Tuesday, December 16, 2008

Vitamin A: Role in the Body & Benefits

Role in the Body
Vitamin A is best known for its role as a component of proteins in the eye, which enable you to see in dim light. In addition, vitamin A boosts immunity, keeps the skin and mucous membranes moist, aids in fat storage and protein use, is necessary for new cell growth and is important in the formation of bone and teeth. Vitamin A can also be made by the body, as needed, from beta-carotene. Beta-carotene has antioxidant properties.

Dietary Sources
Sources of vitamin A include: liver, fatty fish (such as mackerel), egg yolks, cheese, and milk. Beta-carotene is found in red, orange, and yellow-pigmented plant foods and most dark leafy greens. Good sources include: apricots, cantaloupe, peaches, pumpkins, carrots, asparagus, red peppers, sweet potatoes, tomatoes, yellow squash, green beans, broccoli, spinach and turnip greens.

Who Is at Risk for Deficiency?
You may be at risk for vitamin A deficiency if you drink alcohol, smoke, are under severe stress, are pregnant or breastfeeding, take birth control pills, or take certain cholesterol-lowering drugs.

Vitamin A may help protect against night blindness, cataracts, age-related macular degeneration, cancer, and heart disease.

Vitamin A can be toxic if taken in large doses over a long period of time and can cause birth defects if taken in excess during pregnancy. Beta-carotene is not toxic, although larger doses can result in a harmless yellow-orange tint to the skin, which will disappear when levels are reduced. People with liver or kidney disease should talk to their doctor before taking vitamin A supplements.

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