The purpose of the present study was to observe the changes in serum lipids of rats fed a shiitake-containing diet throughout life. The serum triglyceride level of the shiitake diet group tended to be lower than that for the control diet group, but the difference was not significant. The serum phospholipid level was significantly lower in the shiitake diet group than in the control diet group (p<0.001) from 4 weeks to 36 weeks. Serum total cholesterol levels were significantly low in the shiitake diet group compared to the control diet group from 4 weeks to 36 weeks. However, the difference gradually disappeared over more than 48 weeks. Our findings suggested that reducing the serum cholesterol level and the phospholipid level beyond 36 weeks after starting a shiitake-containing diet influenced the average life span and the medium survival rate
