Differential fatty acid accretion in heart, liver and adipose tissues of rats fed beef tallow, fish oil, olive oil and safflower oils at three levels of energy intake.

To examine interactive effects of dietary fatty acid composition and energy restriction on tissue fatty acid accretion, mature rats consumed diets containing beef tallow, fish oil, olive oil or safflower oil with free access or at 85% or 68% of free access energy intakes. Restriction was accomplished by adjustment of dietary carbohydrate level. After 10 wk, animals were killed, and the fatty acid compositions of liver, heart and adipose tissues were examined. Compared with animals given free access to diets, body weight gains were reduced at wk 10 in fish oil- and olive oil-fed groups consuming 85% (P < 0.01) and in all groups consuming 68% (P < 0.005) of free access energy intake. Liver and heart weights were also lower (P < 0.05) in all groups restricted to 68% of free access energy intake. The type of dietary fat and the level of energy restriction influenced fatty acid composition in all three tissues at wk 10. In liver tissue, graded energy restriction increased (P < 0.02) proportions of stearic acid and decreased (P < 0.03) those of palmitic acid. In heart tissue, palmitic acid levels decreased (P < 0.01) with energy restriction. In adipose tissue, significant energy restriction-related changes in fatty acid composition varied with type of fat consumed. These results emphasize the importance of whole-body energy balance in addition to dietary fatty acid supply in utilization of dietary fatty acids for tissue deposition vs. oxidation.