Conjugated linoleic acid
Conjugated linoleic acid (CLA) is a group of altered forms of linoleic acid made by bacteria in the stomachs of cows, sheep, and goats. It is found in small amounts in milk fat and red meat, and sold as a supplement for body fat, where the effect in people is small.
No set daily amount
Small or no effect on body fat in human trials
Upper limit · none set
- Main sources Dairy fat whole milk, butter, and cheese
- Also in Beef and lamb in the fat, not the lean
- In food c9,t11 rumenic acid, most of the CLA in food
- In supplements c9,t11 + t10,c12 in roughly equal parts
Our food library has no CLA figures yet, so this page names the foods without ranking them.
Foods That Contain CLA
Only foods from animals that chew the cud have more than traces.
- Milk fatWhole milk, cream, butter, and full-fat cheese and yogurt. Skimmed milk has little, because the CLA goes with the fat.
- Beef, lamb, and goatIn the fat of the meat. Lean cuts have less than fatty ones.
- Pork, chicken, and fishLittle, since these animals have no rumen to make it.
- Plant foods and oilsLittle or none. Safflower and sunflower oil are the raw material for CLA supplements, but they become CLA only after chemical processing.
What Is CLA?
Ordinary linoleic acid has two double bonds with two single bonds between them. In CLA the two double bonds are next to each other, with one single bond in between, which chemists call conjugated. There are many possible arrangements, and the names, such as c9,t11, give the position of each double bond and whether it is cis or trans.
How Cows and Other Ruminants Make CLA
Grass and feed contain linoleic acid. Bacteria in the rumen, the first stomach of cows, sheep, and goats, rearrange part of it into CLA and into vaccenic acid, another fat. The animal's own tissues then turn some vaccenic acid into more CLA, and both end up in milk and body fat.
The same process explains why diet changes the amount: studies find that milk from cows grazing fresh pasture has more CLA than milk from cows on grain-based feed. It is still a small part of the fat either way, and the fat itself is what you log: butter and cheddar have their full fat breakdown in our food library.
Is CLA a Trans Fat?
Most CLA forms have one trans double bond, so chemically they are trans fats. US labeling rules, though, count only trans fats whose double bonds are not conjugated, so the CLA in a supplement does not appear on the trans fat line. The industrial trans fats that raise LDL cholesterol are a different group.
CLA and Weight Loss: What Human Trials Show
In mice, CLA cut body fat sharply, which is how it became a weight-loss supplement. Trials in people have not repeated that. The NIH Office of Dietary Supplements sums them up as small or no losses of body fat and little change in body weight.
The t10,c12 form, found mostly in supplements rather than food, is the one most studied for body fat, and it is also the one a few small trials linked to worse insulin sensitivity in men with abdominal obesity.
CLA Supplements
Supplements are the other source of CLA. Food supplies only small amounts, so a capsule is a very different dose, with a different mix of forms.
What Is in a CLA Supplement
CLA supplements are made by processing safflower or sunflower oil. They usually hold the c9,t11 and t10,c12 forms in roughly equal parts, while food CLA is mostly c9,t11. Check the label for the CLA content per serving.
CLA Side Effects
- Commonstomach upset, nausea, and loose stools
- In some trialsworse insulin sensitivity with the t10,c12 form
Sources: NIH Office of Dietary Supplements, nutrition textbooks. Not medical advice.
Tracking CLA in Caltide
- Not totaled yetFood data rarely lists CLA, so Caltide does not add it up. It does total omega-6 and the omega-3 fats from your logged foods and ticked supplements in the Nutrition tab.
Related Nutrients
Conjugated Linoleic Acid Sources and References
The figures and claims on this page are checked against these sources.
Questions About Conjugated Linoleic Acid
CLA (conjugated linoleic acid) is a group of forms of linoleic acid, an omega-6 fat, in which two double bonds sit next to each other with one single bond between them. It is not an essential nutrient.
Mainly the fat of milk and meat from cows, sheep, and goats: whole milk, butter, cheese, beef, and lamb. Bacteria in these animals' stomachs make it. Plant foods have little or none.
Only a little, if at all. In human trials, CLA supplements led to small or no losses of body fat and little change in body weight, according to the NIH Office of Dietary Supplements.
Chemically it has a trans double bond, but US labeling rules count only trans fats whose double bonds are not conjugated, so CLA is left out of the trans fat line.
It is generally well tolerated in studies, with stomach upset, nausea, and loose stools the common side effects. A few small trials of the t10,c12 form found worse insulin sensitivity in men with abdominal obesity.
No. Food CLA is mostly one form, c9,t11 (rumenic acid). Supplements are made from safflower or sunflower oil and contain roughly equal amounts of c9,t11 and t10,c12.
Not yet. Food data rarely lists CLA, so Caltide does not total it, but it does total omega-6 and the omega-3 fats.
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