Vitamin A is an important bodybuilding nutrient for animals and human beings. Vitamin A cannot be found free, it is found in several compounds. Vitamin exists in animal foods in the form of alcohol. It is also available in the form of aldehyde as well as acid. Pro-vitamins to vitamin A are available in various plant foods as members of the carotene family. Vitamin A has a Beta-ionone ring where an isoprenoid chain is fixed.
About Vitamin A
The animal form of Vitamin A commonly known as retinol is a yellow-colored fat-soluble, vitamin. It helps in developing great eyesight and bone development. Various other types of vitamin A are used in the preparations of medicines.
Vitamin A was discovered from research activities executed in 1906. It was explored along with other body nutrition elements that help cattle remain healthy. Elmer McCollum of the University of Wisconsin-Madison and Lafayette Mendel and Thomas Osborne of Yale University carried out research works and discovered the fat-soluble Vitamin A.
The intake of Vitamin A is measured in international units (IU) or as retinol equivalents (RE). ( 1 IU is equivalent to 0.3 micrograms of retinol). The production of retinol from provitamins is determined by the amount of retinol present in the body. The amount of absorption of provitamins is based on the number of lipids absorbed with the provitamin. Fats and lipids increase the uptake of provitamin.
Major constituents and Sources of Vitamin A
Some of the major constituents of vitamin A are retinol 1, beta-carotene, alpha-carotene and beta-cryptoxanthin. Carotenoids can be transferred to retinol with the intake of other vitamins like vitamin C, vitamin E, zinc and protein. As recommended by dietitians and nutrition experts, men should consume nine hundred micrograms of vitamin A and women seven hundred micrograms of vitamin A. Vitamin A is found in a variety of natural foods. Some of the foods that have vitamin A in them are carrots, sweet potatoes, broccoli florets, broccoli leaves, spinach, leafy vegetables, collard greens, papaya, peas, beetroot, winter squash, cantaloupe melon, pumpkin, apricots, cabbage, mango, eggs, butter and liver of fish, beef, chicken and turkey.
Deficiency of Vitamin A
Vitamin A deficiency may lead to a series of diseases like night blindness, drying of cornea, triangular spots on eye, corneal degeneration, impaired immunity, hyperkeratosis, hair loss, drying of the mucous membrane, weight loss, fever, insomnia, bone fractures, anemia, diarrhea and softening of the cornea. Again excessive intake of vitamin A can produce a negative result. Intake of excessive vitamin A may lead to nausea, irritability, jaundice anorexia, vomiting, blurry vision, headaches, muscle and abdominal pain and drowsiness. Chronic toxicity occurs with an increased intake of Vitamin A. This may happen due to excessive alcohol consumption. The toxins appear with preformed vitamin A which is a retinoid that is present in various animal livers. The carotenoid forms of Vitamin A do not possess such toxic substances in it. Retinoids are used for treatments of several incurable diseases like retina pigmentation, acute leukemia and various skin diseases. But it is to be noted that retinoid treatments have potential side effects.
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