Overview
Linoleic acid (LA) is an essential omega-6 polyunsaturated fatty acid (PUFA) required for normal growth and health, playing a key role in cell membrane structure and as a precursor to signaling molecules such as prostaglandins and leukotrienes. Conjugated linoleic acid (CLA), a group of isomers of linoleic acid, has been studied for its potential anti-inflammatory, antiadipogenic, and lipid-modulating effects. In humans, CLA supplementation has shown modest effects on reducing body fat mass, particularly in overweight and obese individuals, though results are inconsistent across studies [4][3]. Some trials report a significant reduction in body fat percentage with CLA supplementation (e.g., 3–4 g/day over 6 months), but these changes are often small and of questionable clinical significance [7][2]. Additionally, while animal models show improved lipid profiles, human studies have reported mixed outcomes, including reductions in HDL cholesterol and increases in lipoprotein(a), raising concerns about cardiovascular safety [1]. CLA does not appear to significantly affect immune function in healthy adults [1][6]. Overall, evidence supports only a minor role for CLA in body composition modification, with no established benefit for immune or cardiovascular health in humans.
Dosage Guide
Recommended Daily Allowance
For generally healthy individuals
Therapeutic Doses
For treatment of specific conditions
Upper Intake Limit
Maximum safe daily intake
g— No established UL for linoleic acid; high intakes may promote inflammation if n-3 intake is low
Special Forms
Alternative forms for specific needs
Preferred for potential metabolic and immune benefits with fewer adverse lipid effects
More potent for fat loss but associated with insulin resistance and adverse lipid changes
Clinical Notes
- High-dose CLA supplementation may reduce HDL cholesterol and increase lipoprotein(a), potentially increasing cardiovascular risk
- The t10-c12 CLA isomer has been linked to insulin resistance and fatty liver in some studies
- Balance between omega-6 and omega-3 fatty acids is critical; excessive linoleic acid without adequate n-3 intake may promote inflammation
- CLA supplements are generally well tolerated but may cause gastrointestinal discomfort at doses above 3 g/day
Research
CLA supplementation in humans shows ambiguous effects on body composition and lipid profiles; some unfavorable changes like reduced HDL and increased lipoprotein(a) observed.
Dietary n-6 PUFA intake influences lipoprotein profiles, but study focused on interaction with n-3 PUFA, not direct LA/CLA effects.
Meta-analysis shows CLA supplementation leads to modest but statistically significant weight loss in overweight/obese individuals over 6+ months.
Low-dose PUFA blends including gamma-linolenic acid (derived from LA) modulate inflammatory markers, but CLA not directly tested.
CLA exhibits anti-inflammatory, anticarcinogenic, and antiadipogenic properties in animal models; human relevance remains uncertain.
Meta-analysis finds CLA supplementation significantly reduces fat mass in humans, though effect size diminishes with longer duration.
CLA supplementation (4.2 g/day) for 12 weeks significantly reduced body fat proportion in healthy adults.
3 g/day of CLA (c9-t11 and t10-c12 isomers) for 24 weeks led to significant improvements in body composition in overweight individuals.
