1. Vision: Vitamin A is essential for the production of the protein rhodopsin, which is needed for vision in low-light conditions. It also helps maintain the health of the cornea and other tissues of the eye.
2. Immune Function: Vitamin A plays a critical role in the immune system by supporting the development and function of white blood cells. It also helps to fight off infections and diseases.
3. Growth and Development: Vitamin A is important for the growth and development of cells and tissues throughout the body, including bones and teeth.
4. Reproduction: Vitamin A is essential for the production of sperm and maintaining the health of the female reproductive system.
5. Skin Health: Vitamin A is important for maintaining healthy skin and mucous membranes. It helps to protect the skin from damage caused by the sun and other environmental factors.

1. Animal Sources: Vitamin A is found in high amounts in animal foods, especially liver, egg yolks, and dairy products such as milk, cheese, and butter.
2. Plant Sources: Vitamin A can also be obtained from plant foods, primarily through the consumption of carotenoids, which are converted to vitamin A in the body. The best sources of carotenoids are orange and yellow vegetables such as sweet potatoes, carrots, and squash, as well as dark leafy greens like spinach and kale.
3. Fortified Foods: Some foods, such as cereals, milk, and margarine, are fortified with vitamin A to help people meet their daily needs.

It’s worth noting that too much vitamin A can be harmful, especially in supplement form. High doses of vitamin A can cause toxicity, which can lead to symptoms such as nausea, dizziness, and even death. Therefore, it’s important to obtain vitamin A from food sources and to follow recommended daily intakes to avoid the risk of toxicity. The recommended daily intake of vitamin A for adults is 900 micrograms for men and 700 micrograms for women.