Absorption Kinetics of the Main Conjugated Linoleic Acid Isomers in Commercial-Rich Oil after Oral Administration in Rats

This study aimed to assess the oral absorption and plasma kinetics of two main isomers contained in commercial conjugated linoleic acid (CLA)-rich oil (Tonalin TG-80), rumenic acid (RA), and C18:2 trans-10, cis-12. The isomer plasma disposition after the single oral dose of 3000 mg of Tonalin TG-80/kg, containing 1200 mg/kg of each isomer, was studied in rats. The isomer plasma concentrations were determined by gas chromatography with flame ionization detection. The plasma kinetics showed rapid oral absorption of RA and C18:2 trans-10, cis-12 (t1/2a 0.34 ± 0.09 and 0.53 ± 0.01 h) and slow elimination (t1/2β 25.68 ± 3.29 and 18.12 ± 1.71 h); the maximal isomer plasma concentrations (Cmax) of 8.48 ± 0.98 and 7.67 ± 0.80 μg mL–1, respectively, were estimated at 2.08 ± 0.14 and 2.26 ± 0.11 h. Our results from a preclinical kinetic study in rats help to design future studies in humans for evaluating the CLA isomer dose–response.