Holisticonline.com - Vitamin A Knowledgebase

Vitamin/ Mineral Name: Vitamin A

RDA for Men: 1000 mcg. RE or 5000 IU

RDA for Women: 800 mcg. RE or 4000 IU

RDA for Pregnant Women: 1300 mcg. RE or 6500 IU

RDA for Nursing Women: 1300 mcg. RE or 6500 IU - 8000 IU

Daily Value (DV): 5000 IU

Benefit: Required for normal vision in dim light. The first distinctive effect of the lack of Vitamin A is usually night blindness (inability to see under conditions of darkness). The eyes may take a long time to adapt to dim light in theaters or outdoors at night after leaving lighted area. Vitamin A maintains normal structure and function of mucous membranes and helps in the growth of bones, teeth and skin. Vitamin A deficiency may result in dry skin, itchy eyes, and skin rashes and other eye disorders such as corneal ulcers, dry and brittle hair, loss of appetite and weight, sterility, poor growth, and increased susceptibility to infections. Vitamin A and Cancer: Dr. Saffioti reported that hamsters receiving Vitamin A supplemented diet, the development of cancer induced by blowing smoke containing carcinogenic agents was significantly reduced. Although Vitamin A is not a cure for cancer, this experiment showed that it may help prevent or retard the onset of cancer. This effect of Vitamin A is believed to be from the Vitamin's necessity for integrity and efficiency of the epithelial cells and mucous membranes that line the respiratory passages. Well functioning cells here can help protect the body against air-borne cancer producing particles by their mucus flow and cilia action (tiny hairs that brush away damaging matter). Vitamin A also may help prevent bacteria and viruses from obtaining a freehold, thereby protect the body from infectious diseases. Vitamin A is stored in the liver. Liver is a principal organ for the purification of blood. Foreign poisons often collect there to be detoxified, and it is believed that Vitamin A plays an important role in dealing with substances as pesticide and fertilizer residues, industrial poisons and other toxic drugs.

Food Sources: Fish (especially liver oils) butter and liver fats of various animals. Body can manufacture this vitamin from the "carotene" in yellow vegetables, such as carrots and yellow sweet potatoes, and also in green vegetables such as spinach, turnip, dandelion, and beet greens. Other sources for Vitamin A are: Butternut Squash, Tuna, Cantaloupe, Mangoes, Apricots, Broccoli, and Watermelon. However, the availability of carotenes in foods as sources of Vitamin A for humans is low and extremely variable. In carrots, for example, the carotene is within the indigestible cell walls, and only 1% or less may enter the body. In addition to this, the efficiency of conversion of carotenes to Vitamin A may be as low as one-sixth or less. Thus liver, eggs, whole (but not skim) milk, fortified butter, and margarine are the best dietary sources of Vitamin A.

Effect of Overdose: Daily doses of 100,000 IU's have often been administered to adults for months or years without ill effect. Signs of Vitamin A overdose include nausea, irritability, aching bones, headaches, hair loss, increased pressure in the cranium. These disappear rapidly when the intake of the Vitamin is curtailed. There are only a few reported cases of any person suffering adversely from taking too much Vitamin A.

Description: Although normal cooking and heating does not destroy this vitamin, it is believed that borderline deficiencies of this Vitamin is widespread. Many autopsies have found the deficiency in the liver. Vitamin A deficiency can also caused by the lack of other vitamins and minerals such as Vitamin E, protein, the B vitamin choline, fats, and zinc which are needed for its absorption and utilization. Very often supplementary zinc has to be fed to patients to treat Vitamin A deficiency.