Vitamin A is a fat-soluble vitamin that plays an important role in vision, bone growth, reproduction, cell division, and immunity. It was first discovered in the early 20th century by researchers studying xerophthalmia, a form of blindness caused by vitamin A deficiency.
There are two main types of vitamin A found in food – preformed vitamin A (retinol) and provitamin A carotenoids. Preformed vitamin A is found in animal sources like liver, egg yolks, fortified milk and dairy products. Provitamin A carotenoids are found in plant sources like carrots, sweet potatoes, spinach, cantaloupe, red peppers, mangos, and apricots. The body converts these plant pigments into active vitamin A. Other key facts about this essential vitamin include:
- Needed for rhodopsin formation in the eyes
- Supports immune function and red blood cell production
- Needed for gene transcription and cell differentiation
- Antioxidant properties help protect cells from damage
- Excessive amounts can be toxic and cause hypervitaminosis A
- Deficiency can lead to nyctalopia (night blindness) and xerophthalmia
Vitamin A was an early vitamin discovery that revealed the importance of trace nutrients in human health. Consuming a balance of retinol and provitamin A carotenoids from animal and plant sources helps ensure adequate vitamin A intake.