Incorporation of dietary trans monounsaturated fatty acids into tissues ofWalker 256 tumor-bearing rats

The correlation between dietary trans fatty acids and neoplasia was examine d in the present study. Walker 256 tumor-bearing and control rats were fed a trans monounsaturated fatty acid (MUFA)-rich diet for 8 weeks and the inc orporation of trims fatty acids by tumor tissue was examined. Also, the eff ect of tumor growth on trans fatty acid composition of plasma and liver, an d the content of thiobarbituric acid-reactive substances (TBARS) was determ ined. Walker 256 tumor cells presented both trans and cis MUFAs,given in th e diet. The equivalent diet proportions were 0.66 for trans and 1.14 for ci s. Taking into consideration the proportion of trans MUFAs in plasma (11.47 %), the tumor incorporated these fatty acids in a more efficient manner(18. 27%) than the liver (9.34%). Therefore, the dietary trans fatty acids prese nt in the diet are actively incorporated by the tumor. Tumor growth itself caused marked changes in the proportion of polyunsaturated fatty acids in t he plasma and liver bur provoked only slight modifications in both trans an d cis MUFAs. Tumor growth also reduced the unsaturation index in both plasm a and liver, from 97.79 to 86.83 and from 77.51 to 69.64, respectively. Thi s effect was partially related to an increase in the occurrence of the lipi d oxidation/peroxidation process of TEARS content which was increased in bo th plasma (from 0.428 to 0.505) and liver (from 9.425 to 127.792) due to tu rner growth.