Vitamin A is needed by the body for vision, bone health, immune function and cell differentiation. Retinol is the most usable and active form of vitamin A and is found primarily in foods from animals including liver, milk and cheese. Beta carotene is another form of vitamin A that is found in plant-based foods such as carrots, spinach and peaches. It is recommended that adults consume 700 to 900 micrograms of vitamin A, in the form of retinol, each day.
Vision
While vitamin A deficiency is considered to be rare in the United States, according to the National Institutes of Health Office of Dietary Supplements, approximately 250,000 to 500,000 children in the developing world become blind each year due to vitamin A deficiency. Night blindness is one of the first, noticeable, symptoms of vitamin A deficiency. This affects the ability of your eyes to adapt to changes in light. If not corrected, deficiency can worsen causing additional symptoms of dry eye, corneal ulcers, scarring of the eye and eventual total loss of vision.
Infection
Vitamin A deficiency can decrease the body's ability to fight off infections. According to the Linus Pauling Institute, vitamin A deficiency is a nutritionally acquired immunodeficiency disease. Being even mildly deficient in vitamin A can increase your chances of getting diseases and infections and decreases your body's ability to fight off diseases. Symptoms of vitamin A deficiency include more frequent and prolonged illness.
Zinc Deficiency
Zinc deficiency is often associated with vitamin A deficiency due to it's involvement in vitamin A transport. Zinc is needed to make retinol binding protein, which transports vitamin A throughout the body. Symptoms of deficiency include slowed growth, decreased appetite, hair loss, eye lesions and delayed wound healing.
Causes
Vitamin A deficiency is primarily caused by a lack of vitamin A intake from the diet. While deficiency is rare, it is more often seen in underdeveloped countries where food is not as readily available. Other causes for vitamin A deficiency include malabsorption from diseases such as celiac disease, Crohn's disease and pancreatic disorders. The pancreas secretes enzymes that are needed to break down fats. Because vitamin A is a fat-soluble vitamin, if the body is unable to break down fats, vitamin A cannot be absorbed.
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