Evidence for Nonessentiality of Linolenic Acid in the Diet of the Rat

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Abstract
To determine the effect of long-term deprivation of linolenate on growth and reproduction, female weanling Long-Evans rats were raised on a diet containing 1.25% methyl linoleate (2.7% of calories) as the only source of fatty acids. Control rats were given 1.0% methyl linoleate and 0.25% methyl linolenate. Rats in both groups were fertile and gave birth to normal litters. Pups were raised on the diet containing only linoleate, and both males and females were fertile and produced normal pups. Supplementation of third-generation deficient rats at weaning with the control diet containing linolenate and linoleate did not produce any change in growth compared with littermates continued on the diet that contained only linoleate. Thus, linolenic acid does not appear to be essential for growth or reproduction in rats. Fatty acids of various tissues were analyzed and were found to reflect the compositions of their dietary precursors, as expected; that is, in rats given no dietary θ-3 fatty acids, tissue level of θ-3 fatty acids were very low or undetectable. These, 22:5θ3 and 22:6θ3, were replaced by 22:4θ6 and 22:5θ6.