The of Preformed Vitamin A
All vitamin A is not created equal. Preformed vitamin A, or retinol, is found in animal sources and is easily absorbed by the body. Don't confuse this with provitamin A, or carotenoids, which come from plant sources and which the body has to convert into retinol. Since A is fat-soluble, unlike its vegetable counterpart, it's easier to consume too much. Make sure you monitor your intake, especially if you're taking supplements, as getting too little or too much of the vitamin can result in serious health problems.
Fish Liver Oil
The best concentrated source of preformed vitamin A is the oil taken from fish liver. It usually comes in a capsule, so you don't have to worry about the taste. Fish themselves aren't great sources of vitamin A, but their livers collect and store the vitamin when they eat retinol-rich foods such as algae.
Egg Yolks
Most of the nutrients in an egg are found in the yolk, while the white is mainly protein. Egg yolks are a significant source of vitamin A, as well as other fat-soluble vitamins such as D and E. A whole egg has about 280 IU (international units) of preformed vitamin A.
Liver
Beef and chicken liver are rich in preformed vitamin A, since animals store the vitamin in their liver (as do humans). Eating three ounces of liver will provide you with about 13,000 IU (chicken) or 30,000 IU (beef).
Dairy Products
Whole-fat dairy products are naturally rich in preformed vitamin A, while low-fat or fat-free versions have had the vitamin stripped away in the fat-removal process, though it's often added back. Check products to see if they're "fortified." In fact, fortified foods can have more vitamin A than their whole-fat counterparts: For instance, a cup of fortified skim milk boasts 500 IU; a cup of whole milk has only 305 IU.
Recommended Dose
Adult males over the age of 13 should get 3,000 IU of vitamin A daily. Females of the same age need only 700 IU. However, pregnant women should increase their intake to 770 IU (750 for those younger than 19), and women who breastfeed need as much as 1,300 IU (1,200 for those under 19).
Vitamin A Deficiency
Common signs of vitamin A deficiency include night blindness, a weakened immune system and damaged lung lining. For children, lack of the vitamin slows growth, inhibits bone development and increases the risk of infections.
Hypervitaminosis A
Taking too much vitamin A can result in a condition known as hypervitaminosis A, which occurs when the liver can't store any more of it. This can cause a number of severe symptoms, ranging from blurred vision, dizziness, fatigue and nausea, to vomiting, bone swelling, birth defects, osteoporosis and liver problems.
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