Conjugated linoleic acid, or CLA, is an omega-6 polyunsaturated essential fatty acid, which provides support, flexibility, and structure to cell membranes. The recommendation for CLA for human benefit is 3 grams daily, according to the Linus Pauling Institute. Potential health benefits of CLA involve anti-heart disease effects, anti-cancer effects and body fat reduction. Much more research is needed, but the initial reports appear promising. Food sources of CLA include milk, beef and eggs.
The most abundant source of CLA is beef from grass-fed cows, according a study in the October 1999 issue of the "Journal of Dairy Science." The type of food the cow eats is critical to the amount of conjugated linoleic acid found in beef. Grass-fed cows have much more CLA present than cows fed a typical corn diet. This is due to the amount of omega-3 fatty acids found in grass that is not present in corn. Fresh ground beef contains 4.3 milligrams of CLA per gram of fat.
Milk contains high amounts of CLA, especially from cows that are grass-fed. A study published in 2004 in "Circulation" reports that cows fed grass at higher altitudes tend to have even more CLA content than those fed at lower altitudes due to the omega-3 fatty acid content in the grass. An important point to note about milk is that CLA is found in the fat of the milk, so low-fat and non-fat versions of milk would have smaller amounts than whole milk. Cow's milk contains 5.5 milligrams of CLA per gram of fat.
Eggs are another food source of CLA, which is higher in eggs from chickens that are grass-fed. CLA is found in the egg yolk of eggs. A study published in August 2004 in "Food Chemistry" reports that CLA content was maintained even after frying. The Linus Pauling Institute fortified eggs with CLA in an effort to determine the effects of fortification on CLA levels in hamsters and proved to be effective without adverse events. The idea is to use this same process in eggs for human consumption to improve the amount of CLA in the diet since food sources are limited in the Western diet.