Tuesday, December 6, 2011

Vitamin A

Vitamin A is a fat-soluble vitamin and an antioxidant.  Oil-soluble vitamins can become toxic if taken in megadoses.  Antioxidants are natural compounds that protect the body from free radicals.  Free radicals cause damage to cells and impair the immune system therefore leading to infections and disease.  Free radical damage is thought by scientists to be the basis of aging. 

Main Functions and Uses:
Skin - Needed for the maintenance and repair of the base layer of skin cells.
Eyesight - needed for the formation of rhodopsin which allows us to see at night therefore potects against night blindness. 
Bones and teeth - important in the formation and growth of bones and teeth.
Enhances and supports immunity.
Protects against colds and the flu.
Protects against cancer, heart disease, and other diseases.
Helps with skin disorders such as acne, wrinkling, and fading age spots.

Signs of deficiency:
Night blindness is one of the first signs of Vitamin A deficiency.  Other signs include dry hair and skin, dry eyes, poor growth, acne, frequent colds, and respiratory infections.

Signs of toxicity:
Taking large amounts of synthetic Vitamin A over long periods of time can be toxic mainly to the liver.  Signs of toxicity include abdominal pain, amenorrhea, enlargement of the liver, hair loss, itching, joint pain, nausea and vomiting, and birth defects.  Note: taking large amounts of vitamin A in the form of beta-carotene does not cause problems unless your liver cannot convert beta-carotene to vitamin A (rare).

Food sources:
Apricots, asparagus, beet greens, broccoli, brussels sprouts, cantaloupe, carrots, cherries, collards, dandelion greens, dulse, cod liver oil (Carlson's), kale, lettuce, mango, mustard greens, papayas, parsley, peaches, pumpkin, red cabbage, red peppers, spinach, spirulina, sweet potatoes, Swiss chard, turnip greens, water cress, watermelon, and yellow squash. 

Animal livers -  not recommended.

Best supplement sources:
Natural form of beta-carotene contained in a whole foods multi-vitamin.

Recommended daily amount:
5,000 IU - 10,000 IU

Drugs that interferes with absorption of Vitamin A - antibiotics, laxatives, some cholesterol-lowering drugs, and alcohol. 
If you have liver disease or pregnant, do not take more than 10,000 IU per day without your doctor's approval.

Image: Grant Cochrane / FreeDigitalPhotos.net

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