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Conjugated Linoleic Acid

Uses

What Are Star Ratings?

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.

2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

This supplement has been used in connection with the following health conditions:

Used for Why
2 Stars
Obesity
3.2 to 4.2 grams daily
Though the evidence is conflicting, some studies have shown CLA to be effective at helping people lose body fat.
A double-blind trial found that exercising individuals taking 1,800 mg per day of conjugated linoleic acid (CLA) lost more body fat after 12 weeks than did a similar group taking a placebo.1 However, two other studies found that amounts of CLA from 0.7 to 3.0 grams per day did not affect body composition.2 , 3 Most double-blind trials have found that larger amounts of CLA, 3.2 to 4.2 grams per day, do reduce body fat;4 , 5 , 6 , 7 however, one double-blind study of experienced strength-training athletes reported no effect of 6 grams per day of CLA on body fat, muscle mass, or strength improvement.8
1 Star
Athletic Performance
Refer to label instructions
Conjugated linoleic acid may play a role in reducing body fat. Research has reported that CLA supplementation produces minor gains in muscle size and strength in weight-training men.

Conjugated linoleic acid (CLA) is a slightly altered form of the essential fatty acid linoleic acid. Animal research suggests an effect of CLA supplementation on reducing body fat.9 , 10 Controlled human research has reported that 5.6 to 7.2 grams per day of CLA produces only non-significant gains in muscle size and strength in experienced and inexperienced weight-training men.11 , 12 , 13 A double-blind study of a group of trained men and women reported reduced body fat in the upper arm after 12 weeks of supplementation with 1.8 grams per day of CLA.14 Further research using more accurate techniques for measuring body composition is needed to confirm these findings.

1 Star
Breast Cancer
Refer to label instructions
Preliminary research suggests that CLA might reduce breast cancer risk.

Preliminary animal and test tube research suggests that CLA might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach.15 , 16 , 17 , 18 Whether CLA will have a similar protective effect for people has yet to be demonstrated in human research.

1 Star
Colon Cancer
Refer to label instructions
Preliminary and test tube studies indicate that CLA may reduce the risk of colon cancer.

Preliminary animal and test tube research suggests that CLA might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach.19 , 20 , 21 , 22 One preliminary study in humans suggests that increasing CLA intake may reduce the risk of colorectal cancer.23

1 Star
Lung Cancer
Refer to label instructions
Preliminary research suggests that CLA might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach.

Preliminary animal and test tube research suggests that conjugated linoleic acid might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach.24 , 25 , 26 , 27

1 Star
Multiple Sclerosis
Refer to label instructions
1 Star
Prostate Cancer
Refer to label instructions
Preliminary research suggests that CLA might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach.
Preliminary animal and test tube research suggests that conjugated linoleic acid might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach.28 , 29 , 30 , 31

How It Works

How to Use It

Most studies in humans have used 1.8 to 6 grams per day of CLA.

Where to Find It

CLA is found mainly in dairy products and also in beef and poultry, eggs, and corn oil. Bacteria that live in the intestine of humans can produce CLA from linoleic acid, but supplementation of a rich source of linoleic acid did not produce increases in blood levels of CLA in one human study.32 CLA is available as a supplement.

Possible Deficiencies

No deficiencies of CLA are reported or believed to occur, since it is not an essential nutrient.

Interactions

Interactions with Supplements, Foods, & Other Compounds

At the time of writing, there were no well-known supplement or food interactions with this supplement.

Interactions with Medicines

As of the last update, we found no reported interactions between this supplement and medicines. It is possible that unknown interactions exist. If you take medication, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.
The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Side Effects

Overweight volunteers who took 4.5 grams of CLA per day for one year had an increase in their blood levels of lipoprotein(a), a risk factor for heart disease.33 In a double-blind study of human volunteers, supplementation with 4.2 grams per day of a mixture of cis-9,trans-11 CLA and trans-10,cis-12 CLA for three months increased the concentration of C-reactive protein, another risk factor for heart disease.34 In a study of healthy volunteers, supplementing with 4.5 grams of CLA per day for 12 weeks caused an impairment of blood vessel function (endothelial dysfunction), which is believed to be associated with an increased risk of heart disease.35 Taken together, these findings suggest that long-term use of CLA could increase the risk of developing heart disease.

In a double-blind study of people with type 2 diabetes, supplementing with 3 grams of CLA per day for eight weeks significantly increased blood glucose levels by 6.3% and decreased insulin sensitivity.36 A reduction in insulin sensitivity was also seen in a study of overweight men without diabetes after treatment with 3 grams of CLA per day for three months.37 However, in another study of obese men and women, supplementation with 6 grams of CLA per day for 24 weeks had no significant effect on blood glucose levels or insulin sensitivity.38 Moreover, in a study of young sedentary men, 4 grams of CLA per day for eight weeks improved insulin sensitivity.39 Although the studies are conflicting, it would be prudent for people who have, or are at risk of developing, diabetes to monitor their blood sugar levels during long-term use of CLA. One unpublished human trial reported isolated cases of gastrointestinal upset.40

References

1. Thom E, Wadstein J, Gudmundsen O. Conjugated linoleic acid reduces body fat in healthy exercising humans. J Int Med Res 2001;29:392–6.

2. Mougios V, Matsakas A, Petridou A, et al. Effect of supplementation with conjugated linoleic acid on human serum lipids and body fat. J Nutr Biochem 2001;12:585–94.

3. Zambell KL, Keim NL, Van Loan MD, et al. Conjugated linoleic acid supplementation in humans: effects on body composition and energy expenditure. Lipids 2000;35:777–82.

4. Riserus U, Berglund L, Vessby B. Conjugated linoleic acid (CLA) reduced abdominal adipose tissue in obese middle-aged men with signs of the metabolic syndrome: a randomised controlled trial. Int J Obes Relat Metab Disord 2001;25:1129–35.

5. Smedman A, Vessby B. Conjugated linoleic acid supplementation in humans–metabolic effects. Lipids 2001;36:773-81.

6. Blankson H, Stakkestad JA, Fagertun H, et al. Conjugated linoleic acid reduces body fat mass in overweight and obese humans. J Nutr 2000;130:2943–8.

7. Whigham LD, Watras AC, Schoeller DA. Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr 2007;85:1203–11.

8. Kreider RB, Ferreira MP, Greenwood M, et al. Effects of conjugated linoleic acid supplementation during resistance training on body composition, bone density, strength, and selected hematological markers. J Strength Cond Res 2002;16:325–34.

9. West DB, Delany JP, Camet PM, et al. Effects of conjugated linoleic acid on body fat and energy metabolism in the mouse. Am J Physiol 1998;275:R667–72.

10. Park Y, Albright KJ, Liu W, et al. Effect of conjugated linoleic acid on body composition in mice. Lipids 1997;32:853–8.

11. Ferreira M, Krieder R, Wilson M. Effects of CLA supplementation during resistance training on body composition and strength. J Strength Conditioning Res 1998;11:280.

12. Kreider RB, Ferreira MP, Greenwood M, et al. Effects of conjugated linoleic acid supplementation during resistance training on body composition, bone density, strength, and selected hematological markers. J Strength Cond Res 2002;16:325-34.

13. Lowery LM, Appicelli PA, Lemon PWR. Conjugated linoleic acid enhances muscle size and strength gains in novice bodybuilders. Med Sci Sport Excer 1998;30:S182 [abstract]

14. Thom E, Wadstein J, Gudmundsen O. Conjugated linoleic acid reduces body fat in healthy exercising humans.J Int Med Res 2001;29:392–6.

15. Cesano A, Visonneau S, Scimeca JA, et al. Opposite effects of linoleic acid and conjugated linoleic acid on human prostatic cancer in SCID mice. Anticancer Res 1998;18:1429-34.

16. Thompson H, Zhu Z, Banni S, et al. Morphological and biochemical status of the mammary gland as influenced by conjugated linoleic acid: implication for a reduction in mammary cancer risk. Cancer Res 1997;57:5067-72.

17. Ip C. Review of the effects of trans fatty acids, oleic acid, n-3 polyunsaturated fatty acids, and conjugated linoleic acid on mammary carcinogenesis in animals. Am J Clin Nutr 1997;66(suppl):1523S-29S [review].

18. Parodi PW. Cows’ milk fat components as potential anticarcinogenic agents. J Nutr 1997;127:1055-60 [review].

19. Cesano A, Visonneau S, Scimeca JA, et al. Opposite effects of linoleic acid and conjugated linoleic acid on human prostatic cancer in SCID mice. Anticancer Res 1998;18:1429-34.

20. Thompson H, Zhu Z, Banni S, et al. Morphological and biochemical status of the mammary gland as influenced by conjugated linoleic acid: implication for a reduction in mammary cancer risk. Cancer Res 1997;57:5067-72.

21. Ip C. Review of the effects of trans fatty acids, oleic acid, n-3 polyunsaturated fatty acids, and conjugated linoleic acid on mammary carcinogenesis in animals. Am J Clin Nutr 1997;66(suppl):1523S-29S [review].

22. Parodi PW. Cows’ milk fat components as potential anticarcinogenic agents. J Nutr 1997;127:1055-60 [review].

23. Larsson SC, Bergkvist L, Wolk A. High-fat dairy food and conjugated linoleic acid intakes in relation to colorectal cancer incidence in the Swedish Mammography Cohort. Am J Clin Nutr 2005;82:894–900.

24. Cesano A, Visonneau S, Scimeca JA, et al. Opposite effects of linoleic acid and conjugated linoleic acid on human prostatic cancer in SCID mice. Anticancer Res 1998;18:1429-34.

25. Thompson H, Zhu Z, Banni S, et al. Morphological and biochemical status of the mammary gland as influenced by conjugated linoleic acid: implication for a reduction in mammary cancer risk. Cancer Res 1997;57:5067-72.

26. Ip C. Review of the effects of trans fatty acids, oleic acid, n-3 polyunsaturated fatty acids, and conjugated linoleic acid on mammary carcinogenesis in animals. Am J Clin Nutr 1997;66(suppl):1523S-29S [review].

27. Parodi PW. Cows’ milk fat components as potential anticarcinogenic agents. J Nutr 1997;127:1055-60 [review].

28. Cesano A, Visonneau S, Scimeca JA, et al. Opposite effects of linoleic acid and conjugated linoleic acid on human prostatic cancer in SCID mice. Anticancer Res 1998;18:1429-34.

29. Thompson H, Zhu Z, Banni S, et al. Morphological and biochemical status of the mammary gland as influenced by conjugated linoleic acid: implication for a reduction in mammary cancer risk. Cancer Res 1997;57:5067-72.

30. Ip C. Review of the effects of trans fatty acids, oleic acid, n-3 polyunsaturated fatty acids, and conjugated linoleic acid on mammary carcinogenesis in animals. Am J Clin Nutr 1997;66(suppl):1523S-29S [review].

31. Parodi PW. Cows’ milk fat components as potential anticarcinogenic agents. J Nutr 1997;127:1055-60 [review].

32. Herbel BK, McGuire MK, McGuire MA, et al. Safflower oil consumption does not increase plasma conjugated linoleic acid concentrations in humans. Am J Clin Nutr 1998;67:332–7.

33. Gaullier JM, Halse J, Hoye K, et al. Conjugated linoleic acid supplementation for 1 y reduces body fat mass in healthy overweight humans. Am J Clin Nutr 2004;79:1118–25.

34. Smedman A, Basu S, Jovinge S, Fredrikson GN, Vessby B. Conjugated linoleic acid increased C-reactive protein in human subjects. Br J Nutr 2005;94:791–5.

35. Taylor JS, Williams SR, Rhys R, et al. Conjugated linoleic acid impairs endothelial function. Arterioscler Thromb Vasc Biol2006;26:307–12.

36. Moloney F, Yeow TP, Mullen A, et al. Conjugated linoleic acid supplementation, insulin sensitivity, and lipoprotein metabolism in patients with type 2 diabetes mellitus. Am J Clin Nutr 2004;80:887-95.

37. Riserus U, Vessby B, Arnlov J, Basu S. Effects of cis-9,trans-11 conjugated linoleic acid supplementation on insulin sensitivity, lipid peroxidation, and proinflammatory markers in obese men. Am J Clin Nutr 2004;80:279–83.

38. Whigham LD, O'Shea M, Mohede IC, et al. Safety profile of conjugated linoleic acid in a 12-month trial in obese humans. Food Chem Toxicol 2004 Oct;42(10):1701–9.

39. Eyjolfson V, Spriet LL, Dyck DJ. Conjugated linoleic acid improves insulin sensitivity in young, sedentary humans. Med Sci Sports Exerc 2004;36:814–20.

40. Thom E. A pilot study with the aim of studying the efficacy and tolerability of Tonalin CLA on the body composition in humans. Lillestrom, Norway: Medstat Research Ltd., July 1997 [unpublished].

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