Vitamin A and Beta-Carotene Facts

Vitamin A Fact: What is it? Vitamin A is fat soluble, it is an antioxidant and occurs in two forms - retinol and carotene. The RDA [Food and Nutrition Board, National Academy of Sciences - National Research Council - Recommended Dietaty Allowances. ] for adults is 1000 micrograms RE (Retinol Equivalents. 1 RE = 1 microgram retinol or 6 micrograms §-carotene).

Vitamin A Fact: What are recommended intakes? The allowances, expressed as average daily intakes over time, are intended to provide for individual variations among most normal persons as they live in the United States under usual environment stresses.

Because vitamin A and carotene exist in more than one chemical form, and because they are not equally active, it is usual to give the name retinol to the pure vitamin A. Thus the total vitamin A activity of a food, its retinol equivalent, is determined by how much it contains of retinol, chemicals very similar to retinol but not as active, and a range of carotenes also of varying activity.

Vitamin A maintains the skin and mucous membranes. Promotes growth, strong bones, healthy skin, hair, teeth and gums. Builds up resistance to respiratory infections and shortens the duration of diseases. It counteracts night blindness and aids in the treatment of many eye disorders. Night blindness is an early symptom of a deficiency of vitamin A.

In a dozen case-control and cohort studies, intakes of fruits and vegetables containing carotenoids has been associated with a reduced risk of lung cancer. In contrast little relationship has been found between intake of preformed vitamin A (retinol) and this disease.

Available data thus strongly support the hypothesis that dietary carotenoids reduce the risk of lung cancer, but the data also are compatible with the possibility that some other factor in these foods is responsible for the lower risk. The recommendation to eat a variety of fruits and vegetables is reasonable, but leaves much to chance; if ß-carotene is the anticancer agent, intake of specific fruits and vegetables should be advised. [Willett, W.C., Vitamin A and lung cancer , Nutrition Reviews, 48:201, 1990]

The best natural sources are green leafy vegetable tops, carrots, red peppers, sweet potatoes, yellow fruits, apricots, fish-liver oil and eggs.

Vitamin A is one of the few vitamins in which excess produces definite and severe effects. Toxic symptoms can occur with intake exceeding 100 000 IU's daily. Hypervitaminosis A leads to loss of appetite, a dry, itchy skin often with peeling, intense headaches and an enlarged liver. Recovery is fairly rapid when intake is reduced.

Buy Vitamins Online