The fish oils rich in docosahexaenoic acid (DHA) were obtained from the fats and oils surrounding the eye of tuna. The effects of DHA on body composition and N balance in rats were investigated. The amount of experimental diet intake and the growth rate of rats fed a DHA oil diet (DHA oil group) were the same as those of rats fed a corn oil diet (corn oil group). The liver weight and the proportion of fat in the liver of the DHA oil group were lower than those of the corn oil group, while the N balance of the DHA oil group was higher than that of the corn oil group. Although the serum triglyceride and protein levels of both rat groups were the same, the serum total cholesterol, HDL-cholesterol and glucose levels of the DHA oil group were lower than those of the corn oil group. The activity of serum transaminase of the DHA oil group was lower than that of the corn oil group. This fish oil thus controlled the accumulation of fat in the liver and prevented the decrease of liver function.
