Product Reviews
CLA (Conjugated Linoleic Acid) Supplements Review (for Slimming)

Initial Posting: 6/27/14 Updated: 9/2/2015 CLA Supplements Reviewed by

Sections: Jump to a section by clicking on its name. What It Is:
CLA (conjugated linoleic acid) is a polyunsaturated fatty acid found naturally in milk and meat and produced from safflower and sunflower oils. There are various forms or isomers of CLA that may perform different functions. The cis-9, trans-11 isomer (also written as c9, t11) is the predominant type found in milk and meats. Supplements are typically made from safflower or sunflower oil and have an equal mixture of cis-9, trans-11 isomer and the trans-10, cis-12 isomer (also known as t10, c12).

What It Does:
CLA has been shown to help with slimming by increasing the ratio of muscle to fat, that is, increasing lean body mass. It has not been conclusively shown to reduce overall weight (see Review of Weight Loss Supplements for weight loss products), however, one study of 80 overweight and obese people in China found that 1.7 grams twice daily of CLA for twelve weeks reduced body fat by 2% and body weight by 0.9% (Chen, Nutrition 2012). In this study, serum total cholesterol levels increased by 3.7%, LDL ("bad") cholesterol increased by 3.4%, triglycerides increased by 17% and HDL ("good") cholesterol decreased by 1.4%, although none of these changes was statistically significant. Other studies have found that CLA may lower cholesterol levels but also lower HDL ("good") cholesterol. The trans-10, cis-12 form appears to be the form most associated with changes in body composition, but may have potential side effects (see Concerns and Cautions).

In animal and test tube studies, CLA has shown some ability to inhibit cancer cells. High dietary intake of CLA from high-fat dairy foods has been associated with a reduction of colorectal cancer by up to 39% in women, but it is not known if taking CLA supplements has the same association (Larsson, American Journal of Clinical Nutrition 2005). Preliminary research has also shown higher intake of CLA from foods, particularly from cheese, to be associated with a lower risk of developing breast cancer in postmenopausal women (Aro, Nutrition and Cancer 2000).

Quality Concerns and What CL Tested For:
Neither the FDA nor any other federal or state agency routinely tests supplements for quality prior to sale. It is important to know that a product contains the ingredients that it claims. Too little and you may not get the expected effect and waste your money. Too much, and you may experience negative effects with certain ingredients. tested each supplement for its amount of CLA. All products were also tested for potential contamination with lead, which can occur in supplements.

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