Acute oral safety study of dairy fat rich in trans-10 C18:1 versus vaccenic plus conjugated linoleic acid in rats.

The acute oral toxicity of a trans-10 C18:1-rich milk fat (T10, 20% of total FA), and a trans-11 C18:1+cis-9 trans-11 C18:2-rich milk fat (T11-CLA, 14% and 4.8% of total FA, respectively) was studied in rats receiving a single oral dose of 2000 mg/kg body weight (BW). T10 and T11-CLA milk fats were well tolerated; no adverse effects or mortality were observed during the 2-week observation period. Two weeks following a single oral dose of 2000 mg/kg BW of T10 and T11-CLA milk fats there were no changes in haematological and serum chemistry parameters (excepting plasma lipid) organ weights, gross pathology or histopathology. In rats treated with T10 milk fat a significant increase of triglycerides was observed. In contrast, in rats treated with T11-CLA milk fat significantly decreased triglycerides were detected. It was concluded that dairy fats rich in T10 and T11-CLA have a low order of acute toxicity, the oral lethal dose (DL50) for male and female rats are in excess of 2000 mg/kg BW. Our results suggest that the T10 milk fat treatment tended to increase triglycerides concentrations, whereas the T11-CLA milk fat treatment tended to reduce it.