Vitamin A is a essential fat-soluble vitamin that plays a vital role in various bodily functions, including vision, immune system, and cellgrowth. There are two forms of vitamin A: preformed vitamin A and provitamin A carotenoids. Preformed vitamin A is found in animal products, while provitamin A carotenoids are found in plant-based foods.
Sources of Vitamin A
Preformed vitamin A: liver, fish liveroils, eggs, and dairy products
Provitamin A carotenoids: carrots, sweet potatoes, spinach, kale, and other colorful fruits and vegetables
Functions of Vitamin A
Vitamin A has several important functions in the body:
Vision: Vitamin A is essential for the proper functioning of the retina and low light and color vision.
Immune system: It plays a crucial role in maintaining the integrity of the skin and mucous membranes, which act as barriers to infection.
Cellgrowth and differentiation: Vitamin A is involved in the growth and specialization of cells, particularly in the development of the embryo and fetus.
Deficiency and Toxicity
A deficiency of vitamin A can lead to night blindness, increased susceptibility to infections, and in severe cases, xerophthalmia (a condition that can lead to blindness). On the other hand, excessive intake of vitamin A can lead to toxicity, which can cause symptoms such as nausea, dizziness, and even liver damage.
Recommended Intake
The recommended dietary allowances (RDAs) for vitamin A vary by age and gender. For example, the RDA for children ages 4-8 is 400 micrograms per day, while for adult males it is 900 micrograms per day and for adult females it is 700 micrograms per day.
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