Supplemental information

Trans-palmitoleic acid (TPA), a naturally occurring trans fatty acid found in ruminant-derived products such as dairy, has been associated with various potential health benefits. However, its digestion, absorption, tissue distribution, and metabolic properties following oral administration remain insufficiently understood. Here, we conducted pharmacokinetic analyses in C57BL/6J mice to evaluate the absorption, tissue distribution, and metabolism of TPA following oral administration. Our data showed that the plasma concentration of TPA peaked at 9.1 µg • mL-1 at 15 min post-administration, with a terminal elimination half-life of 201.1 min. Moreover, TPA was efficiently distributed to the heart, lung, liver, kidney, brain and adipose tissue, reaching peak concentrations within 30 to 60 min. These results indicate that TPA is rapidly digested, absorbed, and distributed across multiple tissues in mice, while exhibiting slow metabolic clearance and an extended residence time in vivo. Within 0 to 480 min following oral administration, TPA underwent bioconversion to trans-vaccenic acid (TVA) and cis-9, trans-11 conjugated linoleic acid (9c11t-CLA), both of which are recognized for their extensive health benefits. The bioconversion rates were 71.57%–72.44% for TVA and 44.05%–53.23% for 9c11t-CLA. Furthermore, TPA significantly reduced triglyceride and total cholesterol levels in steatosis hepatocytes. Notably, inhibiting the bioconversion of TPA to TVA and 9c11t-CLA did not impair its ability to reduce lipid accumulation in hepatocytes, suggesting that the beneficial effects of TPA on lipid metabolism are independent of its bioconversion to TVA and 9c11t-CLA. This study provides a reference for dairy fat intake and establishes a foundation for further exploration of the physiological effects of TPA.;;