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Vitamin A (Retinol)
Vitamin A is important in maintaining good vision, healthy skin, and healthy mucous membranes. Research has shown it is also necessary for proper immune system function. Vitamin A is also important for proper growth, bone formation, reproduction, and wound healing. Your liver can store up to a year's supply of vitamin A. The stored supply of this vitamin is used up more quickly if you become ill or have an infection.
Vitamin A is found only in foods from animal sources, especially beef, calf, and chicken liver. Dairy products such as milk, butter, cheese, and ice cream are also good sources. However, beta-carotene, a nutrient found in fruits and vegetables, can be converted to vitamin A in the body as needed. Most dark-green leafy vegetables and most orange vegetables and fruits contain a lot of beta-carotene, and by eating these foods you will increase your body's supply of vitamin A. Vegetables such as sweet potatoes, carrots, and winter squash, and fruits such as cantaloupe and mango are all good sources of beta-carotene.
You can buy natural vitamin A supplements either as retinol or retinyl palmitate. All forms of vitamin A are easily absorbed. Tablets or capsules are available in 10,000 IU, 25,000 IU, and 50,000 IU doses. Your health care provider will help you decide which vitamin A dosage is best for you. Most multivitamins contain the recommended dietary allowance (RDA) for vitamin A. If you are taking a multivitamin, you are probably getting more than enough vitamin A to meet your average needs. You should never take more than 25,000 IU per day (10,000 IU for children) without a health care provider's supervision.
In many cases, taking beta-carotene, the precursor form of vitamin A, is a safer alternative to taking vitamin A. Unlike vitamin A, beta-carotene is water-soluble and does not build up in the body, so it can be taken in larger amounts without the same risk. This makes it a better alternative for children, adults with liver or kidney disease, and pregnant women.
How to Take It
Vitamin A is a fat-soluble vitamin and is absorbed along with the fat in your diet. Supplements containing vitamin A should be taken during or shortly after a meal.
Pregnant women should never take vitamin A supplements, because they can cause birth defects. All prenatal vitamins contain some vitamin A, and taking any more would be dangerous to the fetus.
Too much vitamin A is toxic to the body and can even be fatal. You probably won't get toxic amounts of vitamin A from your daily diet, but taking vitamin A supplements without a health care provider's supervision is not recommended. Vitamin A is found in many different types of vitamin formulas. For example, supplements that say "wellness formula," "immune system formula," "cold formula," "eye health formula," "healthy skin formula," or "acne formula," all may contain vitamin A. If you take a variety of different formulas, you could put yourself at risk for vitamin A toxicity. Some of the symptoms of vitamin A toxicity are lasting headache, fatigue, muscle and joint pain, dry, cracking skin and lips, dry, irritated eyes, nausea or diarrhea, and hair loss.
Alcohol use makes vitamin A toxicity more likely. Consuming more than 25,000 IU of vitamin A per day (adults) and 10,000 IU per day (children) from either food or supplements or both can be toxic. Do not take vitamin A supplements if you are using Accutane, Retin-A or any vitamin Aderived drugs used to treat acne, psoriasis, and other skin problems.
The cholesterol-lowering medications cholestyramine and colestipol interfere with the absorption of vitamin A.
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