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Vitamin A Presentation

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Beth Jones

on 21 November 2012

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Transcript of Vitamin A Presentation

Vitamin A Vitamins are organic substances, which are required in small quantities but cannot be synthesized by the body.
Low levels in the diet of a vitamin will cause a vitamin deficiency disease, which my be fatal if not remedied,
A balanced diet will ensure that the body receives at least its minimum requirement of vitamins.
The body can become adjusted to higher levels of vitamins and can develop deficiency diseases when the level of vitamin intake is lowered to a normal level.
Vitamin A is a versatile vitamin, with roles in gene expression, vision, maintenance of body linings and skin, immune defenses, growth of bones and of the body, and normal development of cells. Vitamin A is a FAT SOUBLE vitamin. Naturally occurring colours... Where can we see this? Vitamin A and Eyesight Night Blindness and Cell Differentiation How can this be used in the Manufacturing process? Vitamin A Deficiency and Toxicity Around the World Retinol (vitamin A) was the FIRST fat-soluble vitamin to be discovered and it occurs ONLY in animal products such as fish oils, dairy products and liver.
However, many green vegetables and carrots contain carotenoid substances which can be converted partially or completely into retinol.
Retinol is one of the active forms of vitamin A made from beta-carotene in animal and human bodies; an antioxidant nutrient. Other active forms are retinal and retinoic acid. Colour compounds are often complex structures. Pigments occurring naturally in foods are often blends of a number of different pigments and a food sometimes has different pigments at different stages of its existence in the 'unharvested state'. For example, a tomato is coloured green with chlorophyll when unripe; this green colour, and chlorophyll, gradually disappears on ripening whilst the red carotenoid, lycopene is synthesised .As animals age their fat becomes more yellow as carotonoids become dissolved in the fat over a long period of time. Carotenoids can readily be seen as the dominant colour of tomatoes, water melons, peaches, peppers, carrots, apricots and spices such as saffron.
The carotenoids are generally stable to heat during processing and cooking but can be readily oxidised in dehydrated foods to form colourless compounds.
The alternating double-single bonds, conjugated double bond system, explains the intense colour of these compounds and their stability in most situations.
Considerable quantities of cartenoids are extracted and used as colours for manufactured foods. However, as the carotenoids are insoluble in water they are often converted into emulsions in water before mixing with a food. The most important applications of cartonoids are in colouring soft drinks, jellies, boiled, sweets, desserts and yogurts. Carotene as a suspension in oil can be used to colour margarine, with the advantage that it adds pro-vitamin A activity to the product. The most familiar function of vitamin A is to sustain normal eyesight.
Vitamin A plays two indispensable roles in the process of light perception at the retina and in the maintenance of a healthy, crystal-clear outer window, the cornea. If the vitamin A supply begins to run low, a lag occurs before the eye can see again after a flash of bright light at night. This lag in the recovery of night vision, termed night blindness, often indicatesa vitamin A deficiency. A bright flash of light can temporarily blind even north well nourished eyes, but if you experience a long recovery period before vision returns, your health-care provider may want to check your vitamin A intake.
Cell Differentiation: Vitamin A is needed by all epithelial tissue (external and internal linings), not just by the cornea. The skin and all those protective linings of lungs, intestines, vagina, urinary tract and bladder serve as barriers to infection and other threats.
An example of vitamin A's health-supporting work is the process of cell differentiation, in which each type of cell develops to perform a specific function.
In short; Cell Differentiation is the process by which immature cells are stimulated to mature and gain the ability to perform functions characteristic of their cell type. Vitamin A deficiency presents a vast problem worldwide, placing a heavy burden on society, Between 3 and 10 million of the world's children suffer from signs of severe vitamin A deficiency - not only xerophthalmia and blindness but diarrhea, appetite loss, and reduced food intake that rapidly worsen their condition.
A staggering 275 million more children suffer from milder deficiency that impairs immunity, leaving them open to infections.
For people who take excess active vitamin A in supplements or fortified foods, toxicity is a real possibility.
The many symptoms of vitamin A toxicity include: nausea, vomiting, diarrhea, joint pain, loss of coordination, rashes, hair loss, stunted growth, possibly irreversible damage to the liver, and enlargement of the spleen.
The earliest symptoms of overdoses include: appetite loss, dizziness, blurred vision, headache, itching of the skin, and irritability. Structure of Retinol When light falls on the eye, it passes through the clear cornea and strikes the cells of the retina, bleaching many molecules of the pigment rhodopsin that lie within those cells. Vitamin A is part of the rhodopsin molecule. When bleaching occurs, the vitamin is broken off, initiating the signal that conveys the sensation of sight to the optic center in the brain.
The vitamin then reunites with the pigment, but a little vitamin A is destroyed each time this reaction takes place, and fresh vitamin A must replenish the supply. Just to review.. Vitamin A is essential to vision, integrity of epithelial tissue, bone growth, reproduction, and more. Vitamin A deficiency causes blindness, sickness, and death and is a major problem worldwide. Overdoses are possible and cause many serious symptoms. Foods are preferable to supplements for supplying vitamin A.
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