# Effects of dietary fats with different n 3 polyunsaturated fatty acid and n 6 polyunsaturated fatty acid ratios on the fatty acid compositions of serum and liver lipid fractions and serum lipoprotein fractions in rats

##### Takita, T.; Nakamura, K.; Hayakawa, T.; Suzuki, K.; Innami, S.

#### Japanese Journal of Nutrition 48(4): 165-176

#### 1990

Accession: 007272521

Changes in the fatty acid compositions of the serum and liver lipid fractions and serum lipoprotein fractions in rats were studied by feeding dietary fats with different n-3 PUFA/n-6 PUFA (n-39/n-6P) ratios by varing the mixing proportion of lard and fish oil. The results obtained are as following: 1) In the serum, as the n-3P/n-6P ratios of dietary fat increased, the proportions of C18:2 in the PL, TG and CE fractions and of C20:4 in the PL and TG fractions decreased gradually, but that of C20:4 in the CE fraction decreased markedly. On the other hand, the proportions of C20:5 in the PL, TG and CE fractions and of C22:6 in the PL and TG fractions increased, but in the PL fraction, the proportion of C20:5 increased gradually at over 2.13 of n-3P/n-6P ratio and that of C22:6 remained unchanged at over 0.95 of n-3P/n-6P ratio. 2) The serum EPA/AA ratios in the PL and CE fractions increased gradually as the n-3P/n-6P ratios of dietary fat increased, and this ratio in the TG fraction increased rapidly to 2.13 of the dietary n-3P/n-6P ratio, and after that slight increase was seen. 3) In the liver, the proportion of C18:2 in the PL and CE fractions decreased gradually as the n-3P/n-6P ratios of dietary fat increased. The proportion of C20:4 decreased rapidly to 0.95 of the dietary n-3P/n-6P ratio and after that decreased slightly. The proportions of C18:2 and C20:4 in the TG fraction decreased slightly. The proportions of C20:5 and C22:6 in each lipid fraction increased as the n-3P/n-6P ratios of dietary fat increased, but those of C20:5 and C22:6 in the PL fraction remained unchanged almost at over 5.37 and 0.95 of n-3P/n-6P ratios respectively. 4) The EPA/AA ratios in the liver lipid fractions raised as the n-3P/n-6P ratios of dietary fat increased, and the increase of that ratio was largest in the TG fraction and lowest in the PL fraction. 5) The proportion of C20:5 in the serum chylomicron and VLDL fraction increased rapidly to 2.13 of the dietary n-3P/n-6P ratio, and after that increased slightly. The proportion of C20:5 in the LDL and HDL fractions increased rapidly to 5.37 of the ratio, and after that a slight change was observed. The proportion of C22:6 in all lipoprotein fractions increased rapidly to 0.95 of the dietary n-3P/n-6P ratio, and after that increased slightly. 6) These findings suggest that the incorporation of n-6 PUFA and n-3 PUFA to the tissue lipid fractions are regulated by dietary n-3P/n-6P ratios.