Vitamin A
Overview: Vitamin A is a fat-soluble vitamin essential for maintaining healthy vision, immune function, and skin health. It exists in two primary forms: preformed vitamin A (retinol and its esterified form, retinyl ester) and provitamin A carotenoids, including beta-carotene, which the body converts into retinol.
Sources: Preformed vitamin A is found in animal products such as liver, fish oils, eggs, and dairy products. Provitamin A carotenoids are abundant in colorful fruits and vegetables like carrots, sweet potatoes, spinach, and kale.
Functions:
Vision: Vitamin A is crucial for the production of rhodopsin, a pigment in the retina that helps in low-light and color vision.
Immune System: It supports the production and function of white blood cells, which help capture and clear bacteria and other pathogens.
Cell Growth: Vitamin A promotes the health and growth of cells and tissues, particularly skin and mucous membranes.
Deficiency: A deficiency in vitamin A can lead to night blindness, an increased risk of infections, and xerophthalmia, a condition that can lead to blindness if untreated. In severe cases, it can cause keratomalacia, an eye disorder that involves dry eyes and corneal ulceration.