Vitamin A is a collective term used to describe a group of related nutrients vital to vision, normal cell and immune system function, reproduction and bone growth. Deficiencies of these nutrients rarely occur in the U.S. Still, doctors use several indicators to assess and monitor potential cases of deficiency.
Background
In developing countries, vitamin A deficiency is associated with malnourishment, according to the National Institutes of Health's Office of Dietary Supplements. Vitamin A deficiency in the U.S. most typically occurs in people who habitually drink excessive amounts of alcohol or follow unusually restricted diets that exclude common sources of the vitamin. The human body needs the mineral zinc to create a protein that transports vitamin A internally, and people with severe zinc deficiencies don't make enough of this protein to promote proper use of the body's vitamin A supply.
Vision-related Indicators
The earliest sign of a vitamin A deficiency is a visual inability to adapt to dark conditions, commonly called night blindness, Oregon State University's Linus Pauling Institute reports. If you have a mild deficiency, you may also develop foamy patches of skin cell debris in the corners of your eyes called Bitot's spots. If you have a severe or long-term vitamin A deficiency, you can develop a drying and thickening of the structures in your eye called xerophthalmia. In advanced cases of deficiency, you can develop haziness in your corneas or an erosion that leads to cornea disintegration.
Immune System Indicators
In term of its effects on the body, a vitamin A deficiency is the equivalent of an immune system disorder, the Linus Pauling Institute notes. Even a mild deficiency can increase a child's chances of developing diarrhea and respiratory disease. The same level of deficiency can also increase a child's chances of dying from an infectious disease like the measles. If a person with a vitamin A deficiency gets an infection, that infection will trigger a further rapid drop in his body's levels of the vitamin. In turn, this drop can trigger a vicious feedback loop, since lowered vitamin A levels increase infection risks.
At-risk U.S. Populations
The Office of Dietary Supplements lists several child populations that should be monitored for signs of vitamin A deficiency. They include all toddlers and preschoolers, children living in areas with known nutritional shortages, immigrants or refugees from countries where vitamin A deficiencies or the measles commonly occur, children living in poverty or near-poverty conditions, and children with inadequate access to immunization services or health care. Other at-risk children include those with poor fat digestion or absorption and those with diseases of the intestines, pancreas or liver.
In addition to those who drink too much alcohol or don't get enough zinc, adults at risk for vitamin A deficiency include those with insufficient intake of protein, iron or overall calories. Consult your doctor for more information on common indicators of a vitamin A deficiency.
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