| Vitamin A | |||||
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Vitamin A is a fat-soluble vitamin which is required by the body for a various of processes.
Being a fat-soluble vitamin means that Vitamin A is stored in the body (in the liver mainly, but also the kidneys) when more than required is consumed.
Vitamin A assists the immune system to fight infection and illness by helping cells repair and grow properly. Vitamin A also helps the cells covered with mucous (respiratory tract and digestive tract) stay smooth and wet, in order to ensure they prevent any bacteria or viruses from infecting the body.
Vitamin A exists in the following forms:
- Retinol (main one)
- Retinal
- Retinoic acid
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- Vitamin A is a fat-soluble vitamin
- Beta-carotene, a water-soluble vitamin, is the precursor of Vitamin A
- Vitamin A is destroyed by exposure to light and high temperatures
- Vitamin A is also destroyed when using copper or iron cooking utensils
- Vitamin A can be found pre-formed in animal foods such as egg yolks, meat and fish
- Low vitamin A levels are linked to lowered immunity and various health conditions
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Vitamin A is required for a wide range of body functions, including to help the body cells repair, grow properly and to keep bones and teeth strong.
Various groups are at risk of vitamin A deficiency, such as: people who smoke, people with various illness and infectious diseases, women taking birth control pills, people taking certain drugs and people who are stressed long-term.
references
- Ambalavanan N, Tyson JE, Kennedy KA, et al. Vitamin A supplementation for extremely low birth weight infants: outcome at 18 to 22 months. Pediatrics 2005;115(3):e249-e254
- Barker ME, Blumsohn A. Is vitamin A consumption a risk factor for osteoporotic fracture?. Proc Nutr Soc. 2003;62:845-850
- Bates CJ. Vitamin A. Lancet. Jan 7 1995;345(8941):31-5
- Chang L-C, et al. Retinoic acid induced glandular differentiation of the oesophagus. Gut, Dec 2006 doi:10.1136/gut.2006.097915
- Cox SE, Arthur P, Kirkwood BR, et al. Vitamin A supplementation increases ratios of proinflammatory to anti-inflammatory cytokine responses in pregnancy and lactation. Clin Exp Immunol. 2006 Jun;144(3):392-400
- Fletcher AE, Breeze E, Shetty PS. Antioxidant vitamins and mortality in older persons: findings from the nutrition add-on study to the Medical Research Council Trial of Assessment and Management of Older People in the Community. AJCN, 2003; Vol 78(5): 999-1010
- Genaro Pde S, Martini LA. Vitamin A supplementation and risk of skeletal fracture. Nutr Rev. Feb 2004;62(2):65-7
- Hathcock JN, Hattan DG, Jenkins MY, et al. Evaluation of vitamin A toxicity. Am J Clin Nutr. Aug 1990;52(2):183-202
- Osiecki, Henry, The Nutrient Bible 2002, BioConcepts Publishing
- Wolbach SB, How PR. Tissue Changes Following Deprivation of Fat-Soluble A Vitamin. The Journal of Experimental Medicine 1925, Vol 42, 753-777
To learn more, go to the following web sites:
- Food Standards Australia and New Zealand
- Dieticians Association of Australia
- Nutrient Reference Values (Australia)
