CLA supplement benefit, risk, side effects and research study information, review
January 1 2017 by Ray Sahelian, M.D. Is this an effective weight loss pill?

Conjugated linoleic acid is a slightly altered form of the essential fatty acid linoleic acid. It is an unsaturated fatty acid found in beef, lamb and dairy products; the CLA in supplements is generally derived from vegetable oils that are rich in linoleic acids.

CLA for weight loss, does it work?
Some studies, mostly in rodents, have shown that CLA may reduce weight but others have shown conflicting results. It's possible that it could be effective as a weight loss supplement but I'm not yet totally convinced of its benefits or safety. Overall, there does not seem to be convincing evidence that it is clearly helpful as a weight loss supplement. However some people do like to use it. I personally think Diet Rx, which has a combination of hoodia extract, green tea extract, ginger, cinnamon, garcinia cambogia, choline, carnitine, 5-HTP, guggul, acetylcarnitine, and several other herbs and nutrients is a better option for  appetite suppression than CLA alone.

Buy CLA supplement, 750 mg per pill, 50 softgels
Conjugated linoleic acid is a recently recognized supplement. CLA is found naturally in a variety of foods, including dairy. This product offers a rich source of conjugated linoleic acid to supplement the diet naturally.

Each capsule provides 750 mg CLA supplement.
Directions, dosage: Take 1, 2 or 3  softgels daily or as recommended by your health care provider. These pills can be taken together the same day as Diet Rx.

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Buy CLA supplement or Diet Rx for appetite suppression
Supplement Facts
Serving Size: 1 Softgel
Servings Per Bottle: 60 Softgels
  Amount Per Capsule % DV
Calories 10  
Total Fat 1 g 2%
Calories from Fat 10  
Polyunsaturated Fat 1 g *
Conjugated Linoleic Acid (from Safflower Oil) Contains 80% Conjugated Linoleic Acid (CLA) 800 mg 1000 mg
† Daily Value or Recommended Daily Intake not established.

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CLA is a family of positional and geometric isomers with 2 conjugated double bonds formed from linoleic acid and linolenic acid. Most dietary CLA in humans is obtained from dairy products, accounting for the cis-9,trans-11 CLA isomer, also known as rumenic acid, for more than 90% of the total CLA intake. Commercial CLA supplements industrially produced, contain trans-10,cis-12 and cis-9,trans-11 CLA isomers in diverse proportions. Different companies making these products may have slightly or moderately different fatty acid compositions.

Review article
Crit Rev Food Sci Nutr. 2017. Systematic evaluation on the effectiveness of conjugated linoleic acid in human health.F The term CLA (conjugated linoleic acid) corresponds to a mixture of positional and geometric isomers of linoleic acid. Two of these isomers (9c, 11t and 10t, 12c) have biological activity. The milk and dairy products are the most abundant source of conjugated linoleic acid. The following research aims to approach aspects regarding the CLA, as well as its relationship with diseases. Conjugated linoleic acids have been studied for their beneficial effects in the prevention and treatment of many diseases, including obesity, cancer, diabetes, and cardiovascular diseases. Scientific information put together the physiological properties of CLA, which serves as inputs to claim their potential as functional ingredients to be used in the prevention and control of several chronic metabolic disorders.

Cancer protection? Tumor reduction?
Integr Cancer Ther. 2013. Effect of conjugated linoleic acid supplementation on inflammatory factors and matrix metalloproteinase enzymes in rectal cancer patients undergoing chemoradiotherapy. The aims of this study were to determine the effect of conjugated linoleic acid (CLA) supplementation on inflammatory factors and matrix metalloproteinase (MMP) enzymes in rectal cancer patients undergoing chemoradiothetrapy. In this randomized, double-blind, placebo-controlled pilot study, 34 volunteer patients with rectal cancer undergoing chemoradiotherapy assigned into the CLA group, receiving 3 g CLA/d, and placebo group receiving placebo capsules (sunflower oil) for 6 weeks. The supplementation began 1 week before starting RT (loading period) and continued every day during treatment. Before and after intervention, serum tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), IL-6, MMP-2, MMP-9, and high-sensitivity C-reactive protein (hsCRP) were measured by enzyme-linked immunosorbent assay (ELISA) kits and immunoturbidimetric method, respectively. Independent t tests and paired t tests were used to compare parameters between and within groups, respectively. In the CLA group, the mean serum TNF-α, IL-1β, hsCRP, MMP-9, and MMP-2 levels reduced insignificantly. However, significant changes in TNF-α, hsCRP, and MMP-9 concentrations were observed in the CLA group when compared with the placebo group. The mean serum IL-6 level remained unchanged in the CLA group but increased remarkably in the placebo group. According to our results, CLA supplementation improved inflammatory factors, MMP-2, and MMP-9 as biomarkers of angiogenesis and tumor invasion. It seems that CLA may provide new complementary treatment by reducing tumor invasion and resistance to cancer treatment in patients with rectal cancer.

Breast cancer

Studies in animals and in vitro suggest that conjugated linoleic acids, a group of fatty acids found mainly in dairy products and in the meat of ruminants, have protective effects against mammary carcinogenesis. However, findings from epidemiologic studies on CLA intake in relation to breast cancer risk are sparse and inconsistent. In 1987–1990, 61,433 cancer-free women completed a food-frequency questionnaire from which it was estimated each woman's CLA intake. The results provide no evidence of a protective effect of CLA against breast cancer development in women. Am J Clin Nutr June 2, 2009.

An 2004 study showed that CLA had beneficial effects on cholesterol metabolism, it had unfavorable effects on blood sugar and insulin sensitivity. Dairy products naturally enriched with cis-9,trans-11 CLA and trans-11 18:1 do not appear to have a significant effect on blood lipid profile. There are several good options for cholesterol management.

Conjugated linoleic acid supplementation, insulin sensitivity, and lipoprotein metabolism in patients with type 2 diabetes mellitus.
American Journal of Clinical Nutrition 2004
Some animal studies have suggested that conjugated linoleic acid CLA supplementation may have therapeutic potential with respect to insulin sensitivity and lipid metabolism, which are important cardiovascular disease (CVD) risk factors associated with type 2 diabetes mellitus. We investigated the effect of CLA supplementation on markers of glucose and insulin metabolism, lipoprotein metabolism, and inflammatory markers of CVD in subjects with type 2 diabetes. The study was a randomized, double-blind, placebo-controlled trial. Thirty-two subjects with stable, diet-controlled type 2 diabetes received CLA (3.0 g/d; 50:50 blend of cis-9,trans-11 CLA and trans-10,cis-12 CLA) or control for 8 wk. A 3-h 75-g oral-glucose-tolerance test was performed, and fasting plasma lipid concentrations and inflammatory markers were measured before and after the intervention. CLA supplementation significantly increased fasting glucose concentrations and reduced insulin sensitivity. Total HDL-cholesterol concentrations increased by 8%, which was due to a significant increase in HDL2-cholesterol concentrations. The ratio of LDL to HDL cholesterol was significantly reduced. CLA supplementation reduced fibrinogen concentrations but had no effect on the inflammatory markers of CVD (C-reactive protein and interleukin 6). CLA supplementation had an adverse effect on insulin and glucose metabolism. Whereas CLA had positive effects on HDL metabolism and fibrinogen, a therapeutic nutrient should not be associated with potentially adverse effects on other clinical markers of type 2 diabetes.

Weight loss
J Am Coll Nutr. 2011. CLA does not impair endothelial function and decreases body weight as compared with safflower oil in overweight and obese male subjects. Conjugated linoleic acid (CLA) showed a wide range of beneficial biological effects with relevance for cardiovascular health in animal models and humans.

Weight loss 2007 study
Data from 18 previous studies were analyzed. It was found that, when given at a dose of 3 grams per day, CLA appeared moderately effective at promoting body fat loss. People who took a CLA supplement lost a modest amount of 0.2 pounds of fat per week compared to placebo. Dr. Leah D. Whigham, of the University of Wisconsin at Madison, found the body-fat benefits of CLA accrued for 6 months, then gradually faded. It is not clear how CLA works, but it may affect enzymes responsible for body fat storage. There have been some concerns raised about the side effects of consuming CLA. Some studies, for instance, have suggested that the fat may promote insulin resistance, a precursor to diabetes. But other studies have either failed to show this effect, or found that CLA improves the body's use of insulin. American Journal of Clinical Nutrition, 2007.
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CLA and weight loss study
A 2004 human study showed that a year treatment with CLA reduces body fat in overweight adults. A 2006 study in humans indicated a CLA supplement did not prevent weight gain. Therefore, at this time, it is premature to claim that it is an effective weight loss supplement.

Conjugated linoleic acid supplementation for 1 y does not prevent weight or body fat regain
American Journal of Clinical Nutrition, 2006
Conjugated linoleic acid is marketed as a safe, simple, and effective dietary supplement to promote the loss of body fat and weight. However, most previous studies have been of short duration and inconclusive, and some recent studies have questioned the safety of long-term supplementation with CLA. Our aim was to assess the effect of 1 year supplementation with CLA (3.4 grams per day) on body weight and body fat regain in moderately obese people. One hundred twenty-two obese healthy subjects with a body mass index (in kg/m2) > 28 underwent an 8-wk dietary run-in with energy restriction (3300–4200 kJ/d). One hundred one subjects who lost >8% of their initial body weight were subsequently randomly assigned to a 1-y double-blind CLA (3.4 g/d) or placebo (olive oil) supplementation regime in combination with a modest hypocaloric diet . After 1 year, no significant difference in body weight or body fat regain was observed between the treatments. The CLA group regained a mean 4.0 kg body weight and 2 kg fat mass compared with a regain of 4 kg body weight and 2.7 kg fat mass in the placebo group. No significant differences in reported adverse effects or indexes of insulin resistance were observed, but a significant increase in the number of leukocytes was observed with CLA supplementation. A 3.4-g daily supplementation for 1 year does not prevent weight or fat mass regain in a healthy obese population.

Lack of effect of dietary conjugated linoleic acids naturally incorporated into butter on the lipid profile and body composition of overweight and obese men
American Journal of Clinical Nutrition 2005
The researchers compared the effects on plasma lipoproteins and body composition of the consumption of a modified butter naturally enriched with CLA (CLA-B: 4.22 g CLA/100 g butter fat) by the addition of sunflower oil to the diet of dairy cows with the consumption of a control butter (CON-B) that was low in CLA (0.38 g CLA/100 g butter fat). The study was a crossover design study including an 8-wk washout period, 16 men were fed each of the 2 experimental isoenergetic diets, providing 15% of energy as protein, 45% as carbohydrates, and 40% as lipids, of which >60% was derived from experimental fats, for 4 wk. Consumption of the CLA-B diet induced a significantly smaller reduction in plasma total cholesterol and in the ratio of total to HDL cholesterol than did consumption of the CON-B diet. Abdominal adipose tissue area showed no difference in accumulation of either visceral or subcutaneous adipose tissue after the 2 experimental diets. These results suggest that a 10-fold CLA enrichment of butter fat does not induce beneficial metabolic effects in overweight or obese men.

Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans
American Journal of Clinical Nutrition 2004
The objective of the study was to ascertain the 1-y effect of CLA on body composition and safety in healthy overweight adults consuming an ad libitum diet. Design: Male and female volunteers (n = 180) with body mass indexes (in kg/m2) of 25–30 were included in a double-blind, placebo-controlled study. Subjects were randomly assigned to 3 groups: CLA free fatty acid (FFA), CLA triacylglycerol, or placebo (olive oil). Change in BFM, as measured by dual-energy X-ray absorptiometry, was the primary outcome. Secondary outcomes included the effects of CLA on LBM, adverse events, and safety variables. Subjects receiving CLA FFA had 1.8 ± 4.3% greater LBM than did subjects receiving placebo. These changes were not associated with diet or exercise. LDL increased in the CLA FFA group, HDL decreased in the CLA triacylglycerol group, and lipoprotein(a) increased in both CLA groups  compared with month 0. Fasting blood glucose concentrations remained unchanged in all 3 groups. Glycated hemoglobin rose in all groups from month 0 concentrations, but there was no significant difference between groups. Adverse events did not differ significantly between groups. Long-term supplementation with CLA FFA or CLA triacylglycerol reduces BFM in healthy overweight adults.

Weight loss in children, safety and risks
Overweight and obese children who took the CLA supplement for seven months showed less fat accumulation than a comparison group of children given a placebo. However, children on the supplement also showed a dip in their blood levels of "good" HDL cholesterol and a lesser gain in bone mass over time. Natalie M. Racine of the University of Wisconsin-Madison says that while CLA might help slow body fat gain, its overall safety and effectiveness for children needs to be studied further. The CLA supplement, marketed as Clarinol, was provided by Netherlands-based manufacturer Lipid Nutrition BV, which also partially funded the study. American Journal of Clinical Nutrition, online March 3, 2010.

The effect of conjugated linoleic acid CLA supplementation after weight loss on body weight regain, body composition, and resting metabolic rate in overweight subjects.
 Int J Obes Relat Metab Disord. 2003.
To study the effects of 13 weeks conjugated linoleic acid CLA supplementation in overweight subjects after weight loss on weight regain, body composition, resting metabolic rate, substrate oxidation, and blood plasma parameters. Subjects either received 1.8 g CLA or placebo per day (low dosage, LD) or 3.6 g CLA or placebo per day (high dosage, HD).  Multiple regression analysis showed that at the end of the 13-week intervention, CLA did not affect % body weight regain. In conclusion, the regain of fat-free mass was favorably, dose-independently affected by a 13-week consumption of 1.8 or 3.6 g CLA per day and consequently increased the resting metabolic rate. However, it did not result in improved body weight maintenance after weight loss.

Effect of conjugated linoleic acid on body composition and plasma lipids in humans: an overview of the literature.
Antonius HM, Utrecht University, Utrecht, Netherlands.
Studies in mice have indicated that feeding diets containing 0.5-1% conjugated linoleic acid considerably reduces body fat. These findings have attracted much interest because of the potential use of CLA as a tool to promote weight loss in humans. Several CLA studies in humans have now been published, and the objective of the present review was to give an overview of these experiments. Most of the studies were done in free-living subjects and were not strictly controlled for nutrient and energy intakes. None of the studies found a significant reduction in body weight, and only 2 studies showed a significant but relatively small body fat-lowering effect. Some studies suggested that CLA may have a tendency to increase lean body mass. Furthermore, there are indications from animal studies that CLA may have effects on plasma lipids. However, only one study in humans showed a significant HDL-cholesterol-lowering effect of CLA; in all the other studies, there were no significant effects on plasma total, LDL-, and HDL-cholesterol concentrations or on plasma triacylglycerol concentrations. Thus, the results of the studies in humans indicate that the effect of CLA on body fat is considerably less than that anticipated from mice studies and that CLA has no major effect on plasma lipids.

Supplementation with conjugated linoleic acid causes isomer-dependent oxidative stress and elevated C-reactive protein: a potential link to fatty acid-induced insulin resistance.
Riserus U, Basu S, Circulation 2002
Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Uppsala, Sweden.
Recently, we reported that the t10c12 CLA-isomer caused insulin resistance in abdominally obese men via unknown mechanisms. The aim of the present study was to examine whether CLA has isomer-specific effects on oxidative stress or inflammatory biomarkers and to investigate the relationship between these factors and induced insulin resistance. In a double-blind placebo-controlled trial, 60 men with metabolic syndrome were randomized to one of 3 groups receiving t10c12 CLA, a CLA mixture, or placebo for 12 weeks. Insulin sensitivity, serum lipids, in vivo lipid peroxidation, plasma vitamin E, plasma C-reactive protein, tumor necrosis factor-alpha, and interleukin-6 were assessed before and after treatment. Supplementation with t10c12 CLA markedly increased 8-iso-PGF(2alpha) and C-reactive protein compared with placebo and independent of changes in hyperglycemia or dyslipidemia. t10c12 CLA supplementation increases oxidative stress and inflammatory biomarkers in obese men. The oxidative stress seems closely related to induced insulin resistance, suggesting a link between the fatty acid-induced lipid peroxidation seen in the present study and insulin resistance. These unfavorable effects of t10c12 CLA might be of clinical importance with regard to cardiovascular disease, in consideration of the widespread use of dietary supplements containing this fatty acid.

Conjugated linoleic acid supplementation in humans--metabolic effects.
Smedman A, Vessby B. Lipids 2001
Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Sweden
Supplementation with conjugated linoleic acid CLA induces a number of physiological effects in experimental animals, including reduced body fat content, decreased aortic lipid deposition, and improved serum lipid profile. Controlled trials on the effects of CLA in humans have hitherto been scarce. The aim of this study was to evaluate the effects of supplementation with CLA in healthy humans on anthropometric and metabolic variables and on the fatty acid composition of serum lipids and thrombocytes. Fifty-three healthy men and women, aged 23-63 yr, were randomly assigned to supplementation with CLA (4.2 g/d) or the same amount of olive oil during 12 wk in a double-blind fashion. The proportion of body fat decreased (-3.8%) in the CLA-treated group, with a significant difference from the control group. Body weight, body mass index, and sagittal abdominal diameter were unchanged. There were no major differences between the groups in serum lipoproteins, nonesterified fatty acids, plasma insulin, blood glucose, or plasminogen activator inhibitor 1. In the CLA group the proportions of stearic, docosatetraenoic, and docosapentaenoic acids increased in serum lipids and thrombocytes, while proportions of palmitic, oleic, and dihomo-gamma-linolenic acids decreased, causing a decrease of the estimated delta-6 and delta-9 and an increase in the delta-5 desaturase activities. These results suggest that supplementation with CLA may reduce the proportion of body fat in humans and that CLA affects fatty acid metabolism.

Inconsistent results
Human studies are evenly split between finding CLA helpful and showing no effect. A study of 180 overweight adults gave some CLA supplements and others placebos. All of the participants were free to eat and exercise as they chose. After one year, people who had been taking CLA supplements lost an average of two to four pounds of body fat, while those receiving placebos lost nothing. The supplements even appeared to boost lean muscle mass among some of the adults. The exercise level between the two groups failed to explain the small changes in body composition. CLA may interrupt several different stages of cancer development. Studies show that CLA can affect the metabolism of carcinogens, protect DNA, slow the growth of cancer cells, promote their destruction, and possibly block the spread of established tumors. In humans, some observational evidence links CLA with breast cancer protection. But controlled studies that could justify a stronger conclusion have only been done in animals. These studies have also produced inconsistent results.

More human studies needed
CLA could improve a person’s immunity. But there are two other areas of possible concern. First, although animal studies show that CLA helps insulin work more effectively, other studies suggest insulin resistance and blood sugar control may be worsened. Second, in some animal studies, CLA seems to decrease fat buildup in blood vessels, but other animal and human studies suggest cholesterol levels and other aspects of heart health become worse. Most researchers say it is too soon to recommend CLA supplements. More human studies must verify the benefits, as well as the risks. The best chemical forms and dose amounts must also be determined. Our normal eating habits provide less than one gram of CLA per day, but studies use doses of three to four grams. Some people have advocated eating higher-fat dairy products to get more CLA. However, CLA is less than one percent of the fat content of these foods. Saturated fat will add up faster than the CLA in these foods. The best plan may be to wait. One recent review of CLA and its anti-cancer effects notes that CLA can accumulate in the body. Studies may now find out whether small amounts of CLA from limited servings of reduced-fat dairy products might add up over time to offer enough cancer and health protection.

Q. Why not eat more foods that have CLA rather than taking a supplement?
A liter of full-fat milk contains about 1 gram. This is not practical in terms of weight loss.

Q. Would taking a CLA supplement along with hoodia help with weight loss more effectively?
   A. It's hard to say, but the combination could work.

I having been reading articles on Tonalin CLA supplement. My question is can it be taken while taking Promise Activ (which is supposed to reduce cholesterol)? Also if you have had a mild heart attack should it be safe to use Tonalin CLA?
   Formerly known as Take Control, Promise Activ contains natural plant sterols. As with any supplement use or combinations, we prefer your health care provider make the decision whether in your particular case Tonalin CLA is appropriate for you alone or in combination with Promise Activ. Tonalin CLA most likely does not appear to have a significant effect on heart and cardiovascular tissues, but more research is needed.

A diet rich in conjugated linoleic acid and butter increases lipid peroxidation but does not affect atherosclerotic, inflammatory, or diabetic risk markers in healthy young men.
J Nutr. 2008. Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, Copenhagen, Denmark.
Intake of conjugated linoleic acid CLA has been demonstrated to beneficially affect risk markers of atherosclerosis and diabetes in rats. CLA is naturally found in milk fat, especially from cows fed a diet high in oleic acid, and increased CLA intake can occur concomitantly with increased milk fat intake. Our objective was to investigate the effect of CLA as part of a diet rich in butter as a source of milk fat on risk markers of atherosclerosis, inflammation, diabetes type II, and lipid peroxidation. A total of 38 healthy young men were given a diet with 115 g/d of CLA-rich fat (5.5 g/d CLA oil, a mixture of 39% cis9, trans11 and 38% trans10, cis12) or of control fat with a low content of CLA in a 5-wk double-blind, randomized, parallel intervention study. The fatty acid composition of plasma triacylglycerol, cholesterol esters, and phospholipids reflected that of the intervention diets. The CLA diet resulted in increased lipid peroxidation compared with the control. We observed no other significant differences in the effect of the interventions diets. In conclusion, when given as part of a diet rich in butter, a mixture of CLA isomers increased lipid peroxidation but did not affect risk markers of cardiovascular disease, inflammation, or fasting insulin and glucose concentrations.

I have been reading up on CLA for fat loss and am contemplating trying it. I read on your website that it is a fatty acid. I currently take fish oil capsules and wonder if I take CLA is this too much fatty acids at the same time? Should I suspend the fish oil for a while? PS Love your website. It is very informative and helpful.
    Different people have different responses to supplements and much depends on one's diet, activity level, other supplements used, etc. There is no simple answer that would apply to everyone.

I was trashed by Cymbalta prescribed off-label for ADD. I gained 35 pounds in 10 months on the drug. And my metabolism is still messed up even off the drug. I’ve read some psycho-pharm recovery info online about using CLA and Omega-3 to facilitate weight loss and metabolic recovery. But other opinions are mixed.