Introvit-ES-100 Oral contains vitamin E and sodium selenite as a source of selenium. Vitamin E is an essential vitamin and together with selenium, the main function of vitamin E is to protect cells against oxidative damage. This protection is especially important for the prevention of oxidation of unsaturated fatty acids in the body in order to maintain the health of the animals. Unsaturated fatty acids are fat compounds that can easily oxidize. Oxidation of these unsaturated fatty acids can cause damage and disturb many processes in the body of the animal. Furthermore, both vitamin E and selenium are important for the maintenance of cell membrane integrity and are involved in the immune and reproductive system.