Conjugated Linoleic Acid
Uses
Conjugated linoleic acid (CLA) is a slightly altered form of the essential fatty acid linoleic acid.
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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 StarsReliable and relatively consistent scientific data showing a substantial health benefit.
2 StarsContradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 StarFor 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 1.7–8 grams daily | Although the evidence is conflicting, the majority of the evidence shows CLA can help people lose body fat, and may promote a small amount of weight loss. Conjugated linoleic acid (CLA) is a group of polyunsaturated fatty acids found mainly in dairy products. In numerous randomized controlled trials lasting from 12 weeks to two years, CLA supplementation has been found to reduce body fat in people with overweight and obesity. Although some trials have reported weight loss attributable to CLA, others have found no effect of CLA on body weight. A meta-analysis of seven placebo-controlled trials lasting six months or longer concluded CLA use is associated with small increases in weight loss and fat loss. One trial evaluated the effect of CLA on weight and fat regain in 101 participants with overweight or obesity who had lost 8% or more body weight: after one year, those taking 3.4 grams of CLA per day had regained the same amount of weight and fat as those taking placebo (olive oil). Importantly, conflicting evidence has emerged regarding the impact of CLA on oxidative stress and insulin resistance. Therefore, the use of CLA by people with type 2 diabetes or signs of insulin resistance should be carefully monitored. |
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. (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. 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. 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. 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. 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. One preliminary study in humans suggests that increasing CLA intake may reduce the risk of colorectal cancer. |
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 might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach. |
1 Star Multiple Sclerosis Refer to label instructions | Omega-6 fatty acids found in sunflower seed oil (a source of linoleic acid) may be beneficial. Studies have reported that linoleic acid reduced relapse severity and length and decreased disability due to MS. Omega-6 fatty acids found in sunflower seed oil (a source of linoleic acid) may be beneficial. Studies have reported that linoleic acid reduced relapse severity and length and decreased disability due to MS. |
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 might reduce the risk of cancers at several sites, including breast, prostate, colorectal, lung, skin, and stomach. |
How It Works
How to Use It
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.1 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
Interactions with Medicines
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.2 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.3 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.4 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.5 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.6 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.7 Moreover, in a study of young sedentary men, 4 grams of CLA per day for eight weeks improved insulin sensitivity.8 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.9
References
1. 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.
2. 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.
3. 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.
4. Taylor JS, Williams SR, Rhys R, et al. Conjugated linoleic acid impairs endothelial function. Arterioscler Thromb Vasc Biol2006;26:307-12.
5. 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.
6. 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.
7. 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.
8. Eyjolfson V, Spriet LL, Dyck DJ. Conjugated linoleic acid improves insulin sensitivity in young, sedentary humans. Med Sci Sports Exerc 2004;36:814-20.
9. 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].
Last Review: 06-01-2015
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