Vitamin A is a fat-soluble vitamin that's essential for several critical bodily functions, including vision, immune response, and cell differentiation. It comes in two primary forms: preformed vitamin A (retinol) found in animal products like liver, fish, and dairy, and provitamin A carotenoids, primarily found in colorful fruits and vegetables such as carrots, sweet potatoes, and spinach. The body can convert carotenoids into retinol, making these plant sources a valuable dietary option, especially for those following a vegetarian or vegan lifestyle.
Aside from its role in maintaining healthy vision—particularly in low-light conditions—vitamin A plays a significant role in skin health and the functioning of the heart, lungs, and kidneys. It also supports the immune system by promoting the development and function of white blood cells. While it's uncommon to experience a deficiency in countries where a balanced diet is accessible, a lack of vitamin A can lead to serious health problems, including night blindness and increased susceptibility to infections. In contrast, excessive intake of vitamin A, particularly through supplements, can be toxic and lead to several health issues, making it crucial to maintain a balanced intake.