Information About Vitamin A

Vitamin A belongs to a class of nutrients called fat-soluble vitamins, which require the presence of dietary fat in the intestinal tract in order to be properly absorbed. Your body has the ability to store excess amounts of vitamin A for use when your dietary intake falls short.

Forms of Vitamin A

The term vitamin A encompasses a family of substances called retinoids, which includes retinol, retinal and retinoic acid. Collectively, these substances are known as preformed vitamin A and are in a form that your body can easily use. Vitamin A is also available in foods as provitamin A carotenoids, which are converted to retinol in your body.

Functions

One of the most important functions of vitamin A is its role in vision. The light-sensitive protein rhodopsin in your retina uses vitamin A to absorb incoming light and translate it into a vision. Vitamin A also plays a role in cell differentiation, which is the process that determines what a cell becomes in your body. Because of this function, vitamin A plays an essential role in the development of the limbs, heart, eyes and ears of a fetus. Vitamin A also plays a role in skin health, and it ensures that the mucus lining in your lungs, kidneys and intestinal tract stays healthy. Vitamin A also allows your immune system to create white blood cells, which help fight off infection.

Daily Needs

Daily recommendations for vitamin A depend on age and sex. Infants between 0 and 6 months require 400 mcg per day, whereas infants from 7 to 12 months need 500 mcg per day. Children between 1 and 3 years should consume 300 mcg daily, and children between 4 and 8 need 400 mcg per day. Adolescents between 9 and 13 should consume 600 mcg daily. When a person reaches 14, vitamin A needs differ by sex. Male teenagers and adults need 900 mcg per day, whereas female teenagers and adults need 700 mcg daily.

Because vitamin A plays an essential role in fetal development, pregnant and breast-feeding women have increased needs. Pregnant women 18 and younger should consume 750 mcg per day, whereas pregnant women over 18 need 770 mcg daily. Breast-feeding women 18 and younger should consume 1,200 mcg per day, whereas breast-feeding women over 18 require 1,300 mcg.

Food Sources

The most popular sources of preformed vitamin A in the American diet include milk, cereals, cheese, halibut, eggs and organ meats. Carrots, spinach, pumpkin, broccoli, apricots, grapefruit, leafy green vegetables and sweet potatoes are popular sources of provitamin A carotenoids.