Sodium selenite is a salt of selenous acid as well as sodium. This is an advanced source of selenium as well as an essential micronutrient needed for various biological processes in the human body. This is utilized as a dietary supplement which can boost the intake of selenium in the body. This is extremely essential for the proper functioning of the immune system, reproductive system and thyroid gland. This is also added to the animal feed as it is a primal source of selenium and assists in the proper growth, health and development of animals.