Vitamin A is fat-soluble. It requires fats as well as minerals to be properly absorbed by your digestive tract.
It can be stored in your body and need not be replenished every day.
It occurs in two forms—preformed vitamin A, called retinol (found only in foods of animal origin), and provitamin A, known as carotene (provided by foods of both plant and animal origin).
Vitamin A is measured in USP Units (United States Pharmacopeia), IU (International Units), and RE (Retinol Equivalents). (See section 168.) 1,000 RE (or 5,000 IU) is the recommended daily dosage for adult males to prevent deficiency. For females it’s 800 RE (4,000 IU). During pregnancy the new RDIs/RDAs do not recommend an increase, but for nursing mothers an additional 500 RE is suggested for the first six months and an additional 400 RE for the second six months.
There is no formal RDI/RDA for beta-carotene, because it is not (yet) officially recognized as an essential nutrient. But anywhere from 10,000–15,000 IUs of beta-carotene are needed to meet the RDI/RDA for vitamin A.
WHAT IT CAN DO FOR YOU:
Counteract night blindness, weak eyesight, and aid in the treatment of many eye disorders. (It permits formation of visual purple in the eye.)
Build resistance to respiratory infections.
Aid in the proper function of the immune system.
Shorten the duration of diseases.
Keep the outer layers of your tissues and organs healthy.
Help in the removal of age spots.
Promote growth, strong bones, healthy skin, hair, teeth, and gums.
Help treat acne, superficial wrinkles, impetigo, boils, carbuncles, and open ulcers when applied externally.
Aid in the treatment of emphysema and hyperthyroidism.
Xerophthalmia, night blindness.
Deficiency often occurs as a result of chronic fat malabsorption. It’s most commonly found in children under five years, usually because of insufficient dietary intake.
BEST NATURAL SOURCE:
Fish liver oil, liver, carrots, dark green and yellow vegetables, eggs, milk and dairy products, margarine, and yellow fruits. (Note: The color intensity of a fruit or vegetable is not necessarily a reliable indicator of its beta-carotene content.)
Usually available in two forms, one derived from natural fish liver oil and the other water dispersible. Water dispersible supplements are either acetate or palmitate and recommended for anyone intolerant to oil, particularly acne sufferers. 5,000 to 10,000 IU are the most common daily doses.
Vitamin A acid (retin A), which has often been used in the treatment of acne, and is now being marketed as a treatment for eradicating superficial wrinkles, is available only by prescription in the United States.