What Is Conjugated Linoleic Acid (CLA)?
Conjugated linoleic acid (CLA) is naturally in the milk and meat of grass-fed cows. Studies show CLA stimulates fat burning, decreases fat storage, and reduces body fat when taken in sufficient amounts.* Conjugated linoleic acid also significantly reduces the formation of inflammatory prostaglandins by inhibiting COX-2, much like other potent COX-2 inhibitors but without unwanted side effects.*
Benefits of Conjugated Linoleic Acid (CLA)
- Fights inflammation*
- Boosts immunity*
- Stimulates fat burning*
- Reduces fat storage*
What You Need to Know About Conjugated Linoleic Acid (CLA)
Conjugated linoleic acid (CLA) is an essential fatty acid, the kind you find in flax seed and other oils. CLA is in high quantities in grass-fed beef and full-fat dairy products.
Like any linolenic acid, CLA has double bonds, and when you subject them to chemical reactions, the double bonds are separated by a single bond. The molecule that results is known as a conjugated fatty acid.
There are probably a couple of dozen conjugated isomers, and the names indicate whether the atoms are on the same side (cis) or opposite side (trans) of a double bond. For example, the cis-9, trans-11 isomer and the cis-10, trans-12 isomer are considered the most biologically active CLA isomers.
According to research conducted at the University of Wisconsin, CLA completely leaned out fat mice. And there's strong evidence that it muscled up rats, mice, chickens, and pigs.
There are also promising human studies. Dr. Michael Pariza, one of the CLA pioneers, recruited 80 obese men and women. He gave half of the group 3 grams of CLA per day, and the other half received 3 grams of sunflower oil.
At the end of 6 months, all the subjects had lost about 5 pounds each, but a third of the subjects taking CLA increased muscle mass. Pariza theorized that CLA's "nutrient partitioning" effect was shunting fat to muscle.
Pariza, as quoted in the March 3, 2001 edition of "Science News," tried to explain the fat-loss phenomenon: "Every fat cell in the body wants to get big. What the cis-10, trans-12 CLA does is force that fat cell to stay little by affecting a number of enzymes that are ordinarily responsible for filling it with lipids."
A study in the Scandinavian Clinical Research Center in Norway engaged 60 overweight volunteers in a 3-month trial. Half of them got 9 grams of olive oil per day, while the other half received between 1.7 and 6.8 grams of the cis-10, trans-12 CLA per day.
Those who swallowed 3.4 grams or more of CLA per day lost 2 to 3 pounds more fat than the others. The group with the higher CLA intake didn't lose any additional fat but gained more muscle mass.
Although Pariza mentioned that CLA might have a "nutrient partitioning" effect, it doesn't give much insight into its plausible activity mechanisms. Theories abound: Perhaps CLA helps maintain a positive nitrogen balance; maybe it's a powerful antioxidant that prevents cell damage and leads to a net increase in growth; or perhaps CLA is an undiscovered growth factor.
Whatever the reason, it seems that CLA is still something to be reckoned with, especially when you look at some of its other alleged benefits.
A researcher named Martha Bleury, who's affiliated with Northwest Hospital in Seattle, reported another mind-blowing study. She gave Type II diabetes patients 6 grams of CLA or 6 grams of plain safflower oil. The CLA group showed a marked decrease in triglyceride levels and a significant drop in fasting blood sugar levels.
Although unsure how it works, she assumes that CLA binds to receptors that promote lower blood sugar.
Of course, in athletics, it's the getting-bigger thing that probably arouses the most interest. Although human studies are still lacking, you can't easily dismiss some of the animal studies. Earlier studies on rats show that those whose diets are supplemented with CLA gain weight much more quickly than control groups.
The authors theorized that all living creatures – at least mammals – are continually confronted by immune stimulation, so much so that it partitions energy away from other biological factors, including growth (Chin, et al, 1994). Reducing this response through CLA supplementation could enhance food efficiency and growth.
Researcher Mark Cook has conducted similar immune stimulation experiments in rats, mice, chicks, and pigs. CLA supplementation blocked physical wasting without reducing the animal's ability to fight disease.
Products Containing Conjugated Linoleic Acid (CLA)
Research on Conjugated Linoleic Acid (CLA)
- Dilzer A et al. Implication of conjugated linoleic acid (CLA) in human health. Crit Rev Food Sci Nutr. 2012;52(6):488-513. doi: 10.1080/10408398.2010.501409.
- Baraldi FG et al. The combination of conjugated linoleic acid (CLA) and extra virgin olive oil increases mitochondrial and body metabolism and prevents CLA-associated insulin resistance and liver hypertrophy in C57Bl/6 mice. J Nutr Biochem. 2016 Feb;28:147-54. doi: 10.1016/j.jnutbio.2015.10.008. Epub 2015 Nov 1.
- O'Shea M et al. Immunomodulatory properties of conjugated linoleic acid. Am J Clin Nutr. 2004 Jun;79(6 Suppl):1199S-1206S. doi: 10.1093/ajcn/79.6.1199S.
- de Educação Física FS et al. A review on effects of conjugated linoleic fatty acid (CLA) upon body composition and energetic metabolism. J Int Soc Sports Nutr. 2015; 12: 36. Published online 2015 Sep 17. doi: 10.1186/s12970-015-0097-4
- House RL et al. Conjugated linoleic acid evokes de-lipidation through the regulation of genes controlling lipid metabolism in adipose and liver tissue. Obes Rev. 2005 Aug;6(3):247-58. doi: 10.1111/j.1467-789X.2005.00198.x.
- Aro A et al. Inverse Association between Dietary and Serum Conjugated Linoleic Acid and Risk of Breast Cancer in Postmenopausal Women. Nutr Cancer. 2000;38(2):151-7.
- Belury M. Dietary conjugated linoleic acid in health: Physiological effects and mechanisms of action. Annu Rev Nutr. 2002;22:505-31.
- Bhattacharya A et al. Conjugated linoleic acid and chromium lower body weight and visceral fat mass in high-fat-diet-fed mice. Lipids. 2006 May;41(5):437-44.
- Bhattacharya A et al. The combination of dietary conjugated linoleic acid and treadmill exercise lowers gain in body fat mass and enhances lean body mass in high fat-fed male Balb/C mice. J Nutr. 2005 May;135(5):1124-30.
- Brown J et al. Isomer-specific regulation of metabolism and PPARgamma signaling by CLA in human preadipocytes. J Lipid Res. 2003 Jul;44(7):1287-300.
- Dhiman TR et al. Conjugated linoleic acid content of milk from cows fed different diets. J Dairy Sci. 1999;82(10):2146-56.
- Diaz ML et al. Chromium picolinate and conjugated linoleic acid do not synergistically influence diet- and exercise-induced changes in body composition and health indexes in overweight women. J Nutr Biochem. 2008 Jan;19(1):61-8.
- Esliger D et al.
The Effects of Conjugated Linoleic Acid Supplementation during Resistance Training.Med Sci Sports Exerc. 2006 Feb;38(2):339-48.
- Granlund L et al. Trans10, cis12-conjugated linoleic acid prevents triacylglycerol accumulation in adipocytes by acting as a PPARgamma modulator. J Lipid Res. 2003 Aug;44(8):1441-52.
- Ide T. Interaction of fish oil and conjugated linoleic acid in affecting hepatic activity of lipogenic enzymes and gene expression in liver and adipose tissue. Diabetes. 2005 Feb;54(2):412-23.
- Kreider RB 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 Aug;16(3):325-34.
- Lowery L et al. Conjugated linoleic acid enhances muscle size and strength gains in novice bodybuilders. Med Sci Sports Exerc. 1998;230(5):S182.
- Lowery L et al. Effects of conjugated linoleic acid on body composition and strength in novice male bodybuilders. International Conference on Weight Lifting and Strength Training Conference Book (Ed. Keijo Hakkinen): Nov. 10-12, 1998 Lahti, Finland pp. 241-242.
- Lowery L et al. Effects of Conjugated Linoleic Acid on the Physiologic Consequences of a Downhill Run. First International Conference on Conjugated Linoleic Acid. June 10-13, 2001; Aalesund, Norway.
- Macaluso F et al, Effect of conjugated linoleic acid on testosterone levels in vitro and in vivo after an acute bout of resistance exercise. J Strength Cond Res. 2012 Jun;26(6):1667-74.
- MacRedmond R et al. Conjugated linoleic acid improves airway hyper-reactivity in overweight mild asthmatics. Clin Exp Allergy. 2010 Jul;40(7):1071-8.
- Moloney F et al. Conjugated linoleic acid supplementation, insulin sensitivity, and lipoprotein metabolism in patients with type 2 diabetes mellitus. Am J Clin Nutr. 2004 Oct;80(4):887-95.
- Mougios V et al. Effect of supplementation with conjugated linoleic acid on human serum lipids and body fat. J Nutr Biochem. 2001;12(10):585-594.
- Pariza M et al. The biologically active isomers of conjugated linoleic acid. Prog Lipid Res. 2001 Jul;40(4):283-98.
- Ponnampalam EN et al. Effect of feeding systems on omega-3 fatty acids, conjugated linoleic acid and trans fatty acids in Australian beef cuts: potential impact on human health. Asia Pac J Clin Nutr. 2006;15(1):21-9.
- Pritchard J et al. Plasma adrenal, gonadal, and conjugated steroids before and after long-term overfeeding in identical twins. J Clin Endocrinol Metab. 1998 Sep;83(9):3277-3284.
- Risérus U et al. 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 Aug;25(8):1129-35.
- Turpeinen AM et al. Bioconversion of vaccenic acid to conjugated linoleic acid in humans. Am J Clin Nutr. 2002;76(3):504-510.
- Wang Y et al.
Conjugated linoleic acid and obesity control: efficacy and mechanisms.Int J Obes Relat Metab Disord. 2004 Aug;28(8):941-55.
- Watras AC et al. The role of conjugated linoleic acid in reducing body fat and preventing holiday weight gain. Int J Obes (Lond). 2007 Mar;31(3):481-7.