1. any β-ionone derivative, except provitamin A carotenoids, possessing qualitatively the biologic activity of retinol; deficiency interferes with the production and resynthesis of rhodopsin, thereby causing night blindness, and produces a keratinizing metaplasia of epithelial cells that may result in xerophthalmia, keratosis, susceptibility to infections, and retarded growth;
2. the original vitamin A, now known as retinol.
A fat-soluble vitamin or a mixture of vitamins, especially vitamin A1 or a mixture of vitamins A1 and A2, occurring principally in fish-liver oils, milk, and some yellow and dark green vegetables, and functioning in normal cell growth and development. Vitamin A deficiency can cause damage to epithelial cells, resulting in hardening and roughening of the skin, degeneration of mucous membranes, and night blindness. Also called retinol.
A yellow crystalline compound, C20H30O, extracted from egg yolks, milk, and cod-liver oil.
A golden yellow oil, C20H28O, occurring chiefly in the livers of freshwater fish and having about 40 percent of the biological activity of vitamin A1.
a fat-soluble, solid terpene alcohol essential for skeletal growth, maintenance of normal mucosal epithelium, reproduction, and visual acuity. It is derived from various carotenoids, mainly beta-carotene, and is present in leafy green vegetables and yellow fruits and vegetables as a precursor and is found preformed in fish liver oils, liver, milk, cheese, butter, and egg yolk. Deficiency leads to atrophy of epithelial tissue resulting in keratomalacia, xerophthalmia, night blindness, and lessened resistance to infection of mucous membranes. Symptoms of hypervitaminosis A are irritability, fatigue, lethargy, abdominal discomfort, painful joints, severe throbbing headache, increased intracranial pressure, insomnia and restlessness, night sweats, loss of body hair, and brittle nails. Also called antiinfection vitamin, antixerophthalmic vitamin
vi·ta·min A (vīt'ă-min)
1. Any β-ionone derivative, except provitamin A carotenoids, possessing qualitatively the biologic activity of retinol; deficiency interferes with the production and resynthesis of rhodopsin, thereby causing night blindness, and produces a keratinizing metaplasia of epithelial cells that may result in xerophthalmia, keratosis, susceptibility to infections, and retarded growth.
2. The original vitamin A, now known as retinol.
vitamin A or
retinol a fat-soluble hydrocarbon, closely related to CAROTENOIDS, that occurs in liver, green vegetables and storage organs such as carrots. It can be produced in the body from the pigment 3-carotene. It is concerned with the normal functioning of the mucous membrane of the eye, respiratory and urinogenital tracts, and forms part of the photochemical reactions in the RODS of the eye. Deficiency of vitamin A leads firstly to night blindness then xerophthalmia, inflamed eyes and eyelids and eventual blindness. The lining of the respiratory tract can become inflamed. Infants obtain a large supply of the vitamin in the mother's first milk (COLOSTRUM).
vitamin A beta-ionine derivative with biological activity of retinol; deficiency causes keratosis, increased susceptibility to infections, night blindness and growth retardation
n a fat-soluble vitamin found in dark-colored vegetables and fruits, meats, dairy products, and whole eggs. Has been used to treat deficiencies, viral infections, and skin disorders. Contraindicated for pregnant women (beta-carotene is recommended instead), especially those taking valproic acid and for patients taking warfarin or isotretinoin. Also called
vi·ta·min A (vīt'ă-min)
1. Any β-ionone derivative, except provitamin A carotenoids, possessing qualitatively the biologic activity of retinol; deficiency interferes with production and resynthesis of rhodopsin, thereby causing night blindness.
2. Retinol, original vitamin A.
a fat-soluble, organic alcohol formed in animal tissues from carotenoids found in plants. Called also retinol. It is formed from carotenoids, principally carotene, in the intestinal epithelium, except by cats, and stored in the liver. It is essential for the proper growth and maintenance of surface epithelium, for the accurate sculpting and proper growth of bones, and for the maintenance of light-sensitive pigments in the eye.
Nutritional deficiency due to lack of carotene in the diet in herbivores and to lack of carotene and preformed vitamin A in the diet in omnivores and carnivores causes hypovitaminosis A. The resulting clinical syndrome varies with species and age. In young animals there is compression of the brain and spinal cord caused by faulty bone growth and characterized by convulsions, blindness and posterior paralysis. In other animals there is night blindness, corneal keratinization, pityriasis, hoof defects, infertility and possibly congenital defects.
Hypovitaminosis in birds is manifested by poor egg production, ocular discharge at first watery then thick and caseous, a nasal discharge and pustular lesions and accumulations of caseous material in the mouth, pharynx, esophagus and trachea.
vitamin A A2
called also dehydroretinol and found in fish livers. Has the same effects and efficiency as retinol; it is absorbed unchanged and is immediately metabolically active.
vitamin A A-responsive dermatosis
seborrhea, particularly in Cocker spaniels, is sometimes found to be responsive to vitamin A.
teratogenic vitamin A A
causes abnormalities in closure of the neural tube in the developing fetus causing defects in the brain, eye and heart.
Patient discussion about vitamin A
Q. Can a food rich in vitamin B12 will help for his depression or vitamin B12 pills are always required? Hi all…..having one question related to my friends depression and its relation to vitamin B12, as a medicine given to him by his Doctor. Can a food rich in vitamin B12 will help for his depression or vitamin B12 pills are always required?
A. Yes low level of vitamin B12 is associated with depression. You can complete its deficiency by having good diet which will cover the B12 requirements. What happens that depressed people tend to eat less of healthy food and which reduces the B12. So, it again reduces the capacity to fight against the depression.
Q. Can someone give me some information on over intake of Vitamin A and its complications in future? I am having short sightedness. I am wearing specks for the past 3 years. Last week my eye sight had doubled. I never thought to control my eye sight by having a good diet, which is rich in vitamin A. Now I am willing to have vitamin A in tablets and I doubt the adverse effects if taken in excess. Can someone give me some information on over intake of Vitamin A and its complications in future?
A. Having tablets will fortify you with vitamin A but long term intake will lead to show the side effects of over intake. You can have these vitamin tablets as per your doctor’s prescription. But you must have them as a diet intake which will keep your vitamin intake balanced and will not lead to any complications. But the over intake of vitamins can lead to vitamin A toxicity. This can show symptoms as fatigue, muscle pain, depression, Fever and liver anemia.
Q. What is a normal Vitamin D level in an 84 year old woman? How would one correct a level of 50 in a Vitamin D level test?
A. More discussions about vitamin A