Mar 7, 2012

THE SKINNY ON VITAMIN A


remember those stories as a kid about eating carrots and developing a super-power of enhanced night vision?! well its true!
dietary carotenoids (like β-carotene), found in carrots, are dietary precursors of retinol (pre-formed vitamin A). vitamin A is important in the maintenance of normal vision - so hey-presto! eating carrots (which contain β-carotene) = improved vision! 

just to make that science-y stuff a bit clearer... precursor = building block and pre-formed = ready-made 

now! vitamin A is not only great for improving vision but is also important in the maintenance of normal reproduction and immunefunction and, as previously noted, comes in a number of forms

preformed vitamin A (or retinol) is found only in animal-derived foods, whereas dietarycarotenoids are found primarily in oils, fruits and vegetables - the vegan-friendly options!

as a vegan you will therefore be looking to access vitamin A via these dietary carotenoids, however it is important to be mindful of their retinol equivalent (RE) value (how much you need to consume to get the enough to make the vitamin A you need)

to simplify... to get 1μg (microgram) of RE you need to consume 1 μg of retinol (animal-derived); or 6 μg of β-carotene; or 12 μg of α-carotene, β-cryptoxanthin and/or otherprovitamin A carotenoids 

 so how much vitamin A do we need each day? well... men should aim for 625 μg/day (EAR*); 900 μg/day (RDI^); and women should try and achieve 500 μg/day(EAR*); 700 μg/day (RDI^)

 the australian national health and medical research council (NHMRC) have not only established the above EAR and RDI values, but gone further and devised a suggested dietary target (SDT) for vitamin A in order to reduce chronic disease risk - promoting an intake of 5,800μg of carotenes for men and 5,000μg of carotenes for women. these intakes can be achived by replacing nutrient-poor, energy-dense foods and drinks with plenty of red-yellow vegetablesand fruits, as well assmall amounts of vegetable oils.

* EAR: estimated average requirement - a daily nutrient level estimated to meet the requirements of half the healthy individuals in a particular life stage and gender group

^ RDI: recommended dietary intake - the average daily dietary intake level that is sufficient to meet the nutrient requirements ofnearly all (97–98 per cent) healthy individuals in a particular life stage and gender group

source: Australian Government Department of Health and Aging, New ZealandMinistry of Health and National Health and Medical Research Council.Nutrient reference values for Australia and New Zealand. Availablefrom http://www.nhmrc.gov.au/publications/

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