Relationship between erucic acid and myocardial changes in male rats

The back and belly fat of pigs fed a diet containing 20% by wt rapeseed oil (22% erucic acid) for 16 weeks was rendered into oil. This rendered pig fat, which contained 5.6% erucic acid, was fed to male rats in three separate experiments at 20% by wt of the diet for 16 weeks. In experiment I rendered pig fat was compared only to Brassica campestris var. Span rapeseed oil containing 4.8% erucic acid. In experiments II and III, rendered pig fat was compared to commercial lard containing 0.2% docosenoic acid, commercial lard to which 5.4% free erucic acid was added, and Span rapeseed oil. There was no significant (P less than 0.01) differences observed in the level of erucic acid in the hearts of rats fed diets of rendered pig fat, Span rapeseed oil, or commercial lard plus erucic acid. However, the incidence (P less than 0.001) and severity (P less than 0.01) of cardiac lesions were significantly higher in Span rapeseed oil fed rats compared to rats fed control diets. The number of rats affected or the severity of lesions in the rendered pig fat fed group was not significantly different from controls. The results of this study indicate that the myocardial lesions associated with feeding 20% rapeseed oil diets are not related to the content of erucic acid per se. The possible reasons why rapeseed oil causes cardiac lesions in rats are discussed. It is suggested that a triglyceride imbalance in the oil might play an important role in causing these lesions in rats.