Vitamin A. Vitamin A is important for maintaining good vision. It is also known as the anti-infective vitamin because of its role in supporting activities of the immune system. The recommended daily intake of vitamin A is 3,000 IU. Too much vitamin A can cause nausea and vomiting and result in weak bones. Vitamin A deficiency is rare in the United States, and you should get plenty as long as you eat your fruits and vegetables. It may be in your multivitamin, but you should not need any additional supplements. Good food sources for vitamin A are carrots, spinach, sweet potatoes, apricots, cantaloupe, broccoli, eggs, milk, and cod liver oil.