Vitamin A refers to a group of substances that all have similar structures and properties, with retinol being one of the most commonly known. Vitamin A is responsible for helping your immune system work properly, helping you to see in low light and keeping skin healthy. There are two forms - vitamin A itself is found in dairy products, eggs, fish livers and meat. The second is beta-carotene, a molecule that the body converts into vitamin A. Also known as pro-vitamin A, it's mainly found in fruits and vegetables, particularly carrots, tomatoes, apricots, spinach, lamb's lettuce and peppers.