The results from the preceding study promoted on investigation of the effects of linoleate supplementation in dietary hardened fish oil (HFO) on rats fed HFO, safflower oil (SFO) and the mixtures of these two oils, 1 : 1 and 5 : 1 mixture by weight for 8 weeks. Weight gain and fatty acid profiles of liver, heart and adipose tissue lipids along with those of fecal lipids were compared.
1) Complete recovery from the unfavorable effects of HFO on the body weight gain was noted to occur with the addition of SFO as a source of linoleic acid, indicating the lowering of rate of weight gain to possibly not be due to trans fatty acids in HFO but to essential fatty acid deficiency.
2) The percentage of 20 : 4 n-6 in liver lipids markedly increased by partial substitution (20%) of SFO for HFO, but further addition failed to have such effect. In contrast, the addition of SFO failed to significantly increase heart lipid content due to the relatively high pre-existing level of arachidonic acid in the HFO group. Small amounts of trans fatty acids were found in the liver, heart and adipose tissue lipids from rats fed SFO, but only small amounts of trans fatty acids of 20 : 1 and 22 : 1 could be detected in these tissues of rats fed HFO, as was also noted in the preceding study.
3) Analysis of fatty acids in fecal lipids indicated trans acids, especially 20 : 1 and 22 : 1, to be preferentially discharged into the feces, while linoleic acid to be excreted when administered in excess though in rats, resumption of the level of this polyunsaturated fatty acid occured easily. Furthermore, the positional isomers of cis and trans monoene fatty acids, absent from dietary fats and tissue lipids, were detected at considerably high levels in the feces.
