As for body-fat loss, some study participants lost nearly 7. Here's how to burn fat naturally. The puzzling part is that the amount of CLA ingested did not seem to be related to observed changes in body composition. In other words, taking more CLA did not lead to more weight loss. This might mean that the type of CLA supplement is more important than the amount, as the type of CLA most actively involved in losing fat the trans , cis isomer, for those of you who like the gritty details is found in the smallest amounts in our diets less than 10 percent of the CLA in our diets is that particular isomer.
Most supplements contain a mixture of the different types of CLA. ICYMI, this is the difference between plant-based and synthetic supplements. More research needs to be done in terms of seeing if specific types of CLA have greater or lesser effects on fat loss. But based on the current findings, despite all the sleek abdominals you see in advertisements, leave CLA pills out of your daily supplement protocol, as it won't help you lose belly fat or any other type of fat.
And steer clear of this weight-loss drug that's making a scary comeback. By Dr. Mike Roussell May 04, Save FB Tweet More. One of the first studies demonstrating negative effects of CLA was performed with 71 subjects including obese men and women of 20 to 50 yr of age. Body was measured by hydrodensitometry, but the results did not show any effect on body composition [ 64 ].
In sedentary young women, intake of 2. Likewise, consumption of 4. Some of the studies observed gender specific effects of CLA intake. Riserus et al. The small sample size and short duration were the major limitations of this study; thus, the effects of CLA in abdominal obesity need to be investigated further in larger studies with longer duration. Long-term 1 yr supplementation daily dose of CLA was 3. In this double-blind placebo-controlled study, female and male 31 volunteers with BMI of 25—30 were included.
In a bicentric study conducted simultaneously at Clermont-Ferrand, France and Maastricht, The Netherlands , eighty-one middle-aged, overweight, healthy men and women were enrolled, and all subjects consumed a drinkable dairy product containing 3 g of high OA sunflower oil daily for 6 wk, the run-in period [ 46 ]. Volunteers were then randomized over five groups receiving daily either 3 g of high OA sunflower oil, 1. Dietary intake was also recorded.
It was concluded that, a daily consumption of a drinkable dairy product containing up to 3 g of CLA isomers for 18 wk had no significant effect on body composition in overweight, middle-aged men and women [ 46 ]. A study from Greece reported that CLA administered first at 0.
Raff et al. This study gained more importance, as it was reported in children aged between 6 and 10 yr, who were overweight or obese, but otherwise healthy [ 67 ] ]. This report also indicates that CLA per se was less efficient to improve BFM; for instance, a recent non cross-over clinical study conducted on 66 non-trained healthy male students for 2 month showed that CLA supplementation had no effect on LBM, BFM, trunk and visceral fats, and waist circumference [ 69 ].
Some clinical studies suggested that administration of CLA might be the most effective strategy in controlling regionalized reduction of fat mass rather than its constitutional reduction, i. For instance, administration of 3. Waist-to-hip ratio also decreased significantly in healthy, overweight and obese men, compared with placebo group. Interestingly, these effects were produced independent of diet and specific lifestyle.
Exercising individuals often add nutritional supplements to their diet to accelerate the increase in muscle mass and strength from heavy resistance-exercise training. Some short- and long-term studies employing high doses of CLA in healthy and obese, sedentary and exercised adults have shown beneficial effects of CLA in reducing fat mass and increasing LBM.
A daily supplementation of 1. In this study, physical exercise was standardized as 90 min in gym, three times a wk; and concluded that CLA reduces the deposition of fat. These results seem to be encouraging, because much lower dose of CLA produced the expected results - when compared to other studies - wherein comparatively 2 to 4 folds higher concentrations of CLA were used.
Effect of CLA Clarinol A supplementation in conjunction with 6 wk of aerobic exercise training on 33 untrained to moderately trained men average age CLA showed no ergogenic benefits on neuromuscular fatigue, and field tests of muscular endurance and power. This combined strategy showed that supervised resistance exercise training is safe and effective for increasing strength in older adults, because aging is associated with lower muscle mass and an increase in body fat.
Similarly, in another double blind and placebo controlled resistance-training study, no decrease in visceral adipose tissue was observed; however a significant reduction in the cross-sectional area of visceral adipose tissue was noticed in the placebo group [ 22 ].
In this study, 30 overweight and moderately obese, but otherwise healthy middle-aged 35 to 55 yr male subjects received 3. Pinkoski et al. Thus, some of the studies showed the effectiveness of CLA in fat mass reduction in subjects during resistance-training program. Contrary to this, no CLA-specific effects were observed on body composition, energy expenditure or appetite in non-obese, regularly exercising individuals comprising 25 men and 27 women , who received either 3.
It suggests that CLA supplementation may promote testosterone synthesis through a molecular pathway that should be investigated in detail. Furthermore, this study becomes much relevant, since the correlation between the production of testosterone and body building still remains a controversy.
Based upon this background, a few clinical investigations were made on the effect of CLA on fat-mass regain after weight loss - with an assumption that CLA could block body fat gain. To check this, overweight adults were administered a very low-calorie diet for 3 wk, followed by CLA supplementation at a dosage of either 1. Subjects took CLA in either dose showed increased regain of fat-free mass and resting metabolic rate, thereby lowering the regain of body fat relative to the control subjects.
Interestingly, they concluded in later findings that the measures of appetite hunger, satiety and fullness favorably and dose-independently affected by the same dose of CLA but had no effect on energy intake at breakfast or improved body-weight maintenance after weight loss [ 76 ]. Apart from a few studies that investigated the effects of CLA supplementation in humans, there were some experiments designed to supplement CLA-enriched dairy products.
Consumption of dairy products such as ultra-heat treated milk, butter, and cheese enriched with 1. Another experiment compared the effects of the consumption of a modified butter, naturally enriched with CLA 4.
Consumption of a drinkable dairy product containing up to 3 g of CLA isomer for 18 wk did not result in any significant effect on body composition in overweight, middle-aged men and women [ 46 ]. Venkatramanan et al.
More precisely, consumption of CLA-enriched milks in either form failed to alter TAG concentrations in the blood; body weight or fat composition [ 51 ]. Thus, in general, dairy products enriched with either of 9- or CLA isomers or its mixture failed to establish a consistent effect on body composition. The question of inconclusive results on efficacy and effectiveness of CLA on body composition and obesity may answer from long-term intervention studies.
Effects of any dietary supplement or food ingredient on body composition should be assessed over an extended period of time to conclude the results, because crash diet procedures seem inappropriate.
In most of the studies, the intervention period lasted only for a few wk, and long-term studies were very few. In a study, subjects including men and women were supplemented with 3. During the first 12 month, significant reduction in BFM and leptin levels was reported. These changes in body composition were not related to diet and exercise.
These studies seem to be important as most of weight loss studies in overweight and obese subjects have demonstrated that most subjects will regain the lost weight within the next 1 to 2 yr [ 43 , 80 ].
Gaullier et al. Energy expenditure, substrate utilization and dietary fat oxidation were measured before and after 6 month of CLA supplementation, which showed that fat oxidation and energy expenditure increased during sleep in subjects received CLA, in comparison to placebo [ 81 ].
Supplementation of CLA 6. Such long-term studies have to be conducted in a cross-over design by including men and women of different age groups to generalize the beneficial effects of CLA. However, all of them failed to reproduce the dramatic results reported in animal and in vitro models, especially mice.
The extensive controversies in clinical studies limit from proposing a definite statement regarding the beneficial effects of CLA on body composition, so as to address the increasing concerns of health professionals, body builders and athletes. Hyper-triacylglycerolemia and elevated plasma cholesterol are suggested as the major risk factors for atherosclerosis and cardio-vascular diseases CVD , and that blood lipid profile, blood pressure, BMI and blood sugar are generally considered as the indicators of heart health.
The lipid profile is a panel of blood tests performed on the patient to determine the risk of CVD. These tests are good indicators of whether someone is likely to have a heart attack or stroke caused by blockage of blood vessels or hardening of the arteries atherosclerosis.
The lipid profile typically includes the baseline measurements of total cholesterol; high density lipoprotein cholesterol HDL-C , often called good cholesterol; low density lipoprotein cholesterol LDL-C , called bad cholesterol; and TAG in plasma [ 82 ]. Normal cholesterol levels vary by age and sex. LDL-C is the major cholesterol carrier in the blood, and if too much it is in circulation, it can slowly build up in the walls of the arteries of heart and brain leading to arteriosclerotic vascular diseases.
Variations in the concentration of these markers in blood plasma from the normal level indicate dysfunctions of human system. The major circulatory markers associated with heart health and their normal levels in blood are listed in Table 3.
Some animal studies suggest the health benefits anti-CVD effects of CLA such as anti-sclerotic and improvements in blood lipid profile, hypolipidaemic and anti-oxidative effects [ 84 — 86 ]. Two different isomers of CLA i. Epidemiological studies showed that plasma HDL-C concentrations have an inverse relationship with the risk of CVD, and it is anticipated that raising plasma HDL-C levels might protect against atherosclerosis [ 83 ].
Supposed effects of CLA supplementation on blood lipid profile also remains inconclusive. Similarly, a dose of 0. In this study, 22 volunteers were enrolled and they were divided into study and control groups in a doubly blind design; the study group received 0.
Diet was controlled, and no significant differences in energy or macronutrient intake were found between the two groups. A significant reduction of HDL-C was observed when 6. But 2. In this non cross-over double-blind, placebo-controlled and randomized study, 51 normolipidaemic subjects were enrolled.
These results further suggested that CLA supplementation significantly improved the lipid profile in human subjects without any adverse effects on body weight, plasma glucose and insulin concentrations; and thus indicates the supposed cardio-protective effects of CLA. Contrary to this, the opposing effects 9- and CLAs were observed by Tricon et al.
But, later, the same group showed that dairy products enriched with 9-CLA 1. Some studies observed neither a beneficial nor an adverse effect of an isomeric blend of 9- and CLA in a ratio other than A 93 d long study in 17 healthy female volunteers to observe the effect of dietary CLA on blood lipids, lipoproteins, and tissue FA composition showed that daily supplementation of 3. Furthermore, no adverse effect of CLA supplementation was reported in this study, though plasma concentration of CLA was increased during the intervention period, i.
Some studies investigated the effect of dairy products on lipid profile. However, human studies with the supplementation of CLA-enriched dairy products in situ enrichment produced contradictory results. Intake of 1. However, levels of CLA and VA in human milk can be modulated if breastfeeding mothers replace conventional dairy and meat products with organic dairy products enriched by natural feeding [ 95 ].
Recently, Penedo et al. Furthermore, sheep cheese naturally enriched in VA, CLA and ALA improved the lipid profile and reduced anandamide an endogenous cannabinoid neurotransmitter and obesity marker in adults with diagnosed mildly hypercholesterolaemia [ 97 ]. CRP is synthesized by liver in response to inflammation. Inflammations may be due to a variety of reasons such as cancer, diabetes, cardiovascular diseases, etc.
A mixture of 9- and CLA isomers with equal proportions also reported an increased CRP, but not of the other inflammatory markers, i. Another study concluded that a mixture of 9- and CLAs had more adverse effects on CVD markers, while 9-CLA isomer appeared to be more neutral in healthy postmenopausal women.
Daily supplementation of 5. The CLA mixture at a dose of 3. High dose of CLA consumption 6. In contrast, CLA in the same composition ratio , but in lower dose i. Pfeuffer et al. It was observed that CLA did not impair endothelial function. Other parameters associated with metabolic syndrome and oxidative stress were not changed or slightly improved.
Forty eight healthy primigravidas with a family history of preeclampsia and with diastolic notch were included in this double-blind and placebo-controlled non cross-over study. Participants were randomized to daily oral doses of elemental calcium 0. The controversial beneficial and detrimental effects of CLA on heart health observed during clinical studied are summarized in Figure 2. All these studies were too randomized in dosage, composition and duration, which make difficult to conclude the positive effects of CLA on heart health.
Moreover, there is a complete lack of uniformity in assessing the effects CLA on heart health, i. Even though the isomeric mixture of 9- and 10 CLA was found to exert some positive effects, it is necessary to elucidate the mechanism of action to ascertain which of these isomers elicited the effect.
Different studies show that the effects of dietary CLA on immune functions in animal as well as human models are highly variable and inconsistent Table 4. For instance, a 93 d long study in 17 young women upon feeding with 3.
Even after immunization with influenza vaccine, the delayed type hypersensitivity response and serum antibody titers were not altered during the intervention period. These data suggest that short-term CLA supplementation in healthy volunteers was safe, but it showed no added benefit to their immune status [ ]. Moreover, short-term consumption of CLA produced no observable physiological change in blood coagulation and platelet function in healthy adult females [ 23 ].
CLA supplementation 3. Although the overall effect was not significant, the results at least suggested that CLA might have a biologically relevant enhancing effect on the response to hepatitis B vaccination, which warrants further study [ ]. Contrary to this, supplementation with the 9- and CLA isomers blend, respectively significantly enhanced phyto-hemagglutinin PHA content, a T-cell mitogen-induced lymphocyte proliferator.
In addition to these effects, delayed hypersensitivity response was decreased during CLA supplementation [ ]. CLA is reported to modify the inflammatory responses associated with allergic airway disease, primarily in animal models.
A prominent study in this regard came from the group of MacRedmond et al. However, daily supplementation of 4. One of the early studies in this direction measured the mean serum phospholipid esterified 9-CLA concentration in peripheral blood; observed it as significantly higher in 98 patients with chronic stable asthma, and 25 patients with acute severe asthma. Thus the supposed role of oxygen-derived free-radical activity in inflamed lung tissue was envisaged [ ].
It shows that, some attempts were made to estimate the effect of CLA on immunity with reference to asthma, but none of them succeeded in reproducing the positive effects such as enhancement of immune function, down regulation of autoimmunity and increased proliferation of lymphocytes , consistently in clinical studies [ — ].
Nevertheless, only a few studies have examined the isomers-specific effects of CLA in humans. In fact, no clinical studies have been conducted to relate CLA consumption with the incidence of cancer, but the data available in this regard are only from epidemiological studies.
Such data can be viewed as a collection of statistical tools used to elucidate the associations of CLA exposures to health outcomes. Regarding clinical studies on cancer, many researchers focused on human breast cancer; for instance, in an elaborate follow-up study using Cox proportional hazards models; Larsson et al.
Chajes et al. High-fat dairy food and CLA intake were examined in 60, women of age 40 to 76 Swedish mammography cohort study with It was found that women who consumed four or more servings of high-fat dairy foods per day including whole milk, full-fat cultured milk, cheese, cream, sour cream and butter showed half the risk of developing colorectal cancer, compared to women who consumed less than one serving per day [ ]. Concerning CLA intake, they found it was associated with an almost 30 percent reduction in the risk of colorectal cancer [ ].
Similarly, the possible role of CLA in preventing testicular cancer was depicted by the decreased CLA content in mitochondrial fractions of testicular cancer as against the normal testicular cells; and that CLA incorporation into nuclei and cytosol was significantly higher than its incorporation into plasma membranes and mitochondria [ ].
Tumors in estrogen receptor ER -negative epithelial cells in the breast are common among premenopausal women [ ]. McCann et al. Another epidemiological study the Netherlands cohort with 6. A few studies examined the relationship between dietary or serum CLA in women and the risk of breast cancer.
Such studies found an inverse association between dietary and serum CLA and risk of breast cancer in postmenopausal women [ ]. But in contrast, the adipose tissue extracts from a population of French patients with invasive breast carcinoma failed to reveal any positive correlation between adipose tissue CLA and the incidence of breast cancer [ ].
Since CLA accumulates in body fat stores, the adipose tissue of breast cancer obtained at the time of surgery could be used as a qualitative biomarker for CLA intake. Thus, the available human clinical studies could not ascertain the anti-cancer property of CLA.
A major limitation in the epidemiological studies is the difficulty in obtaining accurate estimates of dietary CLA intake. Most of the studies were carried out in small populations, where the diversity in food habits was less. Moreover, no clinical studies evaluated the effects of pure CLA preparations or individual isomers on the incidences of cancer. It focuses that well-defined and controlled studies are required to fully understand the effects of CLA intake on the incidence of human cancer.
The life style epidemics, diabetes and obesity are considered as the major causes of morbidity and mortality all over the world; and that obesity and weight gain are associated with an increased risk of diabetes [ ].
The hormone, insulin is responsible for regulating glucose concentration in blood. Insulin resistance is a state in which cells do not respond properly to insulin even if it is available in the blood , which leads to hyperinsulinemia high blood insulin.
Some animal studies demonstrated that CLA supplementation enhances insulin sensitivity; however, the mechanism underlying this effect is unclear [ , ]. Relatively few studies have examined the anti-diabetic properties of CLA in humans. Supplementation of 3.
The CLA supplementation increases oxidative stress and inflammatory biomarkers in obese men [ 60 ]. Oxidative stress seems closely related to induced insulin resistance, which suggests a link between the FA-induced lipid peroxidation; these unfavorable effects of CLA might be of clinical relevance with regard to CVD [ 60 ]. Recently, Shadman et al. In non-diabetic abdominally obese men, 3.
These results are of clinical interest, as hyperproinsulinaemia predicts diabetes and cardiovascular diseases. But, the isomeric mixture of 9- and CLA 3.
Sixteen individuals age, Clinical studies regarding the anti-diabetic effects of CLA are inconclusive. Rather, some of them speculated the reduction in insulin sensitivity; which attract immediate attention of the medical practitioners, because the increased consumption of CLA through dietary supplements might be ill-advised.
It seems that the use of weight-loss supplements containing 9-CLA, CLA or both as mixture is worrying, because most of the clinical studies presented in the previous sections provide mostly neutral or inconclusive results with very few favorable impacts Table 5. In association with this, a few studies reported some adverse effects such as oxidative stress, insulin resistance, gastrointestinal irritation, etc.
Proposed beneficiary and detrimental effects of CLA from clinical studies. Many studies showed increase in the plasma concentration of CLA, which was directly proportional to the quantity of CLA consumed [ 23 , ]. Therefore, the immediate expected biological effect is oxidative stress. Oxidative stress is the reflection of an imbalance between the systemic manifestation of reactive oxygen species and the ability of the body system to readily detoxify them or to repair the resulting damage imparted to cell components like proteins, lipids and nucleic acids.
Prolonged oxidative stress may lead to cancer and heart diseases [ ]. Supplementation with CLA dramatically increased the rates of oxidative stress, to the levels considerably higher than that observed in heavy smokers [ 60 ]; it also enhanced the release of inflammatory biomarkers in obese men [ 60 ].
Long-term CLA supplementation studies lasting for one and two years have found to be well tolerated, but there was an increase in circulatory markers of inflammation such as CRP, TNFs, and ILs [ 59 , ].
Changes in these markers of inflammation and oxidative stress could be related to the increase in insulin resistance associated with the risk of cardiovascular disease [ 79 , ]. Administration of CLA 4. Insulin resistance is a physiological disorder, under which the cells fail to respond to the normal actions of the hormone insulin, though it is sufficiently produced by the body — this impairment leads to hyperglycemia i. Decreased sensitivity or resistance towards insulin upon consumption of CLA was observed in some studies [ 60 , 65 ].
Furthermore, insulin resistance is closely related to the impairment decrease of the expression of glucose transporter-4 GLUT4 , a membrane transporter of glucose. It was proven beyond doubt that CLA decreases the expression of GLUT4 [ ], which shows that indiscriminate use of CLA to treat obesity would lead to type 2 diabetes as the immediate side effect, this would further damage blood vessels and thereby increased risk of CVD [ ].
Moreover, unutilized insulin due to resistance in plasma can contribute to increased appetite especially for carbohydrates and sugary foods , which would add to the gravity of CVD.
A few studies showed mild irritations of intestinal tract such as irritation [ 60 ], laxative effects and flatulence [ 47 ], gas bloating [ 20 ], indigestion, diarrhea and nausea [ 36 , 48 ] in subjects consumed CLA. Most of these effects were considered as mild to moderate and were transient; and one may assume that these effects may be due to the capsule material or the oily nature of the substance or initial adaptive problem with the lipid nutrient.
Consumption of commercial CLA reduced the fat content in cows [ ]. Since milk is the only source of nutrients for infants, decreased milk fat in lactating humans is another concern regarding the CLA consumption. Masters et al. However, another two human studies found no changes in milk fat or protein [ , ], but in these studies, the intervention period was too short about a wk to arrive at a conclusive result.
General view on CLAs is that the 10 - CLA exerts specific effects on adipocytes and liver, whereas both the 9- and CLAs appear to be active in inhibiting carcinogenesis [ 14 ]. It is likely that the inconsistent and often contradictory results on the effectiveness of CLA consumption in human health could be the outcome of a number of factors, including differences in subject groups, age, quantity and duration of CLA intake, composition of CLA mixture, purity of CLA, acceptance of the CLA by the body, food intake, gender and racial differences, genetic polymorphism and also the executed measurements parameters studied for assessing the effect.
Moreover, crucial factors that impact research outcomes include the nature of control supplement placebo , and study design cross-over vs. Determination of a normal CLA content in the blood plasma could help in estimating if a person consumes satisfactory amounts of CLA with the diet, and thus takes advantage of its potential beneficial effects on health.
Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Conjugated linoleic acid CLA is a fatty acid often marketed as a weight loss aid.
Naturally found in dairy products and beef, CLA can be synthesized in the lab as a dietary supplement. Proponents claim that CLA can reduce fat, build muscle, and increase energy and endurance.
Others believe that CLA can enhance immune function while improving high cholesterol and blood pressure levels. Despite its popularity among some athletes, the evidence remains split on whether CLA can deliver on these promises.
Conjugated linoleic acid is found in a plethora of weight loss supplements, either on its own or co-formulated with other ingredients, such as caffeine or guarana. While the supplement is mainly used for weight loss , CLA is believed by some to have other health benefits. In the same year, another review published in Public Health Nutrition reported no difference between the body weight or composition of those who took CLA versus those who took a placebo.
What's more, a component of CLA supplements, known as trans,cis, was found to have a negative impact on blood sugar and could potentially contribute to the development of insulin resistance and atherosclerosis hardening of the arteries.
So conflicting is the research that scientists have a tough time even suggesting how CLA is meant to work. While CLA is believed to suppress appetite, few studies have shown this to have any effect on weight or body fat composition. Based on current evidence, a review published in Nutrition and Metabolism concluded that CLA offered no "promising or consistent health effects so as to uphold it as either a functional or medical food.
Beyond its use in weight loss, proponents of CLA supplementation believe that it can enhance athletic performance by stimulating testosterone production in the Leydig cells of the testicles.
While it is true that CLA has this effect, the level of stimulation rarely translates to increased energy expenditure. In fact, review in the Journal of the International Society of Sports Nutrition found inconclusive evidence on many claims made by proponents of CLA supplementation on athletes.
Other health benefits are also largely unsupported, including CLA's use in treating diabetes, the common cold, allergic rhinitis hay fever , or asthma.
Similarly, while an increased intake of CLA was once linked to a reduction in breast cancer risk, a review of studies was unable to show any association between CLA levels in breast tissue and the risk of cancer, metastasis, or death.
Where CLA may be beneficial is as adjunctive therapy for high blood pressure. When used with Altace ramipril , CLA was shown to achieve better control of hypertension compared to Altace alone, according to a study from China. Conjugated linoleic acid supplements are generally considered safe if taken as prescribed. CLA is mainly metabolized in the liver.
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