Abstract
We previously found that dietary polyunsaturated fatty acids (PUFA) was quickly (starting within 1h) and preferentially incorporated into tissue lipids and suppressed fatty acid synthesis in the liver, whereas dietary monounsaturated fatty acids or saturated fatty acids (MUFA and SFA) were quickly metabolized after intake and the tissue MUFA and SFA are mostly endogenous. Thus, in the present experiment, the effects of various amounts of dietary PUFA, MUFA or SFA on the fatty acid concentrations of tissues were examined in rats fed an equal amount of energy-containing diet/body weight for 1 or 2 weeks. (1) When rats were fed diets containing 0-20% of olive, corn or fish oil, the MUFA concentrations in total lipids of plasma and liver was not significantly increased inspite of a large intake, whereas the PUFA concentrations were increased with increasing dietary intake. Plasma cholesterol ester fatty acid compositions of these rats were similarly changed. The liver lipogenic enzyme activities, and the plasma and liver triacylglycerol concentrations were decreased with increasing dietary PUFA. (2) When rats were fed diets with increasing amount of MUFA or SFA but with a fixed amount of PUFA, the fatty acid concentrations in the tissues were not significantly changed. Therefore, the tissue PUFA concentrations reflected dietary PUFA, whereas the tissue concentrations of MUFA and SFA did not, but were controlled by PUFA.
