Dietary trans-vaccenic acid (trans11-18:1) increases concentration of cis9,trans11-conjugated linoleic acid (rumenic acid) in tissues of lactating mice and suckling pups

Lactating mice were fed trans-vaccenic acid (trans11-18:1, TVA) to assess desaturation of TVA to cis9,trans 11- conjugated linoleic acid (9/11CLA). Diets contained 30 g·kg^-1 18:2n-6 (LA) or 20 g LA plus 10 g 18:0 (SA), TVA, or a CLA mixture (MCLA). Compared with SA, feeding TVA increased 9/11CLA concentrations in blood plasma phospholipid, triglyceride, and free fatty acid fractions. However, concentrations of 9/11CLA in plasma fractions were greater when MCLA was fed compared with SA or TVA. No 9/11CLA was detected in liver of mice fed SA, and it was only 1 mg·g^-1 of total fatty acids in the carcass. In contrast, 9/11CLA content of liver (5 mg·g^-1) and carcass (6 mg·g^-1) of mice fed TVA was similar to liver (5 mg·g^-1) and carcass (7 mg·g^-1) of mice fed MCLA. Mammary tissue of SA fed mice had no detectable 9/11 CLA, compared with 5 or 14 mg·g^-1 for TVA or MCLA-fed mice. Stearoyl-CoA desaturase activity in mammary tissue from TVA-fed dams was 14% greater compared with SA. Activity of this enzyme in liver tissue was similar among treatments. In pups nursing TVA-fed dams, 9/11CLA accounted for 3 mg·g^-1 in liver but no 9/11CLA was detected in the carcass. In pups nursing MCLA-fed dams, however, 9/11CLA accounted for 8 and 6 mg·g^-1 in liver and carcass. Results indicated TVA desaturation enhanced 9/11CLA in tissues and milk fat.