Night blindness, vitamin A deficiency

In this period, the empirical healing of certain diseases by foods was estabUshed. Examples (3) were the treatment of night blindness (vitamin A deficiency) with hver ia many cultures over centuries, of beriberi (vitamin deficiency) by use of unpoHshed rice by the Japanese navy, of scurvy (vitamin C deficiency) by citms fmits ia the British navy or piae needle extracts by North American natives, and pellagra (niacia deficiency) by a dietary shift away from corn-based foods ia many countries. Other, nondietary empirical treatments iavolved, eg, exposure of children ia northern latitudes to sunlight to cute tickets (vitamin D deficiency) (4). 

It is indicated in night blindness, vitamin A deficiency (in infants, in pregnancy, lactation, malabsorption syndrome), for prophylaxis of vitamin A deficiency, acne, ichthyosis, psoriasis, xerophthalmia, Bitot s spots (especially children). 

In this period, the empirical healing of certain diseases by foods was established. Examples (3) were the treatment of night blindness (vitamin A deficiency) with liver in many cultures over centuries, of beriberi (vitamin deficiency) by use of unpolished rice by the Japanese navy, of scurvy (vitamin C... 

A deficiency of vitamin A leads to vision defects, e.g. night blindness. Vitamin A is quite unstable and sensitive to oxidation and light. Excessive... 

In humans, vitamin A deficiency manifests itself in the following ways night blindness, xerophthalmia, Bitot s spots, and corneal involvement and ulceration. Changes in the skin have also been observed. Although vitamin A deficiency is seen in adults, the condition is particularly harmful in the very young. Often, this results from malnutrition (56). 

Patients with vitamin A deficiency may report visual disturbances, night blindness, and dry skin. 

A deficiency of vitamin A results in night blindness. A chronic deficiency results in a thickening of membranes in the cornea which, if untreated, can lead to blindness through perforation of the cornea and loss of the lens. It is estimated that half a million children develop blindness due to vitamin A deficiency every year. Refeeding malnourished children can produce a deficiency of vitamin A (see below). 

Vitamin A deficiency can result from insufficient dietary intake, from malabsorption and it has been recognized that also malfunction of RAR-receptors can lead to symptoms of vitamin A deficiency. These symptoms include skin lesions, night blindness, corneal ulcerations and conjunctivitis and poor bone remodeling. Vitamin A deficiency associated with malnutrition is wide spread in large parts of the world and may be fatal in infants and young children suffering from kwashiorkor or marasmus. 

L B. Supplement with vitamin A. Vitamin A deficiency symptoms include night blindness that can lead to corneal ulceration. This deficiency can occur in patients with impaired liver storage or fat malabsorption. Dairy products, such as milk, are a good source of vitamin A. (3-Carotene, a vitamin A precursor, is found in pigmented vegetables, such as carrots. When a deficiency is diagnosed, it is appropriate to treat the patient with a supplement rather than to rely on increased consumption of vitamin A-rich foods. A patient with pancreatic disease and malabsorption syndrome will need parenteral supplementation. 

Vitamin A is necessary for growth and reproduction, resistance to infection, maintenance and differentiation of epithelial tissues, stability and integrity of membrane structures, and the process of vision. In terms of the last function, vitamin A is a component of rhodopsin or visual purple, a photosensitive pigment in the eye that is needed for vision in dim light. An early mild clinical symptom of vitamin A deficiency is night blindness a severe deficiency of this fat-soluble vitamin results in xerophthalmia, an eye condition leading to blindness. 

A strikingly early symptom of vitamin A deficiency is night blindness. A variety of other symptoms include dry skin and hair, conjunctivitis of the eyes, retardation of growth, and low resistance to infection. The skin symptoms are particularly noticeable in the internal respiratory passages and alimentary canal lining. About 0.7 mg/day of vitamin A is required by an adult. The content of vitamin A in foods is often expressed in terms of international units 1.0 mg of retinol equals 33331.U. 

Cystic fibrosis patients are usually advised to take more than the recommended daily amounts of these vitamins in order to prevent deficiency. A common problem associated with poor absorption of fat-soluble vitamins is deficiency of vitamin K. Vitamin K is required by the liver to produce many blood coagulation factors. Part of the problem for cystic fibrosis patients is their chronic antibiotic therapy, which decreases the bacterial population of the colon colonic bacteria synthesize vitamin K. Vitamin K deficiency leads to prolonged blood-clotting time. Vitamin D deficiency could cause rickets in a child or osteomalacia in adults. Vitamin A deficiency leads to night blindness, skin and other ocular defects. 

A typical RA-receptor is the receptor fiar vitamin A (all-mtws retinol). Vitamin A is essential for pre-and postnatal development. Congenital vitamin A deficiencies are accompanied by a broad spectrum of malformations. In adult life, vitamin A is indispensable for growth, maintenance, and survival of many tissues. It is necessary for vision and reproduction. A lack of vitamin A in the adult causes night blindness and photoreceptor degeneration. But the devel-... 

DEFICIENCY Vitamin A deficiency results in night blindness and xerophthalmia (dry cornea and conjunctiva, sometimes with ulceration of the cornea). Nonocular changes may also occur dry skin and mucous membranes. Deficiency may result from poor dietary intake, or poor absorption, as from bowel disease, or a defect in bile flow that causes fet malabsorption. Poor protein intake may result in a reduced level of the transport protein that carries vitamin A in the blood stream. 

Night blindness—Inability to see at night due to a vitamin A deficiency. 

Early symptoms of vitamin A deficiency are night blindness and dry eyes. Excessive doses of vitamin A cause headaches, dizziness, a sore mouth, skin desquamation, and hair loss. 

Treats vitamin A deficiency, prevents night blindness, treats skin disorders, promotes bone development... 

This condition leads to permanent blindness in about half of cases, and many of those affected are preschool children. Night blindness occurs early in vitamin A deficiency. There is a reduction in rhodopsin concentration, followed by retinal degeneration and loss of photoreceptor cells. Degenerative changes may be due to instability of free opsin or may indicate an additional nutritive function for retinaldehyde (or retinoic acid) in retinal cells. The degenerative changes of retinitis pigmentosa, a relatively common, inherited cause of blindness, closely resemble those of vitamin A deficiency. 

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