CLA (Conjugated Linoleic Acid)
fatty-acidA naturally occurring trans fatty acid found in meat and dairy from ruminants, associated with potential body composition and immune benefits.
Definition
A naturally occurring trans fatty acid found in meat and dairy from ruminants, associated with potential body composition and immune benefits. Differs from industrial trans fats in its health effects.
What Is CLA (Conjugated Linoleic Acid)?
Conjugated linoleic acid (CLA) refers to a group of positional and geometric isomers of linoleic acid (an omega-6 fatty acid) in which the double bonds are conjugated — meaning they alternate with single bonds rather than being separated by a methylene group. The most studied isomers are cis-9, trans-11 CLA (also known as rumenic acid) and trans-10, cis-12 CLA.
CLA is produced naturally through biohydrogenation of linoleic acid by bacteria in the digestive tract of ruminant animals. As a result, dairy products and meat from ruminants — particularly grass-fed animals — are the primary dietary sources. Grass-fed beef and dairy contain approximately 3–5 times more CLA than grain-fed counterparts.
Key Functions and Research Findings
CLA has been investigated extensively for its effects on body composition, metabolism, and immune function:
- Body composition: The trans-10, cis-12 isomer has been shown in some studies to modestly reduce body fat mass, particularly abdominal fat, by inhibiting lipoprotein lipase (an enzyme that facilitates fat storage) and promoting fat oxidation in muscle tissue. Effects are more consistent in animal studies than human trials.
- Insulin sensitivity: Evidence is mixed; some studies suggest CLA may improve insulin sensitivity, while the trans-10, cis-12 isomer has also been associated with reduced insulin sensitivity at high supplemental doses in certain populations.
- Immune modulation: CLA demonstrates immunomodulatory effects, including enhanced antibody production in response to vaccination in some human studies.
- Anticancer potential: Preclinical studies show CLA inhibits proliferation of several cancer cell types, though evidence in humans remains inconclusive.
Typical dietary intake of CLA from food is 150–500 mg/day. Supplements commonly provide 3–6 g/day, which is significantly higher than natural dietary exposure.
Food Sources
- Grass-fed butter: approximately 4–6 mg CLA per gram
- Grass-fed beef: approximately 4–6 mg CLA per gram of fat
- Full-fat dairy (yogurt, cheese): 3–8 mg CLA per gram of fat
- Lamb: comparable CLA content to beef
Plant-based CLA supplements derived from sunflower oil are also available; these primarily contain the trans-10, cis-12 isomer rather than the naturally occurring cis-9, trans-11 form.