Question

what are the effects of vitamin a

Answer 1

Vitamin A is a vitamin. It can be found in many fruits, vegetables,eggs, whole milk, butter, fortified margarine, meat, and oily saltwater fish. It can also be made in a laboratory.Vitamin A is used for treatingvitamin A deficiency. It is also used to reduce complications of diseases such asmalaria, HIV,measles, anddiarrheain children with vitamin A deficiency.Women use vitamin A for heavy menstrual periods,premenstrual syndrome(PMS), vaginal infections,yeast infections, “lumpybreasts” (fibrocystic breast disease), and to preventbreast cancer. Some women with HIV use vitamin A to decrease the risk of transmitting HIV to the baby duringpregnancy,childbirth, or breast-feeding.Men use vitamin A to raise theirsperm count.Some people use vitamin A for improvingvisionand treating eye disorders including age-relatedmacular degeneration(AMD),glaucoma, andcataracts.Vitamin A is also used for skin conditions including acne,eczema,psoriasis,cold sores, wounds, burns,sunburn,keratosis follicularis(Darier’s disease),ichthyosis(noninflammatoryskin scaling),lichen planuspigmentosus, andpityriasis rubra pilaris.It is also used for gastrointestinal ulcers, Crohn’s disease, gum disease,diabetes, Hurler syndrome(mucopolysaccharidosis), sinus infections, hayfever, andurinary tract infections(UTIs).Vitamin A is also used for shigellosis, diseases of thenervous system, nose infections, loss of sense of smell,asthma, persistent headaches,kidney stones, overactivethyroid, iron-poor blood (anemia),deafness, ringing in the ears, and precancerous mouth sores (leukoplakia).Other uses include preventing and treatingcancer, protecting the heart and cardiovascular system, slowing the aging process, and boosting the immune system.Vitamin A is applied to the skin to improve wound healing, reducewrinkles, and to protect theskin against UVradiation.

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Answer 2

The acute and chronic effects of vitamin A toxicity are well documented in the literature. Emerging evidence suggests that subtoxicity without clinical signs of toxicity may be a growing concern, because intake from preformed sources of vitamin A often exceeds the recommended dietary allowances (RDA) for adults, especially in developed countries. Osteoporosis and hip fracture are associated with preformed vitamin A intakes that are only twice the current RDA. Assessing vitamin A status in persons with subtoxicity or toxicity is complicated because serum retinol concentrations are nonsensitive indicators in this range of liver vitamin A reserves. The metabolism in well-nourished persons of preformed vitamin A, provided by either liver or supplements, has been studied by several research groups. To control vitamin A deficiency, large therapeutic doses are administered in developing countries to women and children, who often are undernourished. Nevertheless, little attention has been given to the short-term kinetics (ie, after absorption but before storage) of a large dose of vitamin A or to the short- and long-term effects of such a dose given to lactating women on serum and breast-milk concentrations of retinol and its metabolites. Moreover, appropriate dosing regimens have not been systematically evaluated to ascertain the quantitative improvement in vitamin A status of the women and children who receive these supplements. The known acute and chronic effects of vitamin A toxicity have been reported previously. However, further research is needed to ascertain the areas of the world in which subclinical toxicity exists and to evaluate its effects on overall health and well-being.