When you're trying to consume the appropriate dosage of vitamin A in your daily diet, it's important to get enough, but not too much. Vitamin A deficiencies are rare in the United States, according to the Office of Dietary Supplements, but are a major cause of blindness among malnourished children in developing countries. Americans who drink too much alcohol or abide by strict dietary restrictions can also be at risk of vitamin A deficiency.
Dosages
Vitamin A dosages are designated according to micrograms of Retinol Activity Equivalents, or mcg RAE. This form of measurement is used in order to compensate for variations in the biophysical activity of different forms of vitamin A. These forms include retinol, which is present in animal-based food sources, and provitamin A carotenoids that are found in fruits and vegetables.
Recommended Dietary Allowance
Your vitamin A needs grow as you do. When you're between the ages of 1 and 3, your recommended dietary allowance of vitamin A is 300 mcg RAE. From 4 to 8 years old, you should receive 400 mcg RAE daily. Nine to 13-year-olds require 600 mcg RAE per day. Males aged 14 and up need 900 mcg RAE daily, and women in that age group need 700. Pregnant women between 14 and 18 years old need 750 mcg RAE. Lactating women between the age of 14 and 18 require even larger doses, at 1,200 mcg RAE per day. Women older than 18 who are pregnant should take 770 mcg RAE per day. Lactating women older than 18 should take 1,300 mcg RAE daily.
Functions of Vitamin A
Vitamin A is crucial for the proper functioning of your eyes, according to the Linus Pauling Institute. It also helps cells differentiate into their various forms, becoming specialized skin, bone, muscle or nerve tissue. Vitamin A aids your immune system, supporting mucosal barrier cells that line your airways, digestive system and urinary tract to keep out harmful pathogens.
Deficiency
Vitamin A deficiency can occur due to inadequate dietary intake, fat malabsorption syndromes or liver disease, according to the Merck Manuals Online Medical Library. It commonly manifests in symptoms such as night blindness, dry scaly skin and impaired immunity.
Toxicity
It is important not to take high dosages of vitamin A, as it can be toxic. Symptoms of vitamin A toxicity include headache, nausea, vomiting and skin and hair changes. Vitamin A toxicity can lead to fetal birth defects. Do not exceed the recommended dosage of vitamin A.
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