The
effects of Vitamin A
Vitamin A has a very important role in:
vision (retinal- retina, rod cells & rhodopsin)
ssue repair, hormone synthesis,
antioxidant (in beta-carotene form),
bone growth, reproduction, cell division, cell differentiation (This is the process by where a cell decides what it is about to become)
maintains surface lining of eyes & respiratory system along with the urinary, and intestinal tract (When these linings are deficient in vitamin A, bacteria can easily enter the body and cause infection. )
helps regulate immune system (The immune system fights bacteria and infections by making white blood cells to destroy the bacteria and viruses. Vitamin A also makes lymphocytes-type of white blood cell-stronger so they can function more effectively)
helps maintain integrity of skin & mucous membrane (This helps prevent bacteria from the skin to enter the body)
Deficiency
Vitamin A deficiency does not occur too frequently within the US, but still maintains to be a major problem throughout the world. In developing countries there are about 3 to 10 million children who develope xeropthalmia. About 250,000 to 500,000 go blind from this form of deficiency each year. Iron deficiency can also limit the metabolism of vitamin A. When there is a vitamin A deficiency, many dangerous things can occur:
Night blindness (Night blindness is one of the very first signs of vitamin A deficiency) Deficiency of vitamin A leads to blindness by making the eye very dry, which promotes damage to the retina of the eye.
Stunting of growth
Problems with skin, epithelial cells in respiratory, digestive & genitourinary tracts (Vitamin A is absolutely necessary for the synthesis of substances in mucous produced by the epithelial tissues. A deficiency in this leads to infection or hard keratinized skin.) But the mechanism for this process is still unknown.
Abnormalalities of ename-forming cells of teeth
Abortion
Xeropthalmia (This is the damage to the cornea of the eye)
Excess alcohol intake can easily deplete vitamin A from the body. It is associated with reduced vitamin A intake.
Toxicity / Excess
Red blood cell damage, abdominal cramps, blurred vision, irritability, bone pain, loss of appetite, diarhhea, nose bleeds, growth retardation, hair loss, skin rashes, dry skin, liver disease, nausea, vomitting, headache and increased cerebrospinal pressure.
Forms of vitamin A that come form animal sources such as retinol, retinal or retinoic acid, can become toxic very high dosages. It is important that children are not given adult strength vitamin A supplements that contain high amounts.
Cats can be intoxicated by excess vitamin A. This usually happens when they're fed liver.
The symptoms of toxicity of vitamin A include dermatitis, weight loss, and skin thickening.
Excess of vitamin A rarely happens when eating natural vitamin A rich foods. What does happen is the excess of vitamin A taken through supplements.