A little secret is spreading fast among consumers: Conjugated linoleic acid (CLA) helps to sculpt their bodies by reducing body fat and increasing lean muscle.
CLA refers to a mixture of bioactive geometric isomers of linoleic acid. Two major forms of CLA—c-9,t-11 CLA and t-10,c-12 CLA—exist naturally in the diet and have beneficial effects on health, specifically to improve body composition. At least 3 grams per day dietary CLA is necessary to achieve body fat loss (Journal of Nutrition, 2000; 130:2943-2948).
ABCs of CLA
CLA is naturally found in beef and dairy products, vegetable oils and seafood. Cows and other ruminant animals produce CLA naturally from linoleic acid, which is present in the cows’ diet (e.g., grass). However, obtaining CLA from the diet is problematic, since today it is only present in very low levels in foods, due to less grazing and more feed being consumed by the majority of ruminant animals. In fact, Larry Satter, researcher at the Dairy Forage Research Center, Madison, WI, conducted a study in 2000 comparing the CLA level in milk from cows grazing on pasture to the amount from cows fed hay or silage, and found pasture-grazed cows had 500% more CLA in their milk than those fed silage. So today’s dairy contains approximately 2 to 5 mg CLA per gram of fat and beef contains 3 to 5 mg CLA per gram of fat, making it difficult to get the needed 3.2 grams CLA per day without supplementation.
There is a solution to increasing our consumption of CLA. This can be achieved by supplementation and the fortification of foods. Commercial CLA is produced from linoleic acid (found in high amounts in sunflower and safflower oil) using a process that gently converts the linoleic acid into conjugated linoleic acid.
On July 24, 2008, CLA attained GRAS status for certain food categories. CLA is now allowed in the following applications: yogurt, fluid milk, soy-based beverages, fruit juices, nutritional bars and meal replacement beverages. This now allows the food processor to incorporate a beneficial healthy fat that has been excluded from the definition of trans fatty acids by FDA (Title 21 of the Code of Federal Regulations, Part 101)
Addressing weighty issues
But now the big question: How can a fatty acid help in the fight against obesity?
CLA has been shown to inhibit the activity of lipoprotein lipase, an enzyme involved in the uptake of fat into fat cells, and thus may prevent the accumulation of body fat (Biochimica Et Biophysica Acta, 2001; 1534:27–33).
The most exciting results are in the area of weight management and body composition, as several short-term studies have demonstrated that CLA can positively affect body composition and has a beneficial effect on lean muscle mass (American Journal of Clinical Nutrition, 2004; 79:352-361). These effects on fat loss were confirmed in a recent meta-analysis published in the American Journal of Clinical Nutrition that reported at a dose of 3.2 grams per day, CLA produces a significant, but modest, loss in body fat (2007; 85(5):1203-11).
