Cod liver oil is one of the best natural sources of vitamins A and D, two perfect partners in immune health. Vitamin A, also known as retinol, helps maintain eyesight, night vision, skin, membranes, and immune function. Vitamin D, referred to as the sunshine vitamin, is produced in our bodies from exposure to the sun or can be obtained through supplements. Vitamin D maintains a healthy immune system, among other health benefits., , Recommended dosage (adults): 1 softgel 2 times daily or as directed by a physician.