i found this blurb that does a great job discussing Vitamin A vs synthetic vitamin A. and should assist ones understanding when reading conflicting information on Vitamin A publicized by main stream communities.

Vitamin-A
Vitamin-A was the first fat-soluble vitamin to be discovered. In 1919, it was recognized that egg yolk contained a fat-soluble substance essential for life. In 1924, it was demonstrated that the eye disease, xerophthalmia, in children could be prevented by feeding them butter or cod liver oil. Vitamin-A was purified--separated from its natural constituents--and its refined chemical structure proposed in 1931. Synthesis, an artificial chemically-pure duplication, was accomplished in 1947 at Hoffman-LaRoche, a pharmaceutical company in Switzerland. Vitamin-A is actually a whole family of compounds, including retinol, retinal, retinoids, carotenes, and carotenoids, and always occurs in nature with synergists such as fatty acids, chlorophyll, other vitamins, enzymes, minerals, and trace elements. Retinol, retinal, and retinoids are found in foods of animal origin such as eggs, liver, fish, butter, and cheese.

The scientific term for vitamin-A is retinol, because of its presence in the retina of the eye. The role of retinol in vision was elucidated by a number of brilliant scientists, beginning in 1877 with a German, W. Kuhne, who discovered that the purple retinas from dark-adapted frogs turned yellow when exposed to light. The purple color is restored in a complex biochemical cycle involving vitamin-A, which makes vision possible. Other scientists demonstrated the role of vitamin A in cell differentiation, bone development, reproduction and immune system function. Dr. Weston Price confirmed the value of vitamin-A in traditional diets during his studies of primitive peoples carried out during the 1930s and 1940s. Due to the outstanding scientific work of these and many other researchers, the administration of cod liver oil to growing children--a tradition found among Arctic peoples such as the Scandinavians and Eskimos--became standard practice until after the Second World War.

In recent decades, much vitamin-A research has focused on its role in preventing cancer, and its use in combination with nontoxic therapies in the treatment of cancer. Dr. Max Gerson treated many cases of terminal cancer with excellent results, using raw liver juice, a rich source of vitamin-A. Modern confinement farming practices effectively prevent vitamin-A from incorporation into animal foods and the processing industry would rather use vegetable oils than animal fats. Some vegetable oils contain carotenes but they do not contain true vitamin-A. Only animal fats contain vitamin-A and vitamin-A is present in large amounts only when the animals have a source of carotenes or vitamin-A in the diet, such as green pasture, insects, and fish meal. Many popular books on nutrition insist that humans can obtain vitamin-A from fruits and vegetables. Even worse, FDA regulations allow food processors to label carotenes as vitamin-A. Vitamin-A from butter may be two or three times as potent, unit for unit, as vitamin-A from cod liver oil in some people.

The food industry, and the low-fat school of nutrition that the industry has spawned, benefit greatly from the fact that the public has only vague notions about vitamin-A. In fact, most of the foods that provide large amounts of vitamin-A--butter, egg yolks, liver, organ meats and shellfish--have been demonized. Under optimal conditions, humans can indeed convert carotenes to vitamin-A. This occurs in the upper intestinal tract by the action of bile salts and fat-splitting enzymes. Of the entire family of carotenes, beta-carotene is most easily converted to vitamin-A. The accepted ratio of how many units of beta-carotene is needed to produce one unit of vitamin-A is 6:1 and some research suggests an even higher ratio. This means that you have to eat an awful lot of vegetables and fruits to obtain even the daily minimal conversion. But the transformation of carotene to retinol is rarely optimal. Strenuous physical exercise, periods of physical growth, pregnancy, lactation and infection are stresses that quickly deplete vitamin-A stores.

Diabetics and those with poor thyroid function, which could include at least half the adult U.S. population, cannot make the conversion. In fact, the thyroid gland requires more vitamin-A than the other glands, and cannot function without it (mercury toxicity diminishes the thyroid and pituitary glands' functions). And a diet rich in vitamin-A will help protect the diabetic from the degenerative conditions associated with the disease, such as problems with the retina and with healing (mercury binds with the sulfur in insulin). Children make the conversion very poorly and infants not at all--they must obtain their precious stores of vitamin-A from animal fats--yet the low-fat diet is often recommended for children. Vitamin-A from animal sources (retinol) is primarily absorbed within three to five hours after ingestion in the upper intestinal tract; it is here that the fat-splitting enzymes and bile salts convert carotenes into usable nutrients, though conversion and assimilation takes up to six or seven hours. Carotenes are converted by the action of bile salts (mercury inhibits production of taurocholic acid, a bile salt) and very little bile reaches the intestine when a meal is low in fat. The conversion of carotenes is stimulated by thyroxine, a hormone secreted by the thyroid gland. Zinc, iron, and vitamin-E status also influences carotene conversion. Once converted, the carotenes are absorbed in the same way as retinol and allocated by the liver. Unabsorbed carotene is excreted in the feces.

Butterfat stimulates the secretion of bile needed to convert carotenes from vegetables into vitamin-A, and at the same time supplies very easily absorbed true vitamin-A. Polyunsaturated oils also stimulate the secretion of bile salts but can cause rapid destruction of carotene unless antioxidants are present. It is very unwise, therefore, to depend on plant sources for vitamin-A. This vital nutrient is needed for the growth and repair of body tissues; it helps protect mucous membranes of the mouth, nose, throat and lungs; it prompts the secretion of gastric juices necessary for proper digestion of protein; it helps to build strong bones and teeth and rich blood; it is essential for good eyesight; it aids in the production of RNA; and contributes to the health of the immune system. Strenuous physical exercise, excessive consumption of alcohol, excessive consumption of iron (especially from "fortified" white flour and breakfast cereal), use of a number of popular drugs, excessive consumption of polyunsaturated fatty acids, zinc deficiency and even cold weather can hinder the conversion of carotenes to vitamin-A, as does the low-fat diet.

Natural vitamin-A provided by liver, eggs, butter, cream and cod liver oil is well recognized as providing excellent protection against birth defects. Vitamin-A deficiency in pregnant mothers results in offspring with eye defects, hydrocephalus, displaced kidneys, harelip, cleft palate and major malformations of the heart and large blood vessels. Vitamin-A stores are rapidly depleted during exercise, fever and periods of stress. Vitamin-A deficiencies are widespread and contribute to high infant mortality, blindness, stunting, bone deformities and susceptibility to infection. These occur even in communities that have access to plentiful carotenes in vegetables and fruits. It is required for cellular differentiation (determines the function that cells will have): this assures that the cells which are lost from natural turnover, stress, insult, injury, disease, etc. are reproduced in the exact same form as the ones being replaced. Growing children actually benefit from a diet that contains considerably more calories as fat than as protein. Generous amounts of vitamin-A insure healthy reproduction and offspring with attractive wide faces, straight teeth and strong sturdy bodies. This vitamin assists in normal pregnancy, embryonic development, successful reproduction, fertility, lactation (nursing), and reproductive organ function, spermatogenesis, to adrenal, thyroid, and other gland functions. Vitamin-A is important for normal eyesight; necessary for night vision. A high-fat diet that is rich in vitamin-A will result in steady, even growth, a sturdy physique and high immunity to illness. Vitamin-A-rich foods like liver, egg yolk, cream and shellfish confer resistance to infectious diseases in children and prevent cancer in adults.

Children with measles rapidly use up vitamin-A, which can result in irreversible blindness. An interval of three years between pregnancies, allows mothers to rebuild vitamin-A stores so that subsequent children will not suffer diminished vitality. Kwashiorkor is as much a disease of vitamin-A deficiency, leading to impaired protein absorption, as it is a result of absence of protein in the diet. High-protein, low-fat diets are especially dangerous because protein consumption rapidly depletes vitamin-A stores. Children brought up on high-protein, low-fat diets often experience rapid growth. The results--tall, myopic, lanky individuals with crowded teeth, and poor bone structure, are commonplace in America. High-protein, low-fat diets can even cause blindness. Scarcity of good quality raw dairy products, a rejection of organ meats as old fashioned or unhealthful, and a substitution of vegetable oil for animal fat in cooking all contribute to the physical degeneration and suffering of Third World peoples. Supplies of vitamin-A are so vital to the human organism that mankind is able to store large quantities of it in the liver and other organs. Even people who can efficiently convert carotenes to vitamin-A cannot quickly and adequately replenish vitamin-A stores from plant foods. Many factors interfere with its absorption and utilization. Inadequate fat in the diet, poor production of bile salts, low enzyme status, and compromised liver function can all interfere with the uptake and usage of vitamin-A, especially when given as a supplement in the form of retinol, rather than as a component of whole foods. One tablespoon of cod liver oil contains at least 15,000 IU and one serving of liver (should be from organically raised animals) can contain up to 40,000 IU vitamin-A. Foods high in vitamin-A are especially important for diabetics and those suffering from thyroid conditions. Weston Price considered the fat-soluble vitamins, especially vitamin-A, to be the catalysts on which all other biological processes depend. Efficient mineral uptake and utilization of water-soluble vitamins require sufficient vitamin-A in the diet.

retinol-binding protein. The necessity of enzymes, trace mineral activators, amino acids, and other constituents stresses the point that the whole food comple

Synthetic Vitamin-A
Synthetic vitamin-A interferes with the proper utilization of natural vitamin-A from foods. Pure retinol is added to many fabricated foods like margarine, white flour, extruded breakfast cereals and pizza. A synthetic retinoic acid derivative, isotretinoin (Accutane) is used to treat acne as well as psoriasis, cancer, and oral leukoplakia. Children whose mothers took Accutane during pregnancy were born with nervous system defects, brain damage, congenital heart disease, and more. Depression, crying spells, malaise, and forgetfulness are reported human symptoms. Inflammation of the lips (cheilitis) develops in 90% of the users; conjunctivitis develops in 40%. Muscle damage has also been added to the list. The synovial membranes in joints are supported by vitamin-A. The vitamin-A complex is supportive to the adrenal glands which produce cortisone and other needed hormones; and vitamin-A plays an important role in any inflammation and repair process. Vitamin-A is important to the external and internal mucous membrane tissues as well as to the immune system. However, synthetic retinoic acid metabolites do not reveal any specific supportive mechanism and results are not seen with synthetic, altered fractions.

The whole vitamin-A complex is known to be very functional, but when distilled or synthetic fractions are used, roles and results are questionable at best. Megadoses of synthetic vitamin-A can result in hypertrophy (excessive growth) of the liver and spleen, with elevation of AST (aspartate aminotransferase), a liver enzyme. Liver fibrosis (abnormal formation of fibrous tissue), fat deposition, obstruction of portal blood flow with portal hypertension (high blood pressure) and sclerosis (hardening) of the blood vessels have been found at liver biopsies. Excess synthetic vitamin-A is also associated with calcium deposits in soft tissues, contributes to attacks of gouty arthritis, hair loss, irregular menses, emotional lability, insomnia, restlessness, night sweats, and more. Vitamin-A is essential to spermatogenesis, the production of sperm in men, and it requires alcohol dehydrogenase, an enzyme to convert retinol to retinal. This enzyme may require the trace element, zinc, as well. Excessive doses of synthetic fractions of vitamin-A can convert to a compound that can be more damaging than a deficiency in its effect on the germinal epithelium of the testes. Vitamin-A is present in almost twice the amount in seminal fluid of highly fertile men compared with that of men deficient in sperm. Zinc increases vitamin-A uptake by the seminiferous tubules of the testes. Vitamin-A is bound to a protein, called x is important and effective whereas an isolated portion cannot produce the same results. Excessive fractionated "vitamins" A and E may produce testicular hemorrhaging. Zinc is required to maintain normal concentrations of vitamin-A in the blood plasma.

Diabetic persons tend to have decreased levels of zinc. Since a zinc deficiency may lead to difficulties mobilizing vitamin-A from the liver for use elsewhere in the body, vitamin-A deficiency will worsen the condition. Another essential constituent is fat, as vitamin-A occurs in foods with fatty acids and is a fat-soluble vitamin. It is absorbed much better when natural, unaltered fats are also present. Other fat-soluble vitamins occur with and work with whole vitamin-A complex such as vitamin E complex and essential fatty acids. When vitamin E is deficient, one develops low blood levels of vitamin-A; when vitamin E is restored to the diet, vitamin-A levels become normal. Yet, using chemically-pure fractions of "vitamins" A and E in large doses creates more problems, more imbalances. Fractionated alpha-tocopherol (so-called vitamin-E) can supplant vitamin A in the body, reducing its effectiveness. Administration of the whole food complex brings excellent responses. Stubborn cases of gastrointestinal irritation and even ulceration in the digestive tract that failed to respond to other treatments have totally resolved after use of real vitamin-A complex. Persons with cystitis (inflammation of the bladder) experience relief after a relatively short time taking food concentrates of Vitamin-A and other supportive nutritional complexes. Edema caused by liver pathology is another instance where vitamin-A complex is of particular value; the liver is the chief location of vitamin-A stores. Colds, chronic rhinitis, sinusitis, psoriasis, and many other conditions--especially those involving epithelial tissues--are responsive to the whole vitamin-A complex.

A new strategy that has been the development of and promotion of genetically engineering rice to produce carotenes. Golden rice containing carotenes can't provide true vitamin-A to the world's children but it will further the trend of pushing their parents off the farm and into ghastly slums. The most effective response that consumers have is to boycott processed foods!