Vitamin A

Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, and several provitamin A carotenoids, most notably beta-carotene.

Vitamin-A-Synthese

Sources

Vitamin A can be found in both plant and animal sources. Animal-based sources of vitamin A provide the compound in its retinol form, which is bioavailable and can be readily used by the body. These sources include organ meats (liver, kidney), fish oils, milk, and eggs. Plant-based sources provide provitamin A carotenoids, which are converted into retinol by the body. These sources include fruits and vegetables that are orange, yellow, or green in color, such as carrots, sweet potatoes, spinach, and kale.

Function

Vitamin A plays a crucial role in maintaining normal vision, immune system function, reproduction, and cellular communication. It is also important for the heart, lungs, kidneys, and other organs. Vitamin A is essential for good vision, particularly in low light conditions, and it plays a vital role in maintaining the health of the cornea and conjunctiva.

Deficiency

Vitamin A deficiency is rare in developed countries but is common in developing countries, especially among children and pregnant women. Symptoms of vitamin A deficiency can include night blindness, a dry cornea (xerophthalmia), a weakened immune system, and skin problems such as hyperkeratosis.

Toxicity

Although Vitamin A is essential for health, like all vitamins, it can be harmful in excess. Hypervitaminosis A, which can occur from consuming too much vitamin A from supplements over a short period, can cause dizziness, nausea, headaches, skin irritation, and even hair loss or fracture.

See Also

• Vitamin
• Vitamin A deficiency
• Hypervitaminosis A
• Carotenoid