Also referred to as retinol, vitamin A was one of the first vitamins to be discovered and dates back to the early 1900s. Vitamin A is located in food from animal sources and it is also made synthetically. Vitamin A is vital for normal growth, enhances eyesight, promotes healthy reproduction, and wards off viral infections. There are many sources from which to get vitamin A.
Daily Allowance
Vitamin A is often measured in International Units, which appear on food and supplement labels. Vitamin A can also be measured in micrograms of retinol equivalents. A retinol equivalent is the same as 3.33 International Units. The National Academy of Sciences recommends that for infants up to 12 months, no more than 500 micrograms is needed for daily adequate intake levels. For males and females from 1 to 3 years old, 1,000 International Units daily of vitamin A is recommended. For males and females from 4 to 8 years old, it is recommended that they receive 1,333 International Units of vitamin A daily. For boys and girls between 9 and 13 years old, 2,000 International Units is the recommended dosage. For males 14 and up, 3,000 International Units is the recommended daily amount of vitamin A. For females 14 and up, 2,333 International Units of Vitamin A is required daily.
Fruits and Vegetables
Fruits and vegetables that possess 1,000 International Units or more of Vitamin A are considered to be high in Vitamin A. Fruits and vegetables that have more than 1,000 International Units include apricots, cantaloupes, carrots, collard greens, grapefruit, lettuce, mangoes, spinach, sweet potatoes, tomatoes and watermelon. Fruits and vegetables that possess 500 to 1,000 International Units of vitamin A are referred to as a good source of vitamin A. Fruits and vegetables that have less than 1,000 International Units of vitamin A include asparagus, celery, okra and dried plums. There are some tips to follow to get the most of vitamin A from fruits and vegetables. Select fruits and vegetables that are colorful and bright. When possible, eat fruits and vegetables raw, or slightly steam vegetables.
Animal Sources
Vitamin A that comes from animal sources is an excellent source of the nutrient. The two major sources of vitamin A from animal products include beef liver and turkey giblets. Other resources for this vitamin include chicken liver, fish oil, liverwurst, eggs, fish, butter, cheese and shellfish. The majority of skim milk, low-fat dairy products and powdered milk are usually fortified with the vitamin to remove fat.
Supplements
In most cases, people have no need to take a vitamin A supplement since they receive an adequate amount in their daily diet. A person who is healthy and follows a good diet stocks up enough vitamin A to last for months if they were suddenly denied of eating foods that possess vitamin A. The exceptions to this are people who do not eat well, suffer from a disease that creates malabsorption, or their body is not able to create bile needed to soak up vitamin A. Before adding a vitamin A supplement to your daily intake, check with your physician.
Health Risks
Too much vitamin A in the human body, referred to as hypervitaminosis. This can lead to toxic symptoms as the overflow of vitamin A is stored in the liver. There are four major harmful effects of hypervitaminosis. This includes birth defects, abnormalities in the liver, reduced bone mineral density that could develop into osteoporosis and central nervous system disorders. Toxic indicators can appear after digesting large doses of vitamin A over a small period of time. Symptoms of acute toxicity include nausea, fatigue, vomiting, migraines, blurriness and dizziness.
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