• Regulate the immune system that makes white blood cells. These white blood cells prevent or fight off Infections caused by harmful bacteria and viruses. Vitamin A may also help lymphocytes, a type of infection-fighting white blood cell, function more effectively.
• Protect the surface linings of the eyes and the respiratory, urinary and intestinal tracts.
• Maintain the integrity of skin and mucous membranes that function as a barrier to bacteria and viruses.

Vitamin A occurs in a family of compounds including retinol, retinal and the carotenoids:

1) Retinol (also called preformed Vitamin A)

• One of the most active, usable forms of Vitamin A that can be converted to retinal and retinoic acid, other active forms of the Vitamin A family
• Found in animal foods such as liver, eggs, fish oils and some fortified food products

2) Vegetables (in the form of beta-carotene or proVitamin A)

The amazing transformation of Vitamin A occurs when vegetables are consumed

• Vegetables/plant foods do not contain Vitamin A; they contain darkly colored pigments called proVitamin A carotenoids (Beta-carotene is one popular type that is more efficiently converted to retinol than other carotenoids). To get Vitamin A, the body calls on its assistants (fat and bile) to help synthesize (transform) proVitamin A carotenoids to make Vitamin A appear in a usable form.

In the U.S., approximately 34% of Vitamin A consumed is provided by provitamin A caretenoids.

While Vitamin A deficiency rarely occurs in the United States, it is still a major public health problem in developing countries.

Vitamin A deficiencies can make healthy, normal body functions vanish.

• Night blindness is one of the first signs of Vitamin A deficiency. It's like trying to escape from a maze in the dark. In ancient Egypt, it was known that night blindness could be cured by eating liver, later found to be a rich source of Vitamin A.
• Overall blindness by making the cornea very dry and promoting damage to the retina and cornea.
• Vitamin A deficiencies could also handcuff the body's ability to fight infections.

In countries where immunization programs are not widespread and Vitamin A deficiency is common, millions of children die each year from complications of infectious diseases such as measles. Not enough Vitamin A cause cells lining the lungs to lose their ability to filter out disease-causing micro-organisms. This may contribute to the pneumonia associated with Vitamin A deficiency.

Also, Vitamin A deficiency can occur when Vitamin A is lost through chronic diarrhea and through an overall inadequate intake as is often seen with protein-calorie malnutrition.

• Increase children's risks of developing respiratory and diarrheal infections
• Decrease growth rate
• Slow bone development
• Decrease likelihood of survival from serious illness

Children living in the United States who are considered to be at increased risk for subclinical Vitamin A deficiency include:

• Toddlers and preschool age children
• Children living at or below the poverty level
• Children with inadequate health care or immunizations
• Children living in areas with known nutritional deficiencies
• Recent immigrants or refugees from developing countries with high incidence of Vitamin A deficiency or measles
• Children with diseases of the pancreas, liver, intestines, or with inadequate fat digestion/absorption