference=−0·218; 95 % CI −0·358, −0·077;P=0·002), a non-significant decrease in HDL cholesterol (mean difference=−0·051; 95 % CI −0·188, 0·086;P=0·468), a non-significant increase in total cholesterol (mean difference=0·009; 95 % CI −0·128, 0·146;P=0·896) and a non-significant decrease in TAG (mean difference=−0·065; 95 % CI −0·20, 0·07;P=0·344). Foods enriched with CLA were associated with significantly decreased LDL cholesterol (mean difference=−0·231; 95 % CI −0·438, −0·024;P=0·028), non-significantly increased HDL-C (mean difference=0·075; 95 % CI −0·121, 0·270;P=0·455), non-significantly decreased total cholesterol (mean difference=−0·158; 95 % CI −0·349, 0·042;P=0·124) and non-significantly decreased TAG (mean difference=−0·078; 95 % CI −0·274, 0·117;P=0·433).

Conclusions

According to our analysis, consumption of foods enriched with CLA or CLA supplements has favourable effects on LDL cholesterol levels.

Effect of conjugated linoleic acid and vitamin E on glycemic control, body composition, and inflammatory markers in overweight type2 diabetics

Background

The healthy properties of conjugated linoleic acid (CLA) such as weight loss, reducing cardiovascular risk factors and inflammation have been reported. The trans-10, cis-12 CLA isomer is related to increasing insulin resistance, but the effects of cis-9, trans-11 isomer is not clear. The aim of this study was to investigate the effects of CLA with and without Vitamin E on body weight, body composition, glycemic index, inflammatory and coagulation factors, lipid profile, serum leptin and adiponectin, malondialdehyde (MDA), and blood pressure in type2 diabetes.

Methods

56 patients with type2 diabetes were included in 8 week double-blind control trial that used metformin. They randomly divided into three groups: CLA + VitE, CLA + VitE placebo, CLA placebo + VitE placebo. All variables, anthropometric measurements, and body composition were evaluated at the beginning and the end of study. Statistical analysis and analysis of dietary data were performed using SPSS and nutritionist IV software, respectively.

Results

There were not any significant differences in variable changes among three groups. However, there was a trend to increase in MDA and decrease in apoB100 among CLA consumers.

Conclusion

The results of this study showed that administration of CLA supplementation for 8 weeks does not affect any indicators of metabolic control in overweight type2 diabetic patients.

Microencapsulated conjugated linoleic acid associated with hypocaloric diet reduces body fat in sedentary women with metabolic syndrome

BACKGROUND

Animal studies have suggested beneficial effects of conjugated linoleic acid (CLA) in reducing body fat mass and improvement in the serum lipid profile and glycemia. However, these effects are controversial in humans. The purpose of this study was to investigate the effects of microencapsulated CLA supplementation on body composition, body mass index, waist circumference, and blood pressure in sedentary women with metabolic syndrome.

METHODS

This study was a placebo-controlled and randomized clinical trial. Fourteen women diagnosed with metabolic syndrome received light strawberry jam enriched or not with microencapsulated CLA (3 g/day) as a mixture of 38.57% cis-9, trans-11, and 39.76% trans-10, cis-12 CLA isomers associated with a hypocaloric diet for 90 days. The subjects were monitored to assess variables associated with the metabolic syndrome, in addition to assessing adherence with the intervention.

RESULTS

There were no significant effects of microencapsulated CLA on the lipid profile or blood pressure. Mean plasma insulin concentrations were significantly lower in women supplemented with microencapsulated CLA (Δ T₉₀ - T₀ = -12.87 ± 4.26 μU/mL, P = 0.02). Microencapsulated CLA supplementation did not alter the waist circumference, but there was a reduction in body fat mass detected after 30 days (Δ = -2.68% ± 0.82%, P = 0.02), which was maintained until the 90-day intervention period (Δ = -3.32% ± 1.41%, P = 0.02) in the microencapsulated CLA group. The placebo group showed this effect only after 90 days (Δ = -1.97% ± 0.60%, P = 0.02), but had a reduced waist circumference (Δ T₉₀ - T₀ = -4.25 ± 1.31 cm, P = 0.03).

CONCLUSION

Supplementation with mixed-isomer microencapsulated CLA may have a favorable effect on glycemic control and body fat mass loss at an earlier time in sedentary women with metabolic syndrome, although there were no effects on lipid profile and blood pressure.

Implication of conjugated linoleic acid (CLA) in human health

Conjugated linoleic acid (CLA) has drawn significant attention in the last two decades for its variety of biologically beneficial effects. CLA reduces body fat, cardiovascular diseases and cancer, and modulates immune and inflammatory responses as well as improves bone mass. It has been suggested that the overall effects of CLA are the results of interactions between two major isomers, cis-9,trans-11 and trans-10,cis-12. This review will primarily focus on current CLA publications involving humans, which are also summarized in the tables. Along with a number of beneficial effects of CLA, there are safety considerations for CLA supplementation in humans, which include effects on liver functions, milk fat depression, glucose metabolism, and oxidative stresses.

A high intake of trans fatty acids has little effect on markers of inflammation and oxidative stress in humans

Consumption of industrial trans fatty acids (iTFA) increases LDL cholesterol, decreases HDL cholesterol, and is strongly associated with a higher risk of cardiovascular disease (CVD). However, changes in circulating cholesterol cannot explain the entire effect. Therefore, we studied whether iTFA and conjugated linoleic acid (CLA) affect markers of inflammation and oxidative stress. Sixty-one healthy adults consumed each of 3 diets for 3 wk, in random order. Diets were identical except for 7% of energy provided by oleic acid (control diet), iTFA, or CLA. At the end of the 3 wk, we measured plasma inflammatory markers IL-6, C-reactive protein, tumor necrosis factor receptors I and II (TNF-RI and -RII), monocyte chemotactic protein-1 and E-selectin, and urinary 8-iso-PGF(2α), a marker of lipid peroxidation. Consumption of iTFA caused 4% lower TNF-RI concentrations and 6% higher E-selectin concentrations compared with oleic acid (control) and had no significant effect on other inflammatory markers. CLA did not significantly affect inflammatory markers. The urine concentration of 8-iso-PGF(2α) [geometric mean (95% CI)] was greater after the iTFA [0.54 (0.48, 0.60) nmol/mmol creatinine] and the CLA [1.2 (1.1, 1.3) nmol/mmol creatinine] diet periods than after the control period [0.45 (0.41, 0.50) nmol/mmol creatinine; P < 0.05]. In conclusion, high intakes of iTFA and CLA did not substantially affect plasma concentrations of inflammatory markers, but they increased the urine 8-iso-PGF(2α) concentration. However, it is unlikely this plays a major role in the mechanism by which iTFA increase the risk of CVD. However, more research is needed to fully understand the implications of these findings.

Dietary conjugated linoleic Acid and hepatic steatosis: species-specific effects on liver and adipose lipid metabolism and gene expression

Objective. To summarize the recent studies on effect of conjugated linoleic acid (CLA) on hepatic steatosis and hepatic and adipose lipid metabolism highlighting the potential regulatory mechanisms. Methods. Sixty-four published experiments were summarized in which trans-10, cis-12 CLA was fed either alone or in combination with other CLA isomers to mice, rats, hamsters, and humans were compared. Summary and Conclusions. Dietary trans-10, cis-12 CLA induces a severe hepatic steatosis in mice with a more muted response in other species. Regardless of species, when hepatic steatosis was present, a concurrent decrease in body adiposity was observed, suggesting that hepatic lipid accumulation is a result of uptake of mobilized fatty acids (FA) from adipose tissue and the liver's inability to sufficiently increase FA oxidation and export of synthesized triglycerides. The potential role of liver FA composition, insulin secretion and sensitivity, adipokine, and inflammatory responses are discussed as potential mechanisms behind CLA-induced hepatic steatosis.

Conjugated linoleic acid supplementation for 8 weeks does not affect body composition, lipid profile, or safety biomarkers in overweight, hyperlipidemic men

The usefulness of conjugated linoleic acid (CLA) as a nutraceutical remains ambiguous. Our objective was, therefore, to investigate the effect of CLA on body composition, blood lipids, and safety biomarkers in overweight, hyperlipidemic men. A double-blinded, 3-phase crossover trial was conducted in overweight (BMI ≥ 25 kg/m(2)), borderline hypercholesterolemic [LDL-cholesterol (C) ≥ 2.5 mmol/L] men aged 18-60 y. During three 8-wk phases, each separated by a 4-wk washout period, 27 participants consumed under supervision in random order 3.5 g/d of safflower oil (control), a 50:50 mixture of trans 10, cis 12 and cis 9, trans 11 (c9, t11) CLA:Clarinol G-80, and c9, t11 isomer:c9, t11 CLA. At baseline and endpoint of each phase, body weight, body fat mass, and lean body mass were measured by DXA. Blood lipid profiles and safety biomarkers, including insulin sensitivity, blood concentrations of adiponectin, and inflammatory (high sensitive-C-reactive protein, TNFα, and IL-6) and oxidative (oxidized-LDL) molecules, were measured. The effect of CLA consumption on fatty acid oxidation was also assessed. Compared with the control treatment, the CLA treatments did not affect changes in body weight, body composition, or blood lipids. In addition, CLA did not affect the β-oxidation rate of fatty acids or induce significant alterations in the safety markers tested. In conclusion, although no detrimental effects were caused by supplementation, these results do not confirm a role for CLA in either body weight or blood lipid regulation in humans.

Effect of conjugated linoleic acid on body fat accretion in overweight or obese children

BACKGROUND

Conjugated linoleic acid (CLA) is a supplemental dietary fatty acid that decreases fat mass accretion in young animals.

OBJECTIVE

The aim of this study was to determine CLA's efficacy with regard to change in fat and body mass index (BMI; in kg/m(2)) in children.

DESIGN

We conducted a 7 +/- 0.5-mo randomized, double-blind, placebo-controlled trial of CLA in 62 prepubertal children aged 6-10 y who were overweight or obese but otherwise healthy. The subjects were randomly assigned to receive 3 g/d of 80% CLA (50:50 cis-9,trans-11 and trans-10,cis-12 isomers) or placebo in chocolate milk.

RESULTS

Fifty-three subjects completed the trial (n = 28 in the CLA group, n = 25 in the placebo group). CLA attenuated the increase in BMI (0.5 +/- 0.8) compared with placebo (1.1 +/- 1.1) (P = 0.05). The percentage change in body fat measured by dual-energy X-ray absorptiometry was smaller (P = 0.001) in the CLA group (-0.5 +/- 2.1%) than in the placebo group (1.3 +/- 1.8%). The change in abdominal body fat as a percentage of total body weight was smaller (P = 0.02) in the CLA group (-0.09 +/- 0.9%) than in the placebo group (0.43 +/- 0.6%). There were no significant changes in plasma glucose, insulin, or LDL cholesterol between groups. Plasma HDL cholesterol decreased significantly more (P = 0.05) in the CLA group (-5.1 +/- 7.3 mg/dL) than in the placebo group (-0.7 +/- 8 mg/dL). Bone mineral accretion was lower (P = 0.04) in the CLA group (0.05 +/- 0.03 kg) than in the placebo group (0.07 +/- 0.03 kg). Reported gastrointestinal symptoms did not differ significantly between groups.

CONCLUSIONS

CLA supplementation for 7 +/- 0.5 mo decreased body fatness in 6-10-y-old children who were overweight or obese but did not improve plasma lipids or glucose and decreased HDL more than in the placebo group. Long-term investigation of the safety and efficacy of CLA supplementation in children is recommended.

A meta-analysis of the effects of conjugated linoleic acid on fat-free mass in humans

Treatment of laboratory animals with a 50:50 mixture of c9,t11 and t10,c12 conjugated linoleic acid (CLA) results in fat loss and, to a smaller degree, fat-free mass (FFM) gain. In a previous meta-analysis, we found that CLA produced a fat loss, but that humans were not as responsive as mice. We performed a similar meta-analysis in the same 18 studies to test whether CLA increased FFM. Only placebo-controlled trials that measured body composition were included. We found that FFM increased during CLA treatment (0.3 +/- 0.7 kg; p = 0.05), but that the change did not display an effect of length of treatment (0.001 +/- 0.005 kg.week(-1); p = 0.8), or an effect of dosage (0.1 +/- 0.1 kg.g CLA(-1).day(-1); p = 0.3). We conclude that FFM does increase in humans during CLA treatment, but the onset of the increase is rapid and the total increase is small (<1%).

Dietary supplementation with cis-9,trans-11 conjugated linoleic acid and aortic stiffness in overweight and obese adults

BACKGROUND

Animal studies suggest that dietary cis-9,trans-11 (c9,t11) conjugated linoleic acid (CLA) may inhibit or regress the development of atherosclerosis. The effect of CLA on atherosclerosis has not been assessed in humans.

OBJECTIVE

We investigated the effect of c9,t11 CLA supplementation on aortic pulse wave velocity (a marker of atherosclerosis) and on cardiovascular risk factors in overweight and obese but otherwise apparently healthy subjects.

DESIGN

In a double-blind, randomized, placebo-controlled, parallel-group trial, we randomly assigned 401 subjects, aged 40-70 y and with a body mass index (in kg/m(2)) > or = 25, to receive either 4 g CLA/d (2.5 g c9,t11 CLA/d and 0.6 g trans-10,cis-12 CLA/d) or placebo supplements for 6 mo. Aortic pulse wave velocity, blood pressure, anthropometric characteristics, and concentrations of fasting lipid, glucose, insulin, and C-reactive protein were measured before and after supplementation.

RESULTS

During the intervention, mean (+/-SE) pulse wave velocity did not change in the c9,t11 CLA group (Delta0.00 +/- 0.07) compared with the placebo group (Delta0.09 +/- 0.06). There was no effect of c9,t11 CLA supplementation on blood pressure, body composition, insulin resistance, or concentrations of lipid, glucose, and C-reactive protein.

CONCLUSION

This study does not support an antiatherosclerotic effect or an effect on cardiovascular risk factors of c9,t11 CLA. This trial was registered at www.clinicaltrials.gov as NCT00706745.

Complementary and alternative therapies for weight loss

Although many complementary therapies are promoted for the treatment of obesity, few are truly therapeutic. Evidence suggests that food containing diacylglycerol oil, acupuncture, and hypnosis are the only evidence-based complementary therapies for the treatment of obesity, and, at best, these should be used as adjuvants to the more conventional therapies of calorie restriction and exercise.

Conjugated linoleic acids reduce body fat in healthy postmenopausal women

Isomers of conjugated linoleic acids (CLA) reduce fat mass (FM) and increase insulin sensitivity in some, but not all, murine studies. In humans, this effect is still debatable. In this study, we compared the effect of 2 CLA supplements on total and regional FM assessed by dual energy X-ray absorptiometry, changes in serum insulin and glucose concentrations, and adipose tissue (AT) gene expression in humans. In a double-blind, parallel, 16-wk intervention, we randomized 81 healthy postmenopausal women to 1) 5.5 g/d of 40/40% of cis9,trans11-CLA (c9,t11-CLA) and trans10,cis12-CLA (t10,c12-CLA) (CLA-mix); 2) cis9, trans11-CLA (c9,t11-CLA); or 3) control (olive oil). We assessed all variables before and after the intervention. The CLA-mix group had less total FM (4%) and lower-body FM (7%) than the control (P = 0.02 and < 0.001, respectively). Post hoc analyses showed that serum insulin concentrations were greater in the CLA-mix group (34%) than the control group (P = 0.02) in the highest waist circumference tertile only. AT mRNA expression of glucose transporter 4, leptin, and lipoprotein lipase was lower, whereas expression of tumor necrosis factor-alpha was higher in the CLA-mix group than in the control group (P < 0.04). In conclusion, a 50:50 mixture of c9,t11- and t10,c12-CLA isomers resulted in less total and lower-body FM in postmenopausal women and greater serum insulin concentrations in the highest waist circumference tertile. Future research is needed to confirm the insulin desensitizing effect of the CLA mixture and the effect on the mRNA expression of adipocyte-specific genes in humans.

Conjugated linoleic acid modulation of risk factors associated with atherosclerosis

Conjugated linoleic acid (CLA) has been the subject of extensive investigation regarding its possible benefits on a variety of human diseases. In some animal studies, CLA has been shown to have a beneficial effect on sclerotic lesions associated with atherosclerosis, be a possible anti-carcinogen, increase feed efficiency, and act as a lean body mass supplement. However, the results have been inconsistent, and the effects of CLA on atherogenesis appear to be dose-, isomer-, tissue-, and species-specific. Similarly, CLA trials in humans have resulted in conflicting findings. Both the human and animal study results may be attributed to contrasting doses of CLA, isomers, the coexistence of other dietary fatty acids, length of study, and inter-and/or intra-species diversities. Recent research advances have suggested the importance of CLA isomers in modulating gene expression involved in oxidative damage, fatty acid metabolism, immune/inflammatory responses, and ultimately atherosclerosis. Although the possible mechanisms of action of CLA have been suggested, they have yet to be determined.

Conjugated linoleic acid modulation of risk factors associated with atherosclerosis

Conjugated linoleic acid (CLA) has been the subject of extensive investigation regarding its possible benefits on a variety of human diseases. In some animal studies, CLA has been shown to have a beneficial effect on sclerotic lesions associated with atherosclerosis, be a possible anti-carcinogen, increase feed efficiency, and act as a lean body mass supplement. However, the results have been inconsistent, and the effects of CLA on atherogenesis appear to be dose-, isomer-, tissue-, and species-specific. Similarly, CLA trials in humans have resulted in conflicting findings. Both the human and animal study results may be attributed to contrasting doses of CLA, isomers, the coexistence of other dietary fatty acids, length of study, and inter-and/or intra-species diversities. Recent research advances have suggested the importance of CLA isomers in modulating gene expression involved in oxidative damage, fatty acid metabolism, immune/inflammatory responses, and ultimately atherosclerosis. Although the possible mechanisms of action of CLA have been suggested, they have yet to be determined.