To obtain a lipid metabolism improving agent that promotes an unsaturated fatty acid-synthesizing metabolism, increases the ratio of unsaturated fatty acids in fatty acid compositions and improves animal health and meat quality of animals by administering an activity sustaining type stabilized antioxidant provitamin derivative together with fatty acids.

This lipid metabolism improving agent for animal bodies characteristically includes L-ascorbic phosphates and/or α-tochopherol phosphate. A lipid metabolism improving composition obtained by formulating the improving agent to fatty acids is prepared and a method for increasing the health and improving meat quality of animal bodies by using a feed formulated with the composition is provided.