Vitamin A is a fat-soluble vitamin that’s required for the proper development and functioning of eyes, skin, immune system, and many other parts of the bodies. Vitamin A is found in many fruits, vegetables, eggs, whole milk, butter, fortified margarine, meat, oily saltwater fish, and more. Vitamin A deficiency can occur during protein deficiency, diabetes, over-active thyroid, fever, liver disease, cystic fibrosis, or an inherited disorder called abetalipoproteinemia.