1. ^†Department of Animal Science, University of Nebraska, Lincoln, Nebraska 68583
2. ^‡Department of Animal Science, University of Georgia, Athens, Georgia 30602

Correspondence: Jess L. Miner, Department of Animal Science, University of Nebraska, C220 ANS, Lincoln, NE 68583. E-mail: jminer1@unl.edu

^**The costs of publication of this article were defrayed, in part, by the payment of page charges. This article must, therefore, be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

This study was presented in part at Experimental Biology 2002, New Orleans, LA [(Hargrave KM, Meyer BJ, Miner JL. FASEB J. 2002;16:A230 (abstr.)]. This manuscript has been assigned journal series no. 13830, Agricultural Research Division, University of Nebraska.

Received 28 April 2003; Accepted 24 June 2004.

Abstract

Objective: To determine whether altered dietary essential fatty acid (linoleic and arachidonic acid) concentrations alter sensitivity to conjugated linoleic acid (CLA)-induced body fat loss or DNA fragmentation.

Research Methods and Procedures: Mice were fed diets containing soy oil (control), coconut oil [essential fatty acid deficient (EFAD)], or fish oil (FO) for 42 days, and then diets were supplemented with a mixture of CLA isomers (0.5% of the diet) for 14 days. Body fat index, fat pad and liver weights, DNA fragmentation in adipose tissue, and fatty acid profiles of adipose tissue were determined.

Results: The EFAD diet decreased (p < 0.05) linoleic and arachidonic acid in mouse adipose tissue but did not affect body fat. Dietary CLA caused a reduction (p < 0.05) in body fat. Mice fed the EFAD diet and then supplemented with CLA exhibited a greater reduction (p < 0.001) in body fat (20.21% vs. 6.94% in EFAD and EFAD + CLA-fed mice, respectively) compared with mice fed soy oil. Dietary FO decreased linoleic acid and increased arachidonic acid in mouse adipose tissue. Mice fed FO or CLA were leaner (p < 0.05) than control mice. FO + CLA-fed mice did not differ in body fat compared with FO-fed mice. Adipose tissue apoptosis was increased (p < 0.001) in CLA-supplemented mice and was not affected by fat source.

Discussion: Reductions in linoleic acid concentration made mice more sensitive to CLA-induced body fat loss only when arachidonic acid concentrations were also reduced. Dietary essential fatty acids did not affect CLA-induced DNA fragmentation.