CLA (Conjugated Linoleic Acid)

Conjugated linoleic acid (CLA) is a group of positional and geometric isomers of the poly‑unsaturated fatty acid linoleic acid (C18:2). It is primarily found in nature as the cis‑9, trans‑11 and trans‑10, cis‑12 isomers. CLA is marketed as a dietary supplement, mainly for its potential to modulate body composition and metabolic health.

• Conjugated linoleic acid refers to a group of isomers of C18:2 with conjugated double bonds.
• The predominant isomers are:
  • cis‑9, trans‑11 CLA (IUPAC: (9Z,11E)-octadeca-9,11-dienoic acid)
  • trans‑10, cis‑12 CLA (IUPAC: (10E,12Z)-octadeca-10,12-dienoic acid)
• Molecular formula: C₁₈H₃₀O₂; molecular weight: 280.44 g·mol⁻¹.
• The conjugated double‑bond system (alternating single‑double bonds) confers a higher susceptibility to oxidation and enables interaction with PPAR receptors.
• The isomers differ in the geometry (cis vs. trans) and position of the double bonds, which influences biological potency.
• CLA is a lipophilic compound, soluble in oils and organic solvents, with a melting point of ~40 °C (cis‑9, trans‑11) and ~42 °C (trans‑10, cis‑12).

• Naturally, CLA is present in ruminant adipose tissue and dairy products; typical concentrations are 0.5–2 % of total fatty acids in beef, lamb, and milk fat.
• Commercial supplements are produced either by extraction from bovine or sheep fat using solvent‑extraction and fractionation (e.g., supercritical CO₂) to enrich the CLA isomers, or by microbial fermentation (e.g., Lactobacillus spp.) that convert linoleic acid to CLA via isomerase enzymes.
• Synthetic routes using chemical isomerization of linoleic acid also exist but are less common for food‑grade products.
• Quality considerations include: minimal trans‑fat contamination, verified isomer ratio (≥50 % cis‑9, trans‑11), absence of heavy‑metal residues, and third‑party testing for purity and oxidative stability (e.g., peroxide value <5 meq O₂/kg).
• Standardized, high‑purity (>80 % total CLA) products are recommended for research‑grade or therapeutic use.