Conjugated Linoleic Acid

Uses

Conjugated linoleic acid (CLA) is a slightly altered form of the essential fatty acid linoleic acid.

What Are Star Ratings?

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

Used forWhy
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

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.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

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.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].

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