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Vitamin A - Benefits, Deficiency Symptoms And Food Sources

Alternative names :: Beta carotene, Retinol

What is Vitamin A?

This famed vision-enhancing nutrient was isolated in 1930, the first fat-soluble vitamin to be discovered. The body acquires some of its vitamin A through animal fats. The rest it synthesizes in the intestines from the beta-carotene and other carotenoids abundant in many fruits and vegetables.

Benefits of Vitamin A

Vitamin A is found in two forms: performed vitamin A, known as retinol, and pro vitamin A, called beta carotene. Retinol is found only in foods of animal origin. Beta carotene, a carotenoid, is a pigment found in plants. Beta carotene has a slight nutritional edge, boasting antioxidant properties and the ability to help lower harmful cholesterol levels.

Vitamin A prevents night blindness and other eye problems, as well as some skin disorders, such as acne. It enhances immunity, may help to heal gastrointestinal ulcers, and is needed for the maintenance and repair of epithelial tissue, of which the skin and mucous membranes are composed. It is important in the formation of bones and teeth, aids in fat storage, and protects against colds, flu, and infections of the kidneys, bladder, lungs, and mucous membranes.

Vitamin A acts as an antioxidant, helping to protect the cells against cancer, other diseases and is necessary for new cell growth. It guards against heart disease and stroke, and lowers cholesterol levels. This important vitamin also slows the aging process. Protein cannot be utilized by the body without vitamin A. Vitamin A is a well-known wrinkle eliminator. Applied topically in the form of tretinoin (the active ingredient in Retin-A and Renova), vitamin A reduces fine lines in the skin and helps fade age spots.

The carotenoids are a class of compounds related to vitamin A. In some cases, they can act as precursors of vitamin A; some act as antioxidants or have other important functions. The best known subclass of the carotenoids are the carotenes, of which beta-carotene is the most widely known. Also included in this group are alpha and gamma carotene, and lycopene. When food or supplements containing beta-carotene are consumed, the beta-carotene is converted into vitamin A in the liver. According to recent reports, beta-carotene appears to aid in cancer prevention by scavenging, or neutralizing, free radicals.

Other types of carotenoids that have been identified are the xanthophylls (including beta-cryptoxanthin, canthaxanthin, lutein, and zeaxanthin); the limonoids (including limonene); and the phytosterols (including perillyl alcohol). Science has not yet discovered all of the carotenoids, although one source documents 563 different carotenoids identified so far. Combinations of carotenoids have been shown to be more beneficial than individual carotenoids taken alone.

Recommended Dosage of Vitamin A

The Recommended Dosage for vitamin A are :-

• 5,000 IU (or 3 mg beta carotene) daily for men.
• 4,000 IU (or 2.4 mg beta carotene) daily for women.

Excessive Intake of Vitamin A

Taking large amounts of vitamin A, over 100,000 international units daily, over long periods can be toxic to the body, mainly the liver. Toxic levels of vitamin A are associated with abdominal pain, amenorrhea (cessation of menstruation), enlargement of the liver and spleen, gastrointestinal disturbances, hair loss, itching, joint pain, nausea and vomiting, water on the brain, elevated liver enzymes, and small cracks and scales on the lips and at the comers of the mouth. Excessive intake of vitamin A during pregnancy has been linked to birth defects, including cleft palate and heart defects. It is better to take beta-carotene during pregnancy. If you have a particular disorder that calls for taking high doses of vitamin A, use an emulsified form, which puts less stress on the liver.

No overdose can occur with beta-carotene, although if you take too much, your skin may turn slightly yellow­orange in color. Beta-carotene does not have the same effect as vitamin A in the body and is not harmful in larger amounts unless your liver cannot convert beta-carotene into vitamin A. People with hypothyroidism often have this problem. It is important to take only natural beta-carotene or a natural carotenoid complex. Betatene is the trade name for a type of carotenoid complex extracted from sea algae. It is used as an ingredient in various products by different manufacturers.

Deficiency Symptoms of Vitamin A

Because vitamin A is fat-soluble, it is stored in the body's fat for a long time, making deficiency uncommon. However, deficiency symptoms of vitamin A includes :-

• Dry hair or skin.
• Dryness of the conjunctiva and cornea.
• Poor growth.
• Night blindness.

Other possible results of vitamin A deficiency include abscesses in the ears; insomnia; fatigue; reproductive difficulties; sinusitis, pneumonia, and frequent colds and other respiratory infections; skin disorders, including acne; and weight loss.

Rich Food Sources of Vitamin A

Vitamin A can be found in animal livers, fish liver oils, and green and yellow fruits and vegetables. Foods that contain significant amounts include apricots, asparagus, beet greens, broccoli, cantaloupe, carrots, collards, dandelion greens, dulse, fish liver and fish liver oil, garlic, kale, mustard greens, papayas, peaches, pumpkin, red peppers, spinach, spirulina, sweet potatoes, Swiss chard, turnip greens, watercress, and yellow squash.

It is also present in the following herbs: alfalfa, borage leaves, burdock root, cayenne (capsicum), chickweed, eyebright, fennel seed, hops, horsetail, kelp, lemon grass, mullein, nettle, oat straw, paprika, parsley, peppermint, plantain, raspberry leaf, red clover, rose hips, sage, violet leaves, watercress, and yellow dock. Animal sources of vitamin A are up to six times as strong as vegetable sources.

Cautions

Antibiotics, laxatives, and some cholesterol-lowering drugs interfere with the absorption of vitamin A.